Search

2.1. Compilation of information about Kinorhyncha measurements A bibliographic search of taxonomic studies (descriptions of new taxa, redescriptions, et cetera) related to Kinorhyncha since the discovery of the phylum has been carried out. The keywords ‘Kinorhyncha’, ‘kinorhynch’ and ‘mud dragon’, followed by ‘measurement’, ‘measure’, ‘new species’ and ‘description’ were used in Google Scholar and the Web of Science™ for this survey. For each search, the title, material and methods, species description and morphometric tables of corresponding publications were screened to search for measurement definitions and details. The oldest publication that specified how to take a measurement was retained. All relevant papers were carefully consulted to extract all the information on Kinorhyncha measurements. Not all the information about the measurement uptake methods was included in these publications (e.g. preferred anatomical position to take trunk and segment lengths). Because of that, experts on the phylum, as well as attendees of the VI Scalidophora International Workshop (15–19th August, 2022; Helgoland, Germany) were consulted to compile this missing information., Published as part of González-Casarrubios, Alberto, Cepeda, Diego, Pardos, Fernando, Neuhaus, Birger, Yamasaki, Hiroshi, Herranz, María, Grzelak, Katarzyna, Maiorova, Anastassya, Adrianov, Andrey, Dal Zotto, Matteo, Di Domenico, Maikon, Landers, Stephen C. & Sánchez, Nuria, 2023, Towards a standardisation of morphological measurements in the phylum Kinorhyncha, pp. 217-223 in Zoologischer Anzeiger 302 on page 218, DOI: 10.1016/j.jcz.2022.11.015, http://zenodo.org/record/8164084

Leiocanthus quinquenudus sp. nov. Zoobank code: urn:lsid:zoobank.org:act: 72EC0153-2637-449D-A08D-BDB8E997C413 (Figs. 2���4) Synonymy Leiocanthus sp. 2 ���in Landers et al. 2020: p. 496, Table III. Leiocanthus sp. 2 ���in Hoffman et al. 2021: p.377, Table 4. Material examined. Holotype, adult female, collected on March 17, 2018 at St. 13-2018 in the northern Gulf of Mexico continental shelf: 30.1463�� N, 88.2583�� W (Table 1) at 18 m depth; mounted in Fluoromount G ��, deposited at the NHMD under catalogue number: NHMD-915196. Paratypes, three adult males and two adult females, all of them collected at different stations than the holotype (Table 1), mounted in Fluoromount G �� and stored at NHMD under catalogue numbers: NHMD-915197���915201. One additional female mounted for SEM and deposited in the personal reference collection of SCL. Diagnosis. Leiocanthus with middorsal cuticular elevations on segments 2���6. Unpaired paradorsal setae on segments 2, 4, 6 and 8; paired setae in laterodorsal position on segments 3, 5, 7 and 9, in lateroventral position on segments 2, 4, 6, 8 and 10 (two pairs in the latter), ventrolateral position on segment 5 and ventromedial position on segments 3���4 and 6���9 longitudinally aligned. Anterior margin of segment 1 tergal plate irregularly denticulated, posteriorly followed by a transverse band of minute, circular perforations. Males with sexually dimorphic ventromedial tubes on segment 2, females with ventrolateral setae instead. Lateral terminal spines present. Etymology. The specific epithet of the species derives from the Latin quinque (meaning five) and nudus (meaning naked), referring to the unique lack of ventromedial setae on segment 5 of the species. Description. See Table 2 for measurements and dimensions and Table 3 for summary of seta, spine, tube, glandular cell outlet and sensory spot positions. Head. Only one specimen, which was mounted for LM, had the head everted, hence exact details on the morphology and arrangement of the mouth cone and introvert structures cannot be completely provided. Internal rings of mouth cone not observed. Ring 00 of mouth cone with nine, equally sized outer oral styles, each one composed of a single, flexible unit, wider at the base, bearing a fringed basal sheath, progressively tapering towards a distally pointed tip. Outer oral styles located anterior to each introvert sector, except in the middorsal sector 6 where a style is missing. Introvert with six transverse rings of scalids and 10 longitudinal sectors defined by the position of the primary spinoscalids. Ring 01 of introvert with 10 primary spinoscalids; primary spinoscalids larger than scalids in remaining rings; each primary spinoscalid composed of a basal, rectangular, wide sheath and a distal, elongated, flexible, laterally compressed, distally rounded end-piece. Basal sheath of primary spinoscalids superficially fringed, bearing a rhomboid cuticular piece superficially fringed near the articulation point with the end-piece. Rings 02���06 of introvert with several regular-sized scalids, also composed of a basal, rectangular, superficially fringed, wide sheath and a distal, elongated, flexible, distally rounded end-piece. Exact arrangement of regular-sized scalids cannot be provided due to the collapsed condition of the only available introvert when mounted for LM. A ring of 14 trichoscalids posterior to the scalid rings, arranged as two in the odd-numbered sectors (except sector 1 with a single trichoscalid) and one in the even-numbered sectors of the introvert. TABLE 2. Measurements (in ��m) of six adult specimens of Leiocanthus quinquenudus sp. nov. (three females and three males) from the Gulf of Mexico. Abbreviations: LTS, lateral terminal spine length; MSW-5, maximum sternal width (measured at segment 5); n, number of measured specimens; S, segment length (followed by number of corresponding segment); SD, standard deviation; SSW, standard sternal width (measured at segment 10); TL, trunk length. Neck. Neck with four dorsal and two ventral sclerotized placids (Fig. 2A���B). Mesial dorsal placids subquadrangular, conspicuously higher than lateral ones (Fig. 2B), ca. 26���32 ��m wide at the base; lateral dorsal placids rectangular (Fig. 2B), ca. 20���23 ��m wide at the base. Mesial and lateral dorsal placids with saw-toothed anterior margin and longitudinal striation on the surface (Fig. 2B). Ventral placids even more rectangular, longitudinally compressed, with straight laterodistal margins (Fig. 2A), ca. 17���30 ��m wide at the base. Trunk. Trunk rectangular, stout, triangular in cross-section, composed of 11 segments (Figs. 2A���B, 3A, 4A). Segment 1 with one tergal, two episternal and one midsternal plates; remaining segments with one tergal and two sternal plates (Figs. 2A���D, 3A���J, 4A���H). Maximum sternal width at segment 5 (Table 2), almost constant in width throughout the trunk until segment 8, and progressively tapering along the last trunk segments (Figs. 2A���B, 3A, 4A). Sternal cuticular plates relatively narrow in relation to trunk length (MSW���5:TL interval ratio = 20.6���28.2%) (Table 2), giving the animal a relatively slender appearance (Figs. 2A���B, 3A, 4A). Segments 1���10 with rounded to slightly oval glandular cell outlets, each consisting of a single, round opening located in subdorsal and ventromedial positions, except ventral outlets of segment 1 shifting its position to ventrolateral (Figs. 2A���D, 3 B-J); intraspecific variation of this character was found in a single specimen that showed two round openings in some glandular outlets. Segments 2���10 with paired, small, not always conspicuous cuticular ridges in ventrolateral position, with adjacent, minute glandular cell outlets (Fig. 2A, C). Minute, acicular cuticular hairs widely covering the cuticular surface of segments 1���10, except in ventromedial position, denser at the tergosternal junctions (Fig. 4B���G). Muscular scars in laterodorsal and ventrolateral positions throughout segments 1���10 as rounded to oval, hairless cuticular areas, poorly conspicuous, even less visible on the sternal plates (Figs. 2A���C, 3B���J). Pachycycli and ball-and-socket joints well-developed and thick on segments 2���10 (Figs. 2A���D, 3A, F, H). Apodemes absent. Posterior margin of segments straight, with primary pectinate fringes showing weakly serrated free flaps (Figs. 2A���D, 3B���J, 4B���G). Secondary pectinate fringes as three (dorsal) to two (ventral) transverse rows, finely serrated, becoming slightly wavier at the sternal plates, extending posteriorly in triangular extensions in ventrolateral position (Figs. 2A���D, 3C, H, J). Segment 1 without middorsal process or elevation. Anterolateral margins of tergal plate as low, distally rounded protuberances (Figs. 2 A-B, 3A, 4A). Anterior margin of tergal plate irregularly denticulated, posteriorly followed by a transverse band of minute, circular perforations (Fig. 2B). Anterior margin of sternal plates with several semicircular ridges and a few, scattered, minute, circular depressions (Fig. 2A). Midsternal plate slightly wider at the posterior edge (Figs. 2A, 3A). Sensory spots in subdorsal (two pairs), laterodorsal (one pair), ventrolateral (two pairs longitudinally arranged) and ventromedial (one pair) positions (Figs. 2A���B, 3B). Sensory spots on this and remaining segments rounded to oval, with a single posterior pore surrounded by several rings of micropapillae. Segment 2 with middorsal elevation