Chiton (Rhyssoplax) subassimilis Souverbie

Schwabe, Enrico, Sirenko, Boris I. & Seeto, Johnson, 2008, A checklist of Polyplacophora (Mollusca) from the Fiji islands, Zootaxa 1777, pp. 1-52 : 14-15

Chiton (Rhyssoplax) subassimilis Souverbie in Souverbie & Montrouzier, 1866

( Figure 4 D)

Chresonymy in Kaas et al. (2006: 179, 192).

Chiton subassimilis Souverbie in Souverbie & Montrouzier 1866: 254, pl. 9, fig. 2.; Kaas & Van Belle 1980: 126; 1998: 180; Slieker 2000: 20, 94, 153, pl. 35, fig. 20; Kaas et al. 2006: 179.

syn nov. Chiton spinosetatus Bergenhayn 1930a: 24 , pl. 1, figs 17–28, pl. 2, figs 29–31 (holotype SMNH 972; type locality: Fiji Islands, SW - Viti Levu Island, Kaba [we failed in finding “Kaba”, but the Kaba Point at the Kaba Peninsula is located at 18°00’10’’S 178°42’17’’E in the SE of Viti Levu]; see remarks); Leloup 1952: 38, text-fig. 14, pl. 2, figs 1–2; Kaas & Van Belle 1980: 122; 1998: 175; Kaas et al. 2006: 192.

Chiton (Rhyssoplax) spinosetatus ; Kaas & Van Belle 1980: 122; 1998: 175; Kaas et al. 2006: 192, fig. 75.

Chiton (Rhyssoplax) subassimilis ; Kaas & Van Belle 1998: 180; Schwabe 2000a: 47; 2001: 27; Schwabe & Slieker 2001: 225; Kaas et al. 2006: 179, fig. 67.

Locus typicus: New Caledonia, Art Island [19°43’S 163°39’E].

Primary type: Holotype (MHNB).

Fiji records: Chiton spinosetatus Bergenhayn 1930a: 24 , pl. 1, figs 17–28, pl. 2, figs 29–31. cf. Heterozona ; Morton & Raj 1981: 108, pl. IV.18.

Rhyssoplax spinosetata ; Bullock 1988a: 688, figs 7, 12.

Chiton (Rhyssoplax) spinosetatus ; Kaas et al. 2006: 192, fig. 75.

Material examined: ZSM Mol 20061616: 1 adult spm, Viti Levu, Laucala Bay, north side of Nukumbutho Island 18°10.474'S 178°28.343'E; lowest low tide, landward in calm water close to the beach, 0.5 m, under stones and dead corals, which are mainly covered with algae, leg. Enrico Schwabe, 21 August 2006, wet; ZSM Mol 20061910: 2 subadult spms, Viti Levu, Laucala Bay, South side of Laucala Island, inner side of fringing reef, east of Nukulau Island ("Prison Island "); 18°10.045'S 178°31.837'E, sea weed, isolated stones with algae cover in silty sediment, 0.5–1.5 m, leg. Enrico Schwabe & Michael Schrödl, 30 August 2006, wet; UF 293483: 1 subadult spm, Viti Levu, Laucala Bay, behind USP Maritime Studies buildings 18°09’03’’S 178°27’14’’E, 0–1 m, sand and mud reef flat, under dead coral rubble and Halimeda sp., leg. Lisa Kirkendale & Victor Bonito, 0 6 October 2001 (LAK-005), wet; UF 289172: 1 adult spm, N tip of Ndravuni Island [18°46’S 178°32’E], 1 m, attached to undersides of loose rock slabs, leg. Gustav Paulay, 29 July 1985 (BFIJI-68), wet; UF 289185: 1 subadult spm, Viti Levu, Tailevu, Tailevu coast, Talira, site 1 [17°39’S 178°35’E], 1–2.5 m, on sand, leg. Holthuis, B. & Gustav Paulay, 0 9 December 1986 (BFIJI-123), wet.

Habitat: The present material reveals that this species has a preference for shallow water, living under all kinds of hard substrata in moderately calm water.

Distribution: Kaas et al. (2006: 179) considered C. subassimilis endemic to New Caledonia, overlooking the record of the species from Western Samoa by Schwabe (2000a: 47). Chiton spinosetatus was regarded as endemic to Fiji Islands ( Kaas et al. 2006: 194).

Remarks: Morton & Raj (1981) sketched a species with scales and a stripped perinotum, which they called " Heterozona ". Chiton subassimilis is quite common and shows those characters, so it is highly likely that the authors refer to this species.

The synonymy of Chiton spinosetatus with C. subassimilis is tentative. Schwabe et al. [unpublished data] while revising the New Caledonian shallow water Polyplacophora were able to study the holotype of C. subassimilis , which in their opinion does not show differences to material they illustrated and examined in detail from the Samoan Islands, especially the girdle scales are of the same size, form, and sculpture, and also the tegmentum sculpture is matching. This material also does not show differences to the Fiji specimens of C. spinosetatus . However, the proposed synonymy of Chiton spinosetatus and C. subassimilis can be verified only when valves from the holotype of the latter may be removed (but we were not permitted), as characters like the slit formula could not be assessed from the complete holotype of C. subassimilis . The tegmentum sculpture is identical especially the number of ribs in the central areas, lateral areas and also in the terminal valves (see also Kaas et al. 2006, p. 179 for C. subassimilis and p. 192 for C. spinosetatus ).

It is highly likely that in the original description the type locality was wrongly cited. Despite extensive researches we failed in finding another “Kaba” on Viti Levu, than the locality called Kaba Point at the Kaba Peninsula, which is located at 18°00’10’’S 178°42’17’’E in the SE of Viti Levu.

Figures

FIGURE 4. A – C, Chiton (Rhyssoplax) pulcherrimus Sowerby, 1842. A, Chiton (Rhyssoplax) pulcherrimus Sowerby, 1842, ZISP: Fiji, Vekai Island [17 ° 34 ’ S 178 ° 49 ’ W], Callisto St. 95. right lateral view. B – C, lectotype of Chiton reticulatus Nierstrasz, 1905 ZMA Moll. 3.05. 0 56, Indonesia, Sulawesi Selatan, near the North point of Pulau Selayar (Siboga Station 213). B, dorsal view of the anterior portion. C, dorsal view of the posterior portion. D, Chiton (Rhyssoplax) subassimilis Souverbie in Souverbie & Montrouzier, 1866, ZSM Mol 20061910: Fiji, Viti Levu, Laucala Bay, South side of Laucala Island, inner side of fringing reef, east of Nukulau Island (" Prison Island "); 18 ° 10.045 ' S 178 ° 31.837 ' E, dorsal view. E – F, Chiton (Tegulaplax) hululensis (E. A. Smith in Gardiner, 1903). E, ZSM Mol 20061635: Fiji, Viti Levu, Laucala Bay, North of Makuluva Island, 18 ° 10.890 ' S 178 ° 30.587 ' E, dorsal view. F, habitat photograph of a specimen from the same locality as in fig. E. Scale bars A – E 2 mm, F unknown.