Liloa curta

Liloa curta (Adams, 1850)

Bulla curta Adams, 1850: 582, pl. 124, fig. 100.

Haminea curta — Pilsbry 1895: 368, pl. 40, figs 84, 85.

Haminea curta tomaculum Pilsbry, 1917: 219, fig. 10.

Haminoea curta — Pilsbry 1921: 369, fig. 8a. Kay 1979: 427: fig. 137 I.

Haminoea tomaculum — Pilsbry, 1921: 370.

Haminoea (Liloa) curta — Pilsbry 1921: 369, fig. 8a.

Liloa curta — Habe 1952: 151, pl. 21, fig. 19. Qi 2004: 147, pl. 83, fig. N.

Atys curta — Gosliner et al. 2008: 23.

Type locality. Indo-Pacific (not specified in the original description).

Material examined. Guam, UF 374131, H = 15 mm; the Philippines, 1 shell examined, MNHN, Paris (S12/ OT 575), H = 3.1 mm; the Philippines, 5 spcs dissected, MNHN, Paris (S12/ OT 575), H = 3.4–7.5 mm; the Philippines, 2 spcs dissected, MNHN, Paris (S5/ OT 392), H = 5.4 mm, 6 mm.

Animal (Fig. 1J): Body whitish-translucent, pinkish dots scattered over the body, more dense between eyes and mid part (between mouth and eyes) of cephalic shield; white and red blotches scattered on mantle; eyes visible.

Shell (Figs 3D, 17A–C): Maximum height 18 mm; whitish; thin and fragile, translucent, cylindrically oval, sides slightly convex only, anterior end slightly rounded, posterior end truncated; spire sunken, aperture broad, outer lip thin, base semi-circular; spiral grooves covering entire shell, distance between spiral grooves almost equal, faint irregular axial lines present.

Jaws (Fig. 17D): Present, crescent shape, jaw rodlets with 7–10 denticles.

Radula (Figs 17E, F): Radular formula at mid-point 19–25 x 8–7.1.7–8; median tooth with broad base, large triangular central cusp, small triangular lateral cusps; outer lateral teeth hook-shaped, slender, base with semicircular projection outwardly, groove along the outer margin, size decreases outwardly. Inner-lateral teeth not distinct.

Gizzard plates (Figs 17G, H): Three gizzard plates; widest in the middle, narrower towards both ends, 27–42 ridges, single rows of rods with pointed tips along top edge of ridges, both anterior and posterior sides of ridges covered densely by tiny rods with pointed tips.

Male reproductive system (Fig. 17I): Total length 2.5 mm (H = 7.5 mm). Formed by three parts: prostate, seminal ducts and penial region; prostate oval-rounded, bilobed, proximal lobe narrower, opaque-yellowish, faint striations sometimes present, distal lobe light-brownish; translucent pouch connects to the prostate, light-yellowish mass observed within, pouch opens to two seminal ducts, first seminal duct translucent, with hook-like posterior end, second seminal duct broad and short, translucent, connects to the penial region; penial region elongated, translucent, with opaque inner duct visible.

Ecology. Sandy bottom in shallow water (Qi 2004; Gosliner et al. 2008; present study).

Geographical distribution. Red Sea, Malaysia, the Philippines, China, Japan, Papua New Guinea, Guam, New Caledonia, Hawaii (Habe 1952; Qi 2004; Gosliner et al. 2008; present study).

Remarks. Pilsbry (1917) named a shell that was identical but narrower than Liloa curta as Haminea curta tomaculum. Later, Pilsbry (1921) considered that both “ curta ” and “ tomaculum ” deserved species status. Additionally, Pilsbry (1921) described Haminea olopana, based on a shell that was more convex than Haminea curta and Haminea tomaculum and with spiral grooves more distantly spaced at the centre and placed all three species in the new subgenus Liloa. Kay (1979) synonymised these species under the name Haminoea curta. However, the original description of H. olopana fits Liloa porcellana (Gould, 1859), which possess a cylindrical and translucent shell, with spiral grooves more visible at both ends, arched callus at the end of columella and the anterior end of the shell subtruncated.

The species Liloa curta has been either ascribed to the genus Liloa (e.g. Habe 1952; Qi 2004) or to the genus Atys (e.g. Gosliner et al. 2008). However, this species possesses both shell and anatomical features that are different from the type species Atys naucum. Liloa curta has unique gizzard plates, which have 27–42 ridges, with pointed rods along the top edge and smaller pointed rods densely covering both anterior and posterior sides of ridges. The male reproductive system of this species is also different from other haminoeids. It possesses two seminal ducts interconnected at the entrance of a translucent pouch showing a yellowish mass content. The first seminal duct has a hook-like posterior end, which might be a synapomorphy of the genus Liloa.