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3.1. Redescription of Setaphyes dentatus (Reinhard, 1881) Figs 2–8, Tables 1–2. 3.1.1. Diagnosis Setaphyes with anterior margin of the tergal plate on segment 1 finely denticulated, posteriorly followed by a transverse area of minute cuticular, net-like ridges. Middorsal elevations on segments 2–6, and middorsal processes on segments 1 and 7–9. Posterior end of middorsal structures covered by tufts of elongated, thick hairs whose tips usually surpass the posterior segment margin. Unpaired paradorsal setae on segments 2–9, alternating left and right position along the trunk and showing intraspecific variability but without any specific pattern. Laterodorsal setae on segments 3, 5 and 7. Lateroventral setae on segments 2–10. Ventromedial setae on segments 4–5 and 7–8 in males and 3–5 and 7–9 in females. Patch of conspicuous longitudinal cuticular ridges on segment 10, from laterodorsal to ventrolateral positions. Lateral terminal spines short, slender (males LTS:TL average ratio 21.2 %; females LTS:TL average ratio 15.7 %; males and females average ratio 17.8 %). 3.1.2. Examined material For light microscopy, 136 adult specimens, 53 males and 83 females, were studied from 17 populations belonging to eight marine ecoregions (ZMB 12408–12418, 12616–12740; see Supplementary Table I). Of those, four females from the Anatolian Peninsula are new records for the region. 11 additional adult specimens were examined with SEM: one adult specimen from the Anatolian Peninsula (indeterminate sex: ZMB 12745; station YSL09 R2; 13 July 2019, 41 Ǫ 24.738 ′ N, 036 Ǫ 39.210 ′ E, 76 m depth; collector: Derya Ürkmez), 10 from the Iberian Peninsula, collected by F. Pardos, M. Herranz and N. Sanchez´(one female ZMB 12746, one male ZMB 12747, and three adults ZMB 12748–12750 of indeterminate sex from Algeciras, 8 February 2011, 36 Ǫ 10.741 ′ N, 005 Ǫ 23.243 ′ W, 8 depth; two females ZMB 12754 and 12755 from Huelva, 12 April 2011, 37 Ǫ 08.324 ′ N, 007 Ǫ 20.308 ′ W, 15 m depth; one additional female ZMB 12753, and two indeterminate sex, ZMB 12751 and ZMB 12752, from Huelva, 11 April 2011, 37 Ǫ 10.963 ′ N, 007 Ǫ 16.549 ′ W, 11 m depth). 3.1.3. Description See Table 1 and Supplementary Table III for measurements and dimensions and Table 2 for location of middorsal cuticular specializations, setae, tubes, nephridiopores and sensory spots. Ring 00 of mouth cone with nine, equally sized outer oral styles composed of a single, flexible unit, wider at base, with a fringed sheath, tapering progressively toward the distal, pointed tip (Figs. 3; 4D). Outer oral styles located anterior to each introvert sector, except in the middorsal position (sector 6) where a style is missing (Fig. 3). Inner rings of mouth cone not observed, herein details on the morphology and distribution of inner oral styles are not provided. Introvert with six rings of spinoscalids and 10 longitudinal sectors, each limited by the position of two adjacent primary spinoscalids (Figs 3; 4A; 5A–D). Ring 01 with 10 primary spinoscalids, conspicuously larger than the other ones; primary spinoscalids composed of a basal, rectangular, wide sheath and a distal, elongated, flexible, distally pointed end-piece; basal sheath equipped with a row of elongated fringes, longer in the middle region of the spinoscalid than on the lateral margins (Figs 3; 4A; 5A–C). Ring 02 with 10 spinoscalids, arranged medially in each sector; spinoscalids on this and following rings are also composed of a basal, rectangular, wide sheath and a distal, elongated, flexible, distally pointed end-piece; basal sheath appears hairy at its proximal end and terminates into a short fringe (Figs 3; 4A; 5A–B). Ring 03 with 20 spinoscalids, arranged as two in each sector (Figs 3; 4A; 5A–B). Ring 04 with 10 spinoscalids, arranged medially in each sector (Figs 3; 4A; 5A–B). Ring 05 with 20 spinoscalids, arranged as two in each sector (Figs 3; 4A; 5A–B). Ring 06 with four, smaller spinoscalids, arranged medially in sectors 1, 3, 6 and 9 (Figs 3; 4A; 5A–B). The location of spinoscalids throughout rings 02–06 follows a strict pattern around the introvert: sectors 1, 3, 6 and 9 bear seven spinoscalids, while the remaining sectors carry six spinoscalids (Figs 3; 4A; 5A–B). A ring of 14 hairy trichoscalids present posterior to the spinoscalid 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 (Figs 3; 4A; 5A–B, D). Neck with four dorsal and two ventral sclerotized placids (Figs 2A–B; 4B–C; 5D). Dorsal placids rectangular, mesial ones broader (ca. 24 μm wide at the base) than lateral ones (ca. 22 μm wide