Eumitra, TATE, 1889

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 : 287-288

GENUS EUMITRA TATE, 1889

( FIG. 12)

Type species: † Mitra alokiza Tenison-Woods 1879 ; SD ( Ludbrook, 1958: 71).

Diagnosis: Shell small to medium sized (15–58 mm), fusiform, thin walled, with high orthoconoid spire and slender siphonal canal. Protoconch very low, cyrtoconoid, paucispiral, with glossy whorls and rather small nucleus in all known species. Suture distinct, impressed. Early teleoconch whorls subcylindrical, later evenly convex, sometimes resulting in a slightly acuminate spire profile. Shell smooth, sometimes with very weak axial folds on first teleoconch whorl or fine grooves on shell base and siphonal canal. Siphonal canal, slender, tapering. Siphonal notch absent. Aperture elongate, outer lip evenly convex, smooth. Inner aperture lip either smooth, bearing one very weak or sometimes two distinct, but weak, columellar folds. Shell uniformly pale to light brown. Radula with very small, narrow rachidian, bearing five short robust cusps, only slightly extending beyond preceding tooth margin, but forming ridges, notably elevated above surface of rachidian. Laterals wide with eight to ten strong, pointed subequal cusps.

Distribution: New Caledonia, Coral Sea and the Philippines at bathyal depths, and a further undescribed species referable to Eumitra from Indonesia. Fossil species widely distributed in the Miocene of Europe and in the Australia – New Zealand region.

Recent species included: Eumitra apheles Lozouet , 19912, E. caledonica Lozouet , 19913, E. imbricata Lozouet , 19913, E. richeri Lozouet , 19913. ‘ Eumitra ’ suduirauti Bozzetti , 19973.

Remarks: Eumitra was not included in our molecular analysis, and our understanding of this genus is largely based on published data ( Lozouet, 1991), although additional material from the West Pacific has been examined. The placement of Eumitra in the newly circumscribed Mitrinae is thus tentative and based on the plesiomorphic radula of Eumitra and the presence of a well-developed epiproboscis (YK, unpublished data). Based on shell characters, Eumitra resembles Calcimitra and Profundimitra gen. nov.; however, in the latter two genera species commonly have three or more strong columellar folds. Besides, all studied species of Profundimitra gen. nov. are characterized by a radula with a rachidian as broad as the laterals. Species of Eumitra lacking shell sculpture somewhat resemble the costellariid genera Latiromitra and Costapex ( Fedosov et al., 2017) , which however, can be distinguished by the presence of an operculum, although reduced, and a longer siphonal canal ( Latiromitra ) or three or more distinct columellar folds ( Costapex ). Moreover, in both Latiromitra and Costapex , the early teleoconch whorls are sculptured with strong axial ribs that are absent in Eumitra .

‘ Eumitra ’ suduirauti Bozzetti, 1997 ( Fig. 12E) shows some features (such as a wide aperture, especially wide in its anterior portion, a distinct subsutural ramp, pronounced on late teleoconch whorls, as well, as on early spire whorls) that are uncommon not only in the genus Eumitra , but in the family Mitridae in general. However, as no data on radula morphology or DNA of this odd species are available, we maintain it in the genus Eumitra pending a better placement to be determined in future.

All known species of Eumitra share a paucispiral protoconch that distinguishes them from most other mitrid genera. Nevertheless, given the wide distribution of Eumitra in the fossil record, we cannot rule out the possibility of multiple transitions to non-planktotrophic development in the evolutionary history of the genus, and thus some members of Eumitra might have retained planktotrophic development, and thus a multispiral protoconch.

GENUS NEOTIARA FEDOSOV, HERRMANN, KANTOR &