Homalopoma tosaense Habe, 1953

Helwerda, Renate Ariane, Wesselingh, Frank Pieter & Williams, Suzanne T., 2014, On some Vetigastropoda (Mollusca, Gastropoda) from the Plio-Pleistocene of the Philippines with descriptions of three new species, Zootaxa 3755 (2), pp. 101-135 : 106

Homalopoma tosaense Habe, 1953

( Figures 3–5 )

1982 Homalopoma druidi nov. spec.—Ladd: p. 27–28, pl. 36, figs 5–8.

1999 Homalopoma tosaensis ( Habe, 1953) —Higo et al.: p. 46.

2001 Leptothyra tosaensis ( Habe, 1953) —Higo et al.: p. 17, fig. G198.

2013 Leptothyra tosaensis ( Habe, 1953) —Poppe & Poppe:

http://www.conchology.be/?t=27&family= COLLONIIDAE &species= Leptothyra %20 tosaensis 2013 Homalopoma tosaense Habe, 1953 —Rosenberg: http://marinespecies.org/aphia.php?p=taxdetails&id=737892

Material. Anda 2 (1); Anda 6 (1); AndaDeVos (4).

Characterization. Shell turbiniform, robust, H 3.6 mm, W 3.8 mm; P1 smooth, 1.0 whorls, DN 0.15–0.17 mm; P2, 0.3 whorls, with two robust spiral ribs on median-upper part and third basal spiral rib; P/T boundary distinct terminal varix at 1.3 whorls; T sculpture of spiral ribs; additional spiral ribs between uppermost spiral and suture; spiral and axial lirae in interspaces; umbilicus narrow.

Distribution. Apart from the studied material, this species is known from Tosa Bay and southern Kyushu ( Japan), East China Sea ( Higo et al. 1999), as well as Pliocene deposits of Viti Levu, Fiji ( Ladd 1982).

Remarks. Homalopoma druidi ( Ladd, 1982) is synonymized here with Homalopoma tosaense Habe, 1953 and Leptothyra tosaensis ( Habe, 1953) , because of its overall similar conchology. Although the holotype of Homalopoma druidi ( Ladd, 1982) has a rather high spire when compared to the holotype of Leptothyra tosaensis ( Habe, 1953) , its spire height falls well within the range of intraspecific variation observed on the website: http:// www.conchology.be/?t=27&family= COLLONIIDAE &species= Leptothyra %20 tosaensis . It remains unclear whether the species should be assigned to Leptothyra or Homalopoma , as these genera are not well delimited.

Figures

FIGURES 3 – 5. Colloniidae. 3. Homalopoma tosaense Habe, 1953. RGM 608.201. Locality AndaDeVos. (a) rear view, (b) apertural view, (c) basal view, (d) apical view. For this and remaining figures all material derives from the Piacenzian or Gelasian Santa Cruz Formation of Cabarruyan Island and nearby Luzon island, Philippines. Locality data in Table 1. Scale bars shells = 1 mm, scale bars SEM = 100 µm. 4. Homalopoma tosaense Habe, 1953. RGM 608.202. Locality Anda 2. (a) rear view, (b) apertural view. 5. Homalopoma tosaense Habe, 1953. RGM 608.203. Locality AndaDeVos, SEM detail of protoconch. FIGURES 6 – 7. Seguenziidae. 6. Seguenzia cf. keikoae Poppe, Tagaro & Dekker, 2006. RGM 608.207. Locality Roxas. (a) rear view, (b) side view, (c) apertural view, (d) basal view, (e) apical view, (f) detail of protoconch, scale bar 100 µm. 7. Seguenzia cf. keikoae Poppe, Tagaro & Dekker, 2006. RGM 608.208. Locality Anda 3. (a) rear view, (b) apertural view.