Echinoderes inaequalis, Herranz & Moreleon & Rho & Sørensen, 2023

Herranz, María, Moreleon, Alexis D., Rho, Hyun Soo & Sørensen, Martin V., 2023, Expanding the Echinoderes coulli group (Kinorhyncha: Cyclorhagida) with a new species from the Chuuk Islands, Micronesia, Zoologischer Anzeiger 302, pp. 67-74 : 68-72

publication ID	https://doi.org/ 10.1016/j.jcz.2022.11.010
DOI	https://doi.org/10.5281/zenodo.8171330
persistent identifier	https://treatment.plazi.org/id/039F6C5A-DA3F-FFEB-FF31-A443FBD4FA8E
treatment provided by	Felipe
scientific name	Echinoderes inaequalis
status	sp. nov.

Treatment

Species E. inaequalis View in CoL sp. nov.

urn:lsid:zoobank.org:act:41BC4BF8-

E3B4–445C–87F1–9C6D2CC97AA2.

( Figs. 2–4 View Fig View Fig View Fig , Tables 1–2 View Table 1 View Table 2 ).

3.1.1. Etymology

The species name comes from the Latin in- (un or not) and -aequ¯alis (equal or even), meaning, the uneven one, referring to the distinctive asymmetric distribution of subdorsal tubes on segments 5 to 7.

3.1.2. Diagnosis

Echinoderes with a single, minute middorsal spine on segment 4. Lateroventral tubes on segments 5, 7–9, midlateral tubes on segment 8, and sexually dimorphic laterodorsal tubes on segment 10. Single subdorsal tubes usually in alternating positions on segments 5–7 with intraspecific variation. Small glandular cell outlets type 2 in subdorsal, laterodorsal and ventrolateral positions on segment 2, subdorsal position on segment 4, and midlateral positions on segments 5–7; large, conspicuous, laterodorsal glandular cell outlets type 2 are present on segment 8. Large nephridial areas composed of elongated sieve plates and a posterior pore in sublateral position on segment 9. Short and stout lateral terminal spines with fringed edges. Males with three pairs of slender penile spines, and well-developed laterodorsal tubes on segment 10. Females with short and thin lateral terminal accessory spines, and reduced laterodorsal tubes on segment 10.

3.1.3. Material examined

Holotypic female collected by HSR on March 21st, 2007 from coral sand at 1–2 m depth at Chuuk Islands , Micronesia (locality MAP-19: 007 ◦ 27’11’’N, 151 ◦ 54’15’’E) ( Fig. 1 View Fig ); mounted in Fluoromount G on a glass slide and deposited at the Natural History Museum of Denmark, under catalogue number NHMD-1176540 GoogleMaps .

Paratypes series include five specimens, three females and two males all of them mounted in Fluoromount G on glass slides and deposited at the Natural History Museum of Denmark, under catalogue numbers NHMD-1176541 to 45. Of those, male paratypes NHMD-1176542, NHMD-1176545 and female paratype NHMD-1176541 were collected at the same locality as the holotype; whereas the two remaining female paratypes, NHMD-1176543 and NHMD-1176544, were collected on March 9th, 2007 from subtidal sediment at 30 m depth (locality MAP-01: 007 ◦ 27’27’’N, 151 ◦ 53’52’’E) GoogleMaps .

Additional material includes 17 specimens mounted for SEM and stored in MVS personal reference collection .

3.1.4. Description

Adults with head, neck and eleven trunk segments ( Figs. 2 View Fig , 3A View Fig and 4A View Fig ). Measurements and dimensions are given in Table 1. A View Table 1 summary of sensory spots, spines, tubes and glandular cell outlet positions is provided in Table 2 View Table 2 . Mouth cone and introvert could not be studied in detail due to the poor condition of the SEM specimens prepared 14 years ago.

