Lophiotoma acuta, (PERRY, 1811)

Puillandre, Nicolas, Fedosov, Alexander E., Zaharias, Paul, Aznar-Cormano, Laetitia & Kantor, Yuri I., 2017, A quest for the lost types of Lophiotoma (Gastropoda: Conoidea: Turridae): integrative taxonomy in a nomenclatural mess, Zoological Journal of the Linnean Society 181, pp. 243-271 : 252-256

LOPHIOTOMA ACUTA ( PERRY, 1811)

( FIG. 4)

Pleurotoma acuta Perry, 1811 : pl. 5, fig. 5.

Pleurotoma marmorata Lamarck, 1816 : pl. 439, fig. 6 (non Pleurotoma marmorata Link, 1807 ).

Pleurotoma tigrina Lamarck, 1822: 95 (nom. nov. pro Pleurotoma marmorata Lamarck, 1816 , non Pleurotoma marmorata Link, 1807 ).

Pleurotoma punctata Schubert & Wagner, 1829: 155 , pl. 234, figs 4103 a, b (no locality).

Lophiotoma microsticta Casey, 1904: 130 .

Lophiotoma acuta Perry, 1811 – Powell, 1964 (part.): 303–305, colour plate 180, figs 1–10, 15–18 (non plate 180, figs 14, 19).

Type material: Neotype of Lophiotoma acuta (here designated), MNHN IM-2007-41179, the same specimen is designated as a neotype of Pleurotoma punctata ( Schubert & Wagner, 1829) . Three syntypes of Pleurotoma tigrina, MHNG (MHNG-MOLL-51664). Syntypes of Lophiotoma microsticta ,? USNM [fide Powell (1964), see below]. Type locality Cebu, Philippines.

Type locality: Vanuatu, E Malo Island , 15°43.4′S, 167°15′E, flat sand and dead corals, 6 m (Expedition SANTO 2006, st. DR84, R/ V Aldric) .

Description (neotype) ( Fig. 4A–D): Shell medium thick, narrow fusiform, spire high, siphonal canal long narrow, slightly inclined to left. Protoconch ( Fig. 4D) conical, of nearly three evenly convex whorls, smooth first whorls, posteriormost half whorl with nine axial nearly straight riblets, more densely spaced in posterior part of protoconch. Protoconch diameter 0.78 mm, height 0.85 mm. Teleoconch whorls strongly angulated at shoulder, ten in total. Suture shallow, subsutural region wide, distinctly concave, subsutural cord low, triangular in profile, with 3 weak angular ridges, central one strongest. Subsutural region smooth on upper teleoconch whorls, with one spiral ridge appearing on fourth, two on sixth, three on seventh and seven on last whorl. Paired sinus cords strongest and form strong angulated shoulder. On upper whorls both cords similar in size and rounded on top, on penultimate and last whorls cords distinctly triangular in profile, upper much stronger. Base of spire whorls smooth on first whorl, with one spiral cord on two to sixth whorls, starting from seventh whorl number of cords gradually increases, and penultimate whorl with six slightly different in size narrow cords; interspaces three to four times broader than cords. Base of last whorl with five major spiral cords and several riblets between them, canal with 20 cords, becoming gradually broader, lower and more closely spaced anteriorly. Shell base gradually narrowing towards narrow and long nearly straight siphonal canal. Aperture pear shaped, outer lip concave in upper part and weakly convex below shoul- der, gradually passing into canal. Anal sinus deep, with nearly parallel sides, with straight posterior margin parallel to shell axis; outer lip in side-view rounded and opisthocline, stromboid notch ill-defined. Growth lines indistinct, closely spaced. Shell creamy, protoconch and two first teleoconch whorls light brown. Subsutural cord with regularly spaced brown spots, not extending beyond cord. Sinus cords with distinct dark brown regularly spaced spots occupying whole width of cord and separate on each cord, minor spiral cords with dense brown flecks. Aperture creamy inside. Measurements: SL 38.8 mm, AL (with canal) 19.7 mm, SW 11.0 mm. Radula examined in five specimens, all from Papua New Guinea, very similar in all specimens ( Fig. 5A, B). Radula membrane long, of 55–80 rows of teeth of which 25–30 not fully formed. Marginal teeth duplex. 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 or very weak, of flat poorly developed regularly positioned cusp, looking like folds of membrane.

