DEEP-SEA PROTOBRANCHIA (BIVALVIA) 

 Genus PROTONUCULA Cotton 1930 



Type species. Protonucula verconis Cotton 1930; OD. 



Shell relatively fragile, oval, compressed, glossy, concentric sculp- 

 ture; umbo prominent; hinge plate narrow, chevron teeth squat, 

 broad, continuous; ligament relatively small, external, amphidetic. 



Neilonella salicensis (Seguenza 1877) 



Type specimen. Whereabouts unknown. 



Type locality. Upper Pliocene fossil, southern Italy. 



Cited specimens. BMNH 1995051. 



Leda pusio var./af/or Jeffreys 1876a, p. 190, nom. nud.; 1876b, 



p.430. 

 Leda pusio Jeffreys 1879, p. 578, in part. 

 Leda pusio var. salicensis Seguenza 1877, p. 1 178, pi. 4, fig. 20. 

 Yoldia sericea var.striolata Verrill 1884, p.226; 1885, p.576. 

 Leda salicensis Locard 1898, p.348, pi. 14. figs 22-25. 

 Neilonella subovata Verrill and Bush 1 897, p.57, figs 7, 8. 22; type 



locality: Georges Bank to Cape Hatteras, 1 25-1 73 1 fms; syntype: 



USNM 34826 (examined by HLS). 

 Tindaria (Neilonella) guineensis Thiele 1 93 1 , in Theile and Jaeckel 



1931, p.50, pi. 3, fig.70; type locality; Gulf of Guinea, 710- 



2492m; type: ZMHU (not seen). 

 Neilonella guineensis Knudsen 1970, p.59, text-fig. 39, pi. 5, fig. 3, 



pi. 6, figs 8-10. 

 Neilonella schepmani Prashad 1932, p. 27, pl.l, figs 50, 51; type 



locality; Banda Sea, Siboga sta.221, 2798m; ZMHU (not seen). 

 Pseudoneilonella salicensis Laghi 1986, p. 191, text fig.l, pi. 5, figs 



1-7. 

 Pseudoneilonella latior Laghi 1986, p. 192, text fig. 1 , pi. 7, figs 7a-c. 

 Pseudoneilonella salicensis atlantica Laghi 1986 p. 192, text fig.l, 



pi. 6, figs 1-7. 

 Pseudoneilonella montanaroe Laghi 1986, p. 193, text fig.l, pl.9, 



figs 4-8; type locality: off Portugal, Porcupine Expedition, 400m, 



USNM No. 199739 (not seen). 

 Neilonella striolata (Brugnone) Waren 1989, p. 252, figs 3a, 16a-d. 



Waren (1989) gives a lengthy and detailed discussion of much of 

 the nomenclatoral history of this species although, the history is 

 even more complex than he reports. Waren (1989) synonymized N. 

 salicensis with an earlier described species N. striolata (Brugnone, 

 1876). The type of AA striolata is lost but from the original descrip- 

 tion and figure by Brugnone (1876) and those of Seguenza (1877) 

 (who synonymized it with Yoldia abyssicola Torrell) and later au- 

 thorities (e.g. Jeffreys, 1879; Locard, 1898) it is clear that the 

 posterior part of the shell of N. striolata is significantly different in 

 form to that of N. salicensis. Whereas the posterior shell margin of 

 N. salicensis is acutely rounded that of N. striolata is sub-rostrate 

 with the posterior limit of the shell more ventral in position and the 

 distal postero-dorsal margin more steeply angled (Figs 1,2 & 4). 



The brief description of N. guineensis by Theile in Theile and 

 Jaeckel( 1 93 1 ) was enlarged upon by Knudsen (1970) who com- 

 pared specimens from the Galathea Expedition with those of the 

 Valdivia and Siboga Expeditions. From our examination of the 

 Galathea material from 02"17'S 08T0'E (2770m) and our own speci- 

 mens from 02"32'S 08'18'E (2514m) we conclude that N. guineensis 

 and N. salicensis are the same species. Knudsen (1970) also 

 synonymized N. schepmani with N. guineensis. Although N. 

 schepmani is from the Banda Sea (Prashad, 1932) which might cast 

 doubt on this synonymy, it must be remembered that N. salicensis is 

 a very widespread species and we believe that it is comparable to 



103 



Fig. 1. 'Yoldia abyssicola' Torell. Right valve, redrawn from Seguenza 

 (1877), synonymized with Leda producta Monterosato and Yoldia 

 striolata Brugnone. Scale = 1mm. 



Ledella sublevis, which also has a widespread distribution in the 

 Atlantic and extends into the southwest Pacific (Allen and Hannah, 

 1989). 



Further compexity in the synonymy ofN. salicensis concerns so- 

 called varieties of "Leda pusio Philippi' a species that has recently 

 been investigated by Laghi (1986). 



Fig. 2. Neilonella salicensis. a, view of shell, from Atlantis II station 73 

 in the North America Basin, drawn from the left side; b, outline of shell 

 from Biogas VI station DS 86 in the West European Basin to show 

 difference in shape. Scale = 1mm. 



L. pusio is rostrate and not a neillonellid, but a ledellid, possibly 

 synonymous withL.acuminata (Jeffreys 1 870)(Laghi, 1986). Jeffreys 

 ( 1 879) reporting on Leda pusio taken by the 'Lightning' and 'Porcu- 

 pine' Expeditions, refers to what he thought was a variety of this 

 species which he had previously named L. pusio var. latior 

 (Jeffreys, 1876) and which he changed to L. pusio var.salicensis of 

 Seguenza (1877). Laghi (1986) proposed a new genus 

 Pseudoneilonella to accommodate this latter and raised to species 

 level a number of the records of Jeffreys ( 1 876, 1 879). Since then, 

 Waren (1989) has synonymized these with Neilonella salicensis and 

 this we confirm. 



Jeffreys (1879) also listed a further variety which he called 

 semistriata and which is now regarded as a separate species (Waren, 

 1989). In his detailed analysis Waren (1989, figs 17E & F) also 



