Small, rare and little known: new records and species of Cardiomya (Bivalvia: Cuspidariidae) from Brazil

Tarcilla Carvalho De Lima,Ricardo Silva Absalão,Cléo Dilnei De Castro Oliveira

doi:10.5852/ejt.2020.619

Tarcilla Carvalho De Lima, Ricardo Silva Absalão + Show 1 more

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https://doi.org/10.5852/ejt.2020.619

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Abstract

This paper describes rare Cardiomya species from Brazil which have been hitherto misidentified as Cardiomya cleryana (d’Orbigny, 1842) in literature or museum collections. Cardiomya minerva sp. nov. is proposed as new species and is characterized by its quadrangular shell, short and truncated rostrum, and external ornamentation composed of six radial ribs on the posterior half of the shell flank. Cardiomya striolata (Locard, 1897) described from the Mediterranean Sea and northwestern Atlantic Ocean, is reported from Brazil for the first time; although previously regarded as a junior synonym of Cardiomya costellata (Deshayes, 1835), it is herein considered as a full species and redescribed. This species is characterized by its trapezoidal shell flank, elongated rostrum, tapering towards the tip, and external ornamentation composed of 18–53 radial ribs, the 3–4 posterior ones being the strongest and more widely spaced. Other three previously unknown species are illustrated but not formally named due to the lack of well-preserved articulated shells.

Highlights

Cuspidariidae Dall, 1886 is a family of marine carnivorous bivalves (Allen & Morgan 1981; Morton 1981)
Four species of Cardiomya have been reported from Brazil (Rios 2009; Oliveira et al 2017): Cardiomya cleryana (d’Orbigny, 1842), C. ornatissima (d’Orbigny, 1853), C. striata (Jeffreys, 1876) and C. perrostrata (Dall, 1881)
Considering the specimens from Brazil, Cardiomya striolata has often been misidentified in the literature: [1] part of the specimens listed as C. cleryana in Barroso et al (2016: 6), as well as the figured specimen in Barroso et al (2016: 7, fig. 5). [2] the specimen figured in Machado et al (2016: 3, figs 1A–B) as C. perrostrata and identified as C. cleryana by Oliveira et al (2017: 286). [3] the specimen from CMPHRM 712A reported upon as C. perrostrata by Barroso et al (2016) and later identified as C. striata by Oliveira et al (2017)

Summary

Introduction

Cuspidariidae Dall, 1886 is a family of marine carnivorous bivalves (Allen & Morgan 1981; Morton 1981). Most species are less than 10 mm in length, and many of them are rare, only known by their original descriptions and few subsequent records. This rarity plus the fragility of the cuspidariid shells led to the scarcity of available specimens in scientific collections, where most species are represented only by few and usually broken shells. Four species of Cardiomya have been reported from Brazil (Rios 2009; Oliveira et al 2017): Cardiomya cleryana (d’Orbigny, 1842), C. ornatissima (d’Orbigny, 1853), C. striata (Jeffreys, 1876) and C. perrostrata (Dall, 1881). There are rare and little known Cardiomya still hidden on museums’ shelves.

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