at the base) (Figs 2B; 4B; 5D). Ventral placids (ca. 22–23 μm wide at the base) similar to the dorsal ones but much more elongated, becoming thinner towards the lateral sides (Figs 2A, C; 4C). Trunk with eleven segments (Figs 2 AB; 6AF). Segment 1 with one tergal, two episternal and one trapezoidal, midsternal plate; remaining segments with one tergal and two sternal cuticular plates (Figs 2 AD; 4B–C, F–G; 6A–F). Sternal plates reaching their maximum width at segment 7, almost constant in width throughout the trunk, progressively tapering at the last trunk segments. Sternal cuticular plates relatively narrow (MSW-5:TL average ratio = 24 %). Middorsal elevations on segments 2–6, rectangular, narrow, distally blunted, not projecting beyond the posterior margin of segments (Figs 2B; 4B, F; 6A, C; 7C–D; 8B). Middorsal processes on segments 1 and 7–9, similar in morphology but exceeding the posterior margin of segment (Figs 2B; 4B, F; 6A, E; 7B, F–G; 8H). Paradorsal butterfly to trident-like intracuticular atria associated to middorsal structures (Figs 2B; 4B, F). Lateral margin of middorsal structures surrounded by short, thick cuticular hairs; and posterior ends covered by tufts of elongated, thick hairs whose tips usually surpass the posterior margin of segment (Figs 2B; 7C–D, F–G; 8B) (those of segment 1 remarkably shorter). Middorsal processes progressively longer towards the posterior segments, reaching their maximum length on segment 9 Figs 2B; 4F; 6E; 7F–G; 8H). Cuticular scars (likely glandular cell outlets) as minute, dot-shaped, rounded to oval perforations throughout the cuticle on segments 1–11 (Figs 2A–D; 4B–C, F–G), also present at the base of the middorsal processes and elevations; the number and arrangement of these structures vary greatly among the specimens, not showing any clear pattern. Up to two pairs of cuticular ridges in subdorsal (one pair) and laterodorsal (one pair) positions on segments 2–4; an unpaired middorsal cuticular ridge and up to three pairs in subdorsal (one pair) and laterodorsal (two pairs) positions on segments 5–10; one pair of ventrolateral cuticular ridges on segments 2–10, with adjacent, minute glandular cell outlets (Fig. 2A–D). Conspicuous reticulate pattern of cuticular wrinkles, as a net-like ornamentation, across the most anterior dorsal and ventrolateral margins, at the overlapping area between following segments, on segments 2–10 (Figs 2A–D; 4B–C, F–G). Cuticular hairs acicular, non-bracteate, scattered throughout the trunk on segments 1–10, except in ventromedial position, denser at the tergosternal junctions, not following any particular pattern. Pachycycli and ball-and-socket joints conspicuous on segments 2–8, reduced on most posterior segments (Fig. 2A–D). Apodemes on segments 9–10 (Figs 2A–B, D; 4F–G). Primary pectinate fringes finely serrated (Figs 6A–F; 8B–C, E, G–H); secondary pectinate fringes as a wavy, quite inconspicuous single line in laterodorsal and ventrolateral positions at the anterior most region of the segments (Figs 2A; 8E). Muscular scars as rounded to oval, hairless areas in laterodorsal and ventromedial positions on segments 1–10 (Fig. 2A–D). Segment 1 with anterior dorsal margin finely denticulated, posteriorly followed by a transverse area of cuticular wrinkles forming a net-like band, broader towards the lateral than in the middle region (Figs 2B; 4B; 5D; 7A–B). Anterolateral margins of the tergal plate as short, wide, distally rounded extensions (Figs 2A–C; 6B). Middorsal process with paradorsal, butterfly to trident-like atria of associated paradorsal sensory spots located near the posterior margin of the segment (Figs 2B; 4B). Anterior margin of episternal plates with a pair of ridges forming small, quadrangular depressions; anterior margin of midsternal plate with a single, large rectangular depression (Figs 2A, C; 4C). Episternal plates with usually five, scattered, minute, dot-shaped glandular cell outlets forming a quincunx (Figs 2A, C; 4C). Trapezoidal midsternal plate, wider at the base (ca. 34 μm wide at the most anterior margin, ca. 56 μm wide at the most posterior margin; average ratio = 61 %), with wavy lateral margins at the middle region (Figs 2A, C; 4C). Sensory spots present in paradorsal, subdorsal, laterodorsal and ventrolateral positions (Figs 2A–C; 6A–B). Sensory spots on this and following segments as oval areas with an oval area of cuticular micropapillae surrounding a single pore (Figs 7E; 8D–E). Segment 2 with middorsal elevation with paradorsal, butterfly to trident-like atria of associated paradorsal sensory spots (near the posterior