not projecting beyond the posterior margin of segment, with conspicuous paradorsal, butterfly-like atria of sensory spots (Figs. 2B, 3D). Unpaired seta in paradorsal position, and paired setae in lateroventral and ventrolateral positions, the latter only in females (sexually dimorphic) (Figs. 2A���C, 3C���E, 4B). Sensory spots in paradorsal, subdorsal, laterodorsal and ventromedial positions (Figs. 2A���C, 3C���E, 4B). Males with conspicuously large, sexually dimorphic tubes in ventromedial position (Figs. 2A, 3E). Segment 3 with middorsal elevation as on the preceding segment (Figs. 2B, 3D). Paired setae in laterodorsal and ventromedial positions (Figs. 2A���B, 3D, 4B). Sensory spots in paradorsal, subdorsal, laterodorsal and ventromedial positions, the latter more lateral than the ventromedial setae (Figs. 2A���B, 3D, 4B). Segment 4 with middorsal elevation as on the preceding segments (Fig. 2B). Unpaired seta in paradorsal position, and paired setae in lateroventral and ventromedial positions, the latter longitudinally aligned with those of segment 3 (Figs. 2A���B, 4F). Sensory spots in paradorsal, subdorsal, laterodorsal and ventromedial positions (Figs. 2A���B, 4F). Segment 5 with middorsal elevation as on the preceding segments (Fig. 2B). Paired setae in laterodorsal and ventrolateral positions (Figs. 2 A-���B, 3F, 4D, F). Sensory spots in paradorsal, subdorsal, laterodorsal and ventromedial positions (Figs. 2A���B, 3F, 4D, F). Segment 6 similar to segment 4 in the arrangement of cuticular elevation, setae and sensory spots (Figs. 2A���B, 3F, 4D, G). Segment 7 similar to segment 3 in the arrangement of setae and most sensory spots, but lacking the middorsal elevation and paradorsal sensory spots (Figs. 2A���B, 3H, 4C, G). Bilateral deviation was observed in two specimens, as the ventromedial seta was lacking on one of the sternal plates. Segment 8 without middorsal process or elevation. Unpaired seta in paradorsal position, and paired setae in lateroventral and ventromedial positions, the latter longitudinally aligned with those of the preceding segments (Figs. 2A���B, 3G���H, 4C). Sensory spots in subdorsal (two pairs), laterodorsal (one pair) and ventromedial (one pair) positions (Figs. 2A���B, 3G���H, 4C). Bilateral deviation was observed in two specimens, as the ventromedial seta was lacking on one of the sternal plates. Segment 9 without middorsal process or elevation. Paired setae in laterodorsal and ventromedial positions (Figs. 2A���B, 3G, J, 4E). Deviation was observed in a single male specimen, as the ventromedial pair of setae was absent. Sensory spots in subdorsal (two pairs), laterodorsal (one pair), ventrolateral (one pair) and ventromedial (one pair) positions (Figs. 2A���B, D, 3G, J, 4E). Nephridia externally opening as short cuticular tubes with fringed tips (Fig. 2A). Segment 10 without middorsal process or elevation. Two pairs of setae in lateroventral position (Figs. 2A���B, D, 4E). Sensory spots in subdorsal, laterodorsal, ventrolateral and ventromedial positions (Figs. 2A���B, 3I, 4E). Segment 11 with three pairs of type 3 sensory spots in subdorsal position (Fig. 2B). Males with two pairs of sexually dimorphic penile spines and genital pores (Figs. 2A, 3I). Lateral terminal spines (Figs. 2A���B, D, 3A, 4A) relatively long (LTS:TL interval = 19.7���33.0 %; LTS:TL mean = 27.2%; Table 2). Remarks. The specimen mounted for SEM carried several epibiontic Ciliophora on the sternal plates of segments 1 and 5 (Fig. 4A, H���I)., Published as part of Cepeda, Diego, S��nchez, Nuria, S��rensen, Martin V. & Landers, Stephen C., 2022, Leiocanthus quinquenudus sp. nov. and L. satanicus sp. nov., two new species of pycnophyid Kinorhyncha (Allomalorhagida: Pycnophyidae) from the Gulf of Mexico, pp. 315-336 in Zootaxa 5093 (3) on pages 319-323, DOI: 10.11646/zootaxa.5093.3.3, http://zenodo.org/record/5909853, {"references":["Landers, S., Bassham, R. D., Miller, J. M., Ingels, J., Sanchez, N. & Sorensen, M. V. (2020) Kinorhynch communities from Alabama coastal waters. Marine Biology Research, 16, 494 - 504. https: // doi. org / 10.1080 / 17451000.2020.1789660","Hoffman, K. P., Sanchez, N., Sorensen, M. V., Ingels, J. & Landers, S. C. (2021) Kinorhynch communities of Mobile Bay and the Alabama Continental Shelf. Cahiers de Biologie Marine, 62, 371 - 380. https: // doi. org / 10.21411 / CBM. A. B 0 EA 3 C 57"]}

Leiocanthus satanicus sp. nov. Zoobank code: urn:lsid:zoobank.org:act: 9B48A215-F9C4-4BE2-8D5A-D650133B133 (Figs. 5–8) Synonymy Pycnophyes sp. A —Landers et al. 2018: Table 2. Leiocanthus W —in Landers et al. 2019: p. 5. Material examined. Holotype, adult female, collected on November 12, 2013 at St. 68-2013 in the northern Gulf of Mexico continental shelf: 29.2998° N, 88.7200°W (Table 1) at 59 m depth; mounted in Fluoromount G ®, deposited at the NHMD under catalogue number: NHMD-915202. Paratypes, three adult males and six adult females, one of the females collected at the same station as the holotype, remaining specimens collected at different stations (Table 1), mounted in Fluoromount G ® and deposited at NHMD under catalogue numbers: NHMD-915203–915211. Two additional specimens, one male and one female, mounted for SEM and deposited in the personal reference collections of SCL and MVS. Diagnosis. Leiocanthus with middorsal cuticular elevations on segments 1–6. Unpaired paradorsal setae on segments 4 and 6; paired setae in subdorsal position on segments 2, 4, 6 and 8, in laterodorsal position on segments 3, 5, 7 and 9, paralateral position on segment 1, lateroventral position on segments 2, 4, 6, 8 and 10 (two pairs in the latter), ventrolateral position on segments 1 and 5, ventromedial position on segments 4–7 and 9, and paraventral position on segments 3 and 8. Males with sexually dimorphic ventromedial tubes on segment 2, females with setae instead. Lateral terminal spines absent, minute and bulbous protuberances instead. Anterolateral margins of the tergal plate of segment 1 extended into horn-like, medially recurved, distally pointed projections; anterior margin of tergal plate strongly denticulated, posteriorly followed by a crenulated area; cuticular wrinkles at the central region of the tergal plate. Etymology. The specific epithet of the species refers to the Latin name Satâna, derived from the Hebraic הַשָּׂטָן (ha-shatán), which is a negative entity of the Abrahamic religions that seduces humanity to commit sin. Satan has been traditionally represented in graphic and literary arts as a fallen angel with conspicuous horns, which resembles the recurved anterolateral margins of the segment 1 tergal plate of the new species. Description. See Table 4 for measurements and dimensions and Table 5 for summary of seta, tube, glandular cell outlet, and sensory spot positions. Head. Only two specimens had the head everted, hence exact details on the morphology and arrangement of the mouth cone and introvert structures cannot be completely provided. Internal rings of mouth cone not observed. Ring 00 of mouth cone with nine, equally sized outer oral styles, each one composed of a single, flexible unit, wider at the base, bearing a fringed basal sheath, with a lateral incision about one third from the proximal end, progressively tapering towards a distally rounded tip (Fig. 6C). Outer oral styles located anterior to each introvert sector, except in the middorsal sector 6 where a style is missing. Introvert with six transverse rings of scalids and 10 longitudinal sectors defined by the position of the primary spinoscalids. Ring 01 with 10 primary spinoscalids, larger than the remaining ones, each one composed of a basal, rectangular, wide sheath and a distal, elongated, flexible, laterally compressed, distally rounded end-piece (Fig. 6D, F). Basal sheath of primary spinoscalids superficially fringed, bearing a rhomboid cuticular piece superficially fringed near the articulation point with the end-piece (Fig. 6D inset, F). Rings 02–06 with several regular-sized scalids, conspicuously smaller than the primary spinoscalids, also composed of a basal, rectangular, superficially fringed, wide sheath and a distal, elongated, flexible, distally rounded end–piece (Fig. 6F). Exact arrangement of regular-sized scalids cannot be provided due to the collapsed condition of the only available introverts. Despite this, the odd-numbered sectors seem to possess seven regular-sized scalids arranged as a double diamond (Fig. 6F). A ring of 14 trichoscalids posterior to the scalid rings (Fig. 6E), arranged as two in the odd-numbered sectors (except sector 1 with a single trichoscalid) and one in the even-numbered sectors of the introvert. Neck. Neck with four dorsal and two ventral sclerotized placids (Figs. 5A–B, 6G–H). Mesial dorsal placids sub-quadrangular, conspicuously higher than lateral ones (Figs. 5B, 6G), ca. 33–41 μm wide at the base; lateral dorsal placids rectangular (Figs. 5B, 6G), ca. 23–26 μm wide at the base. Ventral placids even more rectangular, longitudinally compressed, with the posterolateral margins straight to slightly curved towards the sternal plates of the first trunk segment (Figs. 5A, 