Cryptogemma tessellata, (POWELL, 1967)

CRYPTOGEMMA TESSELLATA ( POWELL, 1967) View in CoL

( FIG. 10A–D)

Gemmula tessellata Powell, 1967: 439 View in CoL (22–734a), pl. 315. 183– 219 m, off Waikiki, Oahu Island, Hawaiian Islands (collected by Dr Pat Burgess).

Remarks: This species corresponds to PSH 12 in the study by Puillandre et al. (2012). The protoconch of the holotype is 4.5 whorls according to Powell (1967), and PD = 1.22 mm and PL = 1.64 mm according to measurements inferred from photographs of the holotype. The protoconch exhibits high variability, with PD = 1.175–1.3 mm, PL = 1.525 –1.975 mm and consisting of four to 5.5 whorls.

The radula is of medium length, ~ 1.2 mm (0.29 of AL), composed of 51 transverse rows of teeth. The marginal teeth are 86–91 µm long (mean 89 µm, N = 2, or 2.1% of AL), duplex. The anterior (inner) half of the tooth length is solid, medium broad in dorsal view, triangular. The accessory limb is weak, thin, without constriction, much shorter than the major limb, but of nearly same width (the marginal teeth in Fig. 8F are not fully sclerotized). The central formation has a long, sharp and carinated central cusp, slightly curved in profile, and with lateral conspicuous flaps with distinct margins. The flaps are not completely fused with the cusp. The anterior margin of the central formation is strongly concave ( Fig. 7F).

The ‘light form’ of C. tessellata has been misidentified by Puillandre et al. (2012) as Xenuroturris gemmuloides Powell, 1967 because it shares superficially similar features, such as the white-yellowish shell punctuated with regular brown-orange spots, and the small size (~ 15–25 mm). The ‘brown-orange form’ of C. tessellata , closer to the holotype, is distinctly different from the ‘light form’ not only in colouration, but also in having a stouter outline and a more tuberculate subsutural fold ( Powell, 1967). Although readily distinguished from the other Cryptogemma species owing to its colour pattern and small size, LDA indicates that this species more closely resembles small adults of C. praesignis .

List of COI diagnostic sites (position: character state): [46: C; 61: A; 316: T].

Distribution: The sequenced specimens were found off New Caledonia only, and the holotype is from the Hawaiian Islands ( Fig. 4C), from a depth of ~200 to ~ 500 m ( Fig. 5). The protoconch characteristics, similar in shape, size and number of whorls to C. praesignis , imply that the species might have a much broader range than what is currently documented, possibly covering the entire central Pacific.