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Micromelo undatus (Bruguiere, 1792)

Description: Shell lightweight, spire low. Surface smooth or with indistinct spiral cords, becoming well-defined towards base. Aperture narrow at top, broadening towards base; outer lip thin, inner lip smoothly curved with narrow reflected callus towards base. Colour white with 3 fine red or brown spiral lines, with wavy axial lines inbetween.

Size: Shell up to 16 mm in length.

Distribution: Circum-global in tropical and sub-tropical waters, but this hypothesis remains to be tested genetically. In eastern Australia , as far south as Sydney .

Habitat: “Rocky habitats from the intertidal zone to 5 m. Feeds on cirratulid polychaetes and incorporates their toxins into its own body” (Gosliner, Valdés & Behrens, 2015). Uncommon in northern NSW, rare at Sydney. .

Comparison: The shell is similar to Bullina lineata, differing by much weaker spiral sculpture and a smoothly curved inner lip of the aperture.

Synonymy: Micromelo guamensis (Quoy & Gaimard, 1825) is a previously recognised synonym (see Willan, 1984).

Remarks: Willan (1984) gave a good illustration of the living animal.          

Figs. 1, 2:  Long Reef, Collaroy, NSW. (C.105543).

Fig. 3:  Long Reef, Collaroy, NSW. January 1964. (Photo D.F. McMichael).


Copyright Des Beechey 2017