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Diala megapicalis Ponder & de Keyzer, 1992

Description: Shell conical, height to width ration variable in range 1.93-2.96. Protoconch 1 smooth whorls. Teleoconch up to 8 flat or slightly convex whorls with sutures indented; whorls smooth or with very weak irregular axial growth ridges, and sometimes with up to 6 weak spiral cords. Base with 4-5 flat-topped spiral ribs. Aperture without siphonal canal; outer lip thin, flared anteriorly; columella smooth. Umbilicus sometimes present as fine slit. Colour variable; base colour white to brown, marked with dark brown in axial streaks, tessellated patterns or random patches; sometimes with light spiral bands. Operculum oval, corneous.

Size: Up to 8 mm in length, commonly 3-7 mm.

Distribution: Endemic to Australia; Jervis Bay, NSW, around southern Australia to Shark Bay, WA.

Habitat: Lives intertidally and in the shallow subtidal on algae or seagrass, most often in sheltered positions, rarely in semi-exposed intertidal pools. Common.

Comparison: Separated from other members of the genus by its relatively large protoconch of only 1 whorls and smooth or weakly sculptured shell (apart from base). (In both Fig. 2 and Fig. 3 white colour bands produce a false effect of strong spiral sculpture).

Synonymy: Has been misidentified in Australian literature as Diala semistriata (Philippi, 1849) and Diala varia A. Adams, 1861.

Remarks: This species is generally smooth or with weak spiral sculpture on the whorls, but with stronger spirals on the base, as in Fig. 1 and 2. Occasional specimens are more strongly sculptured as in Fig. 3, but even here the top of whorls is smooth. (In both Fig. 2 and Fig. 3 white colour bands produce a false effect of strong spiral sculpture).

Fig. 1:  Merimbula Lake, NSW (C.316335)

Fig. 2:  Stony Point Jetty, Westernport, Victoria (C.163938, specimen 1))

Fig. 3:  Stony Point Jetty, Westernport, Victoria (C.163938, specimen 2)

 

Copyright Des Beechey 2006