Echinoderes abeli, Anguas-Escalante & Herranz & Martínez-Arce & De Jesús-Navarrete & Sørensen, 2023

Anguas-Escalante, Abril, Herranz, María, Martínez-Arce, Arely, De Jesús-Navarrete, Alberto & Sørensen, Martin V., 2023, New Echinoderes (Kinorhyncha: Cyclorhagida) from Mexico: Molecular barcoding demonstrate species delimitation between highly similar morphospecies, Zoologischer Anzeiger (Zool. Anz.) 302, pp. 146-165 : 148-154

publication ID	https://doi.org/ 10.1016/j.jcz.2022.12.001
persistent identifier	https://treatment.plazi.org/id/9B181279-A262-AD25-B89E-F9F384B33DB7
treatment provided by	Felipe
scientific name	Echinoderes abeli
status

Treatment

Genus Echinoderes View in CoL Clapar`ede, 1863.

E. abeli sp. nov.

Figs. 2–5 View Fig View Fig View Fig View Fig , Tables 2 and 3

urn:lsid:zoobank.org:act:309071B7-67A0-44E0-BC6A-595BFBC6BB68 .

3.1.1. Diagnosis

Echinoderes with very short and stout lateral terminal spines, middorsal spines on segments 4 to 8, and lateroventral spines on segments 6 to 9. Tubes present in lateroventral positions on segments 2 and 5, midlateral positions on segment 4, sublateral positions on segment 8, and in laterodorsal positions on segment 10; laterodorsal tubes show sexual dimorphism. Glandular cell outlets type 2 present in subdorsal positions on segment 2. Posterior margins of segment 11 do not terminate into projecting tergal or sternal extensions. Females with lateral terminal accessory spines, and minute laterodorsal tubes on segment 10. Males with long laterodorsal tubes on segment 10 and three pairs of penile spines.

3.1.2. Etymology

The species is named after biologist Abel Abraham Vargas Espositos, who collected the sediment samples, and always is available to help with samplings in the ECOSUR Laboratory.

3.1.3. Material examined

Holotypic male, collected on Station 8 on Sept. 15, 2019, from medium coarse sand at 62 m depth, near Maria Magdalena Island off the Nayarit state (21 ◦ 28 ′ 04 ′′ N 106 ◦ 19 ′ 12 ′′ W); mounted in Fluoromount G ® between two cover slips attached to a plastic H–S slide, and deposited at the Natural History Museum of Denmark under catalogue number NHMD-920097. Paratype, one female, same collecting data and mounting (although in 100% glycerine), deposited under catalogue number NHMD-920098. Additional material includes two females, same collecting data as holotype, mounted for SEM and stored in the MVS personal reference collection GoogleMaps .

3.1.4. Description

Echinoderes with very short and stout lateral terminal spines. Adults with head, neck, and eleven trunk segments ( Fig. 2A–B View Fig , 3 View Fig , 4A View Fig , 5 View Fig A-B). For a complete overview of measures and dimensions, see Table 2. Distribution of cuticular structures, i.e., sensory spots, glandular cell outlets, spines, and tubes, is summarized in Table 3.

The head consists of a retractable mouth cone and an introvert ( Figs. 3 View Fig and 5C, D View Fig ). Inner oral styles of mouth cone could not be examined. The external mouth cone armature consists of nine outer oral styles; bases of outer oral styles each flanked by a pair of short spikes; two central, distally bifurcated bristles are present more posteriorly ( Fig. 5C View Fig ). The introvert sectors are defined by the ten primary spinoscalids in Ring 01 ( Fig. 3 View Fig ). Each primary spinoscalid consists of a basal sheath and a distal end piece with a blunt tip ( Fig. 5D View Fig ). Each sheath has two transversal fringe rows, with long fringe tips emerging from the most proximal row, and fringe tips from the distal row extending to the end of the sheath. The end pieces are flexible and smooth. Ring 02 and Ring 04 have 10 spinoscalids, Ring 03 has 20 spinoscalids, and Ring 05 has 16 spinoscalids ( Fig. 3 View Fig ). All spinoscalids in these rings are well developed and consist of a basal sheath and a pointed end piece. Distal margins of the basal sheaths of Ring 02 have fringes tips arranged in a Vshape, which are long in the centre and short laterally. Ring 03 has shorter marginal fringe tips, and a central spike-like tip on the proximal part of the sheath. The spinoscalids of Ring 04 resemble those of Ring 02 but are shorter. Spinoscalids in Ring 05 have basal sheaths with marginal fringes tips being long along the lateral sides and short in the middle. Rings 06 has only five spinoscalids located in sectors one, 3, 5, 7, and 9. Spinoscalids in this ring have short and slender end pieces, but the basal sheaths are reduced to a pair of spikes.