6H), ca. 21–30 μm wide at the base. Trunk. Trunk rectangular, stout, triangular in cross–section, composed of 11 segments (Figs. 5A–B, 6A–B, 8A). Segment 1 with one tergal, two episternal, and one midsternal plates; remaining segments with one tergal and two sternal plates (Figs. 5A–D, 6A–B, 7A–K, 8A–F). Maximum sternal width at segment 3 (Table 4), almost constant in width throughout the trunk until segment 3, and progressively tapering along the last trunk segments (Figs. 5A–B, 6A–B, 8A). Sternal cuticular plates relatively narrow in relation to trunk length (MSW–3:TL interval ratio = 21.8–26.8) (Table 4), giving the animal a relatively slender appearance (Figs. 5A–B, 6A–B, 8A). Segments 1–11 with glandular cell outlets with a single round to oval opening: segments 1 and 9–10 with these glandular cell outlets in subdorsal and ventromedial positions, segments 2–8 in subdorsal and paraventral positions, and segment 11 in subdorsal position (Figs. 5A–D, 7A–J); intraspecific variation of this character was found in a couple of specimens that showed up to three round openings per glandular outlet (Fig. 7D); in addition, in some specimens the bilateral pattern was lost as the glandular cell outlet was missing in one side of some tergal plates. Segments 2–10 with paired, small, not always conspicuous cuticular ridges in ventrolateral position, with adjacent, minute glandular cell outlets (Fig. 5A–D). Minute, acicular cuticular hairs, widely covering the cuticular surface of segments 1–10 (except the most anterior halves of the episternal plates of segment 1 where hairs are absent), denser at the tergosternal junctions (Fig. 8B–F). Males with sexually dimorphic longitudinal bands of cuticle densely covered by smaller acicular hairs in ventromedial position of segment 2, under the tubes (Fig. 8C). Very conspicuous, rounded to oval muscular scars without hair-covering in laterodorsal and ventromedial positions (Figs. 5A–D, 7A–J). Pachycycli and ball-andsocket joints well-developed and thick on segments 2–10 (Figs. 5A–D, 7A–H). Apodemes absent. Posterior margin of segments straight, with primary pectinate fringes showing weakly serrated free flaps (Figs. 5A–D, 7A–H, 8A–F). Secondary pectinate fringes as three (dorsal) to two (ventral) transverse rows, finely serrated, becoming wavier at the sternal plates, extending posteriorly in triangular extensions near the location of the muscular scars (Figs. 5A–D, 8C, E, F). Segment 1 with middorsal elevation not projecting beyond the posterior margin of segment, with conspicuous paradorsal, butterfly-like atria of sensory spots (Figs. 5B, 7A). Anterolateral margins of the tergal plate forming conspicuous horn-like, medially recurved, distally pointed projections (Figs. 5A–B, 6A–B, I, 8A–B). Anterior margin of tergal plate strongly denticulated, posteriorly followed by a crenulated area (Figs. 5B, 6K). Anterior margins of sternal plates with several, small, cuticular depressions and some semi-circular ridges (Figs. 5A, 6H). Characteristic cuticular wrinkles at the central region of the tergal plate in subdorsal towards laterodorsal position (Figs. 5B, 6K). Midsternal plate almost rectangular, not extended at its base, with a small lateral indentation near its anterior margin, and a straight posterior margin (Figs. 5A, 6B, 8A). Paired setae in paralateral and ventrolateral positions (Figs. 5A–B, 7A, 8B). Sensory spots in paradorsal (one pair), subdorsal (two pairs, longitudinally aligned), laterodorsal (one pair), paralateral (one pair), ventrolateral (one pair) and ventromedial (one pair) positions (Figs. 5A–B, 7A, 8B). Sensory spots on this and remaining segments oval, with up to three pores surrounded by several rings of micropapillae. Segment 2 with middorsal elevation as on the preceding segment (Figs. 5B, 7D). Paired setae in subdorsal and lateroventral positions; subdorsal setae more mesial than subdorsal sensory spots; ventromedial setae only in females (sexually dimorphic) and located more lateral than the ventromedial sensory spots (Figs. 5 A-C, 7B, D). Sensory spots in paradorsal (one pair), subdorsal (two pairs), laterodorsal (one pair) and ventromedial (one pair) positions (Figs. 5A–C, 7B, D, 8C). Males with conspicuously large, sexually dimorphic tubes in ventromedial position (Figs. 5A, 8C). Segment 3 with middorsal elevation as on the preceding segments (Figs. 5B, 7D). Paired setae in laterodorsal and paraventral positions (Figs. 5A–B, 7C–D, 8C). Sensory spots in paradorsal (one pair), subdorsal (two pairs), laterodorsal (one pair) and ventromedial (one pair) positions (Figs. 5A–B, 7C–D, 8C). Intraspecific variation in the arrangement of the laterodorsal setae has been observed in two specimens, where these structures were laterally displaced, still in laterodorsal position but more lateral than the laterodorsal sensory spots. Segment 4 with middorsal elevation as on the preceding segments (Fig. 5B). Unpaired seta in paradorsal position, and paired setae in subdorsal, lateroventral and ventromedial positions; subdorsal setae flanked by the two pairs of subdorsal sensory spots, ventromedial setae more mesial than those of female segment 2 (Figs. 5A–B, 7C, 8D). Sensory spots in paradorsal (one pair), subdorsal (two pairs), laterodorsal (one pair) and ventromedial (one pair) positions (Figs. 5A–B, 7C, 8D). Segment 5 with middorsal elevation as on the preceding segments (Figs. 5B, 7F). Paired setae in laterodorsal, ventrolateral and ventromedial positions; ventromedial setae more lateral than those of segment 4 (not aligned longitudinally) (Figs. 5A–B, 7E–F, 8D). Sensory spots in paradorsal (one pair), subdorsal (two pairs), laterodorsal (one pair) and ventromedial (one pair) positions (Figs. 5A–B, 7E–F, 8D); the latter pair aligned with that of segment 3. Intraspecific variation in the arrangement of the laterodorsal setae has been observed in a single specimen, where these structures were laterally displaced, still in laterodorsal position but more lateral than the laterodorsal sensory spots. Segment 6 with middorsal elevation as on the preceding segments (Figs. 5B, 7H). Unpaired seta in paradorsal position, and paired setae in subdorsal, lateroventral and ventromedial positions (the former flanked by the subdorsal sensory spots, the latter longitudinally aligned with those of segment 4) (Figs. 5A–B, 7H); deviations from the bilateral symmetry in the position of the ventromedial setae has been observed in a single specimen that had one seta mesially displaced, though still in ventromedial position. Sensory spots in paradorsal (one pair), subdorsal (two pairs), laterodorsal (one pair) and ventromedial (one pair) positions (Figs. 5A–B, 7H); the latter pair aligned with that of segment 4. Segment 7 without middorsal process or elevation. Paired setae in laterodorsal and ventromedial positions, the laterodorsal ones more lateral than the laterodorsal sensory spots, and the ventromedial ones aligned with those of segment 5 and female segment 2 (Figs. 5A–B, 7H). Sensory spots in subdorsal (two pairs), laterodorsal (one pair) and ventromedial (one pair) positions (Figs. 5A–B, 7H); the latter pair aligned with that of segment 3. Intraspecific variation in the arrangement of the laterodorsal setae has been observed in a single specimen, where these structures were mesially displaced, still in laterodorsal position but more mesial than the laterodorsal sensory spots. Segment 8 without middorsal process or elevation. Paired setae in subdorsal, lateroventral and paraventral positions; the former flanked by the subdorsal sensory spots (Figs. 5A–B, 7G, 8E). Deviations from the bilateral pattern in the arrangement of the paraventral setae has been observed in a single specimen, which had the left sternal plate with the seta in ventromedial instead of paraventral position. Sensory spots in subdorsal (three pairs), laterodorsal (one pair) and ventromedial (one pair) positions (Figs. 5A–B, 7G, 8E); the latter pair aligned with that of the preceding segment. Segment 9 without middorsal process or elevation. Paired setae in laterodorsal and ventromedial position; the latter longitudinally aligned with those of segments 5 and 7 (Figs. 5A–B, 7I–J, 8E). Sensory spots in subdorsal (three pairs), laterodorsal (one pair), ventrolateral (one pair) and ventromedial positions (Figs. 5A–B, 7I–J, 8E, H). Nephridia externally opening as short cuticular tubes with fringed tips (Fig. 5A). Segment 10 without middorsal process or elevation. Tergal plates with elongated, dagger-like projections at midlateral posterior margins (Figs. 5A–B, D, 6A–B, J, 8A, F). Two pairs of setae in lateroventral position (Figs. 5A–B, D, 8F). One pair of sensory spots in subdorsal, laterodorsal, ventrolateral and ventromedial positions (Figs. 5A–B, D, 8F). Segment 11 with one pair of type 3 sensory spots in subdorsal position (Figs. 5B, 7K). Males with two pairs of sexually dimorphic penile spines and genital pores (Figs. 5A, 8F). Lateral terminal spines absent; minute, rectangular, distally rounded, bulbous protuberances emerge between tergal and sternal plates, in males superficially covered by hairs (Figs. 5A, D, 7K).

