PUSIA, Swainson, 1840

Fedosov, Alexander E., Puillandre, Nicolas, Herrmann, Manfred, Dgebuadze, Polina & Bouchet, Philippe, 2017, Phylogeny, systematics, and evolution of the family Costellariidae (Gastropoda: Neogastropoda), Zoological Journal of the Linnean Society 179 (3), pp. 541-626 : 601-602

SUBGENUS PUSIA (VEXILLENA) SUBGEN. NOV.

Type species: Vexillum balutense Herrmann, 2009 .

Diagnosis

Shell small to medium sized, fusiform. Protoconch conical, with 3.5 or more glossy, weakly convex whorls, orange or light brown, translucent. Early spire whorls usually slightly flattened, later evenly convex, suture distinct, impressed. Axial sculpture of fine and dense, sometimes strong and evenly spaced ribs, or sometimes absent on late teleoconch whorls. Spiral sculpture of dense fine grooves, pronounced in interspaces between axials, and irregular grooves on shell base, or sometimes absent. Siphonal canal rather long, straight, aperture with three or four distinct columellar folds, adapicalmost fold strongest. Shell intensely coloured with sometimes intricate pattern of light brown or orange blotches. Head-foot pale, with occasional dark blotches and bands on the dorsal surface of foot. Eye tentacles rather long, thin, with basal eyes. Radula rachiglossate with tricuspidate rachidian often bearing small accessory cusps flanking the central major cusp; laterals simple, sickle-shaped unicuspidate. Buccal mass encloses delicate horseshoe-shaped jaw.

Included species

Pusia (Vexillena) balutensis ( Herrmann, 2009) comb. nov., 1 Pusia (Vexillena) choslenae (Cernohorsky, 1982) comb. nov., 1 Pusia (Vexillena) dautzenbergi (Poppe et al., 2006) comb. nov., 2 Pusia (Vexillena) elliscrossi ( Rosenberg & Salisbury, 1991) comb. nov., 2 Pusia (Vexillena) jenyai sp. nov., 1 Pusia (Vexillena) johnwolffi ( Herrmann & Salisbury, 2012) comb. nov., 1? Pusia (Vexillena) vicmanoui ( Turner & Marrow, 2001) comb. nov. 2

Distribution and habitat

West Pacific , from Japan and the Philippines to New Caledonia and the Coral Sea ; at depths greater than 200 m.

Etymology

The name Vexillena is selected to convey the general similarity of this subgenus to Vexillum .

Remarks

Species of Pusia (Vexillena) subgen. nov. share a characteristic colour pattern of spirally and axially aligned brown blotches delineated by narrow lighter bands, or the entire shell is coloured brown, bearing spiral line or series of lighter blotches slightly above the periphery of the whorls. The larger size and relatively higher spire normally allow the distinction of Pusia (Vexillena) from Pusia (Pusia) ; however, the delineation of the subgenera Pusia (Vexillena) and Pusia (Pusia) is somewhat hazy, as some species of the two subgenera are very close in shell proportions, sculpture, and coloration. All studied species of Pusia (Vexillena) are characterized by the rachidian with two minor cusps flanking the central major cusp; in Pusia (Pusia) and Pusia (Ebenomitra) , these minor cusps are absent. Therefore, these cusps may be considered an apomorphy of the Vexillena clade. It is also noteworthy that all known species of Pusia (Vexillena) inhabit depths greater than 200 m (usually 300 – 500 m), and thus do not overlap with Pusia (Pusia) species in bathymetry.

Equally difficult to distinguish are Pusia (Vexillena) subgen. nov. and Tosapusia . Although in most cases the well-developed colour pattern of the shell distinguishes Pusia (Vexillena) subgen. nov., in other characteristics the two groups are close, with shells varying from elongate [ Tosapusia isaoi vs. Pusia (Vexillena) vicmanoui ] to rather broad [ Tosapusia vityaz sp. nov. vs. Pusia (Vexillena) balutensis ], and with remarkably similar sculpture patterns. Consistent differences between the two groups are found in radular morphology, as rachidians of Pusia (Vexillena) subgen. nov. species have characteristic minor cusps. Shells in Vexillena subgen. nov. also have a longer siphonal canal, resulting in a more fusiform and typically more solid shell, compared with species of Alisimitra gen. nov.; moreover, live or fresh specimens of Vexillena subgen. nov. have a distinctive shell colour pattern, not observed in Alisimitra gen. nov. Finally, Costapex gen. nov. differs from Vexillena subgen. nov. in having generally smaller shells, with overall dominating spiral sculpture. Moreover, the adapicalmost columellar fold is notably stronger than the succeeding folds in all species of Vexillena , whereas in species of Costapex gen. nov. the columellar folds are subequal. Finally, species of Vexillena spp. can be easily distinguished from Vexillum by the shape of the siphonal canal, which is usually deeply notched in Vexillum and straight or very shallowly notched in Vexillena .

PUSIA (VEXILLENA) BALUTENSIS ( HERRMANN,