Tosapusia vitiaz, Fedosov & Puillandre & Herrmann & Dgebuadze & Bouchet, 2017

TOSAPUSIA VITIAZ View in CoL SP. NOV.

FEDOSOV, HERRMANN & BOUCHET

FIGURE 8E, F View Figure 8

Type data

Holotype: Papua New Guinea, Vitiaz Strait, BIOPAPUA , station DW3719, 06 ° 03 0 S, 147 ° 36 0 E, 410 m, 1 lv (MNHN IM-2013-40624, 34.3 mm). GoogleMaps

Diagnosis

Shell medium sized, widely fusiform, stout, with tall last adult whorl and aperture, and rather low spire. Protoconch unknown because of errosion. Teleoconch whorls evenly convex, whorl periphery shifted abapically. Spire outline slightly telescopic because of canaliculated suture. Sculpture of numerous, thin axial ribs and lower, but about equally wide, spiral cords, well pronounced in interspaces between ribs. Siphonal canal moderately long, stout. Aperture wide, outer lip evenly convex throughout its length. Inner surface of outer lip with irregular lirae. Five columellar folds, adapicalmost very strong, subsequent folds becoming weaker towards siphonal canal. Shell pale with indistinct darker spiral bands, siphonal canal and apex white.

Description

Shell medium sized, widely fusiform, stout, with tall last adult whorl and rather low spire (w / h 0.4, a / h 0.58, and law / h 0.68). Protoconch missing. Teleoconch of between nine and nine and a half slightly convex whorls. Suture strongly impressed, forming deep groove, giving spire whorls a distinctly stepped outline. Sculpture cancellate, with dense axial ribs (38 on last adult whorl, where ribs are slightly prosocline) and almost equally wide and dense, although lower spiral cords pronounced on late whorls. Adapical third of spire whorl with no distinct spiral cords, succeeding portion with three or four cords on late spire whorls, and about 15 on last adult whorl. Spiral cords evenly spaced with rather shallow quadrate interstices of equal width.

Outline of last adult whorl evenly convex with gradual transition to moderately long, stout siphonal canal. Aperture elongate, outer lip evenly convex, inside with irregular lirae. Five distinct columellar folds, adapicalmost three folds strongest, with slightly flattened profile, and fourth and fifth folds weaker and rounded. Adapical angle of aperture with weak convex callous pad.

Background colour pale with orange spiral bands just below suture, on whorl periphery, and wider band on shell base, early spire whorls and siphonal canal pale.

Radula ( Fig. 7G View Figure 7 ): Radula rachiglossate, about 1.4 mm long and 0.25 mm wide, consisting of about 71 rows. Rachidian tricuspidate with rather wide base (about 40% of radula width), medial projection not pronounced, cusps strong, rather short, pointed, central cusp slightly shorter than lateral cusps, which are directed slightly sideways. Lateral teeth unicuspidate, sickle-shaped, with long cusp slightly bent inwards near the tip.

Morphology of the body: The holotype is a male, exhibiting a penis with an open seminal groove similar to that in Ceratoxancus . The animal does not have an operculum.

Distribution and habitat

Known only from Vitiaz Strait , North Papua New Guinea, at a depth of 410 m.

Etymology

The species name comes from the name of the type locality ( Vitiaz Strait , between New Britain and the Huon Peninsula on the north coast of New Guinea), itself so named by Nicholai Mikluho-Maklai after the Russian corvette Vitiaz that brought him to Astrolabe Bay in September 1871. Used as a noun in apposition.

Remarks

The unusually high aperture and last adult whorl easily distinguish Tosapusia vitiaz sp. nov. from all other congeners. In overall shell morphology and in particular in sculpture, Tosapusia vitiaz sp. nov. most resembles Tosapusia kurodai , but differs in shell proportions, having a comparably even higher last whorl and aperture. The sculpture in Tosapusia vitiaz sp. nov. is notably finer than that in Tosapusia kurodai , and the latter has a narrower subsutural band, a more elongate siphonal canal, and less convex outer lip. Tosapusia vitiaz sp. nov. resembles some species of Ceratoxancus , like Ceratoxancus teramachii Kuroda, 1952 , ( Fig. 26A View Figure 26 ) or Ceratoxancus elongatus Sakurai, 1958 ; however, Ceratoxancus teramachii and Ceratoxancus elongatus have an even broader shell, with very low spire, and tall aperture, in addition to the characteristic labral tooth. Ceratoxancus melichrous Kantor & Bouchet, 1997 ( Fig. 26E View Figure 26 ) has distinctly prosocline axial ribs and a deflected siphonal canal.

Some species of Pusia (Vexillena) subgen. nov. – for example, its type species Pusia balutensis Herrmann, 2009 – have broadly fusiform shells with high last adult whorl, and superficially resemble Tosapusia vitiaz sp. nov. This subgenus has weaker spiral sculpture, however, and specimens commonly have a variegated colour pattern and a closed seminal groove.