Aplotoma brevitentaculata, Criscione & Hallan & Puillandre & Fedosov, 2021

Criscione, Francesco, Hallan, Anders, Puillandre, Nicolas & Fedosov, Alexander, 2021, Where the snails have no name: a molecular phylogeny of Raphitomidae (Neogastropoda: Conoidea) uncovers vast unexplored diversity in the deep seas of temperate southern and eastern Australia, Zoological Journal of the Linnean Society 191, pp. 961-1000 : 980-981

APLOTOMA BREVITENTACULATA SP. NOV.

( FIGS 3C, 6A)

Z o o B a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. org:act: 119007B3-5F12-451E-BF86-C864AEFFB467.

Holotype: Australia, VIC, East Gippsland CMR, 2338 m, IN2017_ V03 _035, (–37.792, 150.382), AMS C.571635.

Distribution: Known from a single locality off East Gippsland, Victoria.

Etymology: The name is composed of the Latin brevis, short, and tentaculatum, with tentacles, referring to the comparatively short cephalic tentacles.

Description

Shell ( Fig. 3C) (SL = 20.5, SW = 10.9) broadly fusiform, thin-walled, opaque. Protoconch of at least two whorls, eroded. Protoconch–teleoconch transition clearly defined, broadly sinuate. Teleoconch of about 5.3 uniformly whitish whorls, suture impressed. Whorls broad, with wide subsutural ramp, straight in early teleoconch whorls and slightly concave on later ones; well-pronounced shoulder situated at approximately mid-height of whorl; lower portion of whorl subcylindrical to cylindrical. Subsutural ramp sculpture of obsolete, low and rounded cords, and evenly spaced, raised arcuate riblets. Supraperipheral two last cords stronger and more narrowly spaced. Teleoconch axial sculpture of 20 or more rounded opisthocline ribs below subsutural ramp, roughly half to one-third of interspaces, becoming indistinct toward suture and obsolete toward base of last whorl. Spiral sculpture of regularly spaced cords, about eight densely placed on penultimate whorl, over 30 on last whorl alternate strong and weak, latter becoming indistinct towards whorl base. Microsculpture of indistinct collabral growth lines. Last adult whorl evenly convex below subsutural ramp, clearly demarcated from straight, moderately short siphonal canal. Aperture elongate, approximately half of shell length; outer lip thin; inner lip whitish, with thin callus, straight. Anal sinus moderately wide, shallow, U-shaped. Cephalic tentacles short, conical, small eyes situated at their outer base. Oesophagus wide; proboscis short, conical; venom gland short.

Radular teeth ( Fig. 6A) of hypodermic type, attaining approximately 115 µm in length, straight, somewhat loosely rolled. Ventral barb absent, dorsal blade approaching one-third of shaft length. Adapical opening subtriangular to elongate-ovate, about onefifth to one-sixth of shaft length. Base not swollen, barely wider than widest part of shaft, with medium coarse texture; lateral process present, more or less perpendicular to orientation of shaft. Basal opening large, circular. Ligament broad.

Remarks

See Remarks below for comparison with Biconitoma cretosa . Polychaete fragments were recovered from the intestine.