Echinoderes kathleenhannae, Sørensen & Macheriotou & Braeckman & Smith & Ingels, 2025

Sørensen, Martin V., Macheriotou, Lara, Braeckman, Ulrike, Smith, Craig R. & Ingels, Jeroen, 2025, Antarctic Kinorhyncha: Seven new species from the Antarctic Peninsula, European Journal of Taxonomy 1000 (1), pp. 1-102 : 51-58

Echinoderes kathleenhannae sp. nov.

urn:lsid:zoobank.org:act:DD7B8B21-DE35-47FC-98F7-B0A8F3832421

Figs 16–18 , Tables 13–14

Diagnosis

Echinoderes with acicular spines in middorsal position on segments 4, 6, and 8, and in lateroventral positions on segments 6 to 9. Tubes present in subdorsal, laterodorsal, sublateral, and ventrolateral positions on segment 2, in lateroventral positions on segment 5, in laterodorsal and lateral accessory positions on segment 8, and in laterodorsal positions on segment 10; tubes on segment 10 show sexual dimorphism and are largest in males. Female papillae or glandular cell outlets type 2 not present. Dorsal glandular cell outlets type 1 are present in middorsal positions on segments 1 to 3, 5, 7, and 10, and in paradorsal positions on segments 4, 6, 8, and 9. Sieve plates present on segment 9 in sublateral positions.

Etymology

The species is dedicated to the musician, artist, activist and rebel girl, Kathleen Hanna.

Material examined

Holotype

ANTARCTICA • ♂ (mounted for LM in Fluoromount G on HS slide); Antarctic Peninsula, CRS 1793; 64°39.53′ S, 62°55.03′ W; 701 m b.s.l.; 11 Apr. 2016; FjordEco2; soft sediment; NHMD 1786779 .

Additional material

ANTARCTICA • 1 ♀ (mounted for SEM); same data as for holotype; MVS • 3 ♂♂, 1 ♀ (mounted for SEM);Antarctic Peninsula, CRS 1832; 64°39.30′ S, 62°55.98′ W; 631 m b.s.l.; 21 Apr. 2016; FjordEco2; soft sediment; MVS .

Description

GENERAL. Adults with head, neck and eleven trunk segments ( Figs 16A–B , 17A , 18A–C ). An overview of measurements and dimensions is given in Table 13. Distributions of cuticular structures, i.e., sensory spots, glandular cell outlets, spines and tubes, are summarized in Table 14.

HEAD. All specimens had their heads fully retracted; thus, information on head morphology is not available.

NECK. With 16 placids. Midventral placid broadest, 12 µm in width and 13 µm in length, whereas all others are narrower, measuring 8 µm in width at their bases. The trichoscalid plates are well-developed and hat-shaped.

SEGMENT 1. Consists of a complete cuticular ring. Sensory spots are present in subdorsal and laterodorsal positions; the sensory spots are small, with numerous micropapillae and two long cuticular hairs attached on the margin of the papillated area. Glandular cell outlets type 1 are present in middorsal and ventrolateral positions. Cuticular hairs emerge from rounded perforation sites and are arranged in four to five rows on the dorsal side, and only two to three rows on the ventral. The posterior segment margin is almost straight and terminates in a pectinate fringe with rather broad fringe tips ( Figs 16A–B , 17B–C , 18D–F ).

SEGMENT 2. Consists of a complete cuticular ring. Tubes are located in subdorsal, laterodorsal, sublateral, and ventrolateral positions; all tubes are very slender, and the proximal thickenings are hardly visible. Sensory spots present in middorsal, laterodorsal, and ventromedial positions; the micropapillary areas around the sensory spots on this, and all following segments, are rounded, with up to five longer micropapillae extending from the posterior part of the papillated areas. Glandular cell outlets type 1 are present in middorsal and ventromedial positions. Bracteate cuticular hairs are arranged in three to four transverse rows; hairs in the first and second anterior rows are rather short, whereas those of the most posterior row are longer. The posterior segment margin is nearly straight. Pectinate fringe of dorsal and lateral margins well-developed, as on preceding segment; pectinate fringe of ventrolateral to midventral margins narrower and with extended, flexible tips ( Figs 16A–B , 17B–C , 18D–F ).