This study analyzed kinorhynch communities from the southern portion of Mobile Bay and the nearshore Alabama continental shelf. A multicorer was used to collect sediment samples from fourteen sites, specifically targeting the flow of freshwater efflux from the Mobile watershed. These sediment samples were analyzed for kinorhynch species, organic matter content, granulometry and trace metals. Kinorhynch specimens were examined via light microscopy and scanning electron microscopy and identified to species level for community analysis. Eleven species of kinorhynchs were recovered from thirteen sites. Four dominant species, Echinoderes augustae, E. bookhouti, E. spinifurca, and Leiocanthus langi were present, in agreement with an earlier survey of Alabama coastal kinorhynchs. Spearman correlations, PCA, and cluster analyses of kinorhynch communities, along with abiotic data, revealed a patchy distribution of kinorhynchs, organic matter and fine sediments in the path of freshwater efflux. Additionally, this study reports four new species records for the northern Gulf of Mexico. R��sum�� : Les communaut��s de Kinorynches de la baie de Mobile et du plateau continental de l'Alabama. Dans cette ��tude, nous avons analys�� les communaut��s de kinorhynches de la partie sud de la baie de Mobile et du plateau continental le long de la c��te de l'Alabama. Un carottier multitube a ��t�� utilis�� pour r��colter des ��chantillons de s��diments de quatorze sites, ciblant sp��cifiquement les ��coulements d'eau douce du bassin versant de Mobile. Ces ��chantillons de s��diment ont ��t�� analys��s pour les kinorhynches, la teneur en mati��re organique, la granulom��trie et les concentrations en m��taux traces L'identification des esp��ces de kinorhynches a ��t�� r��alis��e �� partir d'observations au microscope optique et au microscope ��lectronique �� balayage et a servi de base �� une analyse de la communaut��. Onze esp��ces de kinorhynches ont ��t�� r��colt��es sur treize sites. En accord avec une ��tude ant��rieure des kinorhynches c��tiers de l'Alabama, quatre esp��ces

Paracentrophyes sp. (Figs 7–8) Besides P. sanchezae n. sp., samples from the Gulf of Mexico revealed four female specimens of one additional, yet undescribed species of Paracentrophyes. Three specimens were mounted for SEM, whereas the last one, which unfortunately was not in a good condition, was mounted for LM (Fig. 7). Due to the restricted amount of material, especially for LM, we chose not to make a formal description of the species. We will, however, provide a short diagnostic account, which hopefully will enable researchers to recognize the species if additional specimens are collected in the future. Material. One female specimen, adult or late juvenile stage, collected from mud on November 5, 2009, at station 099-2009 (Fig. 1), at 129 m depth on the Florida Shelf, about 136 km south of Cape San Blas, Florida (position: 28o26’30’’N 085o11’27’’W) mounted in Fluoromount G, deposited at the Natural History Museum of Denmark, under catalogue number ZMUC KIN- 1016. In addition, three female specimens, mounted for SEM and stored in the authors’ personal collections. The first specimen was collected on November 1, 2007, at station 094- 2007 (Fig. 1), at 113 m depth about 125 km southeast of Pensacola, FL, (position: 29o33’56’’N 086o17’34’’W), whereas the two other specimens were collected on November 15, 2013, at station 78-2013 (Fig. 1), at 142 m depth in the innermost extension of the submarine De Soto Canyon, 70 km southeast of Pensacola, Florida (position: 29o53’08’’N 086o47’31’’W). Diagnostic account. Head and mouth cone structures could not be studied in detail. It is however clear that outer oral styles alternate in size between larger and smaller ones. Segment 1 consists of a tergal and a sternal plate; sternal plate partly differentiated in epi- and midsternal plates (Fig. 7 B). Segments 2 to 11 consist of one tergal and two sternal plates (Figs 7 A, D, 8A). Trunk length = 600 µm. Segment 1 almost smooth near anterior margin, and without reticulated areas (Figs. 7 B, 8B). Middorsal spinose processes are present on segments 1 to 9, and midlateral processes on segments 1 to 10. Segments 10 and 11 with middorsal spines, and segment 11 with lateral terminal spines (Figs. 7 C–D, 8F, H). Spines are generally very short, i.e., middorsal spine segment 10 = 17 µm (MDS10/TL ratio 2,8%), middorsal spine segment 11 = 24 µm (MDS11/TL ratio 4,0%) and lateral terminal spines = 30 µm (LTS ratio 5,0%). Perispinal setae are found on a few segments only: ventrolateral positions on segment 1; unpaired paradorsal and paired ventrolateral on segment 5 (Fig. 8 C); unpaired paradorsal on segment 7 (Fig. 8 D); paired paralateral on segment 8 (Fig. 8 D); unpaired paradorsal and paired ventrolateral on segment 9 (Fig. 8 D). One specimen mounted for SEM carried several unidentified loricate, epibionts (Fig. 8 C, F–G). Remarks on diagnostic characters. The species is easily recognized by its very low number of perispinal setae, and by its very short spines. The middorsal processes/spines of segments 10 and 11 in female specimens of Paracentrophyes are usually short, but still, they are even shorter in Paracentrophyes sp. from the Gulf of Mexico (Figs 7 A, C–D, 8A, F, H). The difference in dimensions gets most conspicuous in the lateral terminal spines though, where the LTS/TL ratios for P. quadridentatus, P. praedictus and P. sanchezae n. sp. are around 25–27%. In P. anurus the ratio is considerably smaller, i.e., 9.7%, but in Paracentrophyes sp. from the Gulf of Mexico we find even shorter lateral terminal spines, with an LTS/TL ratio of only 5.0%. Hence, this yet undescribed species is currently the Paracentrophyes with the shortest terminal spines. Also the distribution of perispinal setae, and in particular the general scarcity of them, makes it easy to recognize the species. As noted above under diagnostic traits for P. sanchezae n. sp., the other three species of the genus are generally rich in setae, with continuous series of paired setae in paradorsal, paralateral and ventromedial positions from segment 1 to segment 9 or 10. The number of setae in P. sanchezae n. sp. is considerably lower, but Paracentrophyes sp. from the Gulf of Mexico has even fewer setae, and differs from P. sanchezae n. sp. by lacking perispinal setae in paralateral positions on segments 6 and 7, and in ventrolateral positions on segments 3 and 10. Based on these traits, we believe it would be easy to recognize the new species in future samples.