Remarks: The species is very variable in terms of coloration and shell shape. The base colour can be from pure white to light orange and even light brown (subsutural region, shell base and canal) with lighter sinus area. With some reservation two colour forms can be distinguished, although intermediate specimens can also be found. In the light form, the brown spots are more scarce and usually confined to major cords, especially to subsutural and sinus ones, while the smaller cords have separate brown speckles. In the dark form ( Fig. 4H), the entire shell can be light brown, with a lighter band along the sinus cords. The large brown spots on the subsutural cord dissolve in the lower part into brown band, occupying the entire subsutural zone. The brown spots on minor cords can be as large as those on sinus cords. The canal and anterior part of the aperture can also be brownish. Transitional specimens between forms can be found. The dark form was found within the entire distribution area of the species. In Vanuatu, which is most rich in sequenced material, 66% of specimens were represented by the light form, 24% by the dark form and 10% were attributed to intermediate forms (total number of checked specimens 94). A rather distinct form is found in Vietnam and the Philippines ( Fig. 4J) – the shells are large (reaching 51 mm in our material), relatively heavy and with a less pronounced sinus cord, and the spots and speckles are rather fine, except those on the subsutural cord. In the molecular tree based on COI they are sister to the rest of Lophiotoma acuta , but do not form a monophyletic group. The syntype of Lophiotoma microsticta Casey, 1904 [illustrated by Powell (1964): pl. 233, figs 4–5], with shell of 59.7 mm in length, is rather similar to this form. Protoconchs studied in eight specimens are rather uniform, consisting of 2.75 whorls. Number of axial riblets varies from 6 to 11, protoconch height 0.88–0.95, diameter 0.8–0.83 mm. The species is most similar to L. semfala sp. nov. and some specimens can hardly be distinguished; nevertheless, the morphology of the sinus cords seems to be rather uniform in L. acuta – on the last whorl (in adult specimens) the upper cord is much more pronounced than the lower and has a distinct triangular shape with sharp upper edge, while in L. semfala sp. nov., the cords are nearly similar to each other and are more obtuse and rounded on top ( Fig. 6).

The species was treated as broadly distributed and strongly variable. Powell (1964) listed a number of nominal taxa in the synonymy of this species, including Pleurotoma jickelii Weinkauff, 1875 and Pleurotoma picurata Weinkauff, 1876 . On the basis of molecular and morphological analysis, these two species appeared to be valid. Pleurotoma acuta Perry, 1811 was described without locality data or shell measurements. The original shell illustration is a bit grotesque, although suitable for positive identification. Few existing types described by Perry (1811) are stored in the NHMUK ( Dance, 1986) and the type of P. acuta is not among them. Due to the complicated taxonomic situation with the L. acuta complex, a neotype is here designated. The name Pleurotoma marmorata (non Pleurotoma marmorata Link, 1807 = Turris chaldea Kilburn, Fedosov & Olivera, 2012 ) was listed by Lamarck (1816) (pl. 439, fig. 6, included in references, p. 8). Later Lamarck (1822: 95) renamed the species P. tigrina , citing his own figure, but still proposed the name Pleurotoma marmorata for another species, which became the homonym for the third time. Three syntypes of Pleurotoma tigrina are in MHNG (MHNG-MOLL-51664) ( Fig. 4F–G herein) and it is seemingly conspecific with L. acuta in our current understanding, being closer to the ‘dark’ form. Judging from the syntypes of P. marmorata Lamarck, 1822 (MHNG-MOLL-51663) the species belongs to the genus Unedogemmula and was listed in synonymy of Lophiotoma (Lophioturris) indica (Röding, 1798) by Powell (1964). The syntype of Lophiotoma microsticta Casey, 1904 was illustrated by Powell (1964: pl. 233, figs 4, 5) and claimed to be deposited in USNM. Nevertheless, we were not able to find it in the collections. Judging from the photo it has the same sculpture pattern as L. acuta , that is, the dominating upper sinus cord; therefore, we confirm the opinion of Powell (1964), that it is a synonym of L. acuta . The type material of Pleurotoma punctata was not traced despite queries in the corresponding museums and the original illustration is rather crude, although the general outline is similar to that of L. acuta . In order to fix the problem and to stabilize the nomenclature, we designate the neotype of Pleurotoma acuta Perry, 1811 as the neotype of P. punctata as well; thus, the latter name is now a junior objective synonym of P. acuta . Pleurotoma peaseana Dunker, 1871 [ Pleurotoma (Turris) peaseana Dunker, 1871: 154 (Indian Ocean) ] is another species of doubtful affinity, which was synonymized with L. acuta by Powell (1964). It was illustrated only in Weinkauff (1876, in Weinkauff & Kobelt, 1875 –1887: 66, pl. 2, fig. 10). The illustration depicts a rather stout shell with moderately elongate canal, much shorter than in both L. acuta and L. semfala . The species may not be closely related to L. acuta . We were not able to trace the type despite querying museums where Dunker’s type material might be stored. Powell (1964) synonymized the species with L. acuta without providing any arguments, an opinion followed by Oyama (1966) and Higo, Callomon & Gotō (1999). Moreover, Weinkauff (1876, in Weinkauff & Kobelt, 1875 –1887) described the protoconch of P. peaseana as consisting of three smooth semitranslucent whorls with poorly visible suture, not mentioning the characteristic axial ribs in the posteriormost part of the protoconch. This seems more similar to the protoconch of Unedogemmula and we exclude the species from synonymy of L. acuta .

Distribution: Confirmed distribution of the species (based on sequenced specimens) – tropical Indo-west Pacific (from Vanuatu to Vietnam). Judging from published data, it also includes South Africa ( Kilburn, 1983), Red Sea ( Verbinnen & Dirkx, 2007), Japan ( Okutani, 2000), Fiji, Queensland ( Australia) ( Powell, 1964), New Caledonia (uncatalogued MNHN material).