Lophiotoma picturata, (WEINKAUFF, 1876)

LOPHIOTOMA PICTURATA (WEINKAUFF, 1876) View in CoL

( FIG. 10A–F)

Pleurotoma picturata Weinkauff, 1876 in Weinkauff & Kobelt, 1875 –1887: 66, pl. 2, fig. 10.

Type material: Lectotype (here designated) ZMB Moll 112610, ex-Paetel collection, Philippines, SL 41 mm; paralectotype ZMB Moll 112610.

Type locality: Philippines (originally Indischer Ocean) .

Diagnosis: Shell solid, narrow turriform, with high spire and moderately long siphonal canal. Protoconch of 3.75–4 slightly convex whorls; early three whorls smooth and glossy, latest whorl sculptured with 14–17 axial riblets ( Fig. 10E). Protoconch diameter 0.93–1.12 mm, height 1.13–1.25 mm. Teleoconch whorls distinctly angulated; spire whorls sculptured with fine subsutural cord, and strong bifurcated sinus cord, and fine threads on subsutural area and whorl base. Adapical whorl portion between subsutural cord and sinus cord distinctly concave. Shell base shortly constricted to slender siphonal canal. Shell base with eight to nine fine threads interchanging with sharp narrow spiral ridges, canal with 13–15 threads. Aperture elongate. Anal sinus wide and rather deep, quadrangular in its apex. Aperture usually with 9–12 distinct lirae inside. Background colour cream, with distinct dark-brown spots on subsutural and sinus cords. Brown spots on subsutural cords surrounded by somewhat nebulose lighter brown or reddish blotches. Shell base with indistinct light-brown band. Spiral threads with regular light-brown dots, protoconch light-brown; aperture cream inside. Radula examined in one sequenced specimen from New Ireland (MNHN IM-2013-53422, Fig. 5E). Radula membrane long, of about 50 rows of teeth, of which 20 not fully formed. 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 indistinct.

Remarks: The species is represented in our material by eight specimens from Bismarck Sea (Madang lagoon and New Ireland), ranging in height from 24.5 to 32.1 mm, showing modest variation in conchological characters. The only feature that is found to vary notably is the shape of the anal sinus. It is moderately deep and wide with an angulated outline in specimen MNHN IM-2013-53422 ( Fig. 10C, D), and even wider in Weinkauff ’s type, collected from the Philippines. The sinus is U-shaped, and very deep in some other sequenced specimens.Despite the fact that no specimens of L. picturata from the Philippines were sequenced in the present study, we confidently apply the name to this clade of our molecular tree, based on conchological features that are shared by the studied type specimen from ZMB and sequenced specimens. No other specimens of L. picturata , mentioned by Weinkauff, were studied. Since a species morphologically close to L. picturata – L. bratasusa sp. nov. – was recognized in our analysis, in order to fix the identity of Lophiotoma picturata , we here designate the studied syntype ZMB Moll 112610 as a lectotype, thereby setting the type locality as the Philippines. Morphologically L. picturata is very close to L. bratasusa sp. nov.; however, there are some minor, but rather stable, characters that allow unmistakable differentiation of the two species. Firstly, the two species differ in the number of protoconch whorls – the former species has a protoconch of 3.75–4 whorls, while the latter – with 3.25 whorls only. Correspondingly the diameter and height of the protoconchs are slightly larger in L. picturata ( Fig. 8). Shell proportions and coloration also offer some minute differences. Lophiotoma picturata is more turriform in outline (due to comparatively shorter siphonal canal), and the black or dark brown spots on the subsutural region are surrounded by less contrasting light-brown or reddish blotches. On the contrary, L. bratasusa has a more fusiform outline, and the dark spots on the subsutural region are more contrasting in appearance. Weinkauff (1876 in Weinkauff & Kobelt, 1875 –1887), when describing the species, cited Pleurotoma variegata sensu Reeve (1843) , non Kiener (1840). The illustration of Reeve (1843: pl. 1, species 2) depicts the shell from the dorsal side which has a vague resemblance to P. picturata , although positive identification is hardly possible. Powell (1964) synonymized Pleurotoma picturata with Lophiotoma acuta and this viewpoint was accepted by subsequent authors.

Distribution: Confirmed distribution of the species (based on sequenced specimens) is Papua New Guinea. The lectotype was collected in the Philippines and the original type locality was ‘Indian Ocean’, so its range should be broader, but this needs confirmation.