Holothuria (Mertensiothuria) aphanes Lampert, 1885

Yves, 2003, The holothurian subgenus Mertensiothuria (Aspidochirotida: Holothuriidae) revisited, Journal of Natural History 37, pp. 2487-2519 : 2491-2495

Holothuria (Mertensiothuria) aphanes Lampert, 1885

(figures 2A–J, 3A–H, 12C, D)

Holothuria aphanes Lampert, 1885: 242 ; Ludwig, 1889–92: 329; Oestergren, 1898: 235, figures 3, 4; Sluiter, 1901: 16; Panning, 1935c: 87 (cited as a synonym of H. impatiens ); Panning, 1935d: 14; Cherbonnier, 1955: 149, pl. 31, figure a–o.

Holothuria (Thymiosycia) aphanes: Rowe, 1969: 147 ; Clark and Rowe, 1971: 178; Price, 1982: 11; Cherbonnier, 1988: 93.

Original name. Holothuria aphanes Lampert, 1885 .

Name-bearing type.? Stadliches Museum für Naturkunde, Stuttgart.

Type locality. Egypt ( Kosseir , Red Sea) .

Current status. Holothuria (Thymiosycia) aphanes Lampert, 1885 .

Material examined. Red Sea (Aqaba), 9 December 1985, 3 m depth, coll. Féral and Labat, MNHNP EcHh 7174 (one specimen) .

Description. Specimen 270 mm long, 25 mm wide anteriorly and 40 mm at midbody. Colour in alcohol deep brown dorsally with yellowish tube feet (figure 12C); yellowish ventrally with white tube feet ending in a yellow sucker (figure 12D); tentacles greenish. General aspect very similar to Holothuria (Thymiosycia) impatiens (Forskål, 1775) and Holothuria (Mertensiothuria) papillifera Heding , in Mortensen, 1938. Dorsal tube feet up to 8 mm long, more or less aligned in five to six rows. Ventral tube feet conical, located along the ambulacral areas in three double rows. Tentacles short, 20. Mouth ventral, anus terminal. Specimen auto-eviscerated; only the right respiratory tree remains. Longitudinal muscles with two wide, thin folds. Calcareous ring massive (figure 2A); radial plates quadrangular with an anterior notch; interrradial plates as wide as the radial ones but low and with a strong anterior tooth (figure 2A). Tentacle ampullae short (11 mm long); four Polian vesicles: two medium (4–5 mm long) and two very small (1–2 mm long); one contorted stone canal going upwards and ending in an ovoid madreporic plate (figure 2B).

Ossicles: dorsal and ventral body wall with buttons and tables. Buttons numerous, most of them very regular with three pairs of holes (figure 2D); some with four to five pairs of holes (figure 2D). Buttons from the ventral body wall slightly smaller (58–75 m m long) than the ones from the dorsal body wall (67–90 m m long) (figure 2D, E). Tables (figure 2C) with a rounded disc with smooth margin, perforated by four large central and 10–12 peripheral holes; four pillars united by one cross-beam and ending in a very small crown of short, blunt spines. Tables 50–60 m m across and more or less 50 m m high.

In the dorsal tube feet same ossicles as in the dorsal body wall. Top of the dorsal tube feet with rods (figure 2J), 140–220 m m long, with a few lateral holes, which are located close to the small end plate (180–200 m m across). Ventral tube feet present tables, often with a reduced number of peripheral holes (figure 2H); buttons similar to the ones of the ventral body wall (figure 2G) but smaller and more irregular; and large perforated plates (figure 2F) located close to the end plate (350–400 m m across). Longitudinal muscles with rings (figure 3A), C-shape (figure 3B) and button like ossicles, 15–40 m m long (figure 3C). Tentacles with rods only: some narrow, straight or slightly curved, 40–520 m m long (figure 3D, E), some more massive with wide ragged extremities (figure 3F), and some small, 20–50 m m long, S-shape (figure 3G) and C-shape ossicles (figure 3H), located at the top of the tentacles.

Diagnosis. Present note.

Ecology. No information.

Geographical distribution. Egypt (Aqaba, Kosseir) and Djibouti (Gulf of Aden);? Indonesia (Siau Island).

