Tropidophora zanguebarica (Petit, 1850)

Rowson, B, Warren, B. H. & Ngereza, C. F., 2010, Terrestrial molluscs of Pemba Island, Zanzibar, Tanzania, and its status as an " oceanic " island, ZooKeys 70, pp. 1-39 : 11

5. Tropidophora zanguebarica (Petit, 1850) Fig. 3

Cyclostoma zanguebarica Petit de la Saussaye 1850: 53; pl. III, fig. 5

Notes.

This group needs revision. Pemba shells are almost identical to those from Jozani Forest, Unguja, including in microsculpture and the range of colour patterns, differing mainly in a smaller maximum size and (Unguja 14.0 × 12.5 mm; Pemba 12.0 × 11.5 mm). There is slight variation in the strength of the spiral raised ridges, though none of the shells are as smooth as zanguebarica Petit, 1850 or letourneuxi Bourguignat, 1889 in historical collections (e.g. NMW, MNHN). It is hard to know whether this is infraspecific variation or not. Voeltzkow (1923) recorded " Lygatella letourneuxi (Bgl.)" (sic) from Pemba; Haas (1929) recorded it from Chake Chake. As well as zanguebarica and letourneuxi, Verdcourt (2006) lists two unnamed “species” from “Zanzibar”. Either could correspond to the Pemba taxon; possibly one biological species encompasses all four. One is said to have an affinity to letourneuxi and to Tropidophora scabra (H. Adams, 1867), an extinct Mauritian species that varies in sculpture according to Griffiths and Florens (2006). Intriguingly, these authors describe (p.53) a population of a smooth species of Tropidophora being replaced by a rough one over recent decades. Note: Verdcourt treats all East African Tropidophora in subgenus Otopoma Gray, 1850, but the Asian type species of this belongs in Cyclophoridae not Pomatiidae (=Pomatiasidae) (see Neubert 2003).