margin) (Figs 2B; 4B; 6A; 7 C), surrounded by tufts of elongated, thick hairs with tips usually surpassing the posterior segment margin (Figs 6A; 7C). Unpaired seta in paradorsal position, and paired setae in lateroventral position; females with sexual dimorphism, an additional, pair of setae in ventrolateral position lacking in males. Males with sexually dimorphic tubes in ventromedial position lacking in females(Figs 2A, C; 8A). Sensory spots in paradorsal (near the posterior margin), subdorsal, laterodorsal and ventromedial positions (Figs 2A–C; 4B–C; 6A–B; 7C). Segment 3 with middorsal elevation as on the preceding segment (Figs 2B; 4B; 6A; 7D). Unpaired seta in paradorsal position, and paired setae in laterodorsal and lateroventral positions. Females with an additional, pair of setae in ventromedial position, more mesial than the ventromedial sensory spots. Sensory spots in paradorsal (near the posterior margin), subdorsal, laterodorsal and ventromedial positions; ventromedial sensory spots present in females only (Figs 2A–C; 4B–C; 6A–B, D; 7D). Segment 4 with middorsal elevation as on the preceding segments (Figs 2B; 4A; 6A, C). Unpaired seta in paradorsal position, and paired setae in lateroventral and ventromedial positions. Paired sensory spots in paradorsal (near the posterior margin), subdorsal, laterodorsal and ventromedial positions (Figs 2A–B; 4B–C; 6A, C–D), the latter more lateral than the ventromedial setae. Segment 5 with middorsal elevation as on the preceding segments (Figs 2B; 4B, F; 6C; 8B). Unpaired seta in paradorsal position, and paired setae in laterodorsal, lateroventral and ventromedial positions; laterodorsal setae longitudinally aligned with those of segment 3. Laterodorsal setae longitudinally aligned with those of segment 3. Paired sensory spots in paradorsal (near the posterior margin), subdorsal, laterodorsal and ventromedial positions (Figs 2A–B; 4B–C; 6C–D; 8B–D), the latter more lateral than the ventromedial setae. Segment 6 with middorsal elevation as on the preceding segments (Figs 2B; 4F; 6C; 8B). Unpaired seta in paradorsal position, and paired in lateroventral position. Paired sensory spots in paradorsal (near the posterior margin), subdorsal, laterodorsal and ventromedial positions (Figs 2A–B; 4C, F–G; 6C–D; 8B–C, F). Segment 7 with middorsal process extending beyond the posterior margin of segment (Figs 2B; 7F). Similar to segment 5 in the arrangement of setae and sensory spots (Figs 2A–B; 4F–G; 6C–E; 8C, E). Segment 8 with middorsal process longer than that of the preceding segment (Figs 2B; 4F; 7F). Similar to segment 4 in the arrangement of setae and sensory spots (Figs 2A–B; 4F–G; 6E–F). Segment 9 with middorsal process longer than that of the preceding segment (Figs 2B; 4F; 6E; 7F–G; 8H). Unpaired seta in paradorsal position, and paired in lateroventral position; females with an additional pair of setae in ventromedial position lacking in males (Figs 2A–B, D; 4G; 6F). Sensory spots in paradorsal (near the posterior margin), subdorsal, laterodorsal, and ventrolateral positions (Fig. 2A–B, D). Nephridiopore as small opening surrounded by short tubes in lateroventral position. Segment 10 without middorsal cuticular specialization. Setae in lateroventral position (Figs 2A, D; 6F; 8H). Sensory spots in subdorsal, laterodorsal and ventrolateral positions, the two latter between patches of conspicuous, parallel cuticular ridges, extending throughout the laterodorsal to ventrolateral areas (Figs 2A, D; 4E, G; 8G–H). Tergal plate with rounded posterior margin; sternal plates distally straight in females, more pointed in males. Segment 11 without middorsal cuticular specialization. Males with two pairs of stout, thick penile spines (Figs 2A; 4E). Short lateral terminal spines, longer in males than in females (males LTS:TL average ratio 21.21 %; females LTS:TL average ratio 15.66 %) (Figs 2A–B, D; 4H–I; 6E–F; 8G). 3.1.4. Intraspecific variation Due to the preservation conditions of the studied material, the pattern of sensory spots throughout the trunk could not be fully confirmed in all the LM specimens. The remaining cuticular characters of taxonomic relevance for pycnophyids (i.e. setae, middorsal cuticular specializations, spines, glandular cell outlets, and ornamentation) could be examined in detail in the Anatolian population (four females, one adult specimen for SEM), North Frisian (three females, two males), Italian (one adult specimen) and Iberian (Pontevedra, one female, four males; Algeciras, one male, one female, three adult specimens mounted for SEM; Huelva, one adult specimen mounted for SEM; and