Described sector-wise ( Fig. 3 View Fig ), sectors 1, 3, 5, 7, and 9 are very similar, having spinoscalids arranged as two double diamonds. Sectors 2, 4, 8, and 10 have spinoscalids forming one diamond, anterior to an unpaired, lateral spinoscalid; the lateral spinoscalid is unpaired because a trichoscalid plate takes up the space on the opposite side of the sector. Sector 6 has a single unpaired spinoscalid in Ring 02, and five spinoscalids arranged as a quincunx, in Rings 03 to 05.

The neck has 16 placids, measuring 11 μm in length. The midventral placid is broadest, measuring 13 μm in width at its base, whereas all others are narrower, measuring 6 μm at their bases. The trichoscalid plates, each equipped with a trichoscalid, are well developed; subdorsal and laterodorsal ones are narrow and elongated, and ventromedial ones hat-shaped.

Segment 1 consists of a complete cuticular ring ( Fig. 2A–B View Fig , 4B–C View Fig , 5 View Fig E- F). Sensory spots are located in subdorsal and laterodorsal positions, close to the anterior margin of the segment, and in ventrolateral positions, more medial on the segment; sensory spots on this and the following segment are small and rounded, consisting of a ring of micropapillae and a central pore. Glandular cell outlets type 1 present in middorsal and lateroventral positions; on this and the following nine segments glandular cell outlets type 1 appear in LM as a short string of pearls (e.g., Fig. 4E, G View Fig ), but with the orientation of the string differing; middorsal outlets on present segment arranged longitudinally, and lateroventral ones transverse. Dorsal, lateral, and ventral sides with numerous cuticular hairs emerging through rounded perforation sites. The posterior segment margin is straight along the dorsal and lateral sides, and broadly convex on the ventral side. Pectinate fringe of posterior segment margin with very short, uniform fringe tips along dorsal and lateral sides, but conspicuously longer on the ventral side.

Segment 2 consists of a complete cuticular ring ( Fig. 2A–B View Fig , 4B–C View Fig , 5 View Fig E- F). Pachycyclus of the anterior segment margin is of medium thickness and uninterrupted. Tubes are located in lateroventral positions. Sensory spots are located in middorsal, laterodorsal, and ventromedial positions. Glandular cell outlets type 2 are present in subdorsal positions ( Figs. 2A View Fig , 4C View Fig and 5E, H View Fig ). Glandular cell outlets type 1, oriented longitudinally in middorsal position and obliquely in ventromedial positions. Cuticular hairs on this and following segments are bracteate. On the ventral side, patches with short hairs are present in paraventral and ventrolateral positions and arranged in three more or less well-defined transverse rows. Long hairs present on the anterior part of the dorsal side, arranged in somewhat well-defined transverse rows. Anterior lateral side with four transverse rows of hairs. The posterior segment margin is straight along the dorsal and lateral sides, and the ventral margin is more convex than segment 1. Pectinate fringe of posterior segment margin as preceding segment but with fringe tips smaller along the paraventral margins.

Segment 3, and remaining segments, consisting of one tergal and two sternal plates ( Fig. 2A–B View Fig , 4B–C View Fig ). Pachycyclus of the anterior segment margin of medium thickness and interrupted middorsally and at the tergosternal junctions. Sensory spots present in subdorsal and sublateral positions; sensory spots on this and the following segments more irregular in shape, and with even fewer, marginal micropapillae. Glandular cell outlets type 1 present transversally in middorsal position and obliquely in ventromedial positions. Cuticular hairs present laterally on sternal plates, whereas the paraventral areas are hairless. Tergal cuticular hairs arranged in four more or less well-defined transverse rows. Pectinate fringe pattern of posterior segment as preceding segment 1 but fringe tips slightly longer.

