''Pulchrastele septenarium'' is a 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 ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Trochidae The Trochidae, common name top-snails or top-shells, are a family of various sized sea snails, marine gastropod molluscs in the subclass Vetigastropoda. This family is commonly known as the top-snails because in many species the shell resembles ...

, the top snails. It is the only described species in the genus ''Pulchrastele''.

Description

The shell grows to a length of 13 mm. The solid, pyramidally conical shell is deeply but narrowly umbilicate. The seven

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 floral ...

s are all, with the exception of the two apical which are smooth and glossy, closely spirally seven-ribbed. These ribs are thickly and regularly formed of gemmae (buds or bud-like growth), contiguous and crowded. The interstices between these beaded riblets are indistinctly obliquely striated. 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 ...

is sharply angled at the periphery. At the base there are eight or nine concentric rows of the same kind of beaded ribs as under the whorls. The interstices are very similarly obliquely striate. The

aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An opt ...

is square. The outer lip is slightly thickened, whilst at the columellar margin a small central tooth is observable. Melvill, J.C. & Standen, R. 1899. Report on the marine Mollusca obtained during the first expedition of Prof. A.C. Haddon to the Torres Straits in 1888-89.; The Journal of the Linnean Society of London v.27 (1899-1900)
(described as ''Calliostoma (Eutrochus) septenarium'')

Distribution

This marine species is endemic to Australia and occurs off the

Northern Territory The Northern Territory (commonly abbreviated as NT; formally the Northern Territory of Australia) is an states and territories of Australia, Australian territory in the central and central northern regions of Australia. The Northern Territory ...

and

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , established_ ...

References

* Iredale, T. 1929. ''Queensland molluscan notes, No. 1.'' Memoirs of the Queensland Museum 9(3): 261–297, pls 30–31 * Keen, A.M. & Cox, L.R. 1960. Trochinae, Calliostomatinae. pp. i-xxiii, 1–351 in Moore, R.C. (ed.). ''

Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology'' (or ''TIP'') published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and co ...

. Part I. Mollusca 1''. Boulder, Colorado & Lawrence, Kansas: Geological Society of America & University of Kansas Press xxiii + 351 pp * Wilson, B. 1993. ''Australian Marine Shells. Prosobranch Gastropods''. Kallaroo, Western Australia: Odyssey Publishing Vol. 1 408 pp. * Jansen, P. 1995. ''A review of the genus Clanculus Montfort, 1810 (Gastropoda: Trochidae) in Australia, with description of a new subspecies and the introduction of a nomen novum''. Vita Marina 43(1–2): 39-62 {{Taxonbar, from1=Q7259277, from2=Q7259278 Trochidae Monotypic gastropod genera