Penion Imperfectus

''Penion'' is a genus of large marine snails, commonly known as siphon whelks, classified within the mollusc family Austrosiphonidae, the true whelks.MolluscaBase eds. (2021). MolluscaBase. Penion P. Fischer, 1884. Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=488452 on 2021-12-24

Description

Siphon whelks are large, benthic marine snails, or whelks. Powell A. W. B., ''New Zealand Mollusca'', William Collins Publishers Ltd, Auckland, New Zealand 1979 Willan, R.C., de C. Cook, S., Spencer, H.G., Creese, R.G., O’Shea, S., Jackson, G.D. Phylum Mollusca. In: de C. Cook, S.C. (eds.), ''New Zealand Coastal Marine Invertebrates 1'', 406 – 407. Canterbury University Press, Christchurch, New Zealand

''Penion'' are commonly called siphon whelks because they have a very long siphon. Species typically have a large, pointed operculum. Ponder, W.F. 1973. A review of the Australian species of ''Penion'' Fischer (Neogastropoda: Buccinidae). Journal of the Malacological Society of Australia 2: 401–428. Radulae have 3 or 4 cusps on lateral teeth and 3 cusps on central teeth.

Males have a long, dorso-ventrally flattened penis, and correspondingly females have a large pallial oviduct and albumen gland. However, geometric morphometric investigation of '' P. chathamensis'' indicates that secondary sexual dimorphism is not prominent for shell shape or size.

Shells of ''Penion'' vary significantly in shape, size and colouration, making the distinction of species difficult. Shells are fusiform with a tall spire of roughly equal height to the aperture and siphonal canal combined. Protoconch morphology is also highly variable, from 1.5 - 4.0 whorls in height. The siphonal canal of the shell is often long to protect the elongated siphon. Small shells (or fossils) can be confused with those of '' Aeneator'' or '' Antarctoneptunea''.

Shell size can vary quite significantly among populations of ''Penion''. A species, ''Penion fairfieldae'' was formerly recognised, but recent genetic data has demonstrated that the species is indistinguishable from ''Penion chathamensis''. Shells originally recognised as ''P. fairfieldae'' can be distinguished from ''P. chathamensis'' using shell size, but not using shell shape.

Ecology

Most species occur in deep water, and inhabit soft sediments on the continental shelf. Dell, R.K. 1962. New Zealand Marine Provinces - do they exist? Tuatara, 10: 43 - 52
Online Copy courtesy of New Zealand Electronic Text Collection
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All species of ''Penion'' have a wide ranging diet, and are detritivores and carnivores that actively hunt prey. '' P. sulcatus'' is known to feed on mussels and ''Dosina zelandica zelandica''.Wilson, B. 1994. ''Australian Marine Shells. Prosobranch Gastropods''. Kallaroo, WA : Odyssey Publishing Vol. 2 370 pp. Members of the genus have similar niche placement to species of '' Buccinum'' in the Northern Hemisphere.

Distribution

''Penion'' species are restricted to the Southern Hemisphere. Two extant species are currently classified in waters surrounding Australia and five extant species are documented from New Zealand.

Numerous fossil species are recorded in New Zealand, Australia, Argentina and Chile, and Antarctica.Stilwell, J.D., Zinsmeister, W.J. 1992. Molluscan systematics and biostratigraphy, lower Tertiary La Meseta Formation, Seymour Island, Antarctic Peninsula. American Geophysical Union Antarctica Research Series 55: 126-128. DOI: 10.1029/AR055
In New Zealand, many fossils are found in Wanganui Basin sediments.

During the voyage of HMS ''Beagle'', fossils of ''P. subrectus'' were among palaeontological samples collected by Charles Darwin from the mouth of the Santa Cruz River in Argentina.

Evolution

''Penion'' is currently classified within Buccinidae, the family of true whelks. Alternatively they have been referred to the family of Buccinulidae.

Molecular phylogenetic trees based on mitochondrial genomic and nuclear ribosomal DNA sequence data indicate that ''Penion'' is closely related to two genera: '' Kelletia'' found in the north Pacific Ocean and '' Antarctoneptunea'', distributed in waters surrounding New Zealand and Antarctica. Radulae and opercula morphology is similar between ''Penion'' and ''Kelletia''. It is possible that the earliest known fossils of ''Penion'' belonging to '' P. proavitus'' from the New Zealand Paleocene ( Teurian), actually represent a stem lineage that was the common ancestor of these three genera.

In Australian waters, the sister species '' P. mandarinus'' and '' P. maximus'' have overlapping geographic ranges (sympatry), and may have evolved from a common ancestor via niche differentiation based on prey size and water depth.

In New Zealand, the extinct species ''Penion exoptatus'', ''Penion clifdenensis'', and potentially also ''Penion marwicki'', may belong to the same evolutionary lineage as the extant species ''Penion sulcatus''. This hypothesis is based on geometric morphometric analysis of shell shape and size for all four taxa, as well as the analysis of morphometric variation exhibited all living species of ''Penion''.

