Setaphyes dentatus
Creators: name: González-Casarrubios, Alberto
name: Cepeda, Diego
name: Neuhaus, Birger
name: García-Cobo, Marta
name: Pardos, Fernando
name: Ürkmez, Derya
name: Sánchez, Nuria
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Kinorhyncha
Allomalorhagida
Pycnophyidae
Setaphyes
Setaphyes dentatus

description: 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).
description: 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