Cryptogemma unilineata, (POWELL, 1967)

CRYPTOGEMMA UNILINEATA ( POWELL, 1967) View in CoL

( FIG. 10E–H)

Gemmula congener unilineata Powell, 1967: 437 View in CoL (22– 716a), pl. 313. 366 m, off Waikiki, Oahu Island, Hawaii (Expedition Pele, 13 June 1964).

Remarks: This species corresponds to PSH 13 in the study by Puillandre et al. (2012).

The protoconch is commonly retained, with PD = 1.075 –1.275 mm, PL = 1.375 –1.925 mm and the number of whorls ranging from 4.75 to 5.5 GoogleMaps .

The radula is long, ~ 3 mm in length (0.31 of AL), composed of 99 transverse rows of teeth. The marginal teeth are 121–127 µm long (mean 125 µm, N = 5, or 1.27% of AL), duplex. The anterior (inner) 0.4 of the tooth length is solid, narrow in dorsal view and awl shaped. In the posterior part, the major and accessory limbs are broadly bifurcating, the accessory limb with a clear constriction and bent at about half the tooth length, slightly shorter than the major limb. The central formation has a long, sharp, carinated cusp and lateral flaps with distinct posterior and anterolateral margins. The flaps are not completely fused with the cusp ( Fig. 7G).

This species has been named based on the characteristic carinated brown-orange subsutural band. The brown-orange subsutural band has been found in C. powelli and in some specimens of C. praesignis , and in other Turridae , such as Gemmula cosmoi (Sykes, 1930) , but it is generally smoother and thinner than that of C. unilineata . The LDA indicated that C. unilineata generally has a more angulated shape on the outer aperture lip of the last whorl, indicating a more concave subsutural ramp in comparison to other Cryptogemma . However, we note that the convex hulls ( Fig. 1) of C. unilineata and C. powelli are greatly overlapping; therefore, the strong carinated brown-orange subsutural band remains the best-suited character for distinguishing C. unlineata from C. powelli .

List of COI diagnostic sites (position: character state): [172: G; 307: T; 361: G; 370: C].

Distribution: From East Africa to the central Pacific (Hawaiian and Society Islands) ( Fig. 7D), from ~300 to ~ 800 m deep ( Fig. 5).