Lophiotoma bratasusa, Puillandre & Fedosov & Zaharias & Aznar-Cormano & Kantor, 2017

LOPHIOTOMA BRATASUSA View in CoL SP. NOV.

( FIG. 10G–L)

urn:lsid:zoobank.org:act:768A32A5-678A-4F03-8FC4-270EB8DE197C

Type material: Holotype MNHN IM-2013-51244, SL 26.0 mm; paratype 1, MNHN IM-2013-12566, paratype 2, MNHN IM-2013-53827.

Type locality: Papua New Guinea, Kavieng Lagoon , E of Kulinus I., Silver Sound, 02°42.3′S, 150°39.1′E, 7–10 m, coarse sand, coral patches (Expedition KAVIENG 2014, st. KR54) GoogleMaps .

Etymology: bratasusa – sibling in Pidgin English, refers to the revealed sister relationship between the new species and morphologically similar L. picturata . Used as a noun in apposition.

Description (holotype): Shell solid, narrow fusiform with high spire and rather long siphonal canal. Protoconch of 3.25 slightly convex whorls. Earlier 2.75 whorls smooth and glossy; latest 0.5 whorl sculptured with fine arcuate riblets, widely set at earlier portion and more dense at transition to teleoconch. Protoconch diameter 0.89 mm, height 1.13 mm. Teleoconch of nine angulated whorls, suture shallow and inconspicuous. Subsutural region distinctly concave; suture immediately bordered by fine thread, followed by typically low subsutural cord, and three to seven regularly set spiral threads. Sinus cord bifurcated, formed by two subequal ridges on early whorls, adapical ridge notably stronger on penultimate and last teleoconch whorls. Abapical whorls portion (=whorl’s base) sculptured with four fine threads, fourth slightly stronger than preceding. Shell base shortly constricted to slender siphonal canal, sculpture of shell base of 11 fine threads, fourth and sixth elevated to form sharp spiral ridges. Siphonal canal with 15 threads, spirally oriented and widely set adapically and dense, weakly delineated from one-another and oblique towards canal’s tip. Aperture elongate; outer aperture lip convex adapically, rounded in side view. Anal sinus typically deep and rather narrow with rounded apex. Aperture smooth inside, or bearing 8–9 weak lirae. Background colour cream, with distinct contrast dark-brown spots on subsutural and smaller dots on sinus cords. Spiral threads with regular light-brown dots, giving them appearance of dashed lines. Protoconch orange; inside of aperture cream. Radula (holotype) ( Fig. 5F) long, of about 55 rows of teeth, of which 25 nascent. Radula very similar to other congeners, with duplex marginal teeth. Anterior (inner) half solid, narrowly lanceolate, dorso-ventrally compressed with sharp lateral cutting edges. In posterior half major and accessory limbs bifurcate at about 45° angle, rather thin. Central formation absent.

Remarks: Lophiotoma bratasusa sp. nov. varies notably in shell shape, sculpture pattern and coloration. The two ridges of bisected sinus cord may be equally strong, subequal or differ notably, to the extent that the lower ridge is not stronger than succeeding spiral threads. Dark spots on the subsutural cord, typically well developed, may be lacking entirely in the light form ( Fig. 10L), or on the contrary the light brown band on the shell base may be pronounced, and the tip of the siphonal canal coloured dark-brown ( Fig. 10J). The species is undoubtedly closest to L. picturata , although some differences between the two exist (see remarks under L. picturata ), of which key are the number of protoconch whorls (4 in L. picturata v. 3.25 in L. bratasusa sp. nov.) and the colour pattern on the subsutural cord (with extended lighter blotches in L. picturata or without in L. bratasusa sp. nov.).

Distribution: Confirmed distribution of the species (based on sequenced specimens) is Vanuatu and Papua New Guinea.