Neopsolidium kerguelensis Theel 1886

Neopsolidium kerguelensis (Théel, 1886)

Figure 1 e, f; table 1.

Cucumaria kerguelensis Théel, 1886: 69 –70, pl. 12 figs 6, 7.— Lampert, 1889: 833 –834 (as synonym of Semperia parva (Ludwig, 1874)).— Ludwig, 1898: 25 –27, pl. 1 figs 14–18 (as synonym of Cucumaria parva Ludwig, 1874).— Perrier, 1905: 29.— Ekman, 1925: 93 –96.— Ekman, 1927: 405.— Massin, 1992b: 316, figs 4, 5.

Cucumaria (Semperia) ekmani Ludwig & Heding, 1935: 186 –188, figs 44, 45.

Cucumaria (Semperia) kerguelensis.— Ludwig & Heding, 1935: 186, 189–190, fig. 48.

Trachythyone ekmani.— Cherbonnier, 1974b: 29.

Material examined. Kerguelen I., Royal Sound, Port Jeanne d’Arc, 20 m, BANZARE stn 5, SAM K2369 (1); entrance to Bras Bossière, 4–5 m, sandy bottom, Macrocystis holdfasts, stn 6, SAM K2376 (1); 55 m, stn 15, SAM K2372 (11); S of Kerguelen I., 50 m, stn 47, SAM K2378 (2); SAM K2380 (1); Kerguelen I., shore collection and 20–30 m, stn 52, SAM K2370 (2); shore collection, stn 54, SAM K2373 (9); shore collection and 4–6 m, stn 56a, SAM K2371 (14); shore collection, stn 56b, SAM K2374 (2); 45 m, stn 59, SAM K2368 (1). Heard I., 90 m, SAM K2304 (1); 62–80 m, NMV F84997 (1); 230–247 m, NMV F85002 (1); 514–528 m, NMV F85003 (1); 60 m, NMV F85004 (1).

Diagnosis. Up to 55 mm long (excluding tentacles); body wall firm, leathery; distinct rounded belly with sole ventrally, rounded dorsally, tapered distally, distinct tail; 10 dendritic tentacles, ventral 2 smaller; smaller tube feet of variable size over dorsal and lateral body, anterior and posterior ends; 3 ventral radial series of larger tube feet on sole, each up to 4 rows wide, interradii narrow, bare on sole, not anteriorly or posteriorly; series of tube feet do not cross introvert; distinct, thin calcareous ring, radial and interradial plates elongate, narrow anteriorly, wide with rounded notch posteriorly; single polian vesicle; unbranched gonad tubules.

Mid-dorsal and mid-ventral body wall ossicles plates and cups; plates irregularly round to oval, perforated, knobbed, some with incipient secondary layering, up to 640 µ m long; cups not abundant, variable in size and form and spination, 40–144 µ m long, shallow to deep concave, typically 4 perforations, marginal “spines” pointed or knobbed or digitiform.

Distribution. Marion I., 52–351 m (Massin 1992b); Kerguelen Is, littoral to 55 m; Heard I., 60– 528 m.

Remarks. The specimens examined here accord closely with the description of Cucumaria kerguelensis by Théel (1886) except that his largest specimen was 75 mm long (no record of tentacles included or not, and whether preserved or not), and cupped crosses only were reported (not cups). But Théel did record the presence of small plates with few perforations and presumably these were shallow concave plates/cups, as the cupped crosses that develop into cups were observed. He noted that the larger plates were composed of “several layers”. Presumably this referred to the strongly developed incipient secondary layering seen in this study.

Ludwig & Heding (1935) distinguished their new species Cucumaria (Semperia) ekmani (type locality Kerguelen Is) from Cucumaria kerguelensis by the form of the calcareous ring, and the form of the cupped crosses and cups. The variations in form seen in this study of abundant material from the Kerguelen Is does not support these diagnostic distinctions. Cucumaria ekmani is a junior synonym of Cucumaria kerguelensis.

Cucumaria kerguelensis is similar to Neopsolidium convergens (Hérouard, 1901). It is reassigned here to the previously monotypic genus Neopsolidium Pawson, 1964 on the basis of having: 8 and 2 small ventral tentacles; sole with bare interradii, but not sharply distinguished from rest of body; small tube feet over dorsal and lateral body; cups and predominantly single-layered knobbed perforated plate ossicles up to 680 µ m long in body wall.

Neopsolidium kerguelensis (Heard, Kerguelen Is) is distinguished from Neopsolidium convergens (Magellanic and South Atlantic region) by: larger size, up to 50 mm long (Perrier 1905 recorded up to 27 mm long, Pawson 1964 up to 22 mm long, for N. convergens); larger body wall plates up to 680 µ m long with incipient secondary layering (Pawson 1964 diagnosed smooth, up to 400 µ m long, for N. convergens); presence of cups ventrally (Pawson 1964 diagnosed Neopsolidium as lacking cups ventrally). The diagnosis of Neopsolidium Pawson is close to Trachythyone Studer, 1876, as evidenced by the fact that Lampert (1889) and Ludwig (1898) judged that the now Neopsolidium kerguelensis (this work) was a junior synonym of the now Trachythyone parva. A review of these genera should await molecular genetic data.

Massin (1992b) reviewed the systematic history of Cucumaria kerguelensis and agreed with Ekman (1925) who rejected earlier synonymies with Cucumaria parva by Lampert (1889) and Ludwig (1898). Ekman subsequently (1927) listed Cucumaria kerguelensis as a possible synonym of Cucumaria parva. I agree with Massin (1992b) that they are not synonyms.