COPEPODIDS AND ADULTS OF 



LEPTINOGASTER MAJOR (WILLIAMS, 1907), A POECILOSTOMATOID 



COPEPOD LIVING IN MYA ARENAR1A L. AND 



OTHER MARINE BIVALVE MOLLUSKS 



Arthur G. Humes 1 



ABSTRACT 



The five copepodid stages and adults of Leptinogaster major (Williams, 1907), a poecilostomatoid copepod 

 (family Clausidiidae) living in the mantle cavity of Mya arenaria L. and other marine bivalve mollusks 

 along the coast of eastern North America from Prince Edward Island, Canada, to Louisiana, are described. 

 Copepodid I is Saphirella-\ike in body form. In the adult female the maxilliped is present though much 

 reduced. Sexual differentiation first occurs in Copepodid IV, where the male and female maxillipeds are 

 differently formed. 



The poecilostomatoid copepod Leptinogaster (= 

 Myocheres) major (Williams, 1907) has been reported 

 from the mantle cavity of various marine bivalve 

 mollusks along the eastern shore of North America, 

 from Prince Edward Island, Canada (J. C. Medcof 

 in correspondence with M. S. Wilson) to Louisiana 

 (Causey 1953). This copepod has undergone several 

 name changes, but it seems generally agreed now 

 that it properly belongs in the genus Leptinogaster 

 (see Bocquet and Stock 1958, and Table 1). The 

 seasonal population changes and host relationships 

 of this species have been described by Humes and 

 Cressey (1960), who listed as hosts Mya arenaria 

 L., Tagelus gibbus (Spengler), Venus mercenaria L., 

 and Ensis directus (Conrad). Other hosts include 

 Mactra solidissima Dillwyn (reported by Williams 

 1907), Dosinia gibbus Reeve (reported by Pearse 



Table 1.— Taxonomic history of Leptinogaster major (Williams, 1907). 



Lichomolgus mayor Williams, 1907, p. 77, pi. Ill, 8 figs.; Sharpe 1910, 

 p. 408, placed in Lichomolgidae. 



Myicola major, C. B. Wilson, 1932, p. 347, fig. 208, genus wrongly 

 assigned; Monod and Dollfus 1934, p. 316, placed in Clausiidae; 

 Deevey 1948, p. 22, 1960, p. 34; Sewell 1949, p. 156, placed in 

 Lichomolgidae; Causey 1953, p. 12. 



Myicola spinosa Pearse, 1947, p. 5, figs. 26-31, placed in Myicolidae. 



Myocheres major, M. S. Wilson, 1950, p. 299; M. S. Wilson and lllg 

 1955, p. 136, 138; Allen 1956, p. 62, placed tentatively in Licho- 

 molgidae; Bocquet and Stock 1957a, p. 213, 221, placed in 

 Clausidiidae; Humes and Cressey 1958, p. 932, 934, placed in 

 Clausidiidae; Bacescu and Por 1959, p. 20, placed in Clausi- 

 diidae; Humes and Cressey 1960, p. 307-325. 



Leptinogaster major, Bocquet and Stock, 1958, p. 86-88, placed in 

 Clausidiidae; Gooding 1963, p. 132-136, pi. 17, figs. a-n. 



a Boston University Marine Program, Marine Biological Labor- 

 atory, Woods Hole, MA 02543. 



1947), and Pholas eostata L. (reported by Causey 

 1953). For a list of bivalve hosts and localities see 

 Table 2. 



The copepodid development of Leptinogaster has 

 not been fully described. Bocquet and Stock (1958) 

 mentioned finding copepodids of Leptinogaster 

 histrio (Pelseneer 1929) and figured the maxillipeds 

 of an unknown stage (their fig. 3d, e); they also 

 reported a Copepodid V of Leptinogaster sp. and il- 



Table 2.— Localities and hosts of Leptinogaster major. 



Locality 



Host(s) 



Source 



Ellerslie, Prince 

 Edward Island, 

 Can. 



Bideford River, 

 Prince Edward 

 Island, Can. 



Cotuit, MA 



Marthas Vineyard, 

 MA 



Wickford and 

 Matunuck, Rl 



Delaware Bay 

 Beaufort, NC 



Grand Isle, LA 



Mya arenaria L. 



Mya arenaria L. 



Mya arenaria L. 

 Tagelus gibbus 



(Spengler) 

 Venus mercenaria L. 

 Ensis directus 



(Conrad) 

 in plankton 



Mya arenaria L. 

 Venus mercenaria L. 

 Mactra solidissima 

 Dillwyn 



in plankton 



Tagelus gibbus 



(Spengler) 

 Dosinia discus 



Reeve 

 Venus mercanaria L. 



Pholas eostata L. 



J. C. Medcof in 

 correspondence 

 (23 May 1950) 

 with M. S. Wilson 



J. C. Medcof in 

 correspondence 

 (31 July 1948) with 

 M. S. Wilson 



Humes and 

 Cressey (1960) 



Deevey (1948) 

 Williams (1907) 



Deevey (1960) 

 Pearse (1947) 



Causey (1953) 



Manuscript accepted May 1985. 



FISHERY BULLETIN: VOL. 85, NO. 2, 1986. 



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