Tarragona, four females, three males) populations. Anatolian population: All specimens lack the ventromedial setae on segment 8. North Frisian population: ventromedial seta on segment 2 absent on one sternal plate in one male (ZMB 12418); ventromedial setae on segment 6 present on one sternal plate in one female (ZMB 12413); ventromedial setae on segment 9 absent in one female (ZMB 12408). Iberian population: laterodorsal seta on one side of the tergal plate on segment 2 present in one male (ZMB 12715); laterodorsal seta on segment 3 absent on one side of the tergal plate in one male (ZMB 12640) and in one SEM specimen (ZMB 12751); laterodorsal seta on one side of the tergal plate on segment 4 present in one female (ZMB 12716); ventromedial seta on one sternal plate on segment 4 not detected in one male (ZMB 12640); ventromedial setae on segment 6 present in one male and one female (ZMB 12638 and ZMB 12714) and on the lateral half of the sternal plate in one female (ZMB 12716); ventromedial setae on segment 8 absent in one female (ZMB 12643)., Published as part of González-Casarrubios, Alberto, Cepeda, Diego, Neuhaus, Birger, García-Cobo, Marta, Pardos, Fernando, Ürkmez, Derya & Sánchez, Nuria, 2023, The genus Setaphyes (Kinorhyncha, Pycnophyidae) in European waters: Redescription of Setaphyes dentatus (Reinhard, 1881) and Setaphyes kielensis (Zelinka, 1928), including notes on morphometrics, sexually dimorphic features and reproduction of the genus, pp. 90-111 in Zoologischer Anzeiger 303 on pages 92-98, DOI: 10.1016/j.jcz.2022.12.004, http://zenodo.org/record/8164206, {"references":["Reinhard, W., 1881. Uber Echinoderes und Desmoscolex der Umgebung von Odessa. Zool. Anz. 4 (97), 588 - 592."]}

Six of the eight species of the genus Setaphyes have been described from Europe. In the present contribution, the European Setaphyes species are revised and two of them, S. dentatus (Reinhard, 1881) and S. kielensis (Zelinka, 1928), are redescribed following the current approaches of Kinorhyncha taxonomy. For this purpose, material from 17 localities throughout the Atlantic Ocean and the Mediterranean and Black Seas was investigated. The redescriptions of two of the most common pycnophyid species in Europe include detailed information on intraspecific variation among populations. Setaphyes dentatus is characterized by the presence of middorsal elevations on segments 2–6, and middorsal processes on segments 1, 7–9, unpaired paradorsal setae on segments 2–9; laterodorsal setae on segments 3, 5 and 7; ventromedial setae on segments 4–5, 7–8 in males and 3–5, 7–9 in females; anterior cuticular, reticulate ridges on the tergal plate of segment 1 and conspicuous patch of laterodorsal and ventrolateral longitudinal, cuticular ridges on segment 10. Setaphyes kielensis is characterized by middorsal elevations on segments 1–9; paired paradorsal setae on segments 2–9 (unpaired on segment 8); laterodorsal setae on segments 2–9; ventromedial setae on segments 3–9. Furthermore, morphometric features of the European Setaphyes are analysed. Specifically, the morphometric analyses revealed sex-specific variability in the LTS/TL proportion, with females of all the European species of Setaphyes showing smaller LTS/TL. Thus, the LTS/TL ratio unveils a conspicuous sexual dimorphism in the genus.

Setaphyes algarvensis sp. nov. urn:lsid:zoobank.org:act: EC8A3AB5-D8E0-46D5-8A07-436FB91199EA Figs 2–4, Tables 1–2 Diagnosis Setaphyes with middorsal elevations on segments 1–6, superficially covered by tufts of elongated, thick hairs whose tips sometimes surpass the posterior margin of segment, and middorsal processes on segments 7–9. Paired paradorsal setae on segments 2–7 and 9; seta on segment 8 unpaired. Laterodorsal setae on segments 2–3 and 6–9 in males and 2–9 in females. Paralateral setae on segment 1. Lateroventral setae on segments 2–10 (two pairs on segment 5). Ventrolateral setae on segment 1 in males and 1–3 in females. Ventromedial setae on segments 3–9 in males and 4–9 in females. Small and abundant cuticular scars (likely outlets of glandular cells) scattered throughout the trunk. Lateral terminal spines present, short, slender. Etymology The species name, algarvensis, refers to the Algarve, the southern region of Portugal where the new species was found. Material examined Holotype PORTUGAL • adult ♂, mounted in Fluoromount G ® on a glass slide; Alvor; 37°07.714′ N, 08°36.329′ W; 16 Dec. 2012; intertidal mud with Zostera sp.; NHMD-921475. Paratypes PORTUGAL • 13 adult ♂♂, 1 adult ♀, mounted as the holotype; same collection data as for holotype; NHMD-921477–921489 (♂♂), NHMD-921476 (♀). Additional material PORTUGAL • 8 adult ♂♂, five of them mounted as the holotype and three mounted for SEM; same collection data as for holotype; UCM Meiofauna Collection. Description See Table 1 for measurements and dimensions and Table 2 for a summary of the middorsal cuticular specialization, seta, tube, nephridiopore and sensory spot locations. HEAD. With retractable mouth cone and introvert. Although two of the examined specimens had the head everted, their structures tend to collapse when mounted for LM; hence, only some details on the morphology of oral styles and scalids can be provided. Internal part of mouth cone with several rings of inner oral styles; exact number, arrangement and morphology not determined. External part of mouth cone with single ring of nine equally-sized outer oral styles, arranged as one anterior to each introvert sector, except for middorsal sector 6 where style is missing. Each outer oral style composed of single, flexible unit, wider at base, bearing fringed sheath, progressively tapering toward distally pointed tip. Introvert with six transverse rings of scalids and 10 longitudinal sectors defined by arrangement of primary spinoscalids. Primary spinoscalids larger than remaining scalids, each one composed of basal, rectangular, wide sheath and distal, elongated, distally pointed end-piece. Scalids from remaining rings regular-sized, similar in morphology to primary spinoscalids but smaller, also composed of a longer distal end-piece and a shorter basal sheath. Exact number, arrangement and detailed morphology of scalids not determined. NECK. With four dorsal and two ventral sclerotized placids (Fig. 2A–B). Dorsal placids rectangular, with a slightly convex anterior margin; mesial ones broader (ca 31–33 µm wide at base) than lateral ones (ca 28–30 µm wide at base) (Fig. 2B). Ventral placids (ca 22–23 µm wide at base) morphologically similar to dorsal ones but much more elongated, getting thinner towards lateral sides (Fig. 2A, C). TRUNK HABITUS. With eleven segments (Figs 2A–D, 3A, 4A, G). Segment 1 with one tergal, two episternal and one trapezoidal, midsternal plate; remaining segments with one tergal and two sternal cuticular plates (Figs 2A–D, 3A, 4A, G). Tergal cuticular plates slightly bulging middorsally (Fig. 4A). Sternal plates reach maximum width at segment 7, but almost constant in width across trunk. Sternal cuticular plates relatively narrow in ratio maximum width to total trunk length (MSW:TL average ratio = 25.23%), giving the animal a relatively slender appearance. Middorsal elevations on segments 1–6, rectangular, narrow, distally blunted, not projecting beyond posterior margin of segments (Figs 2B, 3B, F, H, 4A, E). Middorsal elevations covered by tufts of elongated, thick cuticular hairs whose tips may surpass posterior margin of segment (Figs 2B, 4A, E). Middorsal processes on segments 7–9, exceeding posterior margin of segment, also covered by tufts of elongated, thick cuticular hairs (Figs 2B, 3L, 4A, I). Middorsal processes progressively longer towards posterior trunk, reaching maximum length on segment 9 (Figs 2B, 4A, I). Paired, paradorsal, intracuticular butterfly- to trident-like atria associated with middorsal structures (Figs 3B, F, H). Glandular cell outlets as minute, dot-shaped, rounded to oval perforations throughout cuticle on segments 1–11 (Figs 2A–D, 3B, D, F–M, 4H); number and position of these structures vary greatly among examined specimens, not showing any specific pattern. Up to three pairs of conspicuous laterodorsal and ventromedial cuticular ridges on segments 2–10 (Figs 2A–D, 3E, H–J). Cuticular hairs acicular, non-bracteate, distributed across trunk on segments 1–10, not following any particular pattern (Fig. 4F, H, J). Pachycycli and ball-and-socket joints conspicuous on segments 2–9, reduced on segments 10 and 11 (Fig. 2A–B). Apodemes on segments 9–10 (Fig. 2A). Primary pectinate fringes finely serrated (Figs 2A–D, 3L, 4A, C–E, G–I); secondary pectinate fringes as wavy, quite inconspicuous single line (Figs 2A–D, 3J, 4H). Muscular scars as conspicuous, rounded to oval, hairless areas in laterodorsal and ventrolateral positions on segments 1–10 (Fig. 2A–D). SEGMENT 1. Middorsal elevation not projecting beyond posterior margin of segment (Figs 2B, 3B, 4A). Anterolateral margins of tergal plate as triangular, short, wide, distally rounded extensions (Figs 2A–C, 3C–D, 4G). Paired setae in paralateral and ventromedial positions (Figs 2A–C, 3C–E, 4B–C). Two pairs of sensory spots in subdorsal positions; and one pair in paradorsal and