Triviella lowtheri

Triviella lowtheri
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
(unranked):	clade Caenogastropoda clade Hypsogastropoda clade Littorinimorpha
Superfamily:	Velutinoidea
Family:	Triviidae
Subfamily:	Triviinae
Genus:	Triviella
Species:	T. lowtheri
Binomial name
Triviella lowtheri Beals, 2008

Triviella lowtheri is a species of small sea snail, a marine gastropod mollusk in the family Triviidae, the false cowries or trivias.

Description

A NEW SPECIES OF TRIVIELLA FROM SOUTH AFRICA

Martin N. Beals

Key words

    Gastropoda, Triviidae, Triviella lowtheri, new species, South Africa.

Abstract

    A newly discovered Triviidae Troschel, 1863 in the genus Triviella Jousseaume, 1884 is described.  It is a deep-water species from South Africa and is compared to Triviella franziskae Fehse & Massier, 2000.

Introduction

    Triviella are known only from South Africa and Namibia, of which there are 24 species referable to the genus; 23 as listed by Rosenberg & Finley (2001: 28) and Triviella franziskae.  Because of the recent increase in diving, dredging and trawling by both private and commercial interests, 13 of the known Triviella have been named since 1980.  Hence, it is not surprising new species of Triviella continue to be discovered.  
    Late in 2002 Scott Lowther, an avid collector of Triviidae sent me two specimens of what appeared to be an unidentified Triviella.  Another seven shells have since become available, thus providing a viable study series.  Comparative observation shows that distinct conchological differences separate these shells from their closest relative Triviella franziskae.  I have therefore concluded that these eight specimens represent a species new to science.

Triviella lowtheri sp. nov.

Description

    Shell solid, semi-pyriform, inflated, of medium size, length 13.4 to 15.7mm.  Terminals arched, dentate, slightly produced and thickened, anterior more so.  Spire visible, barely produced, covered by several ribs.  Dorsum smooth, glossy, sloping to apex, more gently to anterior; color fawn to light creamy-gray.  Ribbing distinct, rounded, shiny white, most terminating abruptly at open median dorsal area, with no indication of sulcus.  Base slightly rounded, angling inward towards aperture; 12-13 denticles from basal ribbing delineate columellar peristome, continuing adaxially as reduced riblets across columella, less pronounced posteriorly.  Fossula concave, 4-5 riblets cross adaxially, becoming denticles on inner margin.  Thickened labrum with 10-13 denticles, becomes reduced and curved at anterior and posterior, slightly shouldered above.  No funiculum or terminal ridge.  Aperture fairly straight, just widening at anterior, posterior curved.  Basal area, labrum, ribbing, denticles and columella white.

Animal

    The animal was removed from the holotype’s shell and is available for study at the SBMNH.  To date, no images of the living animal are available.

Type locality

    The holotype and seven paratypes were dredged from 100 meters off East London, eastern Cape Province, South Africa.

Type depository and measurements

     The holotype has been deposited in the Santa Barbara Museum of Natural History, number 348454.

Holotype: L 14.7, W 11.5, H 10.2mm, SBMNH 348454 Paratype No.1: L 14.8, W 11.5, H 9.9mm, Collection Scott Lowther Paratype No.2: L 13.7, W 11.0, H 9.0mm, Collection Scott Lowther Paratype No.3: L 14.9, W 12.9, H 11.2mm, Collection Martin Beals Paratype No.4: L 14.2, W 11.4, H 9.6mm, Collection Martin Beals Paratype No.5: L 15.7, W 12.2, H 10.3mm, Collection Martin Beals Paratype No.6: L 13.4, W 11.0, H 9.6mm, Collection Chuck Finley Paratype No.7: L 13.8, W 11.1, H 9.5mm, NM W831/1961*

Etymology

    This species is named for Scott Lowther, an avid collector, who first brought this new trivid to my attention.

Discussion

    Triviella lowtheri most closely resembles T. franziskae, though numerous and distinct differences clearly separate the two species.  The type specimens of T. lowtheri are 13.4-15.7mm in length, semi-pyriform, inflated, and have a higher dorsal profile, which slopes more gently to the anterior; while the type specimens of T. franziskae are larger 15.6-18.0mm, nearly globular, sub-rectangular and dorsally more symmetrically elevated.  Triviella lowtheri have fine transverse riblets extending from the columellar denticles across the columella and 4-5 crossing the fossula; of particular importance is the complete absence of columellar and fossular ribbing in T. franziskae.
    The four type specimens of T. Franziskae were dived at 41m from Kommetjie on the west coast of the Cape Peninsula.  A fifth specimen appearing to be somewhat sub-adult was referenced in the original description (Fehse & Massier, 2000: 125).  This shell (Liltved, 1989: 176) was miscatalogued at SAM (South African Museum in Cape Town) and cannot be located for detailed examination, so its specific species affiliation may be questionable.  If Liltved’s shell is excluded from consideration, these two species are further differentiated by locality and depth; T. lowtheri being an east coast deep-water species, while T. franziskae has a more shallow-water habitat and is from the west coast.   

Acknowledgements

    I would like to thank Dr. Henry Chaney (Santa Barbara Museum of Natural History) for his review of the manuscript.

• NM is the Natal Museum, Pietermaritzburg, South Africa

References Cate, C. N. 1979. A review of the Triviidae (Mollusca: Gastropoda). Memoirs of the San Diego Society of Natural History 10: 1-126. Fehse, D. and W. Massier. 2000. A new Triviella (Gastropoda: Triviidae) from South Africa. La Conchiglia 32 (294-295): 123-126. Liltved, W. R. 1989. Cowries and their relatives of Southern Africa. A study of the Southern African Cypraeacean and Velutinacean gastropod fauna. Seacomber Publications, Cape Town, South Africa: 208 pp., 298 figs. Rosenberg, G. and C. C. Finley. 2001. New species of Triviidae (Mollusca: Gastropoda) from South Africa, Namibia and the Philippines. Proceedings of the Academy of Natural Sciences of Philadelphia 151: 23-30.