Lucilina carnosa ( Kaas, 1979 )

Dell’Angelo, Bruno, Gori, Sandro, Baschieri, Leonardo & Bonfitto, Antonio, 2010, Chitons (Mollusca, Polyplacophora) from the Maldive islands, Zootaxa 2673 (1), pp. 1-38 : 15-16

Lucilina carnosa ( Kaas, 1979)

( Figures 5C–L , 13C–H )

Tonicia (Lucilina) carnosa Kaas 1979: 869 , pl. 3, figs 1–10; 1986: 18, figs 46–48; Dell’Angelo et al. 2004: 54, pl. 5, figs

4–9; Kaas et al. 2006: 323, fig. 133. Tonicia carnosa ; Ferreira 1983: 272, 274. Lucilina carnosa ; Kaas 1996: 372; Schwabe 2004: 3156. Non Tonicia (Lucilina) carnosa ; Kaas 1985: 331; Drivas & Jay 1998: 32, fig. 3 [= L. indica ( Leloup, 1981) , fide

Schwabe 2004: 3153].

Type: Holotype NM H2576 (21.7 x 11.1 mm); paratype NM H2575 (20.5 x 9.5 mm, now disarticulated).

Type locality: Mozambique, Conducia Bay .

Material examined: M13: 65 valves (11 head, 51 intermediate and 3 tail); M17: 5 valves (3 intermediate and 2 tail); M19: 3 valves (1 intermediate and 2 tail); M20: 18 valves (4 head, 12 intermediate and 2 tail); M23: 6 valves (1 head, 4 intermediate and 1 tail); M26: 10 valves (1 head, 8 intermediate and 1 tail); M65: 11 valves (10 intermediate and 1 tail); MLD01A: 1 tail valve; MLD02A: 25 valves (4 head, 16 intermediate and 5 tail); MLD03A: 9 valves (8 intermediate and 1 tail); MLD04B: 2 head valves; MLD05A: 3 valves (2 head and 1 intermediate); MLD05B: 8 valves (1 head and 7 intermediate); LB04: 1 intermediate valve; LB05: 31 valves (4 head, 23 intermediate and 4 tail).

Remarks: Detailed descriptions of this species are given by Kaas (1979) and Kaas et al. (2006).

The valves present a certain degree of variability in some characters. Particularly, the sculpture of the greater part of head valves agrees with the original description ( Kaas 1979: 869 “ about 10 low, wide, radiating riblets, decorated with flat, inverted V-shaped warts directed towards umbo. In shallow interstices eight single rows of ocelli, each splitting up into two or three rows towards margin ”) ( Figs 5C , 13D ), but some head valves show one or two more ocelli rows, with a certain degree of variability ( Fig. 13C ). The number of longitudinal grooves in the pleural areas of intermediate valves is variable, some valves show few and shorter grooves never reaching the front margin ( Figs 5G, I ), and so nearly the whole central area looks smooth (compare with Figs 5E–F , 13E , illustrating a typical intermediate valve). The same occurs in the tail valve (a typical one, agreeing to the species’ description, is illustrated in Figs 5J, L , 13F ). Some appreciable difference is recorded in the tail valve, where the front margin is straight or at most slightly concave, never convex, and 10–13 irregularly and inequidistant slits are present (slit formula 8/1/ 10–13 in contrast to the 8/1/8–10 formula reported by Kaas et al. 2006 and 8/1/9–12 by Dell’Angelo et al. 2004).

The differences described above seemingly fall within the limits of intraspecific variability.

A tail valve from M20 shows a superficial incision in the postmucronal area, which caused the development of a new insertion plate under the one already existing ( Figs 13G–H ).

This is the first report of this species from the Maldive Islands.

Distribution: Lucilina carnosa is known from Madagascar, Mozambique, Réunion, Seychelles, Amirante and the Maldive Islands.

Figures

FIGURE 5A–B, Lucilina perligera Thiele, 1909, Maldive, M13, intermediate valve. A, dorsal view. B, tegmentum granules of the central area. C–L, Lucilina carnosa (Kaas, 1979), Maldive. C–D, head valve, MLD02A. C, dorsal view. D, detail of the sculpture. E–F, intermediate valve, MLD02A. E, dorsal view. F, detail of the sculpture. G–I, intermediate valve, M23. G, dorsal view. H, frontal view. I, detail of the sculpture. J–L, tail valve, MLD02A. J. dorsal view. K, lateral view. L, detail of the sculpture of the antemucronal area. Scale bars 1 mm: A, C, E, G, H, J, K; 500 µm: I; 100 µm: B, D, F, L.

FIGURE 13A–B, Callochiton sp., S. Nilandu Atoll, Maldive, NHM 1903.4.11.71 (living specimen collected by J.S. Gardiner), close-up of the head and tail valves. C–H, Lucilina carnosa (Kaas, 1979), valves, Maldive. C–D, head valves, M13, showing differences in the number of ocelli rows, widths 3 and 3.1 mm, respectively. E, intermediate valve, M13, width 3.5 mm. F, tail valve, M13, width 3.3 mm. G–H, anomalous tail valve, dorsal and posterior views, respectively, M20, width 3.2 mm. I–K, Lucilina sp., valves, Maldive. I, head valve, M13, width 3.1 mm. J, intermediate valve, M20, width 4.7 mm. K, tail valve, M65, width 3.4 mm. L–M, Craspedochiton cf. laqueatus (Sowerby, 1842), head and intermediate valves, Maldive, M65, widths 5.7 and 5.2 mm, respectively. N, Craspedochiton sp., tail valve, Maldive, M65, width 5.8 mm. O–R, Cryptoplax burrowi E.A. Smith, 1884, NHM 1881.11.1.100, syntype, detached valves, coll. Coppinger, Port Molle, Queensland. O–P, intermediate valve, length 4 mm, dorsal and right lateral views, respectively. Q, intermediate valve, length 4.2 mm. R, head valve, length 3.5 mm.