Holothuria (Mertensiothuria) hilla Lesson, 1830

THANDAR, AHMED S., 2007, Additions to the aspidochirotid, molpadid and apodid holothuroids (Echinodermata: Holothuroidea) from the east coast of southern Africa, with descriptions of new species, Zootaxa 1414 (1), pp. 1-62 : 24-25

Holothuria (Mertensiothuria) hilla Lesson, 1830

Figure 10

Holothuria hilla Lesson, 1830: 226 , pl. 79.

Holothuria (Thymiosycia) hilla Massin, 1999: 55 (synonymy & records before 1999).

Holothuria (Mertensiothuria) hilla Samyn & Massin, 2003: 2500 , fig. 5 A–E, 11C, 12F (records after 1999).

Type MNHNP, EcHh 542 .

Type locality Borabora Island (Society Island) .

Previous southern African record Mozambique and east coast of South Africa.

Material examined

SAM-A27931 , Sodwana Reef, Rotenone , St. RW 76–15, scuba-gear, 25.vii. 1976, 17 m , 1 spec., SAM- A27932, Isipingo Beach , KwaZulu-Natal, 26 iv 1979, rock pool, K.S. Ganga & G.C. Naidu, 1 spec. (juvenile).

Description

Sodwana specimen ( SAM-A 27931) 45x 16 mm, strongly contracted, eviscerated and somewhat mutilated due to previous dissection. Colour, in alcohol, greyish with pale areas around podia. Mouth sub-ventral, collar absent; anus terminal, no special anal papillae. Podia scattered, better developed ventrally with some indication here of their arrangement in rows, few and reduced dorsally. Tentacle ampullae short (<0.5 mm). Polian vesicle single, elongate; stone canal straight, madreporite spherical. Cuvierian tubules present. Body wall table discs 46–65 µm (mean 54 µm) ( Figure 10A ), smooth, squarish to roundish, with a single series (or only four) marginal holes; spire 33–42 µm high (mean 36 µm), with single cross-bar, terminating in ring of few short spines. Buttons ( Figure 10B ) smooth, 50–75 µm (mean 61 µm), regular, with 3–5 pairs of large holes. Ventral podial deposits reduced tables, buttons 57–109 µm (mean 74 µm), large multilocular perforated plates ( Figure 10C ), 98–154 µm x 32–109 µm, and end-plates; buttons often asymmetrical and/or reduced to a single series of holes. Table disc of dorsal podia 54–67 µm (mean 58 µm), spire 37–44 µm (mean 41 µm); buttons 61–100 µm (mean 83 µm) and button-like plates and rods ( Figure 10D ) 33–135 µm (mean 91 µm), the latter usually perforate at ends. Tentacle rods slender, 28–144 µm (mean 63 µm), spinulated at ends ( Figure 10E ). Longitudinal muscles with deposits resembling letters of alphabet in both script and print form.

Table discs of Isipingo specimen ( SAM-A 27932) 42–70 µm, with 8–10 marginal and sometimes a second series of much smaller holes outside these; buttons 50–105 µm.

Distribution Tropical-subtropical Indo-West Pacific Ocean, 0– 30 m.

Habitat Benthic, shallow, inshore.

Remarks

Despite the absence of a distinct ring around the anus, the Sodwana specimen is still referred to the widely distributed H. (M) hilla . It is, however, briefly described above as there are some significant differences. The Isipingo specimens, definitely referable to H. hilla , have smaller spicules than those given for the species by Rowe (1969), but their dimensions match those of Pearson’s (1910) Mozambique specimen and of Samyn & Massin’s (2003) Kenya material. The latter workers recently removed the species from Thymiosycia and transferred it to Mertensiothuria .

Figures

FIGURE 10. Holothuria (Mertensiothuria) hilla Lesson, 1833. SAM–A27931. A. tables from ventral body wall; B. buttons from ventral body wall; C. plates from ventral podia; D. rods from dorsal podia; E. rods from tentacles. (All drawn to same scale)