28 



A.V. SYSOEV 



Material, stn 26, 2 specimens. 



Of the two specimens available (H = 9.9 and 6.3 mm, both 

 without protoconch), the smaller is comparable in size to those 

 illustrated by Schepman (8.5 mm, or 8.0 mm according to Shuto, 

 1971) and Thiele (6.25 mm) and quite similar to them. The larger 

 specimen (Fig. 115) differs in having a broader canal, less 

 excavated subsutural slope, and much weaker peripheral spiral 

 keel on the body whorl. The spiral sculpture of both specimens is 

 subobsolete on the body whorl periphery and upper part of the 

 shell base becoming stronger towards the canal. This is in 

 contrast to both Schepman's and Thiele's figures, but agrees well 

 with Shuto's (1971) illustration of the holotype. 



The same species was probably figured by Thiele (1925) as the 

 North- Atlantic Gymnobela extensa (Dall, 1881). Thiele's figure, 

 apparently based on a specimen from Sumatra, differs from his 

 illustration of M. extensaeformis in having obsolete spiral ribs 

 on the body whorl except for those on the lower shell base and 

 canal, but, as mentioned above, this is the feature characteristic 

 of M. extensaeformis. 



Recently this species was assigned by Shuto (1971) to 

 Magnella Dittmar, 1960. Later, Maxwell (1988) synonymized 

 the latter genus with the New Zealand genus Mioawateria Vella, 

 1954. This synonymization seems to be reasonable, though the 

 status of Mioawateria itself remains somewhat uncertain due to 

 great similarity to Gymnobela Verrill, 1884. The main difference 

 between two latter genera is the shape of anal sinus which is very 

 shallow in Mioawateria. At the same time, the shape of sinus in 

 Gymnobela is rather variable, and there are species, traditionally 

 included into Gymnobela, quite comparable to Mioawateria in 

 this character (e.g. G. blakeana (Dall, 1881)). Thus, after 

 comparative examination of broad range of Gymnobela species 

 in respect to the anal sinus shape, Mioawateria may be either a 

 large and very widely distributed genus or a synonym of 

 Gymnobela. 



Distribution. East Africa (Gulf of Aden to Kenya), Sumatra, 

 Banda Sea, 439-2312 m. The present record is the deepest one. 



Genus XANTHODAPHNE Powell, 1942 



Type species: Pleurotoma (Thesbia) membranacea Watson, 1886 

 (original designation) 



Xanthodaphne maldivica Sysoev, new species 



Figs 1 16 & 117 



Material, stn 143, 1 specimen (holotype No. 1993116). 



Description. The shell is narrowly fusiform, slender, thin but 

 solid, light-brown, with glossy surface, consists of the 

 protoconch and 9 teleoconch whorls. The protoconch is partly 

 broken off, but the remaining 1.5 whorls are covered with the 

 typical diagonally cancellated sculpture. The teleoconch whorls 

 are slightly concave in the upper part and weakly convex below. 

 Early teleoconch whorls are angled in the lower part just near the 

 suture, this angulation rapidly shifts upwards and becomes less 

 prominent and practically disappears on the 6th whorl. There is 

 a weak subsutural fold on initial teleoconch whorls. The sutures 

 are very shallow, distinct, and more or less straight. The growth 

 lines are clear, thin, numerous, and strongly curved. The 

 sculpture is represented only by low, wide ribs on the canal; these 

 rapidly become obsolete on the shell base. The shell base is 

 weakly convex and smoothly passes into the canal. The canal is 



straight, not differentiated from narrow aperture. The inner lip is 

 covered with a very weak callus which becomes thicker towards 

 the canal extremity. The anal sinus is wide and moderately deep, 

 subsutural, 'reversed L'-shaped, its deepest part is situated just 

 below the suture. The outer lip strongly projects forward below 

 the sinus. H = 29.0, Hb = 17. 1, Ha = 14.3, D = 9.0 mm. 



The new species differs from all known species of the genus in 

 its slender and narrow shell almost completely devoid of spiral 

 sculpture. 



Distribution. Maldive Islands, 797 m. 



Subfamily MANGELIINAE Fischer, 1883 

 Genus BENTHOMANGELIA Thiele, 1925 



Type species: Surcula trophonoidea Schepman, 1913 (original 

 designation) 



Benthomangelia brachytona (Watson, 1881) 



Figs 118-121 



Pleurotoma (Drillia) brachytona Watson, 1881, p. 415. 

 Pleurotoma (Spirotropis) brachytona Watson - Watson, li 

 324-325, pi. 18, fig. 3. 



\ p. 



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

 south-west of Papua, 800 fms. 



Material, stn 119, 1 shell. 



The specimen from the stn 1 19 (H = 17.1 mm) is quite similar to 

 Watson's illustration and to the photograph of one of two 

 syntypes (which should be designated as lectotype) (Figs 120 & 

 121, H = 15.3 mm according to Watson) (the second syntype is 

 represented by broken and heavily worn shell) stored in the 

 NHM. It differs from the lectotype only in more slender shell 

 (H/D = 2.20 vs. 2.03 (Watson's measurements) or 1 .96 (measured 

 by the photograph) in Watson's specimen) with fewer axial folds. 



Distribution. East Africa and Indonesia, 1463 and 

 1207-1463 m. 



Benthomangelia trophonoidea (Schepman, 1913) 



Fig. 122 



Surcula trophonoidea Schepman, 1913, p. 62(426)-63(427), pi. 



28, fig. 3. 

 Mangelia (Benthomangelia) trophonoidea (Schepman) - Thiele, 



1925, p. 190(224)-191(225), pi. 27(39), fig. 25, text-fig. 25. 

 Benthomangelia trophonoidea (Schepman) - Okutani, 1966. p. 



23, text-fig. 11. 

 ? Marshallena gracilispira Powell, 1969, p. 370-371, pi. 281, fig. 2. 



Type locality. 'Siboga', stn 45, Flores Sea, 794 m. 



Material, stn 185, 1 shell. 



The shell from the JME material is small (H = 10.0 mm, which is 

 smaller than all the previously recorded specimens, i.e. 16 mm 

 (Schepman), 1 5.9 mm (Thiele, measured by the figure), and 15.5 

 mm (Okutani, measured by the figure)) and apparently rather 

 young. It differs from the original description and figure in 

 having prominent tubercles on the subsutural fold of all the shell 

 whorls and in less curved and more developed axial ribs on the 

 subsutural slope. The presence of short plicae on early whorls, 



