Condyloderes notios, 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 : 12-18

Condyloderes notios sp. nov urn:lsid:zoobank.org:act:3F5ACC7E-5173-4871-8465-642D9E7F473C

Figs 2–4 , Tables 5–6

Diagnosis

Condyloderes with acicular spines in middorsal positions on segments 1 to 10, and in lateroventral positions on segments 1 to 9; laterodorsal acicular spines present on segment 10, at least in males. Unpaired cuspidate spines present in paradorsal position on segments 1, 5, and 7. Paired cuspidate spines present in lateral accessory positions on segment 1, in ventrolateral positions on segment 5, in lateroventral positions on segment 8, and in ventrolateral positions on segment 9. Female morphology unknown.

Etymology

The species name notios is from the Greek νότιος = ‘southern’, with reference to the species being the southernmost representative of Condyloderes and only the second member of the genus recorded from the Southern Hemisphere.

Material examined

Holotype ANTARCTICA • ♂ (mounted for LM in Fluoromount G on HS slide); Antarctic Peninsula, CRS 1702; 64°51.15′ S, 62°34.44′ W; 502 m b.s.l.; 30 Nov. 2015; FjordEco 1; soft sediment; NHMD 1784659 .

Additional material

ANTARCTICA – Antarctic Peninsula • 1 juv. (mounted for LM in Fluoromount G on HS slide); CRS 1706; 64°50.47′ S, 62°35.12′ W; 499 m b.s.l.; 1 Dec. 2015; FjordEco1; soft sediment; NHMD 1784660 • 1 juv. (mounted for SEM); CRS 1793; 64°39.53′ S, 62°55.03′ W; 701 m b.s.l.; 11 Apr. 2016; FjordEco2; soft sediment; MVS • 3 ♂♂, 2 juv. (mounted for SEM); 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 2 , 3A , 4A–D ). An overview of measurements and dimensions is given in Table 5. Distributions of cuticular structures, i.e., sensory spots and spines, are summarized in Table 6. Only males and juveniles were available for examination, so female dimorphism remains unknown for this species.

HEAD. Consists of a retractable mouth cone and an introvert ( Fig. 4C ). Only one specimen had its head partially protruded and thus information on head morphology is limited. Outer oral styles are composed of two units, with the proximal unit being considerably thicker than the distal.

INTROVERT. Primary spinoscalids are composed of a single unit, with a basal, transverse fringe and a row of fine hairs extending about ¼ down along the proximal part of the scalid; the distal ¾ are smooth, with a few transverse, partial wrinkles, giving the distal part a finger-like appearance. Remaining scalids appear to be located in introvert rings 2 to 5; they are composed of a basal sheath with a median fringe and a pointed end-piece. Scalids of Ring 4 (located centrally in each introvert sector) are flanked by a pair of thin, thread-like appendages, covered with minute hairs; the hair-covering makes them resemble thin trichoscalids. Trichoscalids are well-developed and located in the posteriormost ring.

NECK. Consists of 16 placids with condyles ( Fig. 4D ). All placids are about 12 µm in length, but differ in width. The midventral placid is the broadest, 15 µm wide. It is flanked by two pairs of narrow placids, each measuring 7 µm in width. From the two pairs of narrow, ventromedial placids, the placids alternate between broad (width: 13 µm) and narrow (width: 7 µm) ones towards the narrow middorsal placid. All condyles form structures with a narrow posterior part that broadens anteriorly, which makes them resemble small mushrooms. The midventral placid has three condyles, whereas other broad placids have two condyles, and narrow ones have a single.

SEGMENT 1. Consists of a complete cuticular ring. Acicular spines are present in middorsal and lateroventral positions, and cuspidate spines are present as an unpaired paradorsal spine and as paired lateral accessory spines; direction (left or right) of lateral shift in position of the unpaired paradorsal cuspidate spine differs between specimens. Sensory spots are present as two pair in subdorsal positions, two pairs in laterodorsal positions, and one pair in ventromedial positions. Sensory spots on this and following eight segments are slightly protruding and composed of numerous micropapillae around a central pore, i.e., corresponding to sensory spot type 6 sensu Neuhaus et al. (2019). The surface of the tergal plate is reticulated at its anterior half and has a narrow zone with minute triangular hairs, in between the reticulated part and the relatively broad free flap; sternal plate surfaces are reticulated throughout, from anterior margin to posterior free flaps; dense coverings of thin cuticular hairs are present in areas anterior to the middorsal and lateroventral acicular spines. The free flaps, marking the posterior segment margins, have longitudinal lines that extend beyond the margins of the free flaps and form minute, pointed tips. The posterior margin is mostly straight, with notches at the attachment sites of the lateroventral spines, and with a small and rather narrow midventral indentation, only expanding over the paraventral areas ( Figs 2A–B , 3B–C , 4D–G ).

