Plekocheilus (Plekocheilus) Guilding, 1828

Breure, Abraham S. H., 2009, New Orthalicidae (Mollusca, Gastropoda) from Venezuelan Guayana: unravelling secrets from the Lost World, Zootaxa 2065, pp. 25-50 : 27-29

Subgenus Plekocheilus (Plekocheilus) Guilding, 1828

Plekocheilus (Plekocheilus) fulminans linterae ( Sowerby, 1890) ( Figs 4 A─D, 9A)

Bulimus fulminans linterae Sowerby, 1890: 582 , pl. 56 fig. 12. Type locality: British Guiana, Mount Roraima; lectotype BMNH 1889.4.25.1 ( Breure 1978).

Material. Guyana, Mount Roraima ( BMNH 1889.4.25.1/ lectotype, 1889.4.25.2/1 paralectotype, SMF 90007/ 1 paralectotype); Ibidem, T. Pain leg., 1938 ( NMW.Z 1981.118.00303/3); Ibidem, 8000 ft [2438 m], T. Pain leg., 1938 ( NMW.Z 1981.118.0 4142/1). British Guiana [= Guyana] (ex Melvill Tomlin, NMW 1955.158.16700/1; ex Preston, RMNH /1).

Remarks. The lectotype and paralectotype from the BMNH collection are figured here for the first time ( Figs 4 A─D). Although we do not precisely know where the type specimens were collected, we may infer from the locality given by Sowerby that it was on the slopes or base at the northeastern side of Roraima-tepui (R.W. McDiarmid, personal communication). Nonetheless, the material collected by T. Pain reveals that this is a highland species. The material also shows that there is some variation in expression of the columellar fold (in two specimens it is hardly noticeable) and in the colour of the lip (in three specimens dark liver coloured, in two other specimens whitish like in the type material).

Plekocheilus (Plekocheilus) fulminans alticola Haas, 1955 ( Figs 4 E─G, 9 B)

Plecocheilus (Plecocheilus) fulminans alticola Haas 1955: 381 , fig. 81. Type locality: Venezuela, State of Bolívar, Chimantá massif, Torono tepui, on slopes bordering Caño Mojado, 2250 m; holotype FMNH 52442.

Material. Venezuela, Estado Bolívar, Chimantá massif, Toronó-tepui, slope bordering Caño Mojado, 2250 m, J.A. Steyermark leg., 21.ii.1955 ( FMNH 52442/ holotype, 52443/1 paratype).

Remarks. The oblique streaks on the ventral side of the last whorl make this form resemble Plekocheilus (Eurytus) juliani Haas, 1955 , but the different sculpture (malleation, Fig. 24B) and the darker colour of the peristome characterize this species. The colour pattern and the darker lip also distinguish this taxon from P. (E.) fulminans linterae .

Figures

FIGURE 4. Shells in Plekocheilus. A ─ D. P. (P.) fulminans linterae (Sowerby, 1890). A ─ C. Lectotype, BMNH 1889.4.25.1; D. Paralectotype BMNH 1889.4. 25.2. Photos P. Crabb. E ─ G. P. (P.) fulminans alticola Haas, 1955, holotype FMNH 52442. H ─ L. P. (Eurytus) fusitorsus (Oberwimmer, 1931). H ─ J. Holotype SMF 5142; K ─ L. FMNH 198500. M ─ O. P. (E.) gibber (Oberwimmer, 1931), holotype SMF 5143. Scale bar— 1 cm.