Echinocucumis hispida

Echinocucumis hispida (Barrett, 1856)

(Figure 5)

Eupyrgus hispida Barrett, 1856: 46, pl. 4, figs a–b. Echinocucumis typica Sars, 1861: 102, pl. 10, figs. 11–20, pl. 11, figs.1–17; Théel, 1886: 9, fig. 3; Cucumaria typica Ludwig, 1901: 149. non Echinocucumis typica Clark, 1923: 418 (= Ypsilothuria bitentaculata). Echinocucumis hispida Deichmann, 1930: 150, pl. 18 (fig. 9); Ludwig & Heding, 1935: 167; Panning, 1949: 454; Pawson,

1965: 8, fig. 2; Hansen, 1988: 306, fig.5; Madsen & Hansen, 1994: 67, fig. 38 (transposed in original paper); Thandar,

1999: 370, figs. 2, 14 A–C.

Diagnosis (see Pawson 1965; Thandar, 1999).

Material examined. MB-A 090925, SM246, off Transkei, south of Port St. Johns, 31° 58.06’ S, 29° 35.06’ E, biological dredge, 1640–1660 m, 27.VI.1979, 1 spec.

Description. Specimen small (juvenile), strongly U-shaped and attenuated at both ends, with oral end lying slightly above level of anal end (Figure 14A). Body wall thin, brittle, now fragmented into two parts. Length along ventral surface about 15 mm, width in mid-body just over 1 mm. Colour greyish-white to off-white. Tube feet in single/double rows (Figure 14A), double rows mid-ventrally and single rows elsewhere; often difficult to distinguish between spires of thecal plates, however, latter are shorter, brittle and stand erect from body wall. Tentacles retracted, anus apparently surrounded by minute papillae. Calcareous ring low as introvert considerably elongated, simple and delicate, composed of separate, asymmetrical, radial and interradial plates, easily separated, number difficult to distinguish because of size and extreme brittleness of specimen. Radial plates bifid anteriorly, slightly concave posteriorly; interradial plates slightly broader and shorter, with a triangular tip. Tentacles dendritic, 8 in number with 6 large, of unequal length and 2 much reduced. Polian vesicle single, elongated, tube like. Madreporite not detected. Oesophagus elongated, main part of alimentary canal confined to mid-body. Cloaca much elongated, more than length of oesophagus. Specimen extremely young, therefore gonad absent. Respiratory trees poorly branched. Thecal plates of body wall large (Figure14C), smooth, irregular, multilocular, spired, with large holes; spire vertical, eccentric, high. Body wall ossicles also include spatulated crosses with perforated or non-perforated arms and an eccentric spire similar to that of thecal plates (Figure 14B); crosses perhaps represent developmental stages of plates. Tube feet ossicles as curved rods with terminal holes and sometimes also a medial spinous projection (Figure 14E) and developing end-plates (Figure 14F). Tentacle ossicles as smooth curved rods with or without terminal holes (Figure 14D).

Distribution. Cosmopolitan, 50–3257 m.

Remarks. The specimen at hand is a juvenile of Echinocucumis hispida, characterised by simple plates with eccentric spire and spatulated crosses, also with eccentric spire (apophysis). The juvenile of this species are well described by Hansen (1988) and Madsen & Hansen (1994). It was Madsen who stated that Echinocucumis is similar to the Cucumariidae genera Staurocucumis and Psolicucumis, perhaps implying that it should be classified within the Cucumariinae. In fact, Smirnov (2012) recently included Echinocucumis in the Cucumariidae and not in its former family Ypsilothuriidae, the latter he restricted to only two genera, Ypsilothuria and Ypsilocucumis. Regrettably, the legends to the illustrations given by Madsen & Hansen (1994) were inadvertently interchanged. The legend to their Figure 38, which illustrated the ossicles of a 14 mm juvenile, was attached to their Figure 43, which represented the ossicles of Psolus squamatus. There were also other transpositions not pertinent here but require corrections. The ossicles of the current juvenile closely match those illustrated by Hansen (1988) and Madsen & Hansen (1994). Thandar (1999) described this species from the south-western part of the Western Cape Province at 2525–3257 m, based on 15 adults and some fragments. It is here noted that there is considerable transformation of the juvenile ossicles of this species with age/growth.