Bull. not. Hist. Mus. Lond. (Zool.) 63(2): 93-122 



Issued 28 November 1997 



The lucinid bivalve genus Cardiolucina Museum ' 



(Mollusca, Rival via, Lucinidae): systematics, 

 anatomy and relationships IgeSrIl library 



JOHN D. TAYLOR^AND EMILY A. GLOVER /v. ^ Q ^ ^(3^ 



Department of Zoology, The Natural History Museum, Cromwell Road, London SW7 5BD, UK 



CONTENTS 



Introduction 93 



Abbreviations 94 



Systematic descriptions 94 



Fossil species of Cardiolucina 1 17 



Species excluded from Cardiolucina 1 18 



Relationships amongst the species 1 18 



Geographical distribution 120 



Conclusions 121 



Acknowledgements 121 



References 121 



SYNOPSIS. The marine lucinid genus Cardiolucina (usually known as Bellucina) comprises 1 1 living species of small, heavily 

 ornamented, subspheroidal bivalves. The type species of the genus is the Miocene fossil C agassizi (Michelotti). A new 

 definition and description of the genus is given. All the living species and the type species are redescribed and illustrated. Two 

 species, C australopilula from Western Australia and C. siquijorensis from the Philippines, are described as new. Anatomical 

 details are given for two species which both contain chemosymbiotic bacteria in the ctenidia. A preliminary phylogenetic 

 analysis using shell characters and Parvilucina as an outgroup, indicates three clades of Cardiolucina. Nine species are found 

 in the Indo-W. Pacific and two in the tropical Atlantic. The greatest diversity occurs around Australia where seven species live. 

 The two Atlantic species are similar to the widespread Indo-Pacific species C. semperiana. The earliest-known species of 

 Cardiolucina is from the Eocene, but the fossil record is very poor. 



INTRODUCTION 



Since the discovery of endosymbiotic sulphur-oxidising bacteria 

 contained in the gills, the biology of bivalves in the family 

 Lucinidae has attracted much attention (Fisher & Hand, 1984; 

 Dando, Southward, Southward, Terwilliger & Terwilliger, 1985; 

 Dando, Southward & Southward, 1986: Southward, 1986; Reid & 

 Brand, 1986; Distel and Felbeck, 1987; Cary, Vetter & Felbeck, 

 1989; Fisher, 1990; Reid, 1990). The symbiosis has so far been 

 recorded in about 25 species of Lucinidae and some species have 

 been shown to be nutritionally dependent on the association (Le 

 Pennec, Beninger & Herry, 1995). The discovery and investigation 

 of the symbiosis has been the key to understanding the many 

 unusual features of lucinoid morphology and habitat distribution 

 (Allen, 1958; Reid & Brand, 1986, Reid, 1990). Despite the bur- 

 geoning biological interest in lucinid bivalves, it is unfortunate 

 that the systematics of family are not well understood, with many 

 taxonomic groups, particularly at the supraspecific level, being 

 rather loosely defined. Most recent comprehensive systematic 

 treatments of Lucinidae (Chavan, 1969; Bretsky, 1976) both pre- 

 date the discovery of chemoautotrophy in the family and, 

 moreover, are based entirely on shell characters. As Hickman 

 (1994) points out, there has been no attempt to incorporate the 



potential wealth of anatomical and biological characters into sys- 

 tematic studies. Furthermore, following closer attention to lucinid 

 biology and the investigation of new habitats it is now being 

 recognised that there are many undescribed species. 



In this paper, we review the species of the lucinid genus 

 Cardiolucina (better known as Bellucina), which are largely tropi- 

 cal, small, subspheroidal bivalves found in the Indo-Pacific and 

 Atlantic Oceans. The impetus for this revision stems from the 

 discovery of two coexisting lucinids in the shallow waters around the 

 Abrolhos Islands. Western Australia (Glover & Taylor, 1997). Both 

 species appeared to be undescribed and one with unusual periostracal 

 extensions has been assigned to a new genus Rastafaria (Taylor & 

 Glover, 1997). The other species, which forms a part of this paper, 

 was evidently a Cardiolucina and seemed similar to C. semperiana 

 Issel, which is widespread in the Indo-West Pacific. However, 

 preliminary research indicated that there is much taxonomic confu- 

 sion within the genus, including the priority of the name Cardiolucina 

 over Bellucina. This led us to revise and redescribe the type species, 

 provide a new diagnosis of the genus, to review the Recent species 

 from the Indo-Pacific and Atlantic Oceans and to describe new 

 species from Western Australia and the Philippines. We have also 

 attempted to identify within the genus Cardiolucina those shell and 

 anatomical characters that might be used in a wider study of lucinid 

 systematics. 



) The Natural History Museum, 1997 



