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Mitrella menkeana (Reeve, 1858) Description: Shell average width for the genus, whorls straight sided or slightly convex, spire straight, aperture about 1/4 of shell length. Protoconch of 2¾ smooth whorls. Spiral sculpture restricted to cords on base; axial sculpture absent. Outer lip sinuous in profile, with shallow sinus; lip thickened externally; thickened internally, with 6-8 denticles decreasing in size from the uppermost or second uppermost. Columella callus sharp-edged in mature shells; axial ridge along edge, sometimes bearing about 5 small denticles. Siphonal canal very short. Colour variable, but with two common patterns; (a) dark brown and white flames descending from suture, with or without circular white spots in quincunx pattern (Fig. 1) (b) fawn or tan background, with dark brown band below suture, occasionally continuous, usually alternating white and brown (Fig. 2). Interior white or fawn. Periostracum smooth. Size: Up to 16 mm in length. Distribution: Endemic to Australia; Jervis Bay, NSW, around southern Australia to Exmouth, WA. Habitat: Intertidal, down to 30 m. Common in southern Australia, rare in NSW. Comparison: With its tall, straight-sided shell, this is most similar to M. lincolnensis, but it is larger with its own distinctive range of colour patterns. The aperture is white or fawn in M. menkeana, but brown in M. lincolnensis. Synonymy: This species was first described as Buccinum acuminatum Menke, 1843, but that name was preoccupied by Buccinum acuminatum Broderip, 1835. The colour form with brown and white axial bands (Fig. 1) was named Columbella xavieriana Tenison-Woods, 1877. A colour form with purple spiral bands was called variety purpureocincta Verco, 1910. Remarks: This species shows a variety of colour forms, but many specimens are variants of two common patterns; the flamed form (Fig. 1) and the banded form (Fig. 2). Fig. 1: Huskisson, Jervis Bay, NSW. Beach worn, protoconch missing. (C.348154) Fig. 2: Semaphone Beach, SA. (C.348178) Fig. 3: Variation |
