Zoila Jousseaume, 1884

Darragh, Thomas A., 2011, A revision of the Australian fossil species of Zoila (Gastropoda: Cypraeidae), Memoirs of Museum Victoria 68, pp. 1-28 : 4-5

Zoila Jousseaume, 1884

Zoila Jousseaume, 1884a:14 .— Jousseaume, 1884b:89.— Cossmann, 1903:146, 149.— Thiele, 1929:275.— Schilder, 1935:336.— Schilder and Schilder, 1939:173.— Wenz, 1941:971.— Dolin, 1991:11 (synonomised Gigantocypraea Schilder, 1927 ). — Wilson and Clarkson, 2004:44.

Cypraeorbis (Zoila) Jousseaume. Schilder, 1926:378 .

Umbilia (Gigantocypraea) Schilder, 1927:86 (type species, original designation, Cypraea gigas McCoy, 1867 , Miocene , Victoria).

Zoila (Zoila) Jousseaume. Schilder, 1935:337 .— Schilder, 1939:177.

Zoila (Gigantocypraea) Schilder. Schilder, 1935:337 .— Schilder, 1939:177.— Wenz, 1941:971.

Cypraea (Zoila) Jousseaume. Wilson and McComb, 1967:469 . — Wilson, 1993:192.

Type species. Cypraea scottii Broderip, 1832 (= Cypraea friendii Gray, 1831 ) by subsequent designation Jousseaume (1884b, p. 89), western and southern Australia.

Diagnosis. Shell small (35 mm) to very large (247 mm) in size, highly glazed, varying in shape, elongate-ovate or pyriform or globose, ventrally flattened. Spire whorls usually covered in callus, rarely protruding. Protoconch, where known, consisting of one to two whorls, the first whorl large, somewhat irregular in shape, deviated slightly from shell axis. Anterior and posterior canals deeply incised, usually short, but on some species produced and bounded by weak to prominent lateral flanges. Aperture narrow, sinuous with weakly to strongly developed short to elongate teeth not extending into aperture or onto fossula. Fossula weakly to strongly developed, broad, slightly to deeply concave and bounded anteriorly by a weak to strong terminal ridge; on some species with very weak sulcus parallel and immediately posterior to terminal ridge.

Time range. Late Paleocene/early Eocene–Recent.

Distribution. India (early Miocene), Indonesia (Pliocene– Pleistocene), Western Australia (late Eocene, Miocene– Recent), South Australia (Miocene, Recent), Victoria (late Oligocene–late Miocene, Recent), Tasmania (early Miocene), New Zealand (late Paleocene/early Eocene).

Remarks. Specimens of Zoila itoigawa Tomida, 1989 from the late Miocene of Japan are poorly preserved and have not been prepared sufficiently to enable generic assignment.

As I have recognised two groups of species, an eastern and a western group, it could be argued that these should be accorded taxonomic status if there are significant morphological differences to separate them, in which case Gigantocypraea could be used for the eastern group. However, I regard these groups as more geographic entities. There are some morphological differences, but I regard them as minor and not of sufficient importance to use as generic characters. Such variations in morphology are to be expected in species that have no pelagic larval stages.

Some species of the eastern group have considerably produced anterior and posterior canals — for example, Zoila platypyga (McCoy) and Z. mulderi (Tate) — but other species have canals similar to the living species of the western group — for example, Z. glomerabilis n. sp. is similar to Z. venusta ( Sowerby, 1846) or Z. gendinganensis (Martin, 1899) .

Columellar dentition varies considerably from species to species. In the living species, columellar dentition can vary from strong to weak even within the one species; for example, Zoila friendi ( Wilson and Clarkson, 2004, pp. 79–80) . Fossil species of the western group all have prominent columellar dentition. In Z. fodinata , the columellar teeth are elongated to form short ridges. In the eastern group, columellar dentition is more highly variable. In Z. platypyga , the columellar dentition is in the form of strong, elongate ridges, whereas in Z. mulderi (Tate) (almost certainly ancestral to the former), the columellar dentition is more like that of the living species, as is the dentition of Z. glomerabilis sp. nov. and Z. dolichorhyncha sp. nov. In Z. gigas , there is no columellar dentition. I do not consider that columellar dentition can be used to provide a consistent taxonomic character to separate the eastern and western group of species of Zoila as implied by Wilson and Clarkson (2004, p. 49).

Fossular morphology also varies somewhat, though the basic pattern throughout all the species is the same — that is, broad, concave and bounded by the terminal ridge. Even within a species, fossular morphology can vary. Compare, for example, the fossulae of specimens of Z. venusta figured on plates 265–276 of Wilson and Clarkson (2004).