The neck consists of 16 placids numbered clockwise from the midventral 1 ( Fig. 3B and C View Fig ). Placids 2–16 are trapezoid measuring 9 μm at the base while the midventral placid is more rectangular and wider measuring 15 μm (Fig.. 2B, 3B–C). All placids articulate with the first trunk segment. Trichoscalid plates bearing trichoscalids appear dorsally on placids 6, 8, 10, 12 and ventrally on placids 2 and 16. Ventral trichoscalid plates are triangular with rounded edges, while dorsal trichoscalid plates are rounded and smaller ( Figs. 2 View Fig , 3B–C View Fig ).

Trunk segments 1 and 2 consist of one closed cuticular ring ( Figs. 2 View Fig , 3 View Fig A-C, 4A-B) while segments 3–11 are composed of one tergal and two sternal plates ( Figs. 2 View Fig , 3A View Fig and 4A View Fig ). Glandular cell outlets type 1 consist of numerous minute pores arranged in a circle, situated in the anterior part of the segments, usually hidden under the posterior part of the previous segment and quite inconspicuous. Dorsal glandular cell outlets type 1 are located middorsally on segments 1–3, 10–11 and paradorsally on segments 4–9 ( Fig. 2 View Fig ). Ventral glandular cell outlets type 1 are lateroventral on segment 1 and ventromedial on segments 2–10 ( Fig. 2 View Fig ). Primary pectinate fringe well developed in all segments, composed of very short fringe tips on segments 1 and 2 ( Figs. 2 View Fig and 4B View Fig ) and long and flexible tips in remaining segments ( Figs. 2 View Fig and 4B View Fig ). Secondary pectinate fringe absent on segment 1, and on segments 2–11 consisting of a single line of minute and regular teeth usually hidden under the primary pectinate fringe of previous segment ( Fig. 4B View Fig ).

Segment 1 with rounded sensory spots formed by a collar of short papillae surrounding at least one pore ( Fig. 4B View Fig ); sensory spots are located near the anterior segment margin in subdorsal and laterodorsal positions, and centrally in ventromedial position ( Figs. 2 View Fig , 3B–C View Fig , 4B View Fig ). Cuticular hairs are abundant and distributed forming a wide belt covering most of the dorsal and ventral surface of the segment, except for the anterior margin of the segment, ventral area with a less dense hair covering ( Figs. 2 View Fig , 3B–C View Fig , 4B View Fig ). All cuticular hairs emerging from round perforation sites in this and the following segments. The posterior segment margin is straight along the dorsal and lateral side but extends slightly posteriorly in the ventromedial and midventral areas.

Segment 2 with glandular cell outlets type 2, located in subdorsal, laterodorsal and ventrolateral positions ( Fig. 2A and B View Fig , 3B–C View Fig , 4B, E View Fig ). These are small with delicate fringed margins. Sensory spots present in middorsal, laterodorsal, midlateral and ventromedial positions; sensory spots on this and the following segments are oval. Hairs densely distributed in a belt covering the segment showing hairless areas in the anterior margin of the segment in ventromedial position ( Fig. 4B–C, E View Fig ). Hairs increasing in length posteriorly.

Segment 3 with sensory spots in subdorsal and sublateral positions ( Fig. 2A and B View Fig ). Dorsal hair pattern dense, cuticular hairs on the ventral side are covering the sternal plates except for hairless areas on the anterior margin of the sternal plates and narrow patches in ventromedial positions in this and the following segments.

Segment 4 with a very short acicular middorsal spine (ca. 11 μm measured from SEM) ( Fig. 2A and B View Fig , 3E View Fig , 4C View Fig ). Glandular cell outlets type 2 present in subdorsal position ( Figs. 2A View Fig , 3E View Fig and 4C View Fig ). Sensory spots present in laterodorsal position. Other characters similar to previous segment.

Segment 5 with lateroventral tubes and a single additional tube in subdorsal position ( Fig. 2A and B View Fig , 3 View Fig D-E, 4D, G). Each tube consists of a short and smooth basal part, and a longer distal part in this and the following segments ( Fig. 4G View Fig ). Glandular cell outlets type 2 present in midlateral position ( Figs. 2A View Fig and 4G View Fig ). Sensory spots present in subdorsal, laterodorsal and ventromedial positions ( Fig. 2A and B View Fig ). Other characters similar to previous segment.

