Genus Haurakia Iredale, 1915

Haurakia Iredale, 1915: 449 .

Haurakiopsis Powell, 1937: 192 .

Vitricithna Laseron, 1956: 452 .

TYPE SPECIES. — Rissoia hamiltoni Suter, 1898: 2, 3, 5; fig. IV (by original designation) accepted as Haurakia hamiltoni (Suter, 1898) . Haurakiopsis: Haurakiopsis pellucida Powell, 1937 (by original designation) accepted as Haurakia pellucida (Powell, 1937) . Vitricithna: Cithna marmorata Hedley, 1907 (by original designation) accepted as Haurakia marmorata (Hedley, 1907) .

DIAGNOSIS. — Shell ovate-conical, with weak or moderately strong axial or smooth ribs; in some species the ribs are interrupted at the periphery due to the presence of a spiral cordlets. Anterior edge of the aperture with shallow, wide excavation, posterior sinus wide, distinct. Protoconch apparently smooth or with one or more spiral threads or rows of minute granules; about 1.5 whorls with large nucleus (when paucispiral) or small nucleus and about 2.5 whorls (when multispiral). Colouration of teleoconch variable with several patterns. Head-foot: long ciliated cephalic tentacles; foot constricted in middle, with posterior mucous gland; anterior and posterior pallial tentacles; a single, slender metapodial tentacle (see Ponder 1985: 29; Kay 1979). Operculum simple, thin, nucleus eccentric, last whorl large (Ponder 1985: 131, fig. 82C).

REMARKS

Previously considered as a subgenus of Pusillina Monterosato, 1884 (Ponder 1985: 29), it is now ranked as a full genus (Criscione et al. 2016). Rissoia hamiltoni (type species of Haurakia) and Cithna marmorata (type species of Vitricithna) share some general teleoconch, head-foot, radular and anatomical features (including male and female genital ones), and their closer affinity with respect to a distinct clade of Pusillina species is supported by molecular data (Criscione et al. 2016). However, Criscione et al. (2016: 14) also treated Haurakia and Vitricithna as distinct genera, scoring a large genetic divergence between the two type species (larger than that scored between widely recognised genera); the issue should be assessed by a denser sampling in a molecular phylogenetic framework. We keep here Cithna marmorata in the genus Haurakia following current treatment [Ponder 1985: 29-30, fig. 82A-E; Hasegawa 2000: 149, pl. 74, fig. Rissoidae-1; both as Pusillina (Haurakia)]. Haurakia, as currently conceived, includes c. 35 species, of which seven fossil, and dates back to the Miocene-Pleistocene of New Zealand and the Oligocene-Miocene of Tasmania (Ponder 1985: 30).