ventromedial positions (Figs 2A–C, 3B, D, 4B–C, F). Sensory spots on this and following segments as oval areas with several rows of cuticular micropapillae surrounding a single pore (Figs 2A–D, 3B, D, F–J, L–M, 4B–C, F, I–J). SEGMENT 2. Middorsal elevation as on preceding segment (Figs 2B, 3F, 4A). Paired setae in paradorsal, laterodorsal and lateroventral position; females with additional, sexually dimorphic pair in ventrolateral position (Figs 2A–C, 3E–G, 4C). Males with sexually dimorphic tubes in ventromedial position (Figs 2A, 3G, 4C, G). Paired sensory spots in paradorsal, subdorsal, laterodorsal and ventromedial positions (Figs 2A–C, 3F–G, 4C). SEGMENT 3. Middorsal elevation as on preceding segments (Figs 2B, 3F, 4A). Paired setae in paradorsal, laterodorsal, lateroventral and ventral positions. Additional paired setae in ventromedial position in males and in ventrolateral position in females (Figs 2A–C, 3E–G, 4C). Paired sensory spots in paradorsal, subdorsal, laterodorsal and ventromedial positions (Figs 2A–C, 3F–G, 4C). SEGMENT 4. Middorsal elevation as on preceding segments (Figs 2B, 4A). Paired setae in paradorsal (except for a single specimen, NHMD-921488, with unpaired paradorsal seta), lateroventral and ventromedial positions; females with additional, sexually dimorphic pair in laterodorsal position (Figs 2A–B, 4C). Paired sensory spots in paradorsal, subdorsal, laterodorsal and ventromedial positions (Figs 2A–B, 4C). SEGMENT 5. Middorsal elevation as on preceding segments (Figs 2B, 3H, 4A, E). One pair of setae in paradorsal (except for one additional male specimen, with unpaired paradorsal seta) and ventromedial positions, and two pairs in lateroventral position; females with additional, sexually dimorphic pair in laterodorsal position (Figs 2A–B, 3H–I, 4D–E). Paired sensory spots in paradorsal, subdorsal, laterodorsal and ventromedial positions (Figs 2A–B, 3H–I). SEGMENT 6. Middorsal elevation as on preceding segments (Figs 2B, 4A). Paired setae in paradorsal, laterodorsal, lateroventral and ventromedial positions (except for single specimen, NHMD-921489, with unpaired paradorsal seta) (Figs 2A–B, 4D). Paired sensory spots in paradorsal, subdorsal, laterodorsal and ventromedial positions (Fig. 2A–B); two specimens with deviation in pattern of sensory spots in this segment: one (NHMD-921475) with two ventral sensory spots on right half of segment (one ventromedial and one ventrolateral) and only ventromedial pair on left half, and another (NHMD- 921486) with one ventromedial sensory spot on left half of segment and without ventral sensory spot on right half of segment. SEGMENT 7. Middorsal process extending beyond posterior margin of segment (Figs 2B, 4A, I). Paired setae in paradorsal (except for single specimen, NHMD-921487, with unpaired paradorsal seta), laterodorsal, lateroventral and ventromedial positions (Fig. 2A–B). Paired sensory spots in paradorsal, subdorsal, laterodorsal and ventromedial positions (Fig. 2A–B). SEGMENT 8. Middorsal process as on preceding segment, slightly longer (Figs 2B, 3L, 4A, I). Unpaired seta in paradorsal position; paired setae in laterodorsal, lateroventral and ventromedial positions (Figs 2A–B, 3L–M, 4I–J). Paired sensory spots in paradorsal, subdorsal, laterodorsal and ventromedial positions (Figs 2A–B, 3L–M, 4I–J). SEGMENT 9. Middorsal process as on preceding segment, slightly longer (Figs 2B, 4A, I). Paired setae in paradorsal, laterodorsal, lateroventral and ventromedial positions (Figs 2A–B, D, 4I). Paired sensory spots in paradorsal, subdorsal, laterodorsal and ventrolateral positions (Figs 2A–B, D, 4I). Nephridiopore in lateroventral position. SEGMENT 10. Without middorsal cuticular specialization. Paired setae in lateroventral position (Figs 2A– B, D, 3J). Paired sensory spots in subdorsal, laterodorsal and ventrolateral positions (Figs 2A–B, D, 3J, 4I). SEGMENT 11. Without middorsal cuticular specialization. Tergal plate triangular, with concave and distally pointed posterior margin; sternal plates with pair of ventral extensions distally rounded (Figs 2A–B, D, 3J–K, 4A, G, I). Males with two sexually dimorphic pairs of stout, thick penile spines (Fig. 2A). Short lateral terminal spines, sexually dimorphic in length (LTS/TL average ratio ca 20% in males and ca 10% in females) (2A–B, D, 3A, J–K, 4G). Statistical analysis (Fig. 5, Table 1) The comparison of the total trunk length (TL) between Setaphyes algarvensis sp. nov. and S. kielensis revealed statistically significant differences (p S. kielensis (Fig. 5B), the ratio LTS/TL was compared between males and females in order to find sexually dimorphic differences. The statistical analysis revealed highly significant gender-based differences within this species (p S. algarvensis sp. nov. as well (Fig. 5B, the arrow points out the single female value), but this fact could not be statistically verified due to the fact that only a single female of this species was collected. Therefore, the LTS/TL ratio was only tested between males of both species, which revealed significant differences (p

