14 results on '"Landers, Stephen C."'
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2. Metabarcoding analysis of meiobenthic biodiversity along the Gulf of Mexico continental shelf
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Brannock, Pamela M., Demopoulos, Amanda W.J., Landers, Stephen C., Waits, Damien S., and Halanych, Kenneth M.
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- 2023
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3. Towards a standardisation of morphological measurements in the phylum Kinorhyncha
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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., and Sánchez, Nuria
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- 2023
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4. Echinoderes zacharyi sp. nov., a new kinorhynch in the E. coulli species group (Kinorhyncha: Cyclorhagida) from the Gulf of Mexico
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Kennedy, Madison C., Sørensen, Martin V., and Landers, Stephen C.
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- 2022
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5. Kinorhynch communities of Mobile Bay, Alabama
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Kennedy, Madison C., primary, Sørensen, Martin V., additional, Sánchez, Nuria, additional, and Landers, Stephen C., additional
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- 2024
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6. Kinorhynch Communities on the Southern Gulf of Mexico Continental Shelf
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Anguas-Escalante, Abril, primary, De Jesús-Navarrete, Alberto, additional, Landers, Stephen C., additional, and Sørensen, Martin Vinther, additional
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- 2024
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7. Kinorhynch communities of Mobile Bay, Alabama
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Kennedy, Madison C., Sørensen, Martin V., Sánchez, Nuria, Landers, Stephen C., Kennedy, Madison C., Sørensen, Martin V., Sánchez, Nuria, and Landers, Stephen C.
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This study investigated kinorhynch communities from Mobile Bay, Alabama across three sampling transects. A multicorer was used to collect sediment samples from fifteen sites along a northwestern transect (sites 0–4), the Mobile Bay ship channel (sites 5–9 and 14), and a northeastern transect (sites 10–13). Each sediment sample was analyzed for kinorhynch community composition, granulometry, organic matter content, and trace metals. Kinorhynchs were identified to species via light microscopy or scanning electron microscopy for community analysis. Two genera and seven species were recovered from thirteen sites. Three abundant species, Echinoderes augustae, Leiocanthus langi, and Echinoderes bookhouti were found, which were known from recent Alabama surveys in the northern Gulf of Mexico. Echinoderes augustae was the dominant taxon, comprising 85% of the animals identified. Spearman correlations, PCA analysis, and abiotic data revealed a sporadic distribution of animals collected from two distinct sediment profiles. The kinorhynch densities correlated positively with fine sediments and select trace metals (which are indicators of freshwater input), but did not correlate with organic matter content or salinity. Additionally, this study reports two new species records for Mobile Bay.
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- 2023
8. Kinorhyncha Reinhard 1885
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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., and Sánchez, Nuria
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Kinorhyncha ,Animalia ,Biodiversity ,Taxonomy - Abstract
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
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- 2023
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9. Kinorhynch diversity in the southern Gulf of Mexico and a description of Dracoderes chaac sp. nov.
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Landers, Stephen C., Hoffman, Kellan P., Sánchez, Nuria, Sørensen, Martin V., Landers, Stephen C., Hoffman, Kellan P., Sánchez, Nuria, and Sørensen, Martin V.
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Sediment collections from the southern Gulf of Mexico between the Texas-Mexico border and the Yucatan Peninsula have resulted in many new kinorhynch species distribution records and the finding and taxonomic description of a new species, Dracoderes chaac sp. nov. This study focused on the non-echinoderid members of the Phylum Kinorhyncha, many of which are rare or restricted to only a few locations. A total of 136 specimens were identified from 24 sediment stations, distributed among the following species: Antygomonas gwenae, Campyloderes vanhoeffeni, Centroderes readae, Condyloderes flosfimbriatus, Co. rohalorum, Cristaphyes panamensis, Dracoderes chaac sp. nov., Leiocanthus corrugatus, L. langi, L. quinquenudus, L. satanicus, Pycnophyes alexandroi, Semnoderes lusca, and Sphenoderes aspidochelone. Additional undescribed species in the genera Leiocanthus, Mixtophyes, and Paracentrophyes were recovered. Statistical analysis of the stations revealed a grouping of locations where the majority of the pycnophyid species were recovered. Some species (e.g., Ca. vanhoeffeni, S. aspidochelone) had an extensive distribution, while others were recorded from one or few locations only (e.g., A. gwenae, Co. rohalorum). Most of the species were reported from earlier collections in the northern Gulf of Mexico on the U.S. continental shelf, between 700-1100 km away.
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- 2022
10. Leiocanthus quinquenudus sp. nov. and L. satanicus sp. nov., two new species of pycnophyid Kinorhyncha (Allomalorhagida: Pycnophyidae) from the Gulf of Mexico
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Cepeda, Diego, Sánchez, Nuria, Sørensen, Martin V., Landers, Stephen C., Cepeda, Diego, Sánchez, Nuria, Sørensen, Martin V., and Landers, Stephen C.
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Two new species of pycnophyid Kinorhyncha, Leiocanthus quinquenudus sp. nov. and L. satanicus sp. nov., are described from soft seafloor sediment samples in the Gulf of Mexico. Leiocanthus quinquenudus sp. nov. is easily distinguished from the other congeners by the absence of ventromedial setae on segment 5, a structure otherwise present in all the other known Leiocanthus. Leiocanthus satanicus sp. nov. lacks lateral terminal spines, a feature only shared by L. langi and L. mainensis among the congeners; otherwise the new species is easily discernible by the arrangement of the paradorsal, laterodorsal and ventromedial setae, and the number of ventral sensory spots per segment. These findings are a significant contribution to the knowledge of the Kinorhyncha biodiversity from the Gulf of Mexico, which has recently been explored in several taxonomical and ecological studies mainly focused on cyclorhagid Kinorhyncha, not pycnophyid kinorhynchs.
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- 2022
11. Black Gill in Marine Decapod Crustaceans: A Review
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Frischer, Marc E., primary, Landers, Stephen C., additional, Walker, Anna N., additional, Powell, Shirley A., additional, and Lee, Richard F., additional
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- 2022
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12. Leiocanthus quinquenudus Cepeda & S��nchez & S��rensen & Landers 2022, sp. nov
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Cepeda, Diego, S��nchez, Nuria, S��rensen, Martin V., and Landers, Stephen C.
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Kinorhyncha ,Allomalorhagida ,Pycnophyidae ,Leiocanthus ,Animalia ,Biodiversity ,Leiocanthus quinquenudus ,Taxonomy - Abstract
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"]}
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- 2022
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13. Leiocanthus satanicus Cepeda & Sánchez & Sørensen & Landers 2022, sp. nov
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Cepeda, Diego, Sánchez, Nuria, Sørensen, Martin V., and Landers, Stephen C.
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Kinorhyncha ,Allomalorhagida ,Leiocanthus satanicus ,Pycnophyidae ,Leiocanthus ,Animalia ,Biodiversity ,Taxonomy - Abstract
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).
- Published
- 2022
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14. Leiocanthus quinquenudus sp. nov. and L. satanicus sp. nov., two new species of pycnophyid Kinorhyncha (Allomalorhagida: Pycnophyidae) from the Gulf of Mexico
- Author
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CEPEDA, DIEGO, primary, SÁNCHEZ, NURIA, additional, SØRENSEN, MARTIN V., additional, and LANDERS, STEPHEN C., additional
- Published
- 2022
- Full Text
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