SEGMENT 3. As remaining segments, consisting of one tergal and two sternal plates. Sensory spots are present in subdorsal and sublateral positions, and glandular cell outlets type 1 in middorsal and ventromedial positions. The hair covering of the tergal and lateral halves of sternal plates is dense on the anterior half of the segment, except in hair-less midlateral areas; bracteate cuticular hairs are arranged in five to six rows, and the hairs in each row get progressively longer towards the more posterior rows. Paraventral areas without bracteate hairs, but with rhomboid patch of well-developed hair-like extensions. Posterior segment margin straight, and pectinate fringe as on preceding segment ( Figs 16A–B , 17B–C ).

SEGMENT 4. With spine in middorsal position; middorsal spines on this and segments 6 and 8 are uniform in length, rather than getting progressively longer towards the more posterior segments. Sensory spots are not present. Glandular cell outlets type 1 are present in paradorsal and ventromedial positions. Cuticular hairs, posterior segment margin, and pectinate fringe as on preceding segment ( Figs 16A–B , 17D–E ).

SEGMENT 5. With tubes in lateroventral positions. Sensory spots present in subdorsal, midlateral and ventromedial positions, and glandular cell outlets type 1 in middorsal and ventromedial positions. Cuticular hairs, posterior segment margin, and pectinate fringe as on preceding segment ( Figs 16A–B , 17D–E , 18G–I ).

SEGMENT 6. With spines in middorsal and lateroventral positions; lateroventral spines on this and following segments are almost uniform in length, rather than getting progressively longer towards the more posterior segments. Sensory spots present in paradorsal, midlateral and ventromedial positions, and glandular cell outlets type 1 in paradorsal and ventromedial positions. Cuticular hairs, posterior segment margin, and pectinate fringe as on preceding segment ( Figs 16A–B , 17D–E , 18G–I ).

SEGMENT 7. With spines in lateroventral positions. Sensory spots present in subdorsal, midlateral, and ventromedial positions, and glandular cell outlets type 1 in middorsal and ventromedial positions. Cuticular hairs, posterior segment margin, and pectinate fringe as on preceding segment ( Figs 16A–B , 17F–G , 18L ).

SEGMENT 8. With spines in middorsal and lateroventral positions, and tubes in laterodorsal and lateral accessory positions. Sensory spots present in paradorsal positions only, and glandular cell outlets type 1 in paradorsal and ventromedial positions. Cuticular hairs as on preceding segment, except for mid- and paradorsal areas, where the bracteate hairs are replaced by very fine hair-like extensions. Posterior segment margin and pectinate fringe as on preceding segment ( Figs 16A–B , 17F–J , 18J–L ).

SEGMENT 9. With spines in lateroventral positions. Sensory spots present in paradorsal, subdorsal, laterodorsal, and ventrolateral positions. Glandular cell outlets type 1 present in paradorsal and ventromedial positions. Small rounded sieve plates present in sublateral positions. Cuticular hairs, posterior segment margin, and pectinate fringe as on preceding segment ( Figs 16A–B , 17H–K , 18J–K ). SEGMENT 10. With sexually dimorphic laterodorsal tubes; male tubes well-developed, located near, but not at, the posterior segment margin; female tubes shorter and attaching at the posterior segment margin. Sensory spots present in subdorsal and ventrolateral positions. Glandular cell outlet type 1 present as two longitudinally arranged outlets in middorsal position, and in ventromedial positions. Cuticular hairs in two to three rows and only present from laterodorsal to ventromedial areas; middorsal and paradorsal areas with rhomboid patch of short, hair-like extensions. The posterior segment margin of the tergal plate is straight, with fringe tips as on preceding segments. Sternal plate margins oblique towards posteriormost midventral point; fringe tips well-developed, like those along the dorsal margin ( Figs 16A–D , 17J–M , 18M–O ).

SEGMENT 11. With lateral terminal spines. Females with lateral terminal accessory spines, measuring around 42 µm (measure estimated from SEM images); males with thin, tubular dorsal and ventral penile spines; medial pair of penile spines cone-shaped and well-developed. Sensory spots present in ventromedial positions. Middorsal protuberance-like structure extends from intersegmentary joint. The segment is devoid of cuticular hairs, but has a dense covering of minute, cuticular hair-like structures on the middorsal protuberance, in the paradorsal areas, and along the inferior margins of the tergal extensions. Tergal extensions are short and triangular with a small denticle on the inferior margins. Sternal extensions short, broadly rounded, and not extending beyond tergal extensions ( Figs 16A–D , 17L–M , 18M–O ).

Distribution

Antarctic Peninsula: Gerlache Strait, 631 to 701 m b.s.l. See Fig. 1 for geographic overview of stations and Table 1 for station and specimen information.

