Rhyssoplax maldivensis (E.A. Smith, 1903 )

Dell’Angelo, Bruno, Gori, Sandro, Baschieri, Leonardo & Bonfitto, Antonio, 2010, Chitons (Mollusca, Polyplacophora) from the Maldive islands, Zootaxa 2673 (1), pp. 1-38 : 13-14

Rhyssoplax maldivensis (E.A. Smith, 1903)

( Figures 4G–I )

Ischnochiton maldivensis E.A. Smith 1903: 596 , 619, pl. 36, figs 7–10.

Chiton (Rhyssoplax) maldivensis ; Schwabe 1997: 26, figs 2–3; Slieker 2000: 48, pl. 12, fig. 20; Anseeuw & Terryn 2004: 14, figs 44–45; Kaas et al. 2006: 170, fig. 63 (bibliography and synonymy).

Type: NHM 1903.9.17.26.

Type locality: Maldive Archipelago, Felidu Atoll.

Material examined: M13: 108 valves (18 head, 73 intermediate and 17 tail); M17: 9 valves (3 head, 5 intermediate and 1 tail); M19: 5 valves (4 intermediate and 1 tail); M20: 30 valves (3 head, 21 intermediate and 6 tail); M23: 9 valves (1 head and 8 intermediate); M26: 9 valves (3 head and 6 intermediate); M65: 23 valves (1 head, 19 intermediate and 3 tail); MLD01A: 8 valves (2 head, 4 intermediate and 2 tail); MLD02A: 55 valves (14 head, 31 intermediate and 10 tail); MLD03A: 3 valves (1 head and 2 tail); MLD04B: 2 intermediate valves; MLD05A: 3 intermediate valves; LB02B: 1 spm (juv., length 2.4 mm); LB04: 8 valves (1 head, 5 intermediate and 2 tail); LB05: 56 valves (4 head, 44 intermediate and 8 tail).

Remarks: A detailed description of this species is given by Kaas et al. (2006).

The valves present a certain degree of variability in some characters. The lateral areas of intermediate valves are well raised, and crossed by nonuniform and sometimes interrupted concentric growth lines, which give the impression of two large and thin radial striae on the lateral area. The same is true for the head valve and postmucronal area. Slit formula is 8–9/1/10–11, with short, blunt, unequal teeth.

Distribution: Rhyssoplax maldivensis is reported from the Red Sea, the Gulf of Aden, and the Maldive Islands.

Figures

FIGURE 4A–C, Callochiton clausadeae Kaas & Van Belle, 1985, tail valve, Maldive, M13. A–B, dorsal and lateral views, respectively. C, detail of the sculpture. D–F, Callochiton sp., S. Nilandu Atoll, Maldive, NHM 1903.4.11.71 (living specimen collected by J.S. Gardiner, not coated). D, detail of the sculpture of an intermediate valve. E, dorsal view of the complete specimen. F, girdle dorsal spicules in situ. G–I, Rhyssoplax maldivensis (E.A. Smith, 1903), Maldive, MLD02A. G, intermediate valve, dorsal view. H–I, tail valve, dorsal and lateral views, respectively. J–O, Tegulaplax hululensis (E.A. Smith, 1903), Maldive, M13. J–L, head valve. J–K, dorsal and lateral views. L, detail of the sculpture. M–O, tail valve. M–N, dorsal and lateral views, respectively. O, detail of the sculpture. Scale bars 1 mm: E, G, J, K, M, N; 500 µm: A, B, D, H, I; 100 µm: C, F, L; 50 µm: O.