SEGMENT 2. As the following eight segments, consists of a tergal and two sternal plates. Acicular spines are present in middorsal and lateroventral positions. Sensory spots are present in paradorsal, subdorsal, laterodorsal (two pairs), and ventromedial positions. Tergal plate and lateral halves of sternal plates are covered with minute, triangular hairs; ventralmost halves of sternal plates with reticulated surfaces. Free flaps as on preceding segment and posterior segment margin mostly straight, but with notches at the attachment sites of the lateroventral spines ( Figs 2A–B , 3B–C , 4E–G ).

SEGMENT 3. As preceding segment, but only with one pair of laterodorsal sensory spots ( Figs 2A–B , 3B–C , 4E ).

SEGMENT 4. As preceding segment, but without laterodorsal sensory spots. Subdorsal sensory spots usually present, but were missing in one specimen ( Figs 2A–B , 3B–C , 4E, H ).

SEGMENT 5. With acicular spines in middorsal and lateroventral positions, and cuspidate spines present as an unpaired paradorsal spine and as paired ventrolateral spines; direction of lateral shift in position of the unpaired paradorsal cuspidate spine differs between specimens and irrespective of position of paradorsal cuspidate spine on segment 1. Sensory spots present in paradorsal, subdorsal, laterodorsal, and ventromedial positions. Cuticular ornamentation, free flap, and posterior segment margin as on preceding segment ( Figs 2A–B , 3B–C , 4H–J ).

SEGMENT 6. With same arrangement of cuticular structures as on segment 3 ( Figs 2A–B , 3B–E , 4H–J ).

SEGMENT 7. With acicular spines in middorsal and lateroventral positions, and an unpaired, cuspidate spine in paradorsal position; direction of lateral shift in position of the unpaired paradorsal cuspidate spine differs between specimens and irrespective of position of paradorsal cuspidate spines on preceding segments. Sensory spots present in paradorsal, subdorsal, laterodorsal, and ventromedial positions. Cuticular ornamentation, free flap, and posterior segment margin as on preceding segment ( Figs 2A–B , 3D–E , 4K–M ).

SEGMENT 8. With acicular spines in middorsal and lateroventral positions, and cuspidate spines also in lateroventral positions, attaching posterior to acicular spines. Sensory spots present in paradorsal, subdorsal, laterodorsal, and ventromedial positions. Cuticular ornamentation, free flap, and posterior segment margin as on preceding segment ( Figs 2A–B , 3D–E, G–H , 4L–M ).

SEGMENT 9. With acicular spines in middorsal and lateroventral positions, and cuspidate spines in ventrolateral positions. Sensory spots present in paradorsal, laterodorsal, and ventromedial positions. A pair of minute nephridiopores, appearing as a tuft of short micropapillae, is located next to, but more dorsal than, the laterodorsal sensory spots ( Fig. 4O ). Cuticular ornamentation, free flap, and posterior segment margin as on preceding segment ( Figs 2A–B , 3D–H , 4N–P ).

SEGMENT 10. With acicular spines in middorsal and laterodorsal positions. Sensory spots type 3, i.e., stalked sensory spots, present in subdorsal positions (but missing in one specimen); sensory spots type 6 present in lateroventral positions, at the posterior segment margin. Cuticular ornamentation, free flap, and posterior segment margin otherwise as on preceding segment ( Figs 2A–B , 3D–H , 4N–P ).

SEGMENT 11. Consists of a tergal and a sternal plate. Lateral terminal accessory spines and midterminal spine are present; lateral terminal accessory spines are about 70% longer than the midterminal. Stalked sensory spots type 3 are present in subdorsal and ventrolateral positions, and sensory spots type 6 in ventromedial positions. The tergal plate is covered with minute, triangular hairs, whereas the sternal plate is mostly smooth and ornamented with fine, longitudinal lines. A free flap with irregular longitudinal lines is present at the tergal plate only; the sternal plate terminates in a finely serrated edge ( Figs 2A–B , 3G–H , 4N–P ).

Distribution

Antarctic Peninsula: Gerlache Strait and Andvord Bay MBA, 499 to 701 m. See Fig. 1 for geographic overview of stations and Table 1 for station and specimen information.

Diagnostic remarks

The placids with condyles, and the segment composition, with segment 1 composed of a closed cuticular ring, segments 2 to 10 composed of one tergal and two sternal plates, and segment 11 of one tergal and one sternal plate, easily assigns the new species to Condyloderes . The genus currently accommodates eleven species, including Condyloderes notios sp. now.