Paracentrophyes sanchezae n. sp. (Figs 2–5; Tabs 1–2) zoobank.org code: urn:lsid:zoobank.org:pub:C8299651-B344-4287-82F9-061C100F70BF Material. Holotype, adult female, collected from mud on November 2, 2014, at station 001-2014 (Fig. 1), at 57 m depth on the continental shelf, south of the Louisiana coast line, and west of the submarine Mississippi Canyon (position: 28o25’48.71’’N, 090o14’10.31’’W), mounted in Fluoromount G, deposited at the Natural History Museum of Denmark, under catalogue number ZMUC KIN- 1014. Paratypic material mounted for LM includes a single adult male, collected from mud on October 20, 2009, at station 031-2009 (Fig. 1), at 54 m depth about 170 km straight south of the Louisiana – Texas state border (position: 28o12’59.76’’N, 093o24’19.08’’W), mounted in Fluoromount G, deposited at the Natural History Museum of Denmark, under catalogue number ZMUC KIN- 1015. Additional paratypes include two males, collected from mud on November 15, 2013, at stations 078-2013 and 079- 2013 (Fig. 1). Station 078-2013 is located at 142 m depth (position: 29o53’07.72’’N, 086o47’31.20’’W), and Station 079-2013 at 125 m depth (position: 29o48’20.77’’N, 086o36’02.37’’W). Both stations are located near each other, south of the Florida panhandle in the northeastern extension of the submarine De Soto Canyon. The specimens are mounted for SEM and deposited at the Natural History Museum of Denmark, under catalogue numbers ZMUC KIN- 1081 and KIN- 1082. Diagnosis. Segments 1 and 11 composed of one tergal and one sternal plate; sternal plate of segment 1 partially differentiated into episternal and midsternal plates. Segments 2 to 10 composed of one tergal and two sternal plates. Middorsal and midlateral spinose processes present on segments 1 to 9 in both sexes; females also with middorsal and midlateral spinose processes on segment 10, and middorsal spine on segment 11; males with flexible middorsal and midlateral spines on segment 10, and midlateral penile spines on segments 10 and 11. Outer oral styles alternating in size between larger and smaller ones; large outer oral spines with 18 basal fringe tips; small outer oral spines with 10 basal fringe tips. Perispinal setae present as unpaired ones in paradorsal position on segments 5 and 9 (occasionally 7), paired ones in paralateral positions on segments 6 to 9 (occasionally 4), and paired ones in ventrolateral positions on segments 1, 3, 5 and 9 (occasionally unpaired on 7 and 8). Etymology. The species is named after Dr Nuria Sánchez in recognition of her contributions to pycnophyid and neocentrophyid taxonomy and systematics. Description. Adults with head, neck and eleven trunk segments (Figs 2, 4 A–B, 5A–B). For complete overview of measures and dimensions, see Table 1. The distribution of cuticular structures, i.e., sensory spots, processes and spines is summarized in Table 2. The head is formed by a retractable mouth cone and an introvert (Figs 3, 5 C–D). The pharynx carries at least two rings of inner oral styles, of which the styles in one ring form elongated helioscalids. It was not possible to determine the exact number or arrangement of inner oral styles. The external mouth cone armature consists of nine outer oral styles, arranged as one style anterior to each introvert sector, except for the middorsal sector 6 (Fig. 3). The outer oral styles alternate in size: larger styles are composed of two joined units, and carry a basal fringe consisting of ca. 18 fringe tips; smaller styles are shorter, thinner, more flexible and consist of a single unit, with a basal fringe consisting of ca. 10 fringe tips (Fig. 5 C). Large outer oral styles are located anterior to introvert sectors 1, 3, 5, 7 and 9, whereas smaller styles are located anterior to sectors 2, 4, 8, and 10 (Fig. 3). The exact appearance and arrangement of scalids on the introvert could only be examined for introvert sectors 1 to 6 plus 10. However, due to the usual symmetry patterns, we would expect the arrangements in sectors 7 to 9 to be identical with those in sectors 5 to 3. The introvert sectors are defined by ten primary spinoscalids in Ring 01 (Figs 3, 5 D). Each primary spinoscalid consists of a basal sheath and a flexible, distal end piece with a blunt tip. The basal sheaths have long, marginal extensions that form transverse fringes, whereas the end pieces have tiny hairs on their proximal halves, and a smooth surface more distally (Fig. 5 D). Spinoscalids of Rings 02 to 06 also consist of a sheath and an end piece. These sheaths also show a marginal fringe, but the fringe tips are considerably shorter than those on the primary spinoscalids. In addition, each sheath shows an elongate row of small structures that either appear as minute denticles (mostly Ring 02), or short hairs (mostly Rings 03 to 06) (Fig. 5 D). Rings 02 and 04 each have 10 spinoscalids, and Rings 03 and 5 have 20, meaning that the spinoscalids of these rings form a quincunx in each sector. Even numbered sectors have no spinoscalids posterior to Ring 05, whereas odd numbered sectors show a single spinoscalid in Ring 06 (Fig. 3). The neck has seven placids, arranged as four dorsal ones and three ventral (Figs 2 A–B, 3). Fourteen trichoscalids are present, located as single ones in sectors 1, 2, 4, 6, 8 and 10, and two in sectors 2, 5, 7 and 9 (Fig. 3). The positions of the trichoscalids do not follow the patterns of the spinoscalids. Trichoscalids are rather slender, consisting of a single unit, densely covered with small hairs. The first trunk segment consists of one tergal and one sternal plate; sternal plate with intracuticular lines, indicating a partial division into one midsternal and two episternal plates (Figs 2 A–B, 4C-D, 5F–G). Segments 2 to 10 consist of one tergal and two sternal plates, and segment 11 of one tergal and one sternal plate (Figs 2 A–B, 4A– B, J–L, 5A–B, I–K). Sternal plates are flattened, while tergal plates are vaulted, giving the specimens a triangular appearance in cross-sections. Segment widths are nearly constant from segments 3 to 8, which gives the specimens a parallel sided and rectangular appearance (Figs 2 A–B, 4A–B, 5A). Segments 1 to 10 in females and 1 to 9 in males with spinose middorsal and midlateral processes (Figs 2 A–B, 4C–F). Middorsal spinose processes with nearly smooth surface, and pointed rigid tip, projecting slightly beyond segment margin. Midlateral processes with minute hairs, and more flexible tips, projecting well beyond segment margin. A minute paralateral pore, probably a glandular cell outlet, is present next to each midlateral process (Fig. 4 E, G). Spinose processes are progressively longer towards the posterior part of the trunk. Markings of muscle attachment sides (muscle scars) are present as small, oval areas in laterodorsal positions on segments 1 to 10, and in paraventral positions on segments 2 to 10 (Figs 2 A–B). Ventral muscle scars on segment 1 are larger, much more elongate, and located in ventromedial positions. On segment 11, muscle scars are small and rounded, and were observed in ventromedial positions only. All segments, from segment 1 to 10, are generally covered with minute, triangular, scale-like hairs, except on the processes, and around sensory spots and muscle scars. Anterior segment parts with reticulated ornamentation. Free flaps posteriorly on segments with striated substructure, and scale-like hairs that appear slightly more elongate. Pectinate fringes on segment margins not present. Segment 1 with anterolateral margins of tergal plate projecting into horn-like extensions (Figs 2 A–B, 4D). Anterior segment margins are denticulated (Fig. 4 C–D). Sensory spots on this and all following segment belong to type 1 (but see exceptions on segment 11 though), consisting of a single pore and numerous minute papillae, forming elevated and slightly oval papillated areas. Tergal plate without setae, but with six pairs of sensory spots: two pairs are located in a subdorsal position on the anterior segment half, close to the paradorsal areas; two pairs in a laterodorsal position, but very close to the subdorsal area; and two pairs are also laterodorsal, but located close to the paralateral line (Figs 2 A, 5G). Sternal plate with one pair of ventrolateral setae, slightly behind the transverse midline of the segment (Figs 2 B, 4D, 5F), and in addition with three pairs of ventromedial sensory spots: One pair is located anteriorly on the plate, near the ventrolateral area; one pair is more medial on the incompletely differentiated episternal plates, at the same level as the setae; and one pair is more anterior, and located within the limits of the incompletely differentiated midsternal plate (Figs 2 B, 5F). Segment 2: tergal plate with three pairs of sensory spots in subdorsal positions, and two pairs in laterodorsal positions (Fig. 2 A). Sternal plates with two sensory spots in ventromedial positions (Fig. 2 B). Segment 3: tergal plate with three pairs of sensory spots in subdorsal positions, and one pair in laterodorsal positions (Fig. 2 A). Sternal plates with ventrolateral setae and two sensory spots in ventromedial positions (Fig. 2 B). Segment 4 with tergal plate as on segment 3; one male specimen and female holotype with setae in paralateral positions (Fig. 4 E), but this was not observed in other specimens. Sternal plates as on segment 2. Segment 5: tergal plate with a single, unpaired paradorsal seta, two pairs of sensory spots in subdorsal positions, and one pair in laterodorsal positions. Sternal plates with ventrolateral setae (Fig. 4 F) and single sensory spots in ventromedial positions. Segment 6: tergal plate with paralateral