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Bembicium melanostomum (Family Littorinidae)

Dark-Mouthed Conniwink

Distribution

Distribution:

This species ranges from NSW, around southern shores, including Vic, Tas and SA, to Fremantle in WA (NSW, VIC, TAS, SA, WA).

Features:

The shell is cone-shaped, wide and keeled on the base whorl. The shell grows to a length of 20mm and grows to 15mm across. A keel is a sharp ridge that is formed when the spirals have a sharp angle to the shell base. The sculpture of the shell consists of spiral ridges or nodules. This species' shell is smaller and less strongly keeled and the base is speckled with brown, producing a darker outer lip than its relation the Gold-mouthed Conniwink, Bembicium auratum. Because of the flattened or even slightly concave base, the mouth shape is oblique, with a thin outer lip. The covering operculum is horny.

The shell colour is grey or brownish, often with darker grey or brown oblique stripes. The stripes are less prominent than the Striped-mouth Conniwink, Bembicium nanum. The shell interior is fawn to dark brown and shiny, with a striped edge. The shell is not nacreous. The columella is orange or fawn.

Ecology/Way of Life:

The Dark-Mouthed Conniwink occurs in sheltered estuaries, inlets, bays, mangrove swamps or on mudflats. It lives on rocks, mangroves and on wooden piles. It is an algae feeder. Hilda Anderson (1958) studied the three species of Bembicium in temperate Australia. She concluded that the three species could only be separated with difficulty using their shell characteristics alone. However, Mrs. Anderson could distinguish them by considering their reproductive systems and their egg masses.

Preferred Image

Interaction with Humans/Threats:

The Dark-mouthed Conniwink has a wide distribution across temperate Australian shores and is abundant within its range. It does not appear to be under threat from human activity because of its abundance, other than the fact that it lives in estuaries, which often suffer greatly from human pollution.

Other Comments:

Bembicium melanostomum Gmelin, 1791. Also known as

B. melanostoma

. Macpherson & Gabriel state that Gmelin described the type species Trochus melanostoma in 1789. The genus has also been called Risella Gray, 1847. Mrs Hilda Anderson described the three species of this genus in southern Australia, and that all other names are synonyms of these three.

Bem in Bembicium comes from the Greek word bema, meaning a step, while bicium may come from bice, meaning brownish-grey. The word bice is of unknown origin. Melanostoma comes from two Greek words, melas or melanos meaning black, and stoma meaning a mouth-like opening.

Further Reading:

Anderson, H. (1958). The gastropod genus Bembicium, Philippi. Aust. J. mar. Freshwater. Res., V.9(4), pp.546-568.

Davey, K. (1998) A Photographic Guide to Seashore Life of Australia. p.99, New Holland Press, Sydney.

Edgar, G.J. (1997). Australian Marine Life: the plants and animals of temperate waters. p.245, Reed.

Jansen, P. (2000), Seashells of South-East Australia. p.28, Capricornia Publications.

Macpherson, J.H. & Gabriel, C.J. (1962). Marine Molluscs of Victoria. p.90, Melbourne University Press.

Marine Research Group of Victoria (1984). Coastal Invertebrates of Victoria: An atlas of selected species. p.46, Museum of Victoria.

Shepherd, S.A. & Thomas, I.M. (1989). Marine Invertebrates of Southern Australia. Pt. II. South Australian Govt. Printing.

Wilson, B.R. & Gillett, K. (1979). A Field Guide to Australian Shells: Prosobranch Gastropods. p.52, Reed.

Acknowledgments:

Text, map & photograph by Keith Davey.

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Images and Multi-media:  
Attached Image  
image/jpeg 9665 bytes Dark-Mouthed Conniwink
Distribution Map  
image/gif 999 bytes Distribution of Dark-Mouthed Conniwink

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