Proposed status. Holothuria (Mertensiothuria) aphanes Lampert, 1885 .

Comments. H. aphanes was considered a synonym of H. impatiens by Oestergren (1898). Panning (1935c) agreed with this opinion. Rowe (1969) revived it from this synonymy and regarded H. aphanes as a valid species; we agree with this opinion as H. aphanes is distinct from H. impatiens in several ways. First, the tables of the body wall of H. aphanes have a very small and narrow crown of spines at the top of the pillars whereas H. impatiens has a larger crown. Second, the ventral tube feet of H. aphanes have large perforated plates typical of the subgenus Mertensiothuria , but not the rods with two central holes and enlarged extremities typical of H. impatiens . Moreover, the presence of very characteristic ossicles in the longitudinal muscles of H. aphanes (already mentioned by Oestergren, 1898) but not in those of H. impatiens is an additional character to separate the species. Because the ossicles located in the muscles of H. aphanes are so close to those typical of the subgenus Mertensiothuria , and because the tables of H. aphanes are very similar to those of H. hilla and H. albofusca , H. aphanes is moved from the subgenus Thymiosycia to the subgenus Mertensiothuria .

H. papillifera is morphologically very close to H. aphanes , both described from nearly the same type locality (Ghardaqa and Kosseir, respectively). Since the intraspecific variability of both species is not known, H. papillifera is possibly a junior synonym of H. aphanes . At present both species are separated by the shape of the tentacle rods and by the size of their ossicles: tables of the body wall of H. papillifera are larger than those of H. aphanes whereas the buttons of H. papillifera are smaller than those of H. aphanes , and this for specimens of similar size (220 and 270 mm long, respectively).

Holothuria aphanes seems restricted to the Red Sea, making Sluiter’s (1901) record from Indonesia dubious.

Holothuria arenacava Samyn, Massin and Muthiga, 2001 Holothuria (Mertensiothuria) arenacava Samyn, Massin and Muthiga, 2001: 102 , figures 1–3.

Original name. Holothuria (Mertensiothuria) arenacava Samyn, Massin and Muthiga, 2001 .

Name-bearing type. Holotype, IRSNB IG 28628 /KMom/9897-6 ; Paratypes, IRSNB IG 28628 /KMom/9897-2 , IRSNB IG 28628 /KMom/9897-3 , IRSNB IG 28628 /KMom/0002-2 ; MRAC 1662 /KMom/9897-1 , MRAC 1663 /KMom/0002-1 , MNHNP EcHh8070/KMom/9897-4, MNHNP EcHh8071/KMom/0002-3, SI E53097 /KMom/0002-4, SI E53098 /KMom/9897-5, NHM 2000.2414/KMom/9897-7, NHM 2000.2415/KMom/0002-5 .

Type locality. Kenya (Mombasa) .

Current status. Holothuria (Mertensiothuria) arenacava Samyn, Massin and Muthiga, 2001 .

Material examined. See Samyn et al., 2001; Kenya (Mombasa), August 1998, 14 m depth, coll. Y. Samyn, IRSNB IG 28268 /KMom/9853 (one specimen) .

Description. See Samyn et al., 2001: 102, figures 1–3.

Diagnosis. See Samyn et al., 2001: 102, figures 1–3.

Ecology. Holothuria arenacava lives in the sand at depths ranging from 9 to 12 m. The animal lies flat, just below the sand surface, only exposing part of its dorsal surface.

Geographical distribution. For now only known from the type locality ( Mombasa) .

Proposed status. Holothuria arenacava Samyn, Massin and Muthiga, 2001 (provisionally not referred to a known subgenus).

Comments. Recently, we described H. arenacava as a new holothurian species from Kenya, and placed it in the subgenus Mertensiothuria (Samyn et al., 2001) . Indeed, the morphology of the calcareous ring and the ossicles from the body wall, the dorsal and ventral tube feet agree very well with the diagnosis of Mertensiothuria . However, H. arenacava , having no ossicles in the longitudinal muscles, can no longer be retained in the subgenus Mertensiothuria . For now, we do not refer it to any of the known subgenera.