setae, three pairs of sensory spots in subdorsal positions, and one pair in laterodorsal positions. Sternal plates as on segments 2 and 4. Segment 7: tergal plate with paralateral setae, two pairs of sensory spots in subdorsal positions, and one pair in laterodorsal positions; one male specimen furthermore with single, unpaired paradorsal seta (Fig. 5 H). Sternal plates as on segments 2, 4 and 6; furthermore, one male specimen (not the same as the one with paradorsal seta) with a single ventrolateral seta on the right sternal plate only. Segment 8 with tergal plate as on segment 6, and sternal plates as on segment 7, except for the single ventrolateral seta that now appears on the left sternal plate only. Segment 9: tergal plate with a single, unpaired paradorsal seta, paired paralateral setae, three pairs of sensory spots in subdorsal positions, and one pair in laterodorsal positions. Sternal plates with ventrolateral setae and two sensory spots in ventromedial positions. Segment 10 with middorsal and midlateral spinose processes present in females only (Fig. 2 A–B); males with flexible middorsal spine and flexible (penile) midlateral spines (Figs 2 C–D, 4I, 5I –K). Tergal plate with two pairs of sensory spots in subdorsal positions, and one pair in laterodorsal positions. Sternal plates with ventrolateral setae, one sensory spot in ventrolateral positions, and one sensory spot in ventromedial positions (Figs 2, 5 I –J). Segment 11 with middorsal spine in both sexes; female middorsal spine acicular and rigid (Figs 2 A, 4H); male middorsal spine flexible as on preceding segment (Figs 2 C, 4I, 5J–K). Males also with flexible (penile) spines in midlateral positions; females without any midlateral structures, neither spines nor processes. Females furthermore with short midterminal process (Fig. 4 J); such a process is not present in males, but SEM images reveal the presence of a very minute, somehow papillated (sensory?) structure that appears from the midventral margin of the sternal plate (Fig. 5 E). Both sexes with long lateral terminal spines (Figs 2, 4 A–B). Tergal plate with one pair of subdorsal sensory spots type 3, protruding from the posterior margin of the plate (Figs 4 I, 5J). Sternal plate with one pair of regular ventromedial sensory spots type 1, located near the posterior segment margin, and in addition, one pair of ventromedial sensory spots type 3, protruding from the posterior margin of the plate (Figs 4 J, L, 5I). Remarks on diagnostic characters. The new species can only be confused with Mixtophyes abyssalis and other species of Paracentrophyes (see Discussion for further considerations regarding the generic assignment of the new species). Females of P. sanchezae n. sp. are most easily distinguished from females of other congeners by their short, midterminal process (Fig. 4 J) which is shared with P. quadridentatus only (Sørensen et al. 2010). Other differential characters that are detectable in both sexes regard the fringes of the outer oral styles, and position of setae on the trunk segments. Differences in number of fringe tips at the bases of the large and small outer oral styles (oos) were first reported by Sørensen et al. (2010). According to this study, the following numbers of fringe tips were observed in the three known species of Paracentrophyes: P. anurus: large oos: 5–7 tips, small oos: 10–12 tips; P. quadridentatus: large oos: 9 tips, small oos: 7 tips; P. praedictus: large oos: 12 tips, small oos: 8 tips. P. sanchezae n. sp. appears to have more fringe tips, with 10 tips on the small oos, equivalent to P. anurus only, and 18 tips on the large oos, which is nearly twice as many as in the congeners. The use of outer oral style fringes as diagnostic character should of course be used with some caution, until the intraspecific consistency of the character has been confirmed from more specimens. Also in regard to distribution of perispinal setae, P. sanchezae n. sp. is very easily distinguished from its congeners, which all generally are much richer in setae. P. anurus and P. praedictus both have paired perispinal setae in paradorsal, paralateral and ventrolateral positions on segments 1 to 9 (Higgins 1983; Sørensen et al. 2010), whereas P. quadridentatus has setae in these positions as well and on segment 10 (Sørensen et al. 2010). Oppositely, paradorsal setae in P. sanchezae n. sp. are unpaired, and restricted to segments 5 and 9 (plus segment 7 in one specimen), paralateral setae are present on segments 6 to 9 only (plus segment 4 in one specimen), and paired ventrolateral setae are restricted to segments 1, 3, 5 and 9 (plus appearing unpaired on segments 7 and 8 in one specimen). Despite its generic assignment, P. sanchezae n. sp. also shows some resemblance to M. abyssalis. However, the two species can first of all be distinguished by the generic difference that separates Paracentrophyes and Mixtophyes, namely the presence of partially developed epi- and midsternal plates on segment 1, present in species of Paracentrophyes only (Fig. 6 A–E, G, I). To confuse things slightly, reexamination of a specimen of M. abyssalis mounted for SEM actually revealed ventral markings on segment 1 (Fig. 6 H) that could indicate a partial differentiation of the sternal plate. However, these markings are more probably due to a strong contraction of the dorso-ventral muscles of the segment. This explanation is supported by the fact that light microscope images show absolutely no traces of intracuticular lines or other indications of a partial differentiation (Fig. 6 F). M. abyssalis furthermore have a longer female middorsal spine on segment 11 (MDS11/TL ratio 17% in M. abyssalis vs. 7% in P. sanchezae n. sp.). In addition, M. abyssalis has no midterminal processes (Sánchez et al. 2014). Regarding the distribution of paradorsal, paralateral, and ventrolateral setae, P. sanchezae n. sp. is actually closer to M. abyssalis than it is to its congeners, but some differences are found also. In M. abyssalis unpaired paradorsal setae are found on segments 7 and 9, opposed to 5 and 9 in P. sanchezae n. sp.; paralateral setae in M. abyssalis are present on segments 2 and 7–9, opposed to 6 to 9 in P. sanchezae n. sp., and ventrolateral setae in M. abyssalis on segments 1 (males only) 5 and 9, opposed to 1, 3, 5 and 9 in P. sanchezae n. sp. M. abyssalis is furthermore considerably larger than P. sanchezae n. sp. (769–871 µm vs. 392–559 µm). Information on details in the mouth cone and hence outer oral styles is unfortunately not available from M. abyssalis.

Paracentrophyes sanchezae n. sp. (Figs 2���5; Tabs 1���2) zoobank.org code: urn:lsid:zoobank.org:pub:C8299651-B344-4287-82F9-061C100F70BF Material. Holotype, adult female, collected from mud on November 2, 2014, at station 001-2014 (Fig. 1), at 57 m depth on the continental shelf, south of the Louisiana coast line, and west of the submarine Mississippi Canyon (position: 28o25���48.71������N, 090o14���10.31������W), mounted in Fluoromount G, deposited at the Natural History Museum of Denmark, under catalogue number ZMUC KIN- 1014. Paratypic material mounted for LM includes a single adult male, collected from mud on October 20, 2009, at station 031-2009 (Fig. 1), at 54 m depth about 170 km straight south of the Louisiana ��� Texas state border (position: 28o12���59.76������N, 093o24���19.08������W), mounted in Fluoromount G, deposited at the Natural History Museum of Denmark, under catalogue number ZMUC KIN- 1015. Additional paratypes include two males, collected from mud on November 15, 2013, at stations 078-2013 and 079- 2013 (Fig. 1). Station 078-2013 is located at 142 m depth (position: 29o53���07.72������N, 086o47���31.20������W), and Station 079-2013 at 125 m depth (position: 29o48���20.77������N, 086o36���02.37������W). Both stations are located near each other, south of the Florida panhandle in the northeastern extension of the submarine De Soto Canyon. The specimens are mounted for SEM and deposited at the Natural History Museum of Denmark, under catalogue numbers ZMUC KIN- 1081 and KIN- 1082. Diagnosis. Segments 1 and 11 composed of one tergal and one sternal plate; sternal plate of segment 1 partially differentiated into episternal and midsternal plates. Segments 2 to 10 composed of one tergal and two sternal plates. Middorsal and midlateral spinose processes present on segments 1 to 9 in both sexes; females also with middorsal and midlateral spinose processes on segment 10, and middorsal spine on segment 11; males with flexible middorsal and midlateral spines on segment 10, and midlateral penile spines on segments 10 and 11. Outer oral styles alternating in size between larger and smaller ones; large outer oral spines with 18 basal fringe tips; small outer oral spines with 10 basal fringe tips. Perispinal setae present as unpaired ones in paradorsal position on segments 5 and 9 (occasionally 7), paired ones in paralateral positions on segments 6 to 9 (occasionally 4), and paired ones in ventrolateral positions on segments 1, 3, 5 and 9 (occasionally unpaired on 7 and 8). Etymology. The species is named after Dr Nuria S��nchez in recognition of her contributions to pycnophyid and neocentrophyid taxonomy and systematics. Description. Adults with head, neck and eleven trunk segments (Figs 2, 4 A���B, 5A���B). For complete overview of measures and dimensions, see Table 1. The distribution of cuticular structures, i.e., sensory spots, processes and spines is summarized in Table 2. The head is formed by a retractable mouth cone and an introvert (Figs 3, 5 C���D). The pharynx carries at least two rings of inner oral styles, of which the styles