Subcancilla, OLSSON & HARBISON, 1953

Fedosov, Alexander, Puillandre, Nicolas, Herrmann, Manfred, Kantor, Yuri, Oliverio, Marco, Dgebuadze, Polina, Modica, Maria Vittoria & Bouchet, Philippe, 2018, The collapse of Mitra: molecular systematics and morphology of the Mitridae (Gastropoda: Neogastropoda), Zoological Journal of the Linnean Society 183, pp. 253-337 : 319-321

GENUS SUBCANCILLA OLSSON & HARBISON, 1953

( FIGS 35D–F, 36)

Type species: Mitra sulcata Swainson, 1825 ; OD.

Diagnosis: Shell small to large (15–125 mm), fusiform, with white or light background colour and contrasting brown lines on crests of spiral cords. Protoconch smooth, with slightly convex or flattened whorls, either pointed, narrowly conical, of about three whorls, or bulbous, of about two whorls. Suture indistinct. Spire moderately high, spire whorls evenly convex, sometimes shouldered in appearance due to strong elevated spiral cords that are rather sharp and widely set. Interspaces between spiral cords sculptured with fine, dense riblets, or smooth with microsculpture of very fine growth lines. Shell base triangular with straight, tapering siphonal canal not delineated from shell base. Siphonal notch deep. Aperture high, about half of shell height, narrow, parallel-sided. Outer aperture lip very gently convex, smooth. Inner lip with three fine, oblique columellar folds. Thin light brown periostracum sometimes present. Radula with narrow rachidian and laterals two to four times wider than rachidian ( Fig. 35D–F), both multicuspidate, either with dense pointed cusps of subequal strength or with one cusp on laterals notably stronger than others and rachidian bearing symmetrical paired cusps also differentiated in length and strength.

Distribution: Tropical East Pacific, Caribbean, subtidal and bathyal depths.

Species included: Subcancilla attenuata (Broderip, 1836) 1, S. belcheri (Hinds, 1843) 3 comb. nov., S. calodinota (S. S. Berry, 1960) 3, S. candida (Reeve, 1845) 3, S. directa (Berry, 1960) 3, S. edithrexae (Sphon, 1976) 3, S. erythrogramma (Tomlin, 1931) 1, S. funiculata (Reeve, 1844) 3, S. gigantea (Reeve, 1844) 3, S. haneti (Petit de la Saussaye, 1852) 3, S. hindsii (Reeve, 1844) 3, S. joapyra Simone & Cunha, 20123, S. larranagai (Carcelles, 1947) 3, S. leonardi (Petuch, 1990) 1 comb. nov., S. leonardhilli Petuch , 19872, Subcancilla lindae Petuch , 19873, S. lopesi Matthews & Coelho , 19693, S. malleti (Petit de la Saussaye, 1852) 3, S. phorminx (S. S. Berry, 1969) 3, † S. scrobiculata (Brocchi, 1814) 3, S. sulcata (Swainson, 1825) 2.

Remarks: Cernohorsky (1991) remarked that the placement of the New World S. sulcata and of Indo-Pacific species in the same genus Subcancilla was inconsistent with their disparate radular morphology; however, no alternative was suggested. Thorsson & Salisbury (2008: 3) stressed that the classification of the Panamic and Caribbean species of Subcancilla , including the type species S. sulcata , has not been addressed sufficiently, and that the ‘exact placement of Subcancilla into the family Mitridae remain[ed] to be absolutely determined’.

Based on our phylogenetic analysis, we demonstrate a close affinity of three East Pacific and one Caribbean species of Subcancilla , and reconsider the contents of the genus, so that only New World species are here assigned to it. The species of Subcancilla can be readily distinguished from other American mitrids by their characteristic sculpture of narrow, elevated, usually widely interspaced, spiral cords, often bearing a brown line on their crests; the same sculptural pattern characterizes Indo-Pacific species in the genera Domiporta and Imbricaria . Members of these three genera are also characterized by similar shell proportions, so that their shells share the same characteristic habitus that has long confused conchologists. Our results demonstrate that the three genera represent three major phylogenetic lineages of Mitridae in the subfamilies Isarinae , Mitrinae and Imbricariinae , and their resemblance is obviously a result of convergence.

The radula differs remarkably in the three studied species, with those of S. attenuata and S. cf. leonardhilli being overall unremarkable underived mitrid radulae, whereas that of S. erythrogramma demonstrates signs of cusp differentiation, resembling imbricariine radulae. The small and unconspicious radula of S. sulcata pictured by Cernohorsky (1991: fig. 79) undoubtedly belongs to the first type.

SUBFAMILY PLEIOPTYGMATINAE QUINN, 1989