A.V. SYSOEV 



Powell (1969, p. 285) mentioned 'a related new species from 

 the Gulf of Aden in 1270 metres', i.e. from stn 184, but did not 

 give a formal description nor reasons for this. However, extreme 

 variants of C. subsuturalis from stn 184 are connected by 

 intermediate forms and can be therefore identified as that 

 species. 



Specimens from two stations off Maldive Islands comprise a 

 distinct group differing from East African shells in smaller size 

 (15.5-21.0 mm at 6-7 teleoconch whorls vs. 21.8-28.7 in typical 

 C. subsuturalis) and more slender shell proportions (H/D ratio is 

 2.82-3.12, mean 2.95 (n = 1 1) vs. 2.10-2.94 (2.10-2.70 in 19 out 

 of 20 shells measured), mean 2.34). These differences are 

 probably connected with geographical isolation of the Maldive 

 Islands resulting in formation of morphologically isolated 

 population of the species. If the above-mentioned metric 

 differences will be confirmed in additional samples, the 

 population of C. subsuturalis from Maldive Islands should be 

 considered as a distinct subspecies. This population represents a 

 transition (both geographical and conchological) to C. exstructa 

 von Martens, 1903, described from Nicobar Islands. The latter 

 species is distinguished only by an even narrower shell (H/D 

 ratio is 3.43 in the holotype) with longer axial folds (as far as it 

 can be judged from von Martens' figure). Examination of type 

 material may however reveal that C. exstructa is a synonym of C. 

 subsuturalis. A similar statement is probably true for C. 

 obtusigemmata Schepman, 1913, which does not differ from C. 

 subsuturalis in essential conchological characters. 



Distribution. East Africa from the Gulf of Aden to Zanzibar, 

 and Maldive Islands, 494-1789 m. 



Comitas erica (Thiele, 1925) 



Fig. 41 



Leucosyrinx erica Thiele, 1925, p. 236, pi. 36(24), fig. 25. 

 Comitas erica (Thiele) — Powell, 1969, p. 284, p. 226, fig. 2. 



Type locality. 'Valdivia', stn 191, off Siberut Id. (Sumatra), 

 750 m. 



Material, stn 143, 2 specimens. Also mentioned by Powell 

 (1969) from stn 1 08 (Zanzibar area, SE of Pemba Island, 786 m). 



Both specimens are very similar to the original figure and the 

 species variability thus seems to be rather low. One of JME 

 specimens is larger than Thiele's holotype (20.9 vs. 1 6.5 mm), but 

 has the appearance of an immature shell. The species was found 

 in the sample also containing C. subsuturalis, but it can be easily 

 distinguished from the latter, by the grayish-white shell with 

 weaker subsutural tubercles, closer-spaced spiral ribs, two of 

 which on the upper shell base are more prominent, and larger 

 protoconch (0.95 mm in diameter vs. 0.7-0.8 mm in C. 

 subsuturalis from the same sample). 



Distribution. Sumatra, Zanzibar and Maldive Islands, 

 750-797 m. 



Comitas pauper a (Watson, 1881) 



Figs 42^48 



Pleurotoma (Drillia) paupera Watson, 1881, p. 41 1. 

 Pleurotoma (Typhlomangelia) paupera Watson - Watson, 1886, 



p. 317-319, pi. 25, fig. 3. 

 Turricula paupera Watson - Powell, 1969, p. 244, pi. 202. 



Type locality. 'Challenger', stn 191, off the Arrou Islands 

 (Arafura Sea, Indonesia), 800 fms. 



Material, stn 62, 2 specimens; stn 185, 3 specimens and 4 

 shells. 



Proper determination of this species is rather intricate due to the 

 very heterogeneous type material. Powell (1969) erroneously 

 described Watson's syntypes as consisting of two shells with 

 rounded lower whorls and obsolescent sculpture and one shell 

 angulate with strong axially costae. He illustrated the latter 

 specimen and designated it as the holotype (correctly named 

 lectotype in the 'Measurement' and 'Types' paragraphs). 

 Actually, one of the two paralectotypes (H = 33.3 mm) has a 

 rounded body whorl with obsolete axials while the axial 

 sculpture on spire whorls is almost the same as in the lectotype 

 (Figs 42 & 43). The second paralectotype (Fig. 44) is represented 

 by a small (H = 18.5 mm) and quite dissimilar shell, 

 characterized by strongly angled whorls with axial sculpture 

 consisting of strong and rounded tubercles at the place of whorl 

 angulation. This specimen is so distinct that one could easily 

 assign it to a separate species if it was not found in the same 

 sample. 



Two at first glance rather different shells from the JME stn 62 

 fit however in the range of variability described above. The larger 

 shell (H = 23.4 mm, Fig. 45) is comparable to the lectotype, but 

 has less convex whorls with a less pronounced subsutural slope. 

 The smaller shell (H = 17.5 mm, Fig. 46) is very similar to the 

 smaller paralectotype, but has even stronger peripheral nodules. 

 Small specimens (14-15 mm in height) from stn 185 (Figs 47 & 

 48) have shells and sculpture intermediate between the extreme 

 variants. In some of the latter specimens, the spiral ribs are more 

 widely spaced on the shell base and reduced in number on the 

 subsutural slope. 



Thus, C. paupera appears to be very variable species with 

 extreme variants being quite dissimilar to each other but 

 connected by intermediate forms. 



The species was included by Powell (1969) into the genus 

 Turricula Schumacher, 1817. However its operculum has a 

 terminal nucleus characteristic of the genus Comitas. 



Surcula suratensis Thiele, 1925 (= Surcula coreanica of von 

 Martens, 1903, not of Adams & Reeve, 1850) is similar to some 

 forms of C paupera and after examination of type material it 

 may appear to be a synonym of the latter. 



Distribution. Indonesia, Gulf of Aden, and Gulf of Oman, 

 1463-2000 m. 



Figs 31^41 Comitas subsuturalis (von Martens, 1902) (31-40) and C. erica (Thiele, 1925) (41). 31, 32 -stn 184, H = 37.3 mm; 33 -stn 184, H = 25.5 

 mm; 34 - stn 1 84, H = 24.0 mm; 35 - stn 33, H = 21. mm; 36 - stn 1 84, H = 28.6 mm; 37 -stn 34, H = 27.0 mm; 38 -stn 184, H = 21. 7 mm; 39 -stn 

 143, H = 21 .0 mm; 40- stn 145, H = 26.2 mm; 41 - stn 143, H = 20.9 mm. 



