Austromitra, FINLAY, 1926

GENUS AUSTROMITRA FINLAY, 1926 View in CoL

FIGURE 24I – M

Type species: Columbella rubiginosa Hutton, 1873 (OD).

Diagnosis

Shell small, usually not exceeding 10 mm, fusiform with rather wide aperture. Protoconch large and bulbous, paucispiral, of fewer than two glossy whorls. Suture distinct, impressed. Whorl outline evenly convex (usually) to distinctly angulated (rarely). Sculpture often represented by fine collabral growth lines only, in some species broad and sometimes strong axial folds developed on teleoconch whorls. Siphonal canal usually short and stout, sometimes moderately long, tapering, sculptured with between three and five oblique cords. Aperture rather wide, with three or four subequal oblique folds on inner lip. Dorsal surface of foot with black patches; eye tentacles long. Radula with wide multicuspidate rachidian, bearing more than ten cusps of varying lengh, and unicuspidate sickle-shaped laterals. Accessory salivary glands paired, rather large; mid-oesophagus notably widened, glandular. Gland of Leiblein rather large, glandular, greenish brown (for a detailed anatomical description, see Ponder, 1972).

Included species

Austromitra rubiginosa (Hutton, 1873) View in CoL ( Fig. 24I), 2 Austromitra aikeni Lussi, 2015 View in CoL , 2 Austromitra analogica (Reeve, 1845) View in CoL , 2 Austromitra angulata (Suter, 1908) View in CoL , 2 Austromitra arnoldi (Verco, 1909) View in CoL , 2 Austromitra bathyraphe (G.B. Sowerby III, 1900) View in CoL , 2 Austromitra bellapicta (Verco, 1909) View in CoL , 2 Austromitra canaliculata (G.B. Sowerby III, 1900) View in CoL , 2 Austromitra capensis (Reeve, 1845) View in CoL , 2 Austromitra cernohorskyi Turner, 2008 View in CoL , Austromitra cinnamomea (A. Adams, 1855) View in CoL , 2 Austromitra decresca Simone View in CoL & Cunha, 2012, 2 Austromitra distincta (Thiele, 1925) View in CoL , 2 Austromitra euzonata (G.B. Sowerby III, 1900) View in CoL , 2 Austromitra gradusspira Lussi, 2015 View in CoL , 2 Austromitra hayesi Turner, 1999 View in CoL , 2 Austromitra ima (Bartsch, 1915) View in CoL , 2 Austromitra kowieensis (G.B. Sowerby III, 1901) View in CoL , 2 Austromitra lawsi Finlay, 1930 View in CoL , 2 Austromitra legrandi (Tenison-Woods, 1876) View in CoL , 2 Austromitra maculosa Turner & Simone, 1998 View in CoL , 2 Austromitra minutenodosa Cernohorsky, 1980 View in CoL ; 2 Austromitra planata (Hutton, 1885) View in CoL , 2 Austromitra retrocurvata (Verco, 1909) View in CoL , 2 Austromitra rhodarion Kilburn, 1972 View in CoL , 2 Austromitra rosenbergi Salisbury, 2015 View in CoL , 2 Austromitra sansibarica (Thiele, 1925) View in CoL , 2 Austromitra schomburgki (Angas, 1878) View in CoL , 2 Austromitra scita (Tenison-Woods, 1876) View in CoL ( Fig. 24L), 1 Austromitra tasmanica (Tenison-Woods, 1876) View in CoL , 2 Austromitra valarieae Lussi, 2015 View in CoL , 2 Austromitra vincta (A. Adams, 1855) View in CoL ( Fig. 24M, N), 1 Austromitra volucra (Hedley, 1915) View in CoL , 1 Austromitra zafra Powell, 1952 View in CoL . 2

Distribution and habitat

Southern Australia, Tasmania, New Caledonia, New Zealand, and South Africa, up to Tanzania, in shallow water down to 450 m (M. Marrow, pers. commun.).

Remarks

The genus Austromitra is primarily distributed in the subtropical and warm temperate waters of the Southern Hemisphere, where it co-occurs with Turriplicifer gen. nov. Both genera are characterized by a weakly developed spiral sculpture and a bulbous protoconch, indicating non-planktotrophic development. Their members can be distinguished by shell size ( Austromitra being notably smaller than adult Turriplicifer gen. nov. species) and proportions (species of Turriplicifer gen. nov. have a rather turriform shell with proportionally taller spire compared with Austromitra ). Species of Austromitra are usually notably smaller than Vexillum , and can be readily distinguished from most costellariid taxa of the tropical Indo-Pacific by their weak sculpture with no spiral elements except those on the siphonal fasciole, and a characteristic paucispiral protoconch. In the detail of the shell sculpture and protoconch, Austromitra is close to species of Atlantilux from the Caribbean and Pusia (Ebenomitra) from the north-eastern Atlantic and Mediterranean. In common with Austromitra , both Pusia (Ebenomitra) and the Caribbean species of Atlantilux have a weakly developed spiral sculpture and possess a large paucispiral protoconch. Telling these three groups apart based on shell morphology is thus somewhat problematic. The radula with tricuspidate rachidian segregates Pusia (Ebenomitra) from both Austromitra and Atlantilux , which possess multicuspidate rachidians. In turn, Atlantilux demonstrates a characteristic sculpture pattern with dense and fine axial ribs in the adapical part of the whorls and on the shell base, whereas the whorl periphery is sculptured with notably stronger and wider elements. This pattern, in combination with whorl periphery shifted abapically, allows for a more or less straightforward recognition of Caribbean Atlantilux species and differentiates them from Austromitra .