Echinoderes pacificus Schmidt, 1974

Sørensen, Martin V., Goetz, Freya E., Herranz, María, Chang, Cheon Young, Chatterjee, Tapas, Durucan, Furkan, Neves, Ricardo C., Yildiz, N. Özlem, Norenburg, Jon & Yamasaki, Hiroshi, 2020, Description, redescription and revision of sixteen putatively closely related species of Echinoderes (Kinorhyncha: Cyclorhagida), with the proposition of a new species group - the Echinoderes dujardinii group, European Journal of Taxonomy 730, pp. 1-101 : 30-32

Echinoderes pacificus Schmidt, 1974

Fig. 8A, D, G ; Tables 7–8

Emended diagnosis

Echinoderes with middorsal spines on segments 4 to 8, and lateroventral spines on segments 6 to 9; middorsal spines on segments 5 to 8 extend well beyond the posterior margin of their respective segments. Tubes present in lateroventral positions on segments 2 and 5, and in midlateral positions on 10; tubes on segment 10 short and stout. Minute glandular cell outlets type 2 in laterodorsal positions on segment 8. Tergal extensions of segment 11 triangular, pointed, well-spaced. Females with female papillae with crescentic and tubular substructure in ventrolateral positions on segment 7 and ventromedial on segment 8. Lateral terminal spines thick in proximal ⅓, but tapered abruptly into very thin distal ⅔.

Material examined

Holotype

GALAPAGOS • 1 ♂; Santa Cruz ; 00°45′ S, 090°19′ W; <1 m b.s.l.; Jul.–Sep. 1972; P. Schmidt leg.; heterogeneous sediment, rich in organic matter; USNM-53335 . Specimen mounted for LM.

Paratypes

GALAPAGOS • 5 ♀♀, 4 ♂♂; same collection data as for holotype; USNM-53336 . Specimens mounted for LM .

Most of the paratypes were in surprisingly good condition, whereas the mounting medium around the holotype was dried out. SEM specimens were not available. See Table 1 for an overview.

Description

The appearance of the species generally follows the original description by Schmidt (1974), and in particular the redescription by Higgins (1977a), hence the following notes only provide additional information not included in the two previous descriptions. For complete overview of measurements and dimensions, see Table 7 . Distribution of cuticular structures, i.e., sensory spots, glandular cell outlets, spines and tubes, is summarized in Table 8.

Spines and tubes are as described by Higgins (1977a), and middorsal spines on segments 5 to 8 extend well beyond the posterior margins of segments from which they originate ( Fig. 8A ). The line art illustrations provided with the redescription also summarize and show the distribution of glandular cell outlets type 1 correctly (white open circles in Higgins 1977a: figs 26–27), even though the nature of these structures are misinterpreted, mostly as sensory spots in the text. Same illustrations also picture laterodorsal glandular cell outlets type 2 on segment 8, and female papillae with a crescentic substructure in ventrolateral positions on segment 7 and ventromedial positions on segment 8. Our observations confirm the presence of these structures ( Fig. 8D ). The substructure of the female papillae is crescentic, as reported by Higgins (1977a), and in addition they also have a relatively strong tubular substructure.

Higgins (1977a) furthermore noted the short, curved midlateral tubes on segment 10 (described as “lateral spine of segment 12”, following the old terminology). We can confirm the distinct appearance of these tubes, and add that they, besides being curved, are conspicuously short and stout, and somewhat truncate ( Fig. 8G ), which make them differ from segment 10 tubes in other species examined for the present study. Another highly characteristic feature regards the shape of the lateral terminal spines. The proximal parts of the spines are conspicuously thick, or swollen, but around ⅓ from the proximal end the spines taper abruptly, and become very thin and nearly seta-like ( Fig. 8G ). Tergal extensions are triangular and well-spaced; sternal extensions are short with ventrolateral seta-like tuft of extended fringe tips.

Figures

Fig. 8. Comparative light micrographs showing selected details of E. pacificus Schmidt, 1974. A. Holotype, ♀ (USNM-53335). D–G. Paratype (USNM-53336). B, E, H. E. kozloffi Higgins, 1977. Holotype, ♀ (USNM-53337). C, F, I. E. sublicarum Higgins, 1977. Paratype, ♀ (USNM-54399). A–C. Segments 8 to 9, dorsal view, showing presence of glandular cell outlets type 2 on segment 8. D–F. Segments 6 to 8, ventral view, position and appearance of sexually dimorphic female papillae. G–I. Segments 10 to 11, with midlateral tubes on segment 10, and lateral terminal spines.