Penion maximus is a species of very large predatory sea snail or whelk, commonly known as giant whelk or great whelk, a marine gastropod mollusc in the family Austrosiphonidae.
Description Penion maximus is the largest species in this genus, measuring 190.5 mm in length. The species could be confused with the sympatric species P. mandarinus, however P. mandarinus is typically smaller and has a smoother shell with a shorter siphonal canal. Their shells are highly coveted due to the intricate designs embedded in onto the shells.
(Original description) The white shell is sprinkled and blotched with light chestnut-brown across the spiral ribs. A broad brown band is positioned between the tubercles on the shoulder of the whorls, while the aperture remains a pure white.
Distribution The range of the species extends from waters off Tasmania and Victoria to lower Queensland.
Evolution Penion maximus is closely related to another Australian species P. mandarinus. The species have overlapping geographic ranges (sympatry) and may have evolved from a common ancestor via niche differentiation based on prey size and water depth.
References
Wilson, B. 1994. Australian marine shells. Prosobranch gastropods. Kallaroo, WA : Odyssey Publishing Vol. 2 370 pp.
External links Grove, S.J. 2011. A Guide to the Seashells and other Marine Molluscs of Tasmania.
Molluscs of Tasmania: Buccinidae - Siphonaliinae: Penion maximus (Tryon, 1881) ('great whelk') Seashells of New South Wales: Penion maximus (Tryon, 1881)