Setaphyes elenae sp. nov. urn:lsid:zoobank.org:act: 6C4FE50F-E39A-451E-B805-60B709B9B9B4 Figs 2–4, Tables 1–3 Diagnosis Setaphyes with shortened, distally rounded middorsal processes on segments 1 and 9, and middorsal elevations on segments 2–9, superficially covered by tufts of elongated, thick hairs whose tips sometimes surpass the posterior margin of segment. Unpaired setae in paradorsal position on segments 1–9. Laterodorsal setae on segments 3, 5, 7 and 9; paralateral setae absent. Lateroventral setae on segments 2–10. Ventromedial setae on segments 3, 5 and 7. Paired, small, dot-shaped intracuticular structures (maybe outlets of glandular cells) present in several positions throughout the trunk, with a specific arrangement that differs from males to females. Males with paired, sexually dimorphic ventromedial tubes on segment 2, and females with paired, sexually dimorphic ventrolateral setae on segment 2. Lateral terminal spines present, relatively short, slender. Segment 11 retractable into segment 10. Etymology The species is dedicated to Ms Elena González, sister of the second author. Material examined Holotype ATLANTIC OCEAN • ♀ adult (mounted in Fluoromount G ®); near Syd-Hällsö Island, Skagerrak (Fig. 1B); 58°56.846′ N, 11°4.896′ E; 55–65 m depth; Ulf Jondelius and Fredrik Pleijel leg.; very fine mud; NHMD 655358. Paratypes ATLANTIC OCEAN • 3 adult ♂♂, 2 adult ♀♀ (all mounted in Fluoromount G ®); same collection data as for holotype; NHMD 655359 to 655363. Additional non-type material ATLANTIC OCEAN • 8 specs (four mounted for LM and four mounted for SEM); same collection data as for holotype; Meiofauna Collection UCM. Description See Table 1 for measurements and dimensions, Table 2 for summary of cuticular elevation, process, seta, tube, nephridiopore and sensory spot locations, and Table 3 for summary of intracuticular, dot-shaped structure locations. Head with retractable mouth cone and introvert. The collected specimens were not suitable for head examinations, hence data on number and arrangement of scalids and oral styles are not available. Neck with four dorsal and two ventral sclerotized placids (Fig. 2 A–B, D). Dorsal placids rectangular, with a slightly convex anterior margin; mesial ones broader than lateral ones (Fig. 2B). Ventral placids morphologically similar to dorsal ones but much more elongated, getting thinner towards the lateral sides (Fig. 2A, D). Trunk with eleven segments (Figs 2 A–B, 3A, H, 4A). Segment 1 with one tergal, two episternal and one sub-trapezoidal, midsternal plate; remaining ones with one tergal and two sternal cuticular plates (Figs 2 A–D, 3A, H). Tergal cuticular plates slightly bulging middorsally. Sternal plates reach their maximum width at segment 5, but are almost constant in width across the trunk, slightly tapering at the last three trunk segments (Figs 2 A–B, 3A, H). Sternal cuticular plates are relatively narrow in the ratio maximum width to total trunk length (MSW-5: TL average ratio = 27.2%), giving the animal a slender appearance (Figs 2 A–B, 3A, H, 4A). Middorsal processes on segments 1 and 9, shortened and distally rounded (Figs 2B, 3B, M, 4G, I); middorsal elevations on segments 2–8, pentagonally-shaped, distally rounded, with intracuticular, butterfly-like atria of paradorsal sensory spots (Figs 2B, 3D, F, I, K, 4B, E). Middorsal elevations superficially covered by tufts of elongated, thick cuticular hairs whose tips sometimes surpass the posterior margin of the segments (Fig. 4B, E). Intracuticular, minute, dot-shaped, rounded to oval structures (maybe outlets of glandular cells) throughout the cuticle on segments 1–10 (Figs 2 A–D, 3B–G, I–N). Location and pairs of these structures per segment differ from males to females (Table 3), and deviations from the bilateral symmetry of their arrangement have been observed in some specimens. Up to three pairs of conspicuous laterodorsal cuticular ridges on segments 2–10 (Figs 2 A– B, 3D–G, I–N). Cuticular hairs acicular, elongated, emerging from oval perforation sites, distributed all over the trunk cuticle. Pachycycli and ball-and-socket joints only conspicuous on segments 