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

LOPHIOTOMA SEMFALA View in CoL SP. NOV.

( FIG. 7)

urn:lsid:zoobank.org:act:9E586542-B03B-4133-93F7-55B79FFD5A33

Type material: Holotype MNHN IM-2007-41337. Type locality: Vanuatu, Aoré I. Aimbuei Bay , 15°32.8′S, 167°11.6′E, white coral sand, 3–8 m (Expedition SANTO 2006, st. LD35, R/V Alis annex). GoogleMaps

Etymology: semfala – the ‘same’ in Bislama, the creole language, one of the official languages of Vanuatu. Used as noun in apposition to reflect the similarity to Lophiotoma acuta .

Description (holotype) ( Fig. 7A–C): Shell medium thick, narrow fusiform, spire high, siphonal canal long narrow, slightly inclined to left. Protoconch conical, eroded, rendering exact whorl count and sculpture examination doubtful, of about three evenly convex whorls. Protoconch diameter 0.73 mm, height 0.85 mm. Teleoconch whorls angulated at shoulder, ten in total. Suture very shallow, indistinct, subsutural region wide, distinctly concave, subsutural cord low, triangular in profile, with three angular ridges on last whorl, central one strongest. On upper teleoconch whorls, only central ridge persists. Subsutural region smooth on upper teleoconch whorls, with one spiral ridge appearing on fourth, two on sixth, three on seventh and five on last whorl. Paired sinus cords strongest forming angulated shoulder. On upper whorls both cords nearly equal in size, obtusely triangular, on penultimate and last whorls cords more angulate, although still rounded on top, only on last whorl upper cord distinctly stronger than lower. Base of spire whorls smooth on first four whorl, with one spiral cord on fifth to sixth whorls, starting from seventh whorl number of cords gradually increases, and penultimate whorl with seven narrow cords of slightly different size, median much stronger; interspaces three to four times broader than cords. Base of last whorl with three 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 shoulder, 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 well defined. Growth lines indistinct, closely spaced. Shell creamy, protoconch and three first teleoconch whorls very light brown. Subsutural cord with regularly spaced brown spots, not extending beyond cord, broader on last three whorls. 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 41.8 mm, AL (with canal) 20.9 mm, SW 10.6 mm. Radula examined in three specimens, two from Papua New Guinea and one from the Philippines, very similar in all examined specimens ( Fig. 5H). Radula membrane medium long, of 33–50 rows of teeth of which 9–16 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 rather thin, bifurcate at about 45° angle. Central formation absent.

Remarks: The new species is represented only by six specimens, including the holotype and despite the limited material, two rather distinct forms can be recognized. The ‘light’ form that includes the holotype has fewer brown spots and the base colour is uniformly creamy. The brown spots on the subsutural cord are in most specimens confined to the cord itself and do not extend beyond, but in the holotype on some whorls there are brownish blurred extensions of the spots to the subsutural region. Available specimens other than the holotype are smaller and less speckled. The ‘dark’ form is represented by two specimens only, one being juvenile ( Fig. 7F–G). It has slightly darker base colour, with a light brown shell base and canal and with the subsutural region below the subsutural cord uniformly brown. There was no correlation between geographic distributions, since one specimen of the dark form was collected in the Philippines, while another in Papua New Guinea at similar depths. The sinus cords of the adult specimen of the dark form are also sharper on top on the last whorl. On most parts of the teleoconch whorls, the sinus cords are either similar in size, or the lower even slightly more pronounced, than the upper, but on the last whorl the situation is reversed. An intact protoconch persists only in the juvenile of the dark form ( Fig. 7G), it consists of 2.75 whorls, diameter 0.68 mm, height 0.73, which is significantly smaller than in holotype, although the existing material is insufficient for estimates of variation. The species is extremely similar to Lophiotoma acuta , which also has dark and light forms. It can be distinguished in most cases by being less pronounced and more rounded on the top sinus cords, providing a less angulated appearance to the shell shoulder, as well as the cords being more similar in size ( Fig. 6, compare A, B with C, D), and domination of the lower cord over the higher one on the teleoconch whorls. The protoconch of Lophiotoma acuta is slightly larger ( Fig. 8), while the radula is longer (consists of 55–80 rows of teeth vs. 33–50 rows in L. semfala sp. nov.).

Distribution: The species was found in the Philippines, Papua New Guinea and Vanuatu. In all these localities, it is sympatric with L. acuta . Judging from available material (only six sequenced specimens), it is much more rare than L. acuta , for which we had sequenced more than 160 specimens. Although we did not sequence any specimens from New Caledonia, judging from the shell characters the species is also found in New Caledonia (uncatalogued MNHN material).