Echinoderes annae sp., 2016

Sørensen, Martin V., Gąsiorowski, Ludwik, Randsø, Phillip V., Sánchez, Nuria & Neves, Ricardo C., 2016, First report of kinorhynchs from Singapore, with the description of three new species, Raffles Bulletin of Zoology 64, pp. 3-27 : 13-19

Echinoderes annae sp. nov.

( Figs. 7–9 )

Material examined. Holotype adult female, collected from muddy, intertidal seagrass aggregations on 19 May 2014, at station SI-06 ( Fig. 1 , Table 1), on Saringat Island , just south of Singapore Island (01°13.531’N 103°51.299’E), mounted in Fluoromount G, deposited at the Lee Kong Chian Natural History Museum, under catalogue number ZRC.MIS.0002 . Paratypes, all mounted in Fluoromount G, were collected at same locality as holotype and include one male, deposited at the Lee Kong Chian Natural History Museum, under catalogue number ZRC.MIS.0003, and two additional males, one female, and one juvenile deposited at the Natural History Museum of Denmark under catalogue numbers ZMUC KIN- 851 to KIN-854 . Additional, non-type material includes six specimens, from same locality as the holotype, mounted for SEM. The SEM specimens were extremely dirty, and contributed with very limited information .

Diagnosis. Echinoderes with short middorsal spine on segment 4, and without any lateroventral acicular spines; tubes present in lateroventral positions on segments 5 and 8, midlateral positions on segment 9, and, in laterodorsal positions on segment 10. Glandular cell outlets type 2 present in subdorsal positions on segments 2 and 4, in laterodorsal positions on segments 2, 6 and 8, in sublateral positions on segments 5 and 7, and in lateroventral positions on segment 2. Sensory spots of type 1 and very small. Large, but narrow and elongated sieve plates present in sublateral positions on segment 9. Males with three pairs of penile spines; females with conspicuously short and stout lateral terminal accessory spines.

Etymology. The new species, Echinoderes annae , is named after Anna – the girlfriend of the author PVR.

Description. Adult with head, neck and eleven trunk segments ( Figs. 7A, B , 8A , 9G ). For measurements and dimensions see Table 4. Distribution of cuticular structures (spines, tubes, glandular cell outlets and sensory spots) is summarised in Table 5. Since all specimens mounted for SEM were covered with dirt to different degrees, the species may have additional sensory spots that were not observed and hence are not reported in the present description.

The head consists of a retractable mouth cone and an introvert. Arrangement of styles and scalids could not be examined. The neck bears 16 placids ( Figs. 8B , 9A, B, G ), measuring 18 µm in length.

Midventral placid broadest, measuring 19 µm in width. Trichoscalid plates present ventrally on placids 2 and 16 and dorsally on placids 6, 8, 10 and 12 ( Figs. 7A, B , 8B ). Ventral trichoscalid plates much broader than dorsal ones.

Segment 1 consists of a complete cuticular ring with sensory spots located near the anterior segment margin in subdorsal and laterodorsal positions ( Fig. 9A ), and medially in ventromedial positions ( Figs. 9B ). Sensory spots on this and following segments are small and rounded with seven to eight short cuticular papillae surrounding two small pores ( Fig. 9D ). Glandular cell outlets type 1 are present in sublateral positions. Cuticular hairs emerge through rounded perforation sites and are distributed evenly around the segment except in the anterior part of segment and around the sensory spots. The segment terminates into a pectinate fringe. Fringe with very short tips along the dorsal and lateral parts of segment margins, whereas the margins of the ventral parts have significantly longer fringe tips. Ventromedial fringe tips longest.

Segment 2 consists of a complete cuticular ring with sensory spots at least in middorsal ( Fig. 9E ), subdorsal and ventromedial positions ( Fig. 9B ). Glandular cell outlets type 1 present in middorsal and ventromedial positions; glandular cell outlets type 2 present in subdorsal, laterodorsal and lateroventral positions ( Figs. 8B, C ). Cuticular hairs and pectinate fringe as on segment 1. Pectinate fringe of segments 1 and 2 considerably shorter than on following segments.

Segment 3, and all following segments, consists of one tergal plate and two sternal plates. Glandular cell outlets type 1 present in middorsal and ventromedial positions. Cuticular hairs as on segment 2. Pectinate fringe of this segment with considerably longer tips than that of preceding segments. Midlateral parts of segment margin with slightly shorter fringe tips. Sensory spots not observed.

Segment 4 with very short middorsal acicular spine ( Figs. 7A , 8E ), and sensory spots at least, in laterodorsal positions. Glandular cell outlets type 1 present only ventromedially; glandular cell outlets type 2 present in subdorsal positions ( Fig. 8E ). Cuticular hairs and pectinate fringe as on segment 3.

Segment 5 with relatively long lateroventral tubes ( Figs. 8D , 9C ). Sensory spots present at least, in subdorsal, midlateral and ventromedial positions ( Fig. 9C ). Glandular cell outlets type 1 present only ventromedially; glandular cell outlets type 2 present in sublateral positions ( Fig. 8D ). Cuticular hairs and pectinate fringe as on segment 4, but without variations in tip length around the segment.

