Holothuria (Stauropora)

Samyn, Yves & Vandenspiegel, Didier, 2016, Sublittoral and bathyal sea cucumbers (Echinodermata: Holothuroidea) from the Northern Mozambique Channel with description of six new species, Zootaxa 4196 (4), pp. 451-497 : 466

Holothuria (Stauropora) bo Samyn sp. nov.

( Fig. 8 A – F)

Material examined. Type material: IE-2007-791 (holotype, collected between Nosy-Bé and Banc du Leven)

Type locality. Madagascar, between Nosy-Bé and Banc du Leven, Station DW 3211 (Decimal coordinates: - 12.53; 47.87).

Etymology. This species is named after Bo Samyn, twin-daughter of Reen Tallon and Yves Samyn, in recognition of her patience, when her dad is writing up some taxonomic work at home. The species epithet has been put in apposition.

Known geographical distribution. For now only known from the type locality.

Taxonomic description (holotype). External anatomy — 117 mm long and 15 – 30 mm wide, with maximum circumference of 65 mm at mid-body (fig. 8A). Body tapering towards anterior and posterior ends. Body wall smooth, slightly wrinkled and somewhat gritty to the touch. Bivium convex, low. Trivium flat. Mouth ventral, not surrounded by a collar of papillae, Tentacles, 20. Anus terminal, wide, not surrounded by papillae. Color in alcohol: bivium grey, with white patches and some irregular brownish markings; trivium also grey with irregular white central area (artefact of preservation?). Ventral and dorsal tube feet very scarce, their distribution cannot be determined due to contraction.

Internal anatomy - Calcareous ring with interradial pieces as wide and half as long as radial ones. Radial pieces with anterior and posterior notch. Interradial pieces with straight posterior margin. Stone canal not observed, Polian vesicle single, 25 mm long, very narrow. Tentacle ampullae short: ± 5 mm long. Gonad not observed. Gut filled with fine muddy sediment. Right respiratory tree well developed reaching anterior end of body; left respiratory tree poorly developed. Longitudinal muscles, bifid and flat, 7 mm wide, edges attached to body wall. Numerous, well developed whitish Cuvierian tubules present.

Ossicles - Tentacles with spiny rods, occasionally with some perforations, 110 – 480 µm long (fig. 8B). Ventral and dorsal body wall with similar tables and buttons and pseudobuttons. Tables with rim of disc slightly undulating and slightly nodulous, 30 up to 70 µm across, perforated by a single cruciform hole and up to 12 small peripheral holes, three to five pillars, zero to two cross beam terminating in a small crown of four to eight spines; deformed tables with reduced spire or deformed disc are predominant in the ventral body wall (fig. 8B,C). Buttons very irregular in outline, some reduced to a central bar with lateral extensions, perforated by two to six uneven holes, 40 to 50 µm long (fig. 8B,C). Ventral tube feet with plates (68 – 100 µm long), rods (180 – 269 µm long) curved and perforated at the extremities and irregular tables similar to those of the body wall (fig. 8D). Dorsal tube feet with plates slightly larger than the ones occurring in the ventral tube feet and a few deformed tables similar to the one occurring in the body wall (fig. 8F). Longitudinal and cloacal suspensor muscles, gonad and cloaca devoid of ossicles.

Remarks. At first we were inclined to classify Holothuria bo sp. nov. in the subgenus Lessonothuria given the shape of the rods of the tube feet (fig. 8C). However, the tables with their central cruciform hole and one or more smaller holes alternating with each arm of the central cross, an upward turned disc and a spire that often is reduced, in combination with the very variable and/or reduced buttons suggest Stauropora ( Rowe, 1969) . This was confirmed by the COI sequence that clearly positioned H. bo in the Stauropora clade (Michonneau, pers. comm.).

Figures

FIGURE 8. Holothuria (Stauropora) bo sp. nov. A: Ventral and dorsal views of holotype; B – E: Ossicles from dorsal body wall (B), ventral body wall (C), ventral tube feet (D) from tentacles (E), and dorsal tube feet (F). Scale bars: A = 1 cm, B – D = 10 µm, E = 50 µm, F = 20 µm.