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Cirsonella reflecta Laseron, 1954

Description: Figured syntype (Figs. 1, 2): Shell minute, spire low. Protoconch low, smooth, with well-defined transition to teleoconch. Teleoconch of 1 whorls. Whorls rounded, smooth except for irregular growth lines. Umbilicus open, deep, partly closed by inner lip of aperture, with 3 spiral ribs commencing at apertural lip and descending into umbilicus. Aperture circular, peristome entire, outer lip a little thickened internally, inner lip thickened and reflected over umbilicus. Shell colourless translucent to opaque white.

Size: Figured syntype: 1.2 mm wide, 1.0 mm high.

Distribution: Syntype from Sow and Pigs Reef, Port Jackson. Specimens tentatively identified as this species are from Port Stephens, Middle Harbour and Port Jackson, NSW, and Pirates Bay, Tasmania.

Habitat: Beach washup and down to 15 m. Common.

Comparison: This is similar in shape to C. weldii, but one-third the size, and has spiral sculpture in the umbilicus.

Remarks: Laseron described this species as having "a narrow shelf commencing from the inner margin [of the aperture] into the umbilicus, which it partly fills". I am unable to recognise a shelf in the umbilicus of the two syntypes, preferring to describe the umbilical sculpture as spiral ribs. Laseron described another species, Cirsonella perplexa Laseron, 1954 (Figs. 3 and 4), which he considered to be "almost indistinguishable" from C. reflecta, differentiating it by the absence of the "shelf". There are 6 syntypes of this second species but only some of them lack the umbilical spirals. Whether C. reflecta and C. perplexa are separate species, and whether the umbilical sculpture is a good distinguishing feature, remains to be determined.

Figs. 1, 2: SYNTYPE of Cirsonella reflecta. Sow and Pigs Reef, Port Jackson, NSW, 11-16 m (C.102813)

Figs. 3, 4: SYNTYPE of Cirsonella perplexa. Off Twofold Bay, NSW, in 73-91 m (C.102814)

 

Copyright Des Beechey 2009