Diagnostic remarks

The new species clearly belongs to Echinoderes , and the presence of laterodorsal and lateral accessory tubes on segment 8 but otherwise absence of tubes on segments 6 and 7 makes the species unique among congeners. Only five species of Echinoderes have the combined presence of laterodorsal and lateral accessory tubes on segment 8, i.e., E. abbreviatus Higgins, 1983 , E. belenae Pardos et al., 2016b , E. brevipes Cepeda et al., 2019b , E. rociae Pardos et al., 2016a , and E. intermedius Sørensen, 2006 ( Higgins 1983; Sørensen 2006; Pardos et al. 2016a, 2016b; Cepeda et al. 2019b). However, the four first mentioned species all have short and stout lateral terminal spines, which makes them very easy to distinguish from E. kathleenhannae sp. nov. Only E. intermedius show some resemblance with the new species, but the presence of midlateral glandular cell outlets type 2 on segment 2 and of lateral accessory tubes on segments 6 and 7 still makes it differ considerably from the new species.

Another species that could be confused with E. kathleenhannae sp. nov. is E. hispanicus . The two species share the same general habitus and spine pattern, and E. hispanicus also has two sets of tubes on segment 8. In E. hispanicus the tubes are located in midlateral and lateral accessory positions ( Pardos et al. 1998), which differs slightly from the laterodorsal and lateral accessory tube positions in E. kathleenhannae . However, especially on the more posterior segments, the laterodorsal and midlateral positions are so close to each other that they can be difficult to distinguish; thus, the tube positions on segment 8 are not in themselves suitable for species differentiation. The easy way to distinguish the two species is by the number of tubes on segment 2, where E. kathleenhannae has four pairs, whereas E. hispanicus lacks the laterodorsal tubes and therefore has only three pairs of tubes.

The distribution of glandular cell outlets type 1 in E. kathleenhannae sp. nov. follows the MD Seg. 1–3, 5, 7, PD 4, 6, 8–9 pattern, as is the case with the two congeners described above.

Figures

Fig. 16. Line art illustrations of Echinoderes kathleenhannae sp. nov. A. Male, dorsal view. B. Male, ventral view. C. Female, segments 10 to 11, dorsal view. D. Female, segments 10 to 11, ventral view.

Fig. 17. Light micrographs showing overviews and details of Echinoderes kathleenhannae sp. nov., male, holotype (NHMD 1786779). A. Ventral overview. B. Segments 1 to 3, dorsal view. C. Segments 1 to 3, ventral view. D. Segments 4 to 6, dorsal view. E. Segments 4 to 6, ventral view. F. Segments 7 to 8, dorsal view. G. Segments 7 to 8, ventral view. H. Segments 8 to 9, focused on laterodorsal tube on segment 8. I. Segments 8 to 9, dorsal view. J. Segments 8 (posterior part) to 10. K. Segments 9 to 10, dorsal view. L. Segments 10 to 11, focused on tergal extensions, showing male sexual dimorphism. M. Segments 10 to 11, ventral view, showing male sexual dimorphism. Scale bars: A = 100 µm; B–M = 20 µm.

Fig. 18. Scanning electron micrographs showing overviews and details of Echinoderes kathleenhannae sp. nov. A. Dorsal overview of male. B. Left lateral overview of female. C. Ventral overview of female. D. Segments 1 to 2, dorsal view. E. Segments 1 to 2, left lateral view. F. Segments 1 to 2, ventral view. G. Segments 5 to 6, dorsal view. H. Segments 5 to 6, left lateral view. I. Segments 5 to 6, ventral view. J. Segments 8 to 9, laterodorsal view. K. Segments 8 to 9, left lateral view. L. Segments 7 to 8, ventral view. M. Segments 10 to 11, dorsal view, showing female sexual dimorphism. N. Segments 10 to 11, left lateral view, showing male sexual dimorphism. O. Segments 10 to 11, ventral view, showing female sexual dimorphism. Scale bars: A–C = 100 µm; D–J, L = 20 µm; K, M–O = 10 µm.

Fig. 1. Map showing the sampling stations. A. Overview of Antarctica, with the Antarctic Peninsula framed. Previous records of Polacanthoderes martinezi Sørensen, 2008 (green dots) and P. shiraseae Yamasaki et al., 2022 (red dots) are marked. B. Antarctic Peninsula with sampling area framed. C. Sampling area with station numbers and stations indicated as yellow dots. Study sites in Andvord Bay refer to OBA – Outer Basin A; MBA – Middle Basin A; IBB – Inner Basin B. Only stations yielding adult kinorhynch specimens are included.