2–3, reduced on posterior segments (Fig. 2 A–B, D). Apodemes on segments 7–10 (Fig. 2 A–C). Primary pectinate fringe finely serrated; secondary pectinate fringe as a double tranverse, hairy-like, wavy row; free flaps covering the anterior part of subsequent segment (Figs 2 A–D, 4D). Muscular scars as rounded to oval, hairless areas in laterodorsal and ventromedial positions on segments 1–10 (those of segment 1 in subdorsal and ventrolateral positions), quite inconspicuous (Fig. 2 A–D). Segment 1 with shortened, distally rounded middorsal process still extending beyond the posterior margin of segment (Figs 2B, 3B, 4G). Anterolateral margins of the tergal plate as horn-shaped, short, wide, distally curved and pointed extensions (Figs 2 A–B, D, 3A–C, H, 4A). Anterior margin of segment with a reticule-like ornamentation dorsally (Figs 2B, 3B, 4C). Setae absent. Two pairs of sensory spots . in ventrolateral position longitudinally arranged, and one pair in paradorsal, subdorsal and laterodorsal positions (Figs 2 A–B, D, 3B–C, 4G). Sensory spots on this and subsequent segments as oval areas with several rows of cuticular micropapillae surrounding a single pore (Fig. 4B, G, J). Segment 2 with middorsal elevation not projecting beyond the posterior margin of segment (Figs 2B, 3D, 4E). Unpaired seta in paradorsal position, on this and following segments indifferently located to the right or to the left of the middorsal cuticular specialization, not following any particular pattern, near the anterior margin of the segment (Figs 2B, 3D, 4E); paired setae in lateroventral position (Figs 2 A–B, D, 3E); females furthermore with paired, sexually dimorphic setae in ventrolateral position (Figs 2A, 3E). Sexually dimorphic male tubes in ventromedial position (Fig. 2D); detailed morphology of these tubes not determined. Paired sensory spots in paradorsal, laterodorsal and ventrolateral position, the latter near the ventrolateral-ventromedial limit, not longitudinally aligned with the following ventromedial sensory spots (Figs 2 A–B, D, 3D–E). Segment 3 with middorsal elevation as on the preceding segment (Figs 2B, 3F). Unpaired seta in paradorsal position (Figs 2B, 3F); paired setae in laterodorsal, lateroventral and ventromedial positions (Figs 2 A–B, 3F–G). Paired sensory spots in paradorsal, subdorsal, laterodorsal and ventromedial positions, the latter mesially shifted compared to the previous ones, aligned with those of the following segments (Figs 2 A–B, 3F–G). Segment 4 with middorsal elevation as on the preceding segment (Figs 2B, 3I, 4B). Unpaired seta in paradorsal position (Figs 2B, 3I); paired setae in lateroventral position (Figs 2 A–B, 3J). Paired sensory spots in paradorsal, subdorsal, laterodorsal and ventromedial positions (Figs 2 A–B, 3I–J). Segment 5 similar to segment 3 in the arrangement of the cuticular elevation, setae and sensory spots (Figs 2 A–B, 4F, H). Segment 6 similar to segment 4 in the arrangement of the cuticular elevation, setae and sensory spots (Fig. 2 A–B). Segment 7 similar to segments 3 and 5 in the arrangement of the cuticular elevation, setae and sensory spots (Fig. 2 A–B). Segment 8 with middorsal elevation as on the preceding segment (Figs 2B, 3K). Unpaired seta in paradorsal position (Figs 2B, 3K); paired setae in lateroventral position (Fig. 2 A–B). Two pairs of sensory spots in subdorsal position, and one pair in paradorsal, laterodorsal and ventromedial positions (Figs 2 A–B, 3K–L, 4J). Segment 9 with middorsal process as that of segment 1 (Figs 2B, 3M, 4I). Unpaired seta in paradorsal (Figs 2B and 3M); paired setae in laterodorsal and lateroventral positions (Fig. 2 A–B). Two pairs of sensory spots in subdorsal position, and one pair in paradorsal, laterodorsal and ventromedial positions (Figs 2 A–B, 3M–N, 4I). Nephridiopores in lateroventral position. Segment 10 without middorsal cuticular specialization. Paired setae in lateroventral position (Figs 2 A– C, 4I). Two pairs of sensory spots in subdorsal position, and one pair in laterodorsal and ventrolateral positions, the latter near the tergosternal junction (Figs 2 A–C, 4I). Segment 11 without cuticular appendages, partly retractable into segment 10 (Fig. 4A, I). Tergal plate triangular, with a concave and distally pointed posterior margin; sternal plates form a pair of ventral extensions rounded distally (Figs 2 A–C, 4I). Males with two sexually dimorphic pairs of stout, thick penile spines (Fig. 2C). Lateral terminal spines’ length differs from males (relatively longer, LTS average ratio = 158.93 μm) to females (relatively shorter, LTS average ratio = 100.9 μm)