in one ring form elongated helioscalids. It was not possible to determine the exact number or arrangement of inner oral styles. The external mouth cone armature consists of nine outer oral styles, arranged as one style anterior to each introvert sector, except for the middorsal sector 6 (Fig. 3). The outer oral styles alternate in size: larger styles are composed of two joined units, and carry a basal fringe consisting of ca. 18 fringe tips; smaller styles are shorter, thinner, more flexible and consist of a single unit, with a basal fringe consisting of ca. 10 fringe tips (Fig. 5 C). Large outer oral styles are located anterior to introvert sectors 1, 3, 5, 7 and 9, whereas smaller styles are located anterior to sectors 2, 4, 8, and 10 (Fig. 3). The exact appearance and arrangement of scalids on the introvert could only be examined for introvert sectors 1 to 6 plus 10. However, due to the usual symmetry patterns, we would expect the arrangements in sectors 7 to 9 to be identical with those in sectors 5 to 3. The introvert sectors are defined by ten primary spinoscalids in Ring 01 (Figs 3, 5 D). Each primary spinoscalid consists of a basal sheath and a flexible, distal end piece with a blunt tip. The basal sheaths have long, marginal extensions that form transverse fringes, whereas the end pieces have tiny hairs on their proximal halves, and a smooth surface more distally (Fig. 5 D). Spinoscalids of Rings 02 to 06 also consist of a sheath and an end piece. These sheaths also show a marginal fringe, but the fringe tips are considerably shorter than those on the primary spinoscalids. In addition, each sheath shows an elongate row of small structures that either appear as minute denticles (mostly Ring 02), or short hairs (mostly Rings 03 to 06) (Fig. 5 D). Rings 02 and 04 each have 10 spinoscalids, and Rings 03 and 5 have 20, meaning that the spinoscalids of these rings form a quincunx in each sector. Even numbered sectors have no spinoscalids posterior to Ring 05, whereas odd numbered sectors show a single spinoscalid in Ring 06 (Fig. 3). The neck has seven placids, arranged as four dorsal ones and three ventral (Figs 2 A���B, 3). Fourteen trichoscalids are present, located as single ones in sectors 1, 2, 4, 6, 8 and 10, and two in sectors 2, 5, 7 and 9 (Fig. 3). The positions of the trichoscalids do not follow the patterns of the spinoscalids. Trichoscalids are rather slender, consisting of a single unit, densely covered with small hairs. The first trunk segment consists of one tergal and one sternal plate; sternal plate with intracuticular lines, indicating a partial division into one midsternal and two episternal plates (Figs 2 A���B, 4C-D, 5F���G). Segments 2 to 10 consist of one tergal and two sternal plates, and segment 11 of one tergal and one sternal plate (Figs 2 A���B, 4A��� B, J���L, 5A���B, I���K). Sternal plates are flattened, while tergal plates are vaulted, giving the specimens a triangular appearance in cross-sections. Segment widths are nearly constant from segments 3 to 8, which gives the specimens a parallel sided and rectangular appearance (Figs 2 A���B, 4A���B, 5A). Segments 1 to 10 in females and 1 to 9 in males with spinose middorsal and midlateral processes (Figs 2 A���B, 4C���F). Middorsal spinose processes with nearly smooth surface, and pointed rigid tip, projecting slightly beyond segment margin. Midlateral processes with minute hairs, and more flexible tips, projecting well beyond segment margin. A minute paralateral pore, probably a glandular cell outlet, is present next to each midlateral process (Fig. 4 E, G). Spinose processes are progressively longer towards the posterior part of the trunk. Markings of muscle attachment sides (muscle scars) are present as small, oval areas in laterodorsal positions on segments 1 to 10, and in paraventral positions on segments 2 to 10 (Figs 2 A���B). Ventral muscle scars on segment 1 are larger, much more elongate, and located in ventromedial positions. On segment 11, muscle scars are small and rounded, and were observed in ventromedial positions only. All segments, from segment 1 to 10, are generally covered with minute, triangular, scale-like hairs, except on the processes, and around sensory spots and muscle scars. Anterior segment parts with reticulated ornamentation. Free flaps posteriorly on segments with striated substructure, and scale-like hairs that appear slightly more elongate. Pectinate fringes on segment margins not present. Segment 1 with anterolateral margins of tergal plate projecting into horn-like extensions (Figs 2 A���B, 4D). Anterior segment margins are denticulated (Fig. 4 C���D). Sensory spots on this and all following segment belong to type 1 (but see exceptions on segment 11 though), consisting of a single pore and numerous minute papillae, forming elevated and slightly oval papillated areas. Tergal plate without setae, but with six pairs of sensory spots: two pairs are located in a subdorsal position on the anterior segment half, close to the paradorsal areas; two pairs in a laterodorsal position, but very close to the subdorsal area; and two pairs are also laterodorsal, but located close to the paralateral line (Figs 2 A, 5G). Sternal plate with one pair of ventrolateral setae, slightly behind the transverse midline of the segment (Figs 2 B, 4D, 5F), and in addition with three pairs of ventromedial sensory spots: One pair is located anteriorly on the plate, near the ventrolateral area; one pair is more medial on the incompletely differentiated episternal plates, at the same level as the setae; and one pair is more anterior, and located within the limits of the incompletely differentiated midsternal plate (Figs 2 B, 5F). Segment 2: tergal plate with three pairs of sensory spots in subdorsal positions, and two pairs in laterodorsal positions (Fig. 2 A). Sternal plates with two sensory spots in ventromedial positions (Fig. 2 B). Segment 3: tergal plate with three pairs of sensory spots in subdorsal positions, and one pair in laterodorsal positions (Fig. 2 A). Sternal plates with ventrolateral setae and two sensory spots in ventromedial positions (Fig. 2 B). Segment 4 with tergal plate as on segment 3; one male specimen and female holotype with setae in paralateral positions (Fig. 4 E), but this was not observed in other specimens. Sternal plates as on segment 2. Segment 5: tergal plate with a single, unpaired paradorsal seta, two pairs of sensory spots in subdorsal positions, and one pair in laterodorsal positions. Sternal plates with ventrolateral setae (Fig. 4 F) and single sensory spots in ventromedial positions. Segment 6: tergal plate with paralateral setae, three pairs of sensory spots in subdorsal positions, and one pair in laterodorsal positions. Sternal plates as on segments 2 and 4. Segment 7: tergal plate with paralateral setae, two pairs of sensory spots in subdorsal positions, and one pair in laterodorsal positions; one male specimen furthermore with single, unpaired paradorsal seta (Fig. 5 H). Sternal plates as on segments 2, 4 and 6; furthermore, one male specimen (not the same as the one with paradorsal seta) with a single ventrolateral seta on the right sternal plate only. Segment 8 with tergal plate as on segment 6, and sternal plates as on segment 7, except for the single ventrolateral seta that now appears on the left sternal plate only. Segment 9: tergal plate with a single, unpaired paradorsal seta, paired paralateral setae, three pairs of sensory spots in subdorsal positions, and one pair in laterodorsal positions. Sternal plates with ventrolateral setae and two sensory spots in ventromedial positions. Segment 10 with middorsal and midlateral spinose processes present in females only (Fig. 2 A���B); males with flexible middorsal spine and flexible (penile) midlateral spines (Figs 2 C���D, 4I, 5I ���K). Tergal plate with two pairs of sensory spots in subdorsal positions, and one pair in laterodorsal positions. Sternal plates with ventrolateral setae, one sensory spot in ventrolateral positions, and one sensory spot in ventromedial positions (Figs 2, 5 I ���J). Segment 11 with middorsal spine in both sexes; female middorsal spine acicular and rigid (Figs 2 A, 4H); male middorsal spine flexible as on preceding segment (Figs 2 C, 4I, 5J���K). Males also with flexible (penile) spines in midlateral positions; females without any midlateral structures, neither spines nor processes. Females furthermore with short midterminal process (Fig. 4 J); such a process is not present in males, but SEM images reveal the presence of a very minute, somehow papillated (sensory?) structure that appears from the midventral margin of the sternal plate (Fig. 5 E). Both sexes with long lateral terminal spines (Figs 2, 4 A���B). Tergal plate with one pair of subdorsal sensory spots type 3, protruding from the posterior margin of the plate (Figs 4 I, 5J). Sternal plate with one pair of regular ventromedial sensory spots type 1, located near the posterior segment margin, and in addition, one pair of ventromedial sensory spots type 3, protruding from the posterior margin of the plate (Figs 4 J, L, 5I). Remarks on diagnostic characters. The new species can only be confused with Mixtophyes abyssalis and other species of Paracentrophyes (see Discussion for further considerations regarding the generic assignment of the new species). Females of P. sanchezae n. sp. are most easily distinguished from females of other congeners by their short, midterminal process (Fig. 4 J) which is shared with P. quadridentatus only (S��rensen et al. 2010). Other differential characters that are detectable in both sexes regard the fringes of