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Posted: Jul 21 2018

 Transennella stimpsoni Dall, 1902, Banded Transennella

During my search for samples of T. stimpsoni for a photo session, John Wolff pointed out that Huber (2010) has suggested that an earlier name for Transennella stimpsoni is Transennella angulifera (G. B. Sowerby II 1851). Here are Huber's comments:

"SF35: Transennella: Small, solid, ovate specimens with a characteristic undulate-striate margin are easily identified as Transennella. The specific attribution is more difficult. Furthermore, a couple of neglected BMNH-types are available, undoubtedly belonging to this exclusively American genus:

The 11.2 mm holotype of Tapes hanleyi Sowerby II, 1852 from Brazil, Rio is still present in the BMNH type collection; the outer color is now bleached, but internally still well preserved deep purple. Characteristic is the fine, dense commarginal sculpture, an ovate elongate, somewhat rostrate shape and the broad, ascending rounded pallial sinus. Fischer-Piette saw the BMNH type, wrote in sched. “not a Tapes” and reported it in Fischer-Piette & Métivier (1971 p. 103) as non TAPETINAE. Indeed hanleyi is without doubt a Transennella. From shape, color, size and pallial sinus it fits precisely stimpsoni, as illustrated by Brazilian authors. Stimpsoni is known to
occur in Rio and to grow up to 15 mm in Brazil (BRASIL). T. cubaniana, also known from Brasil is more rounded and grows smaller.

Furthermore, the depicted, 14.4 mm and a smaller 10.5 mm syntype of Cytherea angulifera Sowerby II, 1851 are present in the BMNH type collection. As noted by Jukes-Browne (1913) this proved to represent a further
Transennella from Museum Cuming, but described and labelled without locality. It is similarly shaped as hanleyi and also finely commarginally ridged. The color is white with red-brown tented blotches, inside white. The pallial
sinus extends about as far as midline, ascending and rounded. This species was treated by various authors, nobody gave a locality. From all Transennella studied angulifera most closely resembles hanleyi. This is also the only Caribbean species known to reach the size of angulifera. Furthermore, internally all white stimpsoni are known from Rio de Janeiro. As finally a 14.4 mm specimen from Rio is available which closely approaches the larger angulifera syntype in size, shape and sculpture, angulifera is understood as the even earlier name for hanleyi. The type locality of angulifera is here clarified as Rio de Janeiro State. T. stimpsoni is a junior synonym. From the T. angulifera studied, and the variability in shape and color encountered, it should be verified that T. gerrardi is indeed distinct and a valid species."

Huber, Markus. 2010 Compendium of Bivalves. ConchBooks, Germany.

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