Dallithyris murrayi Muir-Wood 1959

Dallithyris murrayi Muir-Wood, 1959 (Fig. 2D–K) 1959 Dallithyris murrayi Muir-Wood, pp. 305–307, pl. 2, figs. 1, 4–8; pl. 3, figs. 1–4; pl. 5, fig. 8. 1983 Dallithyris murrayi Muir-Wood —Cooper, p. 251, pl. 10, figs. 13–19, pl. 65, figs. 29, 30. 2010 Dallithyris murrayi Muir-Wood —Zezina, p. 1183. Material examined. NW Australia, Lacepede Archepelago, stn SO1/84/055, 15°57.2’S, 120°46.2’E to 15°59.0’S, 120°44.6’E, 296–298 m, 10 February 1984, coll. S.M. Slack-Smith —one complete specimen (WAM Z59452); Kimberley, Cape Leveque, stn SO1/84/082, 13°07.2’S, 123°15.7’E, 400 m, 15 February 1984, coll. S.M. Slack-Smith —two complete specimens (WAM Z59468). Depth range. 296–400 m. Measurements. Length 36.1 mm, width 30.8, thickness 24.2 mm; length 34.3 mm, width 32.5 mm, thickness 22.9 mm. Remarks. Dallithyris murrayi has been so far known from the Maldive Islands and the Saya de Malha Bank (Muir-Wood 1959; Zezina 2010). The present finding is its first record from the eastern Indian Ocean. In the studied material D. murrayi is a rare species, being represented by three specimens. The shell is subpentagonal in outline, ventri-biconvex. Its surface is smooth with indistinct growth lines. The beak is suberect to erect with a rounded, labiate foramen of epithyrid type. Symphytium is very small. The laterial commissure is dorsally convex, while anterior commissure widely uniplicate. The pedicle is very short, distally splitting into numerous strands. Dallithyris murrayi can be easily distinguished from D. fulva (Blochmann, 1906), the species from southeastern Australia and Tasmania; in comparison to the former species, the shell of D. fulva is oval elongate in outline with rectimarginate lateral and anterior commissures (Blochmann 1906, 1908, 1914; Cooper 1983).