Gulella (Molarella) subhyalina (Smith, 1890)

Muratov, Igor V., 2010, Terrestrial molluscs of Cabo Delgado and adjacent inland areas of north-eastern Mozambique, African Invertebrates 51 (2), pp. 255-255 : 273

Gulella (Molarella) subhyalina (Smith, 1890)

Fig. 35

Ennea subhyalina: Smith 1890: 165 , pl. 6, fig. 13 (Mamboya, north-eastern Tanzania; 6.00× 2.25 mm).

A not very common eastern African species, with a general distribution from northern Tanzania to northern Mozambique. Found at one station inland. Differs from other Streptaxidae in the area by the smooth cylindrical shell with a single large parietal lamella, two upper palatal, one deeply positioned lower palatal, one basal lamella and two columellar lamellae.

The type of Ennea subhyalina does not have the lower palatal tooth. There are several other species and forms with a smooth cylindrical shell and similar dentition. Ennea ingens described by Sturany (1898: 23, pl. 1, fig. 9) from the coast of KwaZulu-Natal (Durban) is much larger (9.0× 3.2 mm) and also has only two palatal teeth. Ennea gwendolineae described by Preston (1910: 527, fig. 3) from Shimba Hills south-west of Mombasa in south-eastern Kenya, also has only two palatal teeth and is smaller (5.0× 1.5 mm) but otherwise very similar to subhyalina . Surprisingly, Preston did not mention subhyalina in the original description of gwendolineae , instead comparing his new species with the much more different E. subflavescens , which was described by Smith (1890: 165, pl. 6, fig. 14) on the same page with subhyalina and illustrated next to it. Connolly (1922 b: 501, pl. 14, fig. 27) described G. (M.) gwendolineae scissidens from Tanzania (Dar es Salaam) with an additional “more deep-set” lower palatal tooth. With the exception of its much smaller size (4.1× 1.6 mm), scissidens is otherwise almost identical in shell shape, dentition and lack of sculpture to subhyalina from north-eastern Mozambique. Considering the very close similarities between gwendolineae + scissidens, and subhyalina + shells with an additional lower palatal tooth from north-eastern Mozambique, it is quite possible that all of them may well be just variations of one species with a distribution from south-eastern Kenya to north-eastern Mozambique. Therefore, it seems unnecessary to give a separate name to the seventoothed variety from north-eastern Mozambique.

Figures

Figs 30–38.Streptaxidae:(30) Edentulina affinis,33.4×17.6 mm,stn 5; (31) Taylorialeroyi, 14.4×21.0 mm, stn 5; (32) Gonaxis cf. percivali, 9.4×6.9 mm, stn 1; (33) G. denticulatus, 7.0×4.6 mm, stn 11; (34) Gulella sexdentata var. liederi, 9.4×4.8 mm, stn 1; (35) G. subhyalina, 6.5×2.3 mm, stn 1; (36) G. perissodonta, 3.2×1.5 mm, stn 7; (37) Gulella delgada sp. n., 4.0×1.8 mm, 1st syntype, stn 7; (38) Streptostele herma, 3.8×1.2 mm, stn 7. Scale bar 10 mm in Figs 30–31; 3 mm in Figs 32–34; 1 mm in Figs 35–38.