Holothuria (Platyperona) difficilis Semper, 1868

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 : 27-28

Holothuria (Platyperona) difficilis Semper, 1868

Figure 12

Holothuria difficilis Semper, 1868:92 , p1.30, fig.1.

Holothuria (Platyperona) difficilis Massin, 1999:38 (synonymy & records before 1999), figs. 28 & 29; Samyn, 2003:65 (synonymy & records after 1999), fig. 26, 54A.

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

Material examined

SAM-A27934 , KZN, North Pier , Durban, G.C. Naidu, 8 x 1977, 1 spec. (juvenile) ; SAM-A27935 , Vetch’s Pier, Durban, J. Maxwell, 27 iv 1982, 1– 2 m, under rock, 2 spec.

Description

Specimens small, largest 60 mm long. Colour in life olive green to brown with black papillae arising from yellowish green warts, one specimen with bright yellow patch on ventral surface near anus. Cuvierian tubules present. Table discs 30–80 µm and with eight marginal holes ( Figure 12A ); spire height 48–85 µm. Dorsal buttons ( Figure 12B ) with 3–4 pairs of holes; ventral buttons ( Figure 12C ) larger, with 6–7 pairs of holes, and occasionally an incomplete third series outside main series, buttons 80–140 µm. Rods and fenestrated plates of papillae ( Figure 12D ) with uneven margins. Tubefeet with rods and plates ( Figure 12E ), the latter with somewhat serrate margins and numerous small holes in 2–4 series. All podial spicules also with characteristic median optical discontinuity.

Local distribution Known only from around Durban, KZN and Mozambique, 0–6 m. General distribution Throughout tropical Indo-Pacific but not reported from the Arabian and Indian Peninsulas .

Habitat Under stones, in sand.

Remarks

The three species ( H. sanctori Delle Chiaje, 1828 ; H. parvula Selenka, 1867 ; H. difficilis Semper, 1868 ) originally included in Platyperona by Rowe (1969), are well keyed by Deichmann (1958) who also provides information regarding the colouration, presence or absence of Cuvierian tubules and the synonyms of H. difficilis . However, she does not mention the occurrence of any green forms of H. difficilis but this colouration is recorded for the consubgeneric H. parvula from the West Atlantic region. Since then H. (P.) rowei Pawson & Gust, 1981 ; H. (P.) crossnieri Cherbonnier, 1988 and H. (?P.) insolita Cherbonnier, 1988 have been described and H. samoana Ludwig, 1875 referred to this subgenus by Rowe (in Rowe & Gates 1995). Perhaps not all species are valid and must await a critical re-examination. Since H. difficilis is so widely distributed, several variations, probably at subspecific level, must be expected between such geographically isolated populations as those of the East Pacific, West Pacific and West Indian Oceans. This is perhaps the chief reason for the application of so many names to a species which is otherwise well characterised. Deichmann (1958) relegated many names to the synonymy of H. difficilis and this is partially supported by Rowe (in Rowe & Gates, 1995). However, some of the names may have to be reinstated, as our knowledge of the intraspecific variations within H. difficilis increases. Colouration, presence or absence of warts and Cuvierian tubules, the maximum size at maturity, the relative dimensions of spicules and the type of podial deposits may offer satisfactory characters. H.L. Clark’s (1923), Kalk’s (1959) and Thandar & Samyn’s (2004) are the only published records of this species from southern Africa but the latter two include no taxonomic data while that of H.L. Clark (a record overlooked by Clark & Rowe, 1971) was based on specimens from Mozambique.

Figures

FIGURE 12. Holothuria (Platyperona) difficilis Semper. SAM–A27934. Durban. A. Tables from dorsal body wall; B. buttons from dorsal body wall; C. buttons from ventral body wall; D. papillae rod and plate; E. tubefeet plates; F. madreporite; G. part of calcareous ring. (A.–C. scale a; D. scale b)