Echinoderes, Yamasaki & Neuhaus & George, 2018

Yamasaki, Hiroshi, Neuhaus, Birger & George, Kai Horst, 2018, New species of Echinoderes (Kinorhyncha: Cyclorhagida) from Mediterranean seamounts and from the deep-sea floor in the Northeast Atlantic Ocean, including notes on two undescribed species, Zootaxa 4387 (3), pp. 541-566 : 561-564

Echinoderes sp. 2

( Fig. 12 ; Tables 8, 9)

Material examined. One adult female (ZMB 11595), collected at station 742 in the deep-sea plain near the Sedlo Seamount ( Fig. 1A, B ; Table 1), mounted as glycerol-paraffin slide on a Cobb aluminum frame.

Brief description. Adult with head, neck, and eleven trunk segments ( Fig. 12A ). See Table 8 for measurements and Table 9 for cuticular structures (sensory spots, glandular cell outlets, spines, and tubes). Further cuticular structures may be present especially on segments 3–7 as well as on the ventral side of segment 2, but these were difficult to study because of the broken specimen.

Head not examined in detail.

Neck with 16 placids. Midventral placid broadest. Remaining placids similar in size.

Segment 1 consisting of complete cuticular ring. Sensory spots located at least in subdorsal and laterodorsal position. Type-1 glandular cell outlets present at least in middorsal and lateroventral position. No spines and tubes present.

Segment 2 with complete cuticular ring as segment 1. Sensory spots present at least in middorsal position. Type-2 glandular cell outlets in laterodorsal position. No spines and tubes on the dorsal to lateral area, but the ventral area could not be observed.

Segment 3 and following eight segments consisting of one tergal and two sternal plates. Cuticular structures not observable on segment 3.

Segment 4 with middorsal acicular spine ( Fig. 12B ). Additional spines and tubes absent.

Segment 5 with middorsal acicular spine and lateroventral tubes ( Fig. 12B, C ). Additional spines and tubes absent.

Segment 6 with middorsal and lateroventral acicular spines ( Fig. 12B–D ). Additional spines and tubes absent.

Segment 7 with lateroventral acicular spines ( Fig. 12C, D ). Additional spines and tubes absent.

Segment 8 with middorsal and lateroventral acicular spines ( Fig. 12E, F ). Lateral accessory tubes present ( Fig. 12F ). Type-1 glandular cell outlets present in paradorsal and ventromedial position ( Fig. 12F ).

Segment 9 with lateroventral acicular spines ( Fig. 12F ). Paradorsal and ventrolateral sensory spots present ( Fig. 12E, F ). Type-1 glandular cell outlets present in paradorsal and ventromedial position.

Segment 10 with laterodorsal tubes. Sensory spots present at least in ventrolateral position ( Fig. 12F ). Two type-1 glandular cell outlets aligned middorsally ( Fig. 12E ). Additional pair of type-1 glandular cell outlets present in ventromedial position.

Segment 11 with lateral terminal spines ( Fig. 12A ). Lateral terminal accessory spine present in observed female specimen ( Fig. 12A ). Two type-1 glandular cell outlet present middorsally ( Fig. 12E ).

Remarks. Echinoderes sp. 2 shares with Echinoderes augustae Sørensen & Landers, 2014 , Echinoderes dujardinii Claparède, 1863 , Echinoderes gerardi Higgins, 1978 , Echinoderes muricatus Pardos et al., 2016 the presence of middorsal acicular spines on segments 4–8, lateroventral spines/tubes on segments 5–9, lateral accessory spines/tubes on segment 8 and the absence of any tube on the dorsal side on segment 2 (Claparède 1863; Higgins 1977, 1978; Sørensen & Landers 2014; Pardos et al. 2016a).

Echinoderes sp. 2 can be easily distinguished from E. augustae , E. dujardinii , and E. gerardi by the spine lengths: Echinoderes sp. 2 has relatively long middorsal spines (e.g., 86 µm on segment 7 and 110 µm on segment 8) and long lateral terminal spines (224 µm), whereas E. augustae has short middorsal spines (e.g., 44–63 µm and 51–74 µm on segments 7 and 8, respectively) and very short lateral terminal spines (31–44 µm), and E. dujardinii and E. gerardi have very short middorsal acicular spines (e.g., 13–23 µm and 16–27 µm on segments 7 and 8, respectively in E. dujardinii ; and 10 µm and 12 µm on segments 7 and 8, respectively in E. gerardi ) and slightly shorter lateral terminal spines (160–192 µm in E. dujardinii and 172 µm in E. gerardi ) ( Higgins 1977, 1978; Sørensen & Landers 2014).

Echinoderes sp. 2 and E. muricatus reveal more or less a similar lengths of spines. But Echinoderes sp. 2 differs from E. muricatus at least in the presence of type-2 glandular cell outlets on segment 2 (Pardos et al. 2016a).

Although many characters could not be observed because of the broken specimen, Echinoderes sp. 2 can be assumed to represent an undescribed species. However, we do not formally describe the species as a new species, because we had only a single deteriorated specimen available for study.

Figures

FIGURE 12. Echinoderes sp. 2, Nomarski photomicrographs of a female specimen (ZMB 11595). A, entire animal; B, segments 1–6, lateral view (rightside); C, segments 3–7, lateralview (rightside); D, segments 6and 7, lateral view (right side); E, segments 8–11, dorsal view; F, segments 8–11, ventral view. Abbreviations: lat, lateral accessory tube; ltas, lateral terminal accessory spine; lts, lateral terminal spine; lvs, lateroventral acicular spine; lvt, lateroventral tube; mds, middorsal acicular spine. Digits after abbreviations indicate the corresponding segment number. Black arrows, sensory spots; white arrowheads, type-1 glandular cell outlets; black arrowhead, type-2 glandular cell outlet.

FIGURE1. Map of the sampling localities.A, map of northeast Atlantic Ocean and Mediterranean Sea; B, enlarged map of the Sedlo seamount and surrounding deep-sea floor; C, enlarged map of the Anaximenes Seamount; D, enlarged map of the Eratosthenes Seamount.