Liotipoma dimorpha Mclean 2012, n. sp.
Creators: name: Mclean, James Hamilton
Publisher: name: Zenodo
Year: 2012
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Trochida
Colloniidae
Liotipoma
Liotipoma dimorpha

description: <i>Liotipoma dimorpha</i> n. sp. (Figs 2G; 6; 7) TYPE MATERIAL. — Holotype: LIFOU, stn 1442, Loyalty Islands, Lifou, Cape Aimé Martin, Santal Bay, 20°46.4’N, 157°02.0’E, 47 m, diving team, 13-14.XI.2000, &amp;male; shell, H 3.0, D 4.3 mm (MNHN 24761, Fig. 6 A-D). Paratypes:same data as holotype, &amp;female; shell, H. 3.0, D 5.1 mm (MNHN 24764, Fig. 7 A-D). — MONTROUZIER expedition, stn 1331, New Caledonia, Grand Koumac Reef, &amp;male; shell, H 2.6, D 4.0 mm (MNHN 24763, Fig. 6 E-H). — stn 1450, &amp;female; shell, H 2.5, D 4.5 mm (MNHN 24765, Fig.7 E-H). ADDITIONAL MATERIAL. — <b>Loyalty Islands</b>. LIFOU, stn 1435, Loyalty Islands, Lifou, Pointe Lefèvre, Santal Bay, 20°55.2’S, 167°00.7’E, 5-30 m, 8.XI.2000, diving team, 1 immature with operculum (MNHN, Fig. 2G); 1 &amp;male; shell at 4.6 mm diameter and 2 immature (MNHN). — LIFOU stn 1434, Huca Hutighé, Santal Bay, 20°52.5’S, 167°08.1’E, 5-20 m, 6.XI.2000, diving team, 7 &amp;male;&amp;male; shells, of which the largest is 4.8 mm diameter, plus 3 immature specimens (MNHN). — LIFOU stn 1432, Shelter Reef, Santal Bay, 20°53.5’S, 167°01.7’E, 12-32 m, 21.XI.2000, diving team, 2 mature &amp;male;&amp;male; shells at 4.8 mm diameter, plus 7 immature (MNHN). <b>New Caledonia</b>. MONTROUZIER expedition, stn 1331, Grand Koumac Reef, Koumac Sector, 20°40’S, 162°12’E, 55-57 m, X.1993, 2 specimens, lip not fully formed on second specimen (MNHN, Fig. 6 E-H). TYPE LOCALITY. — Loyalty Islands, Lifou. DISTRIBUTION. — Lifou, Loyalty Islands, and Koumac Reef, New Caledonia. ETYMOLOGY. — The name means two forms, with regard to sexual dimorphism. DESCRIPTION <i>Male shell (Fig. 6)</i> Whorls 3.3; profile moderately high for genus; keel at periphery, slightly higher than mid-whorl; profile below shoulder evenly rounded; subtending cord not strongly projecting. Axial sculpture of strong ribs, 23-25 on last whorl in basal view; strongly spinose in early whorls, more closely spaced in final quarter whorl; spines projecting forward in direction of growth. Spiral sculpture of three cords on shoulder, beaded at intersections with axial ribs. Base with strong subtending cord, and two cords of nearly equal strength between peripheral cord and subtending cord; base with shallow pits on outer side of subtending cord. Umbilicus bordered by broad emergent cord, overridden by narrow axial ribs; umbilicus narrow, obstructed by massive extension of inner lip. Final lip massive, extending for &amp;frac13; of final quarter whorl, with successively decreasing layers of deposition, with indentations conforming to spiral sculpture. Plane of aperture aligned to intersect axis of coiling at umbilicus. Aperture nearly radial, tongue short, triangular, in same plane as plane of aperture. H 3.0, D 4.3 mm (holotype). <i>Female shell (Fig. 7)</i> Of higher profile than male shell; emergent cord high on whorl (in basal view), forming protruding carination that enlarges umbilical cavity, subtending cord and first basal cord narrow, interconnected by extensions of axial ribs; tongue not projecting into umbilical cavity for specimen of Figure 7 A-D, slightly projecting in specimen of Figure 7 E-H. H 3.0, D 5.1 (Fig. 7 A-D). <i>Operculum (Fig. 2G)</i> Known from immature specimen, with narrow pit in center. REMARKS <i>Liotipoma dimorpha</i> n. sp. is characterised by having forward directed spines, a narrow subtending cord and an even narrower first basal cord, by which it differs from <i>L. mutabilis</i> n. sp., in which the subtending cord and the first basal cords are significantly broader. By that distinction it also possible to connect the female shell to the male shell and also to separate the separate the female shell from that species. The female shell of this species (Fig. 7) is unlike the female shell of both <i>L. wallisensis</i> and <i>L. mutabilis</i> n. sp. in having the emergent cord positioned higher (in umbilical view), so that the tongue does not depress it. Female shells are larger than male shells, as expected. The two illustrated male shells differ in the length and direction of the tongue, but these differences are considered intraspecific. In Figure 6 A-D it is shorter and in Figure 6 E-H it is longer and not in alignment with the plane of the aperture.
description: Published as part of <i>Mclean, James Hamilton, 2012, New species and genera of colloniids from Indo-Pacific coral reefs, with the definition of a new subfamily Liotipomatinae n. subfam. (Turbinoidea, Colloniidae), pp. 343-376 in Zoosystema 34 (2)</i> on pages 356-358, DOI: 10.5252/z2012n2a10, http://zenodo.org/record/5165469