Human use

''Penion'' shells are prized by shell collectors.

Shells found in middens of historic Māori settlements indicate that '' P. sulcatus'' may have been intentionally foraged as a food-source.

Species

Species and subspecies in the genus ''Penion'' include:

* † ''Penion affixus'' ( Finlay, 1930)
* † ''Penion antarctocarinatus'' (Stilwell & Zinsmeister, 1992)
* † ''Penion asper'' (Marwick, 1928)
* † ''Penion australocapax'' Stilwell & Zinsmeister, 1992
* † ''Penion bartrumi'' (Laws, 1941)
* † ''Penion brazieri'' ( Fleming, 1955)
* ''Penion chathamensis'' (Powell, 1938)
* † ''Penion clifdenensis'' ( Finlay, 1930)
* † ''Penion crassus'' Frassinetti, 2000
* † ''Penion crawfordi'' ( Hutton, 1873)
* ''Penion cuvierianus'' (Powell, 1927) Ponder, W.F. 1975. Identity of ''Penion dilatatus'' (Quoy & Gaimard, 1833) (Mollusca: Buccinidae). New Zealand Journal of Marine and Freshwater Research 9 (4): 569-571..
* † ''Penion darwinianus'' (Philippi, 1887)
* † ''Penion diversus'' Frassinetti, 2000
* † ''Penion domeykoanus'' (Philippi, 1887)
* † ''Penion exoptatus'' (Powell & Bartrum, 1929)
* † ''Penion finlayi'' (Laws, 1930)
* † ''Penion gauli'' (Marwick, 1928)
* † ''Penion haweraensis'' (Powell, 1931)
* † ''Penion hiatulus'' (Powell, 1947)
* † ''Penion huttoni'' (L.R. King, 1934)
* † ''Penion imperfectus'' (Powell, 1947)
* † ''Penion interjunctus'' ( Finlay, 1930)
* † ''Penion koruahinensis'' (Powell & Bartrum, 1928)
* ''Penion lineatus'' Marshall, Hills & Vaux, 2018
* † '' Penion longirostris'' (Tate, 1888)
* † ''Penion macsporrani'' (Philippi, 1887)
* '' Penion mandarinus'' (Duclos, P.L., 1831)
* † ''Penion marwicki'' ( Finlay, 1930)
* '' Penion maximus'' ( Tryon, G.W., 1881)
* † '' Penion oncodes'' (Philippi, 1887)
* ''Penion ormesi'' (Powell, 1927)
* † ''Penion parans'' ( Finlay, 1930)
* † ''Penion patagonensis'' Reichler, 2010
* † ''Penion petitianus'' (d'Orbigny, 1842)
* † ''Penion proavitus'' ( Finlay & Marwick, 1937)
* † ''Penion roblini'' (Tenison Woods, 1876)
* † ''Penion spatiosus'' (Tate, 1888)
* † ''Penion subrectus'' (Ihering, 1899)
* † ''Penion subreflexus'' (G.B. Sowerby I, 1846)
* † ''Penion subregularis'' (d'Orbigny, 1852)
* ''Penion sulcatus'' ( Lamarck, 1816)
* † ''Penion winthropi'' (Marwick, 1965)

''Nomina dubia''

Beu 2009 lists the following Antarctic fossil species as nomina dubia:
* † ''Penion gazdzicki'' (Karczewski, 1987), previously ''Neptunea'' and ''Beringius'', potentially '' Antarctoneptunea''

Species brought into synonymy

* ''Penion adustus'' (Philippi, 1845): synonym of ''Penion sulcatus'' (Lamarck, 1816)
* ''Penion cuvierianus jeakingsi'' (Powell, 1947): synonym of ''Penion ormesi'' (Powell, 1927)
* ''Penion dilatatus'' (Quoy & Gaimard, 1833): synonym of ''Penion sulcatus'' (Lamarck, 1816)
* ''Penion fairfieldae'' (Powell, 1947): synonym of ''Penion chathamensis'' (Powell, 1938)

Reclassified species

* ''Penion benthicolus'' Dell, 1956: accepted as ''Antarctoneptunea benthicola'' (Dell, 1956)

References

External links

Museum of New Zealand Te Papa Tongarewa, Taxon: ''Penion'' (Genus)

Auckland War Memorial Museum: ''Penion'' specimens


* ttp://www.molluscs.otago.ac.nz/ Checklist of the Recent Mollusca Recorded from the New Zealand Exclusive Economic Zone
Molluscs of Tasmania: Buccinidae - Siphonaliinae: Genus ''Penion'' Fischer, 1884 - “whelks”

Further reading

* Powell A. W. B., ''New Zealand Mollusca'', William Collins Publishers Ltd, Auckland, New Zealand 1979

{{Taxonbar, from=Q585580

Austrosiphonidae
Extant Miocene first appearances