the outer oral styles, and position of setae on the trunk segments. Differences in number of fringe tips at the bases of the large and small outer oral styles (oos) were first reported by S��rensen et al. (2010). According to this study, the following numbers of fringe tips were observed in the three known species of Paracentrophyes: P. anurus: large oos: 5���7 tips, small oos: 10���12 tips; P. quadridentatus: large oos: 9 tips, small oos: 7 tips; P. praedictus: large oos: 12 tips, small oos: 8 tips. P. sanchezae n. sp. appears to have more fringe tips, with 10 tips on the small oos, equivalent to P. anurus only, and 18 tips on the large oos, which is nearly twice as many as in the congeners. The use of outer oral style fringes as diagnostic character should of course be used with some caution, until the intraspecific consistency of the character has been confirmed from more specimens. Also in regard to distribution of perispinal setae, P. sanchezae n. sp. is very easily distinguished from its congeners, which all generally are much richer in setae. P. anurus and P. praedictus both have paired perispinal setae in paradorsal, paralateral and ventrolateral positions on segments 1 to 9 (Higgins 1983; S��rensen et al. 2010), whereas P. quadridentatus has setae in these positions as well and on segment 10 (S��rensen et al. 2010). Oppositely, paradorsal setae in P. sanchezae n. sp. are unpaired, and restricted to segments 5 and 9 (plus segment 7 in one specimen), paralateral setae are present on segments 6 to 9 only (plus segment 4 in one specimen), and paired ventrolateral setae are restricted to segments 1, 3, 5 and 9 (plus appearing unpaired on segments 7 and 8 in one specimen). Despite its generic assignment, P. sanchezae n. sp. also shows some resemblance to M. abyssalis. However, the two species can first of all be distinguished by the generic difference that separates Paracentrophyes and Mixtophyes, namely the presence of partially developed epi- and midsternal plates on segment 1, present in species of Paracentrophyes only (Fig. 6 A���E, G, I). To confuse things slightly, reexamination of a specimen of M. abyssalis mounted for SEM actually revealed ventral markings on segment 1 (Fig. 6 H) that could indicate a partial differentiation of the sternal plate. However, these markings are more probably due to a strong contraction of the dorso-ventral muscles of the segment. This explanation is supported by the fact that light microscope images show absolutely no traces of intracuticular lines or other indications of a partial differentiation (Fig. 6 F). M. abyssalis furthermore have a longer female middorsal spine on segment 11 (MDS11/TL ratio 17% in M. abyssalis vs. 7% in P. sanchezae n. sp.). In addition, M. abyssalis has no midterminal processes (S��nchez et al. 2014). Regarding the distribution of paradorsal, paralateral, and ventrolateral setae, P. sanchezae n. sp. is actually closer to M. abyssalis than it is to its congeners, but some differences are found also. In M. abyssalis unpaired paradorsal setae are found on segments 7 and 9, opposed to 5 and 9 in P. sanchezae n. sp.; paralateral setae in M. abyssalis are present on segments 2 and 7���9, opposed to 6 to 9 in P. sanchezae n. sp., and ventrolateral setae in M. abyssalis on segments 1 (males only) 5 and 9, opposed to 1, 3, 5 and 9 in P. sanchezae n. sp. M. abyssalis is furthermore considerably larger than P. sanchezae n. sp. (769���871 ��m vs. 392���559 ��m). Information on details in the mouth cone and hence outer oral styles is unfortunately not available from M. abyssalis., Published as part of S��rensen, Martin V. & Landers, Stephen C., 2017, Description of a new kinorhynch species, Paracentrophyes sanchezae n. sp. (Kinorhyncha: Allomalorhagida) from the Gulf of Mexico, with differential notes on one additional, yet undescribed species of the genus, pp. 61-76 in Zootaxa 4242 (1) on pages 63-72, DOI: 10.11646/zootaxa.4242.1.3, http://zenodo.org/record/375999, {"references":["Sorensen, M. V., Pardos, F., Herranz, M. & Rho, H. S. (2010) New data on the genus Paracentrophyes (Homalorhagida, Kinorhyncha), with the description of a new species from the West Pacific. The Open Zoology Journal, 3, 42 - 59. http: // dx. doi. org / 10.2174 / 1874336601003010042","Higgins, R. P. (1983) The Atlantic Barrier Reef ecosystem at Carrie Bow Cay, Belize. II. Kinorhyncha. Smithsonian Contributions to Marine Science, 18, 1 ‾ 131.","Sanchez, N., Pardos, F. & Sorensen, M. V. (2014) A new kinorhynch genus, Mixtophyes (Kinorhyncha: Homalorhagida), from the Guinea Basin deep-sea, with new data on the family Neocentrophyidae. Helgoland Marine Research, 68, 221 - 239. http: // dx. doi. org / 10.1007 / s 10152 - 014 - 0383 - 6"]}

Paracentrophyes sp. (Figs 7���8) Besides P. sanchezae n. sp., samples from the Gulf of Mexico revealed four female specimens of one additional, yet undescribed species of Paracentrophyes. Three specimens were mounted for SEM, whereas the last one, which unfortunately was not in a good condition, was mounted for LM (Fig. 7). Due to the restricted amount of material, especially for LM, we chose not to make a formal description of the species. We will, however, provide a short diagnostic account, which hopefully will enable researchers to recognize the species if additional specimens are collected in the future. Material. One female specimen, adult or late juvenile stage, collected from mud on November 5, 2009, at station 099-2009 (Fig. 1), at 129 m depth on the Florida Shelf, about 136 km south of Cape San Blas, Florida (position: 28o26���30������N 085o11���27������W) mounted in Fluoromount G, deposited at the Natural History Museum of Denmark, under catalogue number ZMUC KIN- 1016. In addition, three female specimens, mounted for SEM and stored in the authors��� personal collections. The first specimen was collected on November 1, 2007, at station 094- 2007 (Fig. 1), at 113 m depth about 125 km southeast of Pensacola, FL, (position: 29o33���56������N 086o17���34������W), whereas the two other specimens were collected on November 15, 2013, at station 78-2013 (Fig. 1), at 142 m depth in the innermost extension of the submarine De Soto Canyon, 70 km southeast of Pensacola, Florida (position: 29o53���08������N 086o47���31������W). Diagnostic account. Head and mouth cone structures could not be studied in detail. It is however clear that outer oral styles alternate in size between larger and smaller ones. Segment 1 consists of a tergal and a sternal plate; sternal plate partly differentiated in epi- and midsternal plates (Fig. 7 B). Segments 2 to 11 consist of one tergal and two sternal plates (Figs 7 A, D, 8A). Trunk length = 600 ��m. Segment 1 almost smooth near anterior margin, and without reticulated areas (Figs. 7 B, 8B). Middorsal spinose processes are present on segments 1 to 9, and midlateral processes on segments 1 to 10. Segments 10 and 11 with middorsal spines, and segment 11 with lateral terminal spines (Figs. 7 C���D, 8F, H). Spines are generally very short, i.e., middorsal spine segment 10 = 17 ��m (MDS10/TL ratio 2,8%), middorsal spine segment 11 = 24 ��m (MDS11/TL ratio 4,0%) and lateral terminal spines = 30 ��m (LTS ratio 5,0%). Perispinal setae are found on a few segments only: ventrolateral positions on segment 1; unpaired paradorsal and paired ventrolateral on segment 5 (Fig. 8 C); unpaired paradorsal on segment 7 (Fig. 8 D); paired paralateral on segment 8 (Fig. 8 D); unpaired paradorsal and paired ventrolateral on segment 9 (Fig. 8 D). One specimen mounted for SEM carried several unidentified loricate, epibionts (Fig. 8 C, F���G). Remarks on diagnostic characters. The species is easily recognized by its very low number of perispinal setae, and by its very short spines. The middorsal processes/spines of segments 10 and 11 in female specimens of Paracentrophyes are usually short, but still, they are even shorter in Paracentrophyes sp. from the Gulf of Mexico (Figs 7 A, C���D, 8A, F, H). The difference in dimensions gets most conspicuous in the lateral terminal spines though, where the LTS/TL ratios for P. quadridentatus, P. praedictus and P. sanchezae n. sp. are around 25���27%. In P. anurus the ratio is considerably smaller, i.e., 9.7%, but in Paracentrophyes sp. from the Gulf of Mexico we find even shorter lateral terminal spines, with an LTS/TL ratio of only 5.0%. Hence, this yet undescribed species is currently the Paracentrophyes with the shortest terminal spines. Also the distribution of perispinal setae, and in particular the general scarcity of them, makes it easy to recognize the species. As noted above under diagnostic traits for P. sanchezae n. sp., the other three species of the genus are generally rich in setae, with continuous series of paired setae in paradorsal, paralateral and ventromedial positions from segment 1 to segment 9 or 10. The number of setae in P. sanchezae n. sp. is considerably lower, but Paracentrophyes sp. from the Gulf of Mexico has even fewer setae, and differs from P. sanchezae n. sp. by lacking perispinal setae in paralateral positions on segments 6 and 7, and in ventrolateral positions on segments 3 and 10. Based on these traits, we believe it would be easy to recognize the new species in future samples., Published as part of S��rensen, Martin V. & Landers, Stephen C., 2017, Description of a new kinorhynch species, Paracentrophyes sanchezae n. sp. (Kinorhyncha: Allomalorhagida) from the Gulf of Mexico, with differential notes on one additional, yet undescribed species of the genus, pp. 61-76 in Zootaxa 4242 (1) on pages 72-74, DOI: 10.11646/zootaxa.4242.1.3, http://zenodo.org/record/375999