''Paracomitas protransenna'' is an extinct species of

sea snail Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the ...

, a marine

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

mollusk in the family

Pseudomelatomidae Pseudomelatomidae is a family of predatory sea snails, marine gastropods included in the superfamily Conoidea (previously Conacea) and part of the Neogastropoda ( Bouchet & Rocroi, 2005). In 1995 Kantor elevated the subfamily Pseudomelatominae ...

, the turrids and allies.MolluscaBase (2018). Paracomitas protransenna (P. Marshall & R. Murdoch, 1923) †. Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=831513 on 2019-01-06

Description

The length of the shell attains 13 mm, its diameter 5 mm. (Original description) The small shell is narrowly fusiform. The spire is turreted. The shell contains seven or eight

whorl A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs). Whorls in nature File:Photograph and axial plane flo ...

s. It shows a strongly projecting rounded keel at middle on the spire-whorls, concave above and below, on the

body whorl The body whorl is part of the morphology of the shell in those gastropod mollusks that possess a coiled shell. The term is also sometimes used in a similar way to describe the shell of a cephalopod mollusk. In gastropods In gastropods, the b ...

a well-marked concave area below keel followed by a second keel less pronounced, anterior to this rather abruptly contracted. The aperture and

siphonal canal The siphonal canal is an anatomical feature of the shells of certain groups of sea snails within the clade Neogastropoda. Some sea marine gastropods have a soft tubular anterior extension of the mantle called a siphon through which water is ...

are slightly longer than the spire. The

protoconch A protoconch (meaning first or earliest or original shell) is an embryonic or larval shell which occurs in some classes of molluscs, e.g., the initial chamber of an ammonite or the larval shell of a gastropod. In older texts it is also called ...

consists of about 1½ smooth whorls, the lower distinctly carinate, apex blunt. The sutures are linear, margined above and below, variable, some examples indistinct. Sculpture—spirals con sist of numerous fine lines on the keel and above and below it, indistinct in some specimens, on the body whorl usually more pronounced. The axials consist of growth lines only, variable in strength, arcuate between the keel and suture above. The aperture is small, ovate and produced into a long siphonal canal. The outer lip is angled at the keel, thence concave followed by a convexity, and beneath this rapidly narrowing to the siphonal canal. The columella is narrowly callused, straight in the middle portion, narrowing and slightly twisted to the left.P. Marshall & R. Murdoch, ''Some Tertiary Mollusca, with Descriptions of New Species.''; Transactions and Proceedings of the Royal Society of New Zealand , vol. 54, 1923
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Distribution

This extinct marine species is endemic to New Zealand.

References

* Maxwell, P.A. (2009). Cenozoic Mollusca. pp 232–254 in Gordon, D.P. (ed.) New Zealand inventory of biodiversity. Volume one. Kingdom Animalia: Radiata, Lophotrochozoa, Deuterostomia. Canterbury University Press, Christchurch {{DEFAULTSORT:Paracomitas Protransenna protransenna Gastropods described in 1923 Gastropods of New Zealand