Molpadia liska Pawson, 1977

Bohn, Jens Michael, 2006, Crinoidea and Holothuroidea (Echinodermata) of the abyssal Angola Basin — Results of the DIVA­ 1 expedition of FS " Meteor " (Cruise M 48 / 1), Zootaxa 1276, pp. 1-31 : 19-21

Molpadia liska Pawson, 1977

( Figs 9 B–G, 11)

Molpadia liska Pawson, 1977: 115 –116, figs 6 (a–g, i), 7 (a–b, d)

Material. M 48/1­333: 1 specimen ( ZSM 20043068), 1 specimen ( ZSM 20043069). M 48/ 1­349: 4 specimens ( ZSM 20020025). M 48/1­351: 5 specimens ( ZSM 20020028).

Description. The specimens range from 24 to 63 mm in length, and 6 to 13 mm in width (at calcareous ring). The body is approximately cylindrical, with a tapering posterior end, resulting in a very short tail (only few millimetres long). Preserved specimens are dirty­white with a tinge of pink. Fifteen retracted tentacles encompass the terminal mouth. Likewise, the anus is terminal and in each radius there are few short anal papillae.

The calcareous ring is solid, smooth and composed of five radial plates ( Fig. 9 B: ldr, lvr), with prominent posterior projections and five much smaller interradial plates ( Fig. 9 B: llir).

The tentacle ampullae are short. Longitudinal muscle bands are undivided. There is one tubular polian vesicle in the left ventral radius. The single stone canal is long and embedded in the dorsal mesentery and has a large oval madreporite body close to the dorsal body wall. The gonad consists of tufts of branching, tubules on both sides of the dorsal mesentery. The intestine forms a large loop (as long as body) and the respiratory trees are conspicuous.

The calcareous deposits of the body wall ( Figs 9 C–D) and the tail ( Figs 9 E–F) are exclusively tables with 3–9 holes and a large solid spire, derived from three fused pillars, with 4–6 terminal hooklets. The tables of the body wall in the current specimens on average range from 95 to 121 (Tab. 2) and usually have 4 or 5 holes, while the tables from the tail are smaller, on average 86 to 105 in diameter (Tab. 2) and have fewer holes (3 or 4). There are no phosphatic deposits, but anal teeth are present ( Fig. 9 G).

Remarks. The current specimens agree in all details with Molpadia liska as characterised by Pawson (1977): body wall and tail deposits similar, exclusively tables with solid spires composed of three fused pillars, with usually three perforations but often with more up to a maximum of eight. Table deposit diameters of the current specimens are also in accordance with the table sizes as presented by Pawson (Tab. 2). There is only one other species known to possess similar table deposits in the body wall and in the tail: Molpadia discors Pawson, 1977 . This species differs from Molpadia liska by its invariable number of three holes per table, which in Molpadia liska may be up to eight or nine ( Pawson 1977). Another closely related species, which may result in misidentifications, is Molpadia blakei (Théel, 1886) , which with certainty is known from the northern Atlantic deep­sea ( Pawson et al. 2001). This species differs from M. liska by the presence of fusiform rods (mean length: 256) in the tail, which are perforated by large holes and have a low spire ( Pawson et al. 2001).

TABLE 2. Molpadia liska Pawson, 1977 . Means, standard deviations (in parentheses) and range of diameter of tables from body wall (D bw,) and from tail (D t,) compared to range of mean values as presented by Pawson (1977) for the type specimens. n —number of measurements.

This is the first record of this species for the Atlantic Ocean, and the known depth range is considerably increased from 4740 to more than 5420 m.

Distribution. ( Fig. 11 ) South­eastern Atlantic Ocean, south­western Pacific Ocean and Southern Ocean, 3111–5426 m ( Pawson 1977; herein).

Figures

FIGURE 9. (A) Molpadiodemas atlanticus (R. Perrier, 1898). Rod­like deposits from tentacles. (B – G) Molpadia liska Pawson, 1977. (B) Calcareous ring, left lateral view (ldr — left dorso­lateral radial plate, llir — left lateral interradial plate, lvr — left ventro­lateral radial plate). (C) Table from body wall (JMB­ 01141). (D) Tables from body wall (JMB­ 01646). (E) Tables from tail (JMB­ 01141). (F) Tables from tail (JMB­ 01646). (G) Anal tooth (JMB­ 01646).

FIGURE 11. Distribution of Molpadia liska Pawson, 1977.