DEEP-SEA CONOIDEAN GASTROPODS 



15 



Distribution. According to Kilburn (1989), P. suturalis is a 

 central West Pacific species (from Taiwan and Singapore to 

 Queensland and Western Australia). 



Ptychobela cf. nodulosa (Gmelin, 1791) 



Fig. 84 



Murex nodulosus Gmelin, 1 79 1 , p. 3562. 

 Clavatula crenularis Lamarck, 1816, p. 9, pi. 440, figs 3a, b. 

 Ptychobela nodulosa (Gmelin) - Kilburn, 1989, p. 187-190, figs 

 1-2) & 3^1 (neotype). 



Type locality, unknown. 



Material, stn 188, 1 shell. 



The situation with this species is the same as in the preceding 

 case. The JME shell resembles rather closely the neotype of P. 

 nodulosa designated and illustrated by Kilburn ( 1 989) in the shell 

 outline and the character of sculpture. However, it lacks the 

 characteristic colour pattern of P. nodulosa being of uniform 

 light-brown colour (the shell was dead collected and probably 

 faded), and has a slightly higher spire (Hs/H = 0.49 vs. 0.41 in the 

 neotype of P. nodulosa) and more convex whorls. A 

 characteristic feature of the shell considered is that axial folds 

 extend from suture to suture on the uppermost whorls and only 

 on 8th teleoconch whorl the typical subsutural slope without 

 axial sculpture is developed. 



Subfamily TURRINAE H. & A.Adams, 1953 

 Genus GEMMULA Weinkauff, 1875 



Type species: Pleurotoma gemmata Reeve, 1843 (subsequent 

 designation Cossmann, 1896) (= Gemmula hindsiana Berry, 

 1958) 



Gemmula (Gemmula) vagata (E.A.Smith, 1895) 



Figs 63-65 



Pleurotoma vagata E.A.Smith, 1895, p. 3, pi. 1, fig. 3; 1904, p. 



456; Alcock etai, 1907, pi. 14, figs 3, 3a. 

 Gemmula vagata (E.A.Smith) - Powell, 1964, p. 258-259, pi. 196, 



fig. 10. 



Type locality. 'Investigator', stn 172, off Trincomalee, 

 Ceylon, 200-350 fms. 



Material, stn 176, 8 shells, stn 188, 3 shells. 



The largest shell is 49.8 mm in height (apex slightly broken). 

 Examination of a growth series showed that its characteristic 

 features (i.e. almost vertical sides of whorls, very strongly 

 excavated subsutural fold, and channelled sutures) are 

 developed only when the shell reaches a certain size 

 (approximately 35 mm in height and more than 10 teleoconch 

 whorls). Young shells can be determined only by comparison 

 with larger specimens. A peculiar and previously undescribed 

 feature of the species is the presence of spiral lirae inside the 

 aperture in large individuals. 



Distribution. Gulf of Aden to Andaman Islands, 338-1061 

 m. 



Gemmula (Gemmula) amabilis (Jickeli in Weinkauff, 



1875) 



Figs 66, 67 & 71 



Pleurotoma amabilis Jickeli in Weinkauff, 1875, p. 29, pi. 6, figs 



4,6. 

 Pleurotoma (Gemmula) amabilis Weinkauff- Sturany, 1903, pi. 



3, figs 3a-c. 

 Gemmula amabilis (Weinkauff) - Powell, 1964, p. 261-262, pi. 



200, fig. 1, pi. 201, figs 3-7. 

 IGemmula amabilis (Weinkauff) - Kosuge, 1990, p. 153-154, pi. 



55, fig. 13, text-fig. 6; Kosuge, 1992, p. 163, pi. 58, fig. 1, 



text-figs 7, 11,12-14. 



Type locality. Massawa (Ethiopia), Red Sea. 



Material, stn 34, 18 specimens and shells; stn 1 19, 1 shell; stn 

 145, 1 specimen and 2 shells; stn 176, 2 shells; stn 185, 1 shell; stn 

 188, 2 shells; stn 193, 3 specimens. 



The taxonomy of this species is rather confused. The name 

 amabilis had long been unused until Powell (1964) applied it to 

 shells from the JME material (the specimen from the JME stn 

 176 figured by him (Powell, 1964, p. 200, fig. 1) was not found). 

 However, Powell expressed some doubts on the identification of 

 JME specimens as G amabilis, having indicated certain 

 differences from the sketchy and rather inadequate original 

 figures. 



Kilburn (1983) reported that the types of Pleurotoma amabilis 

 were probably lost and therefore the name amabilis must remain 

 a nomen dubium. He also compared the specimen figured by 

 Powell with G pulchella Shuto, 1961 from the Pliocene of Japan. 

 The latter species is characterized by smaller and much more 

 numerous gemmules (29 on the body whorl of 10.2 mm holotype 

 and up to 34 at the shell height of 26.57 mm - Shuto, 1965). 



Later on, Kosuge (1990, 1992) used the name amabilis for 

 North-Western Australian shells and at the same time 

 mentioned that Powell's specimen differs from the original 

 drawings and, as far as it can be judged from the text (Kosuge, 

 1990, p. 154), may not be conspecific with amabilis. The shells 

 figured by Kosuge as G amabilis, actually resemble G 

 gemmulina (von Martens, 1902) sensu Powell, 1964 more in the 

 shell outlines and the character of spiral sculpture of alternating 

 primary cords and intermediate threads. The latter species is 

 distributed from Taiwan to Indonesia (Powell, 1964), which is 

 far closer to North-Western Australia than the Red Sea and the 

 Gulf of Aden. 



Despite the obviously ambiguos status of the name amabilis, 

 it seems reasonable to conserve its application to the Gulf of 

 Aden shells similar to those described by Powell, because no 

 other available name for them exists. Perhaps, the examination 

 of a large series of the Red Sea Gemmula, especially from the 

 type locality of amabilis, would clear up the question of proper 

 application of the name. The specimens of G amabilis are 

 characterized by a small slender shell (up to 25.9 mm, usually 

 22-25 mm) with more or less channelled sutures, a moderately 

 developed subsutural fold covered by 1-3 riblets, 2-3 prominent 

 and widely spaced cords on the upper shell base without 

 intermediate threads, few (usually two) thin threads on the 

 subsutural slope, and 16-24 peripheral gemmae on the body 

 whorl (usually 22, mean 20.7 at the shell height 18.2-25.9 mm; 

 the number of gemmae does not show a strict correlation with 

 the shell height). This deep-water species, due to its small size, 

 can be confused with young specimens of other species of 

 Gemmula. However, the presence of the 'tertiary' apertural 