Segment 6 with sensory spots at least in ventromedial positions ( Fig. 9C ). Glandular cell outlets type 1 present in paradorsal and ventromedial positions; glandular cell outlets type 2 present in laterodorsal positions ( Fig. 8D, G ). Cuticular hairs and pectinate fringe as on preceding segment.

Segment 7 with sensory spots present, at least in subdorsal and ventrolateral positions ( Fig. 9F ). Glandular cell outlets type 1 present in paradorsal and ventromedial positions; glandular cell outlets type 2 present in sublateral positions ( Fig. 8G ), as on segment 5. Fringe tips of pectinate fringe slightly longer on middorsal margin than those on preceding segments. Cuticular hairs as on preceding segment.

Segment 8 with lateroventral tubes ( Figs. 8F , 9F ). Sensory spots present at least in ventromedial positions ( Fig. 9F ). Glandular cell outlets type 1 present in paradorsal ( Fig. 8G ) and ventromedial positions; glandular cell outlets type 2 present in laterodorsal positions ( Fig. 8F, G ), as on segment 6.

Segment 9 with midlateral tubes ( Figs. 8F, J , 9I ), and a pair of large, elongated sieve plates in sublateral positions ( Fig. 8F ). Sensory spots present at least in laterodorsal positions. Glandular cell outlets type 1 present in paradorsal and ventromedial positions ( Figs. 8F, J ). Pectinate fringe and cuticular hairs as on preceding segment.

Segment 10 with sexually dimorphic laterodorsal tubes near the posterior segment margin ( Fig. 8H ). Tubes are apparently similar in length but differ in width of both the proximal shaft and the distal tip. In males, the distal parts of the tubes are much thinner, and the proximal shaft is slightly longer than those in females ( Figs. 7A, C , 8H ). Sensory spots present at least in subdorsal positions. Glandular cell outlets type 1 present in paradorsal and ventromedial positions ( Fig. 8F ). Cuticular hairs as on preceding segments. Pectinate fringe of posterior margin with shorter and thinner tips than those on preceding segments.

Segment 11 with conspicuously short and stout lateral terminal spines ( Fig. 8H, I ), with a ring of fine trichoids or cuticular markings around each spine, about 1/3 from its proximal end. Males with three pairs of penile spines ( Fig. 8H ); females with short lateral terminal accessory spines ( Fig. 8I ). Segment with few cuticular hairs only. Sensory spots not observed. Glandular cell outlets absent. Tergal extensions elongate and triangular ( Figs. 7 , 8I ).

Figures

Fig. 7. Line art illustration of Echinoderes annae sp. nov. A, female, dorsal view. B, female, ventral view. C, male, dorsal view, segments 10–11. D, male, ventral view, segments 10–11. Abbreviations: gco1/2, glandular cell outlet type 1 or 2; ldt, laterodorsal tube; ltas, lateral terminal accessory spine; lts, lateral terminal spine; lvt, lateroventral tube; mds, middorsal spine; mlt, midlateral tube; pe, penile spine; si, sieve plate; ss sensory spot.

Fig. 8. Light micrographs showing overviews and details of neck and trunk morphology in female holotype, ZRC.MIS.0002 and male paratype, KIN-851, of Echinoderes annae sp. nov. A, lateroventral overview. B, neck and segments 1–2, lateroventral view. C, neck and segments 1–2, laterodorsal view. D, segments 3–7, lateroventral view. E, segment 4, middorsal. F, segments 8–10, lateroventral view. G, segments 6–8, dorsal view. H, segments 10–11, dorsal view, showing male morphology. I, segment 11, ventral view, showing female morphology. J, segments 9, laterodorsal view. Abbreviations: gco1/2, glandular cell outlet type 1 or 2; ldt, laterodorsal tube; ltas, lateral terminal accessory spine; lts, lateral terminal spine; lvt, lateroventral tube; mds, middorsal spine; mlt, midlateral tube; mvp, midventral placid; pe1–3, penile spines; si, sieve plate; te, tergal extensions; trp, trichoscalid plate. Dashed circles mark glandular cell outlet type 1.

Fig. 9. Scanning electron micrographs of male specimen, showing overviews and details of neck and trunk morphology in Echinoderes annae sp. nov. A, neck and segment 1, lateral view. B, neck and segments 1–3, midventral view. C, segments 5–6, midventral view. D, detail showing midlateral sensory spot on segment 5. E, segment 2, middorsal. F, segments 7–8, midventral view. G, lateral overview. H, segment 7, sublateral view. I, segments 9–11, lateral view. Abbreviations: gco2, glandular cell outlet type 2; ld, laterodorsal sensory spot; lvt, lateroventral tube; md, middorsal sensory spot; ml, midlateral sensory spot; mlt, midlateral tube; mvp, midventral placid; pe1–2, penile spines; vm, ventromedial sensory spot.

Fig. 1. Map showing the sampling localities south of Singapore Island. Inset to the lower right shows the Malaya Peninsula and Indonesian Archipelago, with Singapore indicated in the square.