Segment 4 ( Fig. 2A–B View Fig , 4D View Fig , 5H View Fig ) with acicular spine in middorsal position and tubes in midlateral positions. Sensory spots not present. Glandular cell outlets type 1 present obliquely in paradorsal and ventromedial positions. Cuticular hair patterns and pachycycli as on preceding segment. Pectinate fringe of posterior segment margin on the tergal plate short and small but slightly longer in paradorsal positions, fringe tips with uninform length along tergal plate and conspicuously longer on the sternal plates.

Segment 5 ( Fig. 2A–B View Fig , 4 View Fig D-E) with acicular spine in middorsal position and tubes in lateroventral positions. Sensory spots present in midlateral and ventromedial positions. Glandular cell outlets type 1 present obliquely in paradorsal and ventromedial positions. Pachycycli, cuticular hair pattern, and pectinate fringe as on preceding segment.

Segment 6 ( Fig. 2A–B View Fig , 4 View Fig D-E) with acicular spines in middorsal and lateroventral positions. Sensory spots present in paradorsal, laterodorsal, and ventromedial positions. Glandular cell outlets type 1 present obliquely in paradorsal and ventromedial positions. Cuticular hairs covering anterolateral parts of sternal plates and arranged in three more or less well-defined transverse rows on tergal plate. Pachycycli and pectinate fringe as on preceding segment.

Segment 7 ( Fig. 2A–B View Fig , 4 View Fig E-G, 5G) with acicular spines in middorsal and lateroventral positions. Sensory spots present in paradorsal, subdorsal, laterodorsal, and ventromedial (but more lateral) positions. Glandular cell outlets type 1 present obliquely in paradorsal and ventromedial positions. Cuticular hair patterns, pachycycli and pectinate fringe as on preceding segment.

Segment 8 ( Fig. 2A–B View Fig , 4 View Fig F-G, 5G) with acicular spine in middorsal and lateroventral positions, and tubes in sublateral positions. Sensory spots present in paradorsal, laterodorsal positions. Glandular cell outlets type 1 present obliquely in paradorsal and ventromedial positions. Numerous disorganized cuticular hairs present, covering more than half of the tergal plate and anterolateral parts of sternal plates. Pachycycli and pectinate fringe of as on preceding segment.

Segment 9 ( Fig. 2A–B View Fig , 4F View Fig ) with acicular spines in lateroventral positions. Sensory spots present in paradorsal, subdorsal, and ventrolateral positions. Glandular cell outlets type 1 present obliquely in paradorsal and ventromedial positions. Small, oval sieve plate present in sublateral positions. Pachycycli, pectinate fringe of posterior segment margin, and cuticular hairs as on preceding segment.

Segment 10 ( Fig. 2A–D View Fig , 4 View Fig H-J, 5J-K) with sexually dimorphic tubes in laterodorsal positions, inserting at posterior segment margin; tubes in females minute ( Figs. 2A View Fig and 5K View Fig ) and tubes in males long ( Fig. 2C–D View Fig , 4I View Fig ). Sensory spots present in subdorsal and ventrolateral positions. Glandular cell outlets type 1 present as two longitudinally arranged middorsal ones and a longitudinal pair in paraventral positions. The posterior segment margin of the tergal plate is straight, whereas margins of sternal plates are deeply concave; fringe tips of pectinate fringe are wider than those on preceding segments. Cuticular hairs arranged in six more or less well-defined transverse rows completely covering the tergal and sternal plates. Pachycyclus interrupted only at tergosternal junctions.

Segment 11 with conspicuously stout and short lateral terminal spines ( Fig. 2A–D View Fig , 4A View Fig , H-J, 5I–K). Sensory spots present in ventromedial positions near posterior margins of sternal plates. A middorsal protuberance with a glandular cell outlet type 1 emerges from the intersegmental joint between segments 10 and 11 ( Fig. 2A, C View Fig ,44J, 5I). Males with three pairs of penile spines; dorsal and ventral penile spines are thin, flexible tubes, whereas the median penile spine is short ( Fig. 2C–D View Fig , 3H–I View Fig ); females with short, thin lateral terminal accessory spines ( Fig. 2A–B View Fig , 4J View Fig , 5I, K View Fig ). The segment does not terminate into distinct tergal or sternal extensions; tergal plate with nearly straight posterior minute fringe tips ( Fig. 5I View Fig ), and sternal plates posteriorly rounded with more well-developed fringe tips in paraventral areas.