CHARITODORONIDAE FEDOSOV, HERRMANN, KANTOR & BOUCHET, 2018

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 : 282

FAMILY CHARITODORONIDAE FEDOSOV, HERRMANN, KANTOR & BOUCHET FAM. NOV.

( FIG. 8)

Diagnosis: Shell small (13–35 mm), fusiform, white or pale, sometimes with dark bands, or covered with brown periostracum. Protoconch white, bulbous, of about 1.5 smooth glossy whorls and with large nucleus. Suture distinct, impressed. Spire tall, orthoconoid; spire whorls evenly convex, smooth or sculptured with weak spiral grooves or cords. Sometimes distinct cancellate sculpture developed. Siphonal canal moderately long, robust or tapering, sometimes slightly recurved at its tip; siphonal notch shallow. Aperture wide, elongate; outer aperture lip smooth, evenly convex. Inner lip with no columellar folds.

Head–foot pale, with sometimes nebulose dark bands. Tentacles moderately long with eyes situated laterally at about mid-length. Siphon long. Osphradium as long as gill, attaining about 2/3 of the length of the latter. Proboscis well developed, without distinct proboscis rim; epiproboscis absent. Radula with narrow rachidian, bearing five subequal cusps, and wide, multicuspidate laterals, with cusps being more dense and stout proximally and becoming more slender towards radula margins; lateral 1/5 portion of teeth smooth. Mid-oesophagus muscular; mid-gut gland absent. Salivary gland single with paired ducts opening in buccal tube ventrally and anterior to radular diverticulum.

Remarks: The newly proposed family Charitodoronidae is distinctive in many ways. The shell bears no columellar folds and rather resembles a buccinoid shell; for this reason, many Charitodoron species were originally erroneously placed in Columbella . The bulbous protoconch is unusual for Mitridae and suggests a non-planktotrophic development, consistent with the narrow distribution range. Despite Charitodoron being close to mitrids in radula morphology, it does not possess the key morphological innovation of the Mitridae , the epiproboscis. The obvious morphological distinctiveness of Charitodoron and its position in the molecular tree as a sister group to all other Mitridae justify its recognition in a separate family.