Calcimitra, HUANG, 2011

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 : 283-287

GENUS CALCIMITRA HUANG, 2011

( FIGS 10B, C, 11)

Type species: Calcimitra kingtsio Huang, 2011 ; OD.

Diagnosis: Shell medium sized to large (35–125 mm), elongate-fusiform, with high orthoconoid or slightly acuminate spire and slender, tapering siphonal canal. Protoconch narrowly conical, multispiral, of about three smooth convex whorls. Suture deeply impressed or canaliculate. Spire whorls flattened to evenly convex, smooth or sculptured with weak and irregular, or distinct, evenly set cords. Interspaces between spiral cords sometimes ornamented with fine collabral growth lines or dense riblets sometimes forming fine cancellate sculpture pattern. Siphonal canal long, tapering, with shallow or indistinct siphonal notch. Aperture elongate, its outer lip smooth, evenly convex. Inner aperture lip often calloused, sometimes reflected, bearing three to four fine columellar folds. Shell white, pale to orange, sometimes bearing pattern of reddish or brownish axial bands; fresh specimens often covered with brown periostracum. Radula with rather narrow rachidian, bearing six to eight subequal cusps; laterals wide, bearing 12–20 pointed cusps ( Fig. 10B, C), two proximal cusps rather short, weaker than the next five ones that are strongest; marginal five to eight cusps gradually diminishing.

Distribution: Indo-Pacific, bathyal depths, mud, sometimes on sunken wood.

Species included: Calcimitra arnoldeyasi (Poppe, Tagaro & Salisbury, 2010) 3 comb. nov., C. brinkae (Salisbury & Kilburn, 1996) 3 comb. nov., C. brunetta (Chino & Herrmann, 2015) 3 comb. nov., C. chiangfucius ( Huang & Salisbury, 2017) 2 comb. nov., C. christinae ( Poppe, 2008) 1 comb. nov., C. chuoi ( Huang & Salisbury, 2017) 3 comb. nov., C. glaphyria (Turner, 2001) 1 comb. nov., C. hilli ( Cernohorsky, 1976) 3 comb. nov., C. invicta ( Huang & Salisbury, 2017) 1 comb. nov., C. kingtsio Huang , 20113, C. labecula (Herrmann & Dekkers, 2009) 1 comb. nov., C. lussii (Turner & Salisbury, 2007) 3 comb. nov., C. marrowi (Turner, 2001) 3 comb. nov., C. meyeriana (Salisbury, 1992) 3 comb. nov., C. morchii (A. Adams, 1855) 2 comb. nov., C. philosopha ( Huang & Salisbury, 2017) 2 comb. nov., C. poppei (Guillot de Suduiraut, 2000) 3 comb. nov., C. salva (Turner, 2001) 3 comb. nov., C. subflava (Kuroda & Habe, 1971) 3 comb. nov., C. taiwanbale ( Huang & Salisbury, 2017) 3 comb. nov., C. triplicata (Martens, 1904) 1 comb. nov., C. verweyi (Knudsen, 1970) 3 comb. nov.

Remarks: The five species included in clade 13 of the COI -based tree show considerable variation in shell morphology, both intra- and interspecifically. Six sequenced specimens of C. glaphyria display a range of sculpture types, from smooth shells resembling C. kingtsio to distinct, cancellated ones, and differently sculptured specimens can be found in the same general locality. While typical Calcimitra are medium-sized, thin-walled shells, our phylogenetic analysis placed ‘ Mitra ’ invicta in the same phylogenetic clade. The latter is a recently described species representative of a group of large deep-water mitrids (here referred to as the C. morchii complex) that possess heavy, strongly sculptured shells ( Huang & Salisbury, 2017). The close affinity of these conchologically diverse species is consistent with a generally conservative radular morphology in C. kingtsio ( Huang, 2011) , C. morchii , C. chiangfucius , C. philosopha ( Huang & Salisbury, 2017) , C. glaphyria and C. invicta (herein). The intraspecific variation in sculpture pattern demonstrated by C. glaphyria challenges the status of the species in the C. morchii complex accepted by Huang & Salisbury (2017). The distinction of C. chiangfucius , C. taiwanbale and C. invicta is based on subtle differences in shell morphology; they may prove to represent variants of a single species, and more comprehensive sampling is necessary to clarify species boundaries.

Magnamitra sandrogorii strongly resembles some of the larger species of Calcimitra , and the distinction of these two genera based on shell characters is problematic. The spiral sculpture in M. sandrogorii is even stronger than in species of the C. morchii complex, and the main distinction between the two genera is in the radula. In Magnamitra , the rachidian has a very strong unpaired central cusp that notably exceeds lateral cusps, whereas all studied species of Calcimitra possess a rachidian with equal or subequal cusps. Furthermore, rachidian and laterals have comparable width in M. sandrogorii , whereas in species of Calcimitra the width of the rachidian does not exceed half of the laterals width. Species of Profundimitra gen. nov. superficially resemble Calcimitra , but the latter genus can be recognized by the generally larger shells with proportionally longer siphonal canal and often calloused inner aperture lip. The radulae of species of Calcimitra and Profundimitra gen. nov. differ greatly, the latter having rachidian and marginals of about equal width. Species of Eumitra are also similar to Calcimitra in shell proportions and sculpture; however, Eumitra can be distinguished by its columellar folds, which are reduced to not more than two very weak folds, while in Calcimitra there are four (very rarely three) distinct ones.

Some species of Calcimitra , in particular C. triplicata , resemblance the Miocene fossil genus Clifdenia , both in whorl outline with evenly rounded inflated shoulders, and in shape and orientation of columellar plaits (A. Beu, personal communication). Based on this resemblance, we tentatively allocate Clifdenia to the subfamily Mitrinae .