Segment 6 with a single subdorsal tube usually, but not consistently, in alternating position in respect to the single tube on segment 5 ( Figs. 2A View Fig , 3G View Fig and 4H View Fig ). Glandular cell outlets type 2 present in midlateral position ( Figs. 2A View Fig and 3G View Fig ). Sensory spots present in subdorsal, sublateral and ventromedial positions ( Fig. 2A and B View Fig ). Remaining characters as on previous segments.

Segment 7 with lateroventral tubes, and an additional single tube located in subdorsal position, the latter usually alternating in position with the unpaired tube of the preceding segment ( Fig. 2A and B View Fig , 3 View Fig F-G, 4H). Glandular cell outlets type 2 present in midlateral position ( Fig. 3G View Fig ). Sensory spots present in subdorsal, laterodorsal and ventrolateral positions ( Fig. 2A and B View Fig , 4H View Fig ). Remaining characters as on previous segments.

Segment 8 with tubes in lateroventral and midlateral positions ( Fig. 2A and B View Fig , 4F View Fig ). Large glandular cell outlets type 2 with fringed edges present in laterodorsal position ( Fig. 2A and B View Fig , 3K View Fig , 4F View Fig ). Sensory spots present in subdorsal position. Other characters similar to previous segments.

Segment 9 with tubes in lateroventral position. Sensory spots present in subdorsal, laterodorsal, midlateral and ventrolateral positions ( Fig. 2A and B View Fig , 3J View Fig ). Elongated nephridial areas present in sublateral position, and consisting of an oval perforated sieve plate (ca. 12 μm) with a posterior round pore ( Fig. 3 View Fig J- J’, 4I). Other characters similar to previous segments.

Segment 10 with tubes in laterodorsal positions, at or near the posterior segment margin. In males the tubes are long and similar of those described on segments 5–9 (Fig.. 2C and 4M), whereas in females the tubes lack the basal part, showing just a flexible and short tubular structure ( Figs. 2A View Fig and 4J View Fig ). Very elongated sensory spots composed of two or three rows of short parallel papillae present in subdorsal and ventrolateral positions ( Figs. 2 View Fig , 4 View Fig J-K). The posterior segment margin of the tergal plate is straight and with a small, but well-developed, pectinate fringe, whereas the margins of the sternal plates are concave, extending posteriorly near the midventral junction, and with well-developed fringe tips ( Fig. 2B, D View Fig , 4K View Fig ).

Segment 11 with short and stout lateral terminal spines with lateral fringes, and a short fringe wrapping the spine medially ( Figs. 2 View Fig and 3A, H–I View Fig , 4J View Fig ). Males with three pairs of tubular, and flexible penile spines, two of them long, and one slightly shorter ( Fig. 2B and C View Fig , 3H View Fig , 4 View Fig L-M). Females with a pair of short, thin and hairy lateral terminal accessory spines ( Fig. 2A and B View Fig , 3I View Fig , 4 View Fig J-K). Sensory spots are present in subdorsal position (two pairs) and in ventromedial position. The ventromedial sensory spots are very small, and located at the posterior margin of the sternal plate ( Fig. 4K View Fig ). One of the subdorsal pairs of sensory spots is also small and located on the margin of the tergal extensions ( Fig. 2 View Fig ). The tergal plate is covered in hair-like extensions without perforation sites; sternal plates with a ventromedial fringed area ( Fig. 2B, D View Fig , 4K View Fig ). The margins of the sternal plates are curved and covered by long hairs that get shorter towards the lateroventral area ( Fig. 4K View Fig ). Tergal extensions are pointed extending further than the sternal plates and with a small distal notch ( Figs. 2 View Fig , 3H–I View Fig , 4 View Fig J-K).