20 



A.V. SYSOEV 



as a result of damage and subsequent repair, is very small, 

 subquadrate, with central nucleus (Fig. 12). 



All specimens of B. symbiophora bear actinians on their shells 

 and are often entirely covered with them. 



The new species differs from all known Recent species of 

 Borsonia, in its stout shell with typically uniform spiral sculpture 

 and smooth columella. 



The species is quite comparable with species of Borsonia and, 

 especially of the Cordieria subgenus primarily differing in the 

 absence of columellar plicae and the presence of operculum. 

 However, the prominence (and even presence) of columellar 

 plicae can vary greatly among species of the same genus and 

 sometimes among shells of the same species. The presence of an 

 operculum also cannot be considered as a diagnostic character 

 because it is very patchily distributed in the subfamily, where 

 repeated and independent reduction and loss of operculum 

 undoubtedly occurred, and many faunas demonstrate a full 

 range of species with well developed, vestigial or missing 

 operculum (e.g. Eastern Pacific - see McLean, 1 97 1 ). 



B. symbiophora is also similar to species of the subgenus 

 Borsonellopsis McLean, 1971 of the genus Borsonella Dall, 1890. 

 The type species of Borsonellopsis, Leucosyrinx erosina Dall, 

 1908, possesses similar sculpture and shell outlines as well as a 

 vestigial operculum, and lacks columellar plicae. On the other 

 hand, it differs considerably from Borsonella s.str. and may not 

 be congeneric. 



Distribution. Gulf of Aden and off Mombasa (Kenya), 

 1789-23 12 m. 



Genus BA THYTOMA Harris & Burrows, 1 89 1 



Type species: Murex cataphractus Brocchi, 1814 (monotypy) 



Subgenus PARABATHYTOMA Shuto, 1961 



Type species: Pleurotoma striatotuberculata Yokoyama, 1928 

 (original designation) 



The differences between the generally accepted subgenera of 

 Bathytoma (see Powell, 1966) seem to be rather slight. Kilburn 

 ( 1 986) mentioned that Parabathytoma differs from Micantapex 

 in having radular teeth without an elongate base and in the 

 absence of brephic arcuate riblets at the place of the protoconch 

 transition into teleoconch whorls. However, in all the species 

 described below, the presence of long, curved teeth without an 

 elongate base is associated with the presence of arcuate riblets at 

 the place of the protoconch termination, i.e. these species 

 possess characters of both Parabathytoma and Micantapex 

 sensu Kilburn. Thus, the only feature distinguishing these 

 subgenera is the shape of radular teeth. The question is further 

 complicated by the fact that the type species of Parabathytoma is 

 a fossil Pleurotoma striatotuberculata Yokoyama, 1928, while the 

 radula of type species of Micantapex, Bathytoma agnata Hedley 

 & Petterd, 1906, is unknown. Nevertheless, the species listed 

 below are provisionally included into Parabathytoma on the 

 basis of their radular morphology. 



Bathytoma (Parabathytoma) prodicia Kilburn, 1986 



Figs 90 & 91 



Bathytoma (Parabathytoma) regnans (non Melvill, 1918) - 



Kilburn, 1971, p. 31, figs 2c, 2f, 4b 

 Bathytoma (Parabathytoma) prodicia Kilburn, 1986, p. 643, figs 



22-23. 



Type locality. East of 

 Mozambique), 300-310 fms. 



Material, stn 119, 1 shell. 



Bazaruto Island (Southern 



The shell from the JME material differs from the holotype 

 figured by Kilburn in having less prominent peripheral nodules, 

 shallower anal sinus, and flattened shell base. However, all other 

 essential conchological characters including the shell 

 proportions (D/H = 0.43, Ha/H = 0.52) are similar to B. prodicia. 

 An additional smaller (H = 23.5 mm) specimen collected off 

 Zanzibar by R/V 'Vityaz' (stn 4680, 740 m) is in some respects 

 intermediate between the typical B. prodicia and the JME shell. 



Distribution. Southern Mozambique to Zanzibar, 420-1463 

 m. 



Bathytoma (Parabathytoma) oldhami (E.A.Smith, 1899) 



Figs 7 & 92-93 



Pleurotoma (Bathytoma) oldhami E.A.Smith, 1899, p. 238. 

 Pleurotoma oldhami E.A.Smith -Alcock&McArdle, 1901, pi. 9, 

 figs 2, 2a. 



Type locality. 'Investigator', stn 229, off Travancore coast, 

 360 fms. 



Material, stn 145, 1 specimen. 



The JME specimen is of approximately the same size as the 

 holotype and very similar to the figure of the latter, differing 

 only in slightly broader shell (H = 41.0 mm, D = 15.8 mm vs. 43 

 and 15 mm in the holotype). The protoconch consists of about 

 1.5 smooth globose whorls followed by several arcuate axial 

 riblets which gradually become stronger and pass into the 

 teleoconch sculpture. The radular teeth (Fig. 7) are long and 

 strongly curved, of typical shape for the subgenus. The mean 

 tooth lengtrris 0.77 mm. 



Distribution. Southern India and Maldive Islands, 494-658 

 m. 



Bathytoma (Parabathytoma) regnans Melvill, 1918 



Figs 8, 16 & 94-97 



Bathytoma regnans Melvill, 1918, p. 68, textfig. 

 Bathytoma regnans Melvill - Kilburn, 1986, p. 718, fig. 168 

 (holotype). 



Type locality. Indian Ocean, Investigator Expedition 

 (probably the Bay of Bengal). 



Material, stn 34, 1 specimen and 5 shells; stn 188, 2 shells; stn 

 193, 6 shells. 





Figs 90-101 Clathurellinae. 90, 91 - Bathytoma (Parabathytoma) prodicia Kilburn, 1986, stn 1 19, H = 32.3 mm; 92, 93 - B. (P.) oldhami^. .A. 

 Smith, 1 899), stn 145, H = 41 .0 mm; 94-97 - B (P.) regnans Melvill, 1918, stn 188 (94, 97), 34 (95) and 193 (96), H = 27.5 (94), 26.6 (95), 24.4 (96) 

 and 25.5 (97) mm; 98-100- B. (P)fissa (von Martens, 1901), stn 176, H = 35.3 (98), 34.7 (99) and 38.4 (100) mm; 101 - Typhlosyrinx praecipua 

 (E.A. Smith, 1 899), stn 1 84, H = 30.2 mm. 



