Synallactes cf. mollis Cherbonnier, 1952

Thandar, Ahmed S., 2008, Additions to the holothuroid fauna of the southern African temperate faunistic provinces, with descriptions of new species, Zootaxa 1697 (1), pp. 1-57 : 41-43

Synallactes cf. mollis Cherbonnier, 1952

Figure 16

Type SAM.

Type locality R. V. ‘ Africana’ St. 723.V.7B, off west coast of WCP, 31 o 30' S, 17 o 00' E, ca. 366 m.

Material examined

SAM-A28023, R.V. ‘ Africana’, South Coast Inshore Biomass and Horse Mackerel Survey , St. A15343- 116-DT02, off Plettenberg Bay , 35 o 03' S, 24 o 06' E, 28.ix. 1993, 1006 m, 1 spec.

Description

Specimen eviscerated, cylindrical to barrel-shaped due to strong contraction, ventral surface flattened, dorsal conspicuously arched. Length 75 mm, width in mid-body 37 mm. Mouth anterior, ventral; anus terminal, ventrally directed. Papillae dorsal and ventro-lateral, in six rows, arising from wart-like prominences of vary ing length, 11 –12 papillae in each ventro-lateral ambulacra, longest (including wart) about 10 mm, dorsal and latero-dorsal papillae also about 12 per row, longest (including wart) about 10 mm, mid-dorsal papillae reduced, also about 12 per row, longest (including wart) about 4 mm, stopping 7 mm short of anus. No special papillae around mouth, few dorsal ones reaching level of anus. Tube feet restricted to ventral ambulacra with one or two also in interambulacra, those of the ventro-lateral ambulacra in two zig-zag rows with well-developed suckers, those of the mid-ventral ambulacrum in 3-4 rows, usually in groups with naked areas in between, reaching level of mouth of mouth and, except for one foot per row, not reaching level of anus. Colour in alcohol light buff, tube feet of same colouration but warts of papillae greyish. Body wall slightly rough to the touch; contracted thickness 7 mm.

Internal organs lost, including calcareous ring and associated structures, only posterior ends of longitudinal muscles and cloaca intact. Longitudinal muscles apparently paired, perhaps due to strong contraction.

Spicules of body wall comprise tables of two sizes, dorsal ones larger and more numerous. Discs of large dorsal tables ( Figure 16B ) 150-410 µm (mean 275 µm), 3-4-armed in approximate ratio of 3:2, arms often branched, sometimes dichotomously, with branches frequently anastomosing to form racquet-like expansions, perforated by up to 10 holes ( Figure 16C ), arms never fused to form complete disc; spire of moderate height, 55-110 µm (mean 72 µm), often short, ending in about three teeth, which may be further subdivided. Small tables (crosses) rare dorsally, often reduced, with cross-like disc ( Figure 16A ), 35-140 µm (mean 87 µm), with short non-perforate arms or arms perforated by 1-(2) holes at ends; spire height at least half diameter of disc, 20-95 µm (mean 54 µm). Large tables of ventral integument with discs smaller than those of dorsal tables ( Figure 16G ), 105-340 µm (mean 181 µm), also with 3-4, rarely bifurcating arms, each pierced by up to five holes, rarely more; spire height 55-70 µm (mean 64 µm); discs of smaller tables (crosses) ( Figure 16F ) 55-110 µm (mean 84 µm), similar to those of dorsal body wall, also appearing as simple crosses, arms with or without terminal holes; spire 45-50 µm (mean 48 µm) with or without holes at tip. Rods of papillae ( Figure 16D ) of variable size, 160-813 µm (mean 398 µm), and usually smooth or adorned with a few spines, terminally branched, with or without perforations, sometimes with a short third arm which may or may not be further subdivided. Rods of tube feet ( Figure 16E ) 215-790 µm (mean 507 µm), similar in form to those of papillae, but usually without perforations at ends; ‘end-plates’ 975-1190 µm, complex, consisting of several simple, overlying plates, typical of genus.

Distribution Off south and west coast of WCP, 366-1006 m.

Remarks

The single specimen approaches S. mollis Cherbonnier, 1952 , described from off the west coast of South Africa at 366 m, as well as the preceding species (see Table 2). In Cherbonnier’s description of S. mollis and my examination of the holotype, the ventral tube feet are in 4-6 rows, there are no large tables with bifurcating arms and the arms have fewer(4) holes instead of 11 found in my cf. S. mollis . The latter specimen resembles the holotype in the absence of special oral papillae and the general appearance of the spicules. It appears that this is the only difference between the two forms. It differs from S. samyni in the absence of any special oral papillae, the extension of the tube feet to the level of the mouth and the rarity of larger tables with bifurcating arms. The single specimen also comes quite close to S. challengeri ( Théel, 1886) , recently re-described by ( Massin 1992), from the Kerguelen Archipelago. However, in this species, according to Massin, the mouth is surrounded by 16 long papillae, sometimes arranged in four bundles, and the dorsal and ventral body wall has scarce spicules. In addition, the ends of the table arms in S. challengeri often branch and the branches anastomose to form open or closed table discs.

Figures

FIGURE 16. Synallactes cf mollis.Cherbonnier, SAM-A28023. A. Small tables (crosses) from dorsal body wall; B. large tables from dorsal body wall; C. end of arms of dorsal tables; D. rods from dorsal papillae; E. rods from tube feet; F. smalltables(crosses)fromventralbodywall;G.largetablesfromventralbodywall.Alldrawntosamescale.