The new species is most easily distinguished from its congeners by its unique cuspidate spine pattern. The presence of cuspidate spines in mid- or paradorsal positions is only shared with three other species, i.e., Condyloderes agnetis Dal Zotto et al., 2019 , C. shirleyi Neuhaus et al., 2019 , and C. storchi Higgins in Martorelli & Higgins, 2004. However, none of the three species have paradorsal cuspidate spines on segment 1, which in itself makes C. notios sp. nov. differ from all other congeners. Of the three species, the Mediterranean C. agnetis differs the most, by having paired paradorsal cuspidate spines on segments 3 and 7 ( Dal Zotto et al. 2019), opposite to the unpaired ones on segments 1, 5, and 7 in C. notios . In both species the cuspidate spines are reported as paradorsal, but in C. agnetis the cuspidate spines are clearly more laterally displaced, and thus very close to being subdorsal. In contrast, the unpaired paradorsal cuspidate spines in C. notios are so close to the middorsal line that they almost could be interpreted as middorsal.

Condyloderes shirleyi and C. storchi show more similarity to the new species, as they both have unpaired middorsal or paradorsal cuspidate spines on segments 5 and 7, but besides lacking a paradorsal cuspidate spine on segment 1, their cuspidate spine pattern in the lateral series also differs considerably. Condyloderes shirleyi differs by having cuspidate spines in the lateral series of segments 2, 6, and 7, but not on segment 1 ( Neuhaus et al. 2019), and C. shirleyi by having lateral accessory cuspidate spines on segment 4 ( Martorelli & Higgins 2004; Neuhaus et al. 2019).

If compared with the remaining Condyloderes species without cuspidate spines in the dorsal series, C. notios sp. nov. shows most resemblance with C. clarae Dal Zotto et al., 2019 and C. flosfimbriatus Sørensen et al., 2019 , as they also have cuspidate spines in the lateral or ventral series of segments 5, 8 and 9, but none of them have lateral accessory cuspidate spines on segment 1 ( Dal Zotto et al. 2019; Sørensen et al. 2019). Among its ten congeners, C. notios clearly shows greatest resemblance with C. storchi , which also happens to be the only other species of Condyloderes described from the southern hemisphere.

Figures

Fig. 2. Line art illustrations of Condyloderes notios sp. nov. A. Male, dorsal view. B. Male, ventral view.

Fig. 3. Light micrographs showing overviews and details in male holotype (NHMD 1784659) of Condyloderes notios sp. nov. A. Ventral overview. B. Segments 1 to 6, dorsal view. C. Segments 1 to 6, ventral view. D. Segments 6 to 10, dorsal view. E. Segments 6 to 10, ventral view. F. Segments 9 to 11, dorsal view. G. Segments 8 to 11, focused inside specimen. H. Segments 8 to 11, ventral view. Scale bars: A = 100 µm; B–H = 25 µm.

Fig. 4. Scanning electron micrographs showing overviews and details of male Condyloderes notios sp. nov. A. Right lateral overview. B. Ventral overview. C. Partly retracted introvert focused on midventral sector 1. D. Close-up of neck region, showing midventral and ventromedial placids. E. Segments 1 to 4, dorsal view; note that the paradorsal cuspidate spine broke off in this specimen. F. Segments 1 to 2, left lateral view. G. Segments 1 to 2, ventral view. H. Segments 4 to 7, dorsal view. I. Segments 5 to 6, left lateral view. J. Segments 5 to 6, ventral view. K. Segments 7 to 9, dorsal view. L. Segments 7 to 8, left lateral view. M. Segments 7 to 8, ventral view. N. Segments 9 to 11, dorsal view. O. Segments 9 to 11, left lateral view; inset shows close-up of laterodorsal sensory spot (left) and nephridiopore (right). P. Segments 10 to 11, ventral view. Scale bars: A – B = 100 µm; C, E – P = 20 µm; D = 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.

Tables

Table 6. Summary of nature and location of sensory spots, tubes, and spines arranged by series in Condyloderes notios sp. nov. * marks unpaired structures in otherwise paired positions. –x indicates number of specimens (out of 4 examined adults) in which the character trait is missing.

Position
Segment	MD	PD	SD	LD	LA	LV	VL	VM
1	ac	cu*	ss6,ss6	ss6,ss6	cu	ac	–	ss6
2	ac	ss6	ss6	ss6,ss6	–	ac	–	ss6
3	ac	ss6	ss6	ss6	–	ac	–	ss6
4	ac	ss6	ss6-1	–	–	ac	–	ss6
5	ac	cu*,ss6	ss6	ss6	–	ac	cu	ss6
6	ac	ss6	ss6	ss6	–	ac	–	ss6
7	ac	cu*,ss6	ss6	ss6	–	ac	–	ss6
8	ac	ss6	ss6	ss6	–	ac, cu	–	ss6
9	ac	ss6	–	ne,ss6	–	ac	cu	ss6
10	ac	–	ss3-1	ac	–	ss6	–	–
11	mts	–	ss3	–	ltas	–	ss3	ss6