Plekocheilus (Eurytus) gibber ( Oberwimmer, 1931 ) Oberwimmer, 1931

Breure, Abraham S. H., 2009, New Orthalicidae (Mollusca, Gastropoda) from Venezuelan Guayana: unravelling secrets from the Lost World, Zootaxa 2065, pp. 25-50 : 36

Plekocheilus (Eurytus) gibber ( Oberwimmer, 1931) comb.nov.

( Figs 4 M─ O, 9H)

Auris (Antitragus) gibber Oberwimmer, 1931: 192 , figs 2, 5. Type locality: Venezuela, Staat Orinocco, Sierra Maraguaca [= Cerro Marahuaka], 2170 m; holotype SMF 5143.

Material. Venezuela, Estado Amazonas, Cerro Marahuaka, 2170 m ( SMF 5143/ holotype).

Remarks. Only the type material is known, making it difficult to judge any intraspecific variation. The taxonomic placement of this species has thus been somewhat enigmatic, the shape of the aperture and the conspicuous but weak fold setting it apart from other members in the genus. Breure (1978) placed it in the subgenus Eudolichotis because of these characteristics. After restudying the holotype in the context of this revision, it is clear that the granulation on the last whorl is very similar to that of Plekocheilus (Eurytus) tatei . The material of P. (E.) mundiperditi contains a specimen with a similarly shaped aperture that is immature (FMNH 52440). The type of P. (E.) gibber , however, has an expanded lip and a convex fold in the columella, both characteristics of maturity. This species is here placed in the Plekocheilus (Eurytus) juliani -group, awaiting further anatomical or DNA studies; see also the discussion part below. Because of this new combination, Antitragus Oberwimmer, 1931 —which was erected solely for this species—should now be considered a junior subjective synonym of Eurytus Albers, 1860 .

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.