Plekocheilus (Eurytus) huberi, Breure, Abraham S. H., 2009

Breure, Abraham S. H., 2009, New Orthalicidae (Mollusca, Gastropoda) from Venezuelan Guayana: unravelling secrets from the Lost World, Zootaxa 2065, pp. 25-50 : 37

Plekocheilus (Eurytus) huberi spec.nov.

( Figs 2 B─D, 5J─M, 9G)

Diagnosis. Characterized by a slender, thin shell, light chestnut-brown with descending, narrow reddishbrown “lightning” stripes; an almost lustreless surface, very finely granulated on the last whorl.

Description. Shell up to 47.9 mm (further dimension given in Table 1 ), 2.0 times longer than wide, imperforate, slenderly ovate, sides hardly convex, (rather) thin. Colour yellowish- to light chestnut-brown, with descending oblique stripes of reddish-brown, on the penultimate whorl with a tendency to be continuous, on the last whorl waved, broken up into separate stripes or dissolved into an irregular pattern of reddish-brown spots and some lines; upper whorls lighter, whitish, eroded. Surface hardly shining, upper whorls with growth striae, on the penultimate and last whorl also with spiral series of finely incised lines of almost equal strength, its visibility depending on the angle of view. Protoconch smooth (eroded). Whorls 4.3, rather flat, the last whorl slightly swollen; suture impressed, somewhat descending in front. Aperture elongate-ovate, somewhat pointed above, the stripes or spots from the outside shining through, in some specimens whitish inside, 1.7 times longer than wide, 0.56 times the total length; peristome thin and hardly reflexed, whitish. Columellar margin slightly curved, with a very weak fold above, hardly and narrowly dilated above. Parietal wall with a thin, whitish callus.

Genitalia. Penis subcylindrical, distally with a somewhat swollen appendix, passing subdistally into the long epiphallus, which is partly contorted and tapering towards the transition to the flagellum. The flagellum is somewhat tapering, ca. 1/8 the total length of the penial complex. The vas deferens is free, shorter than the length of the penis and epiphallus. Vagina rather short; proximal part of spermathecal duct subcylindrical, its intermediate part widened before distally tapering towards the globose spermatheca. Spermoviduct very contorted; albumen gland moderately long.

Type material. Venezuela, Estado Amazonas, Cerro de la Neblina massif, ridge at Brazil-Venezuelan border divide [00° 53’ N 65° 56’ W], 2000 m, T. Plowman & W. Thomas leg., 16.iv.1984, on south slope in a cloud forest in terrestrial bromeliads. Holotype UF 284764, paratypes: Ibidem, 5.3 km NE Pico Phelps at the base of the escarpment 1 km NE Pico Maguire, Camp VII [00° 50’ 40” N 65° 58’ 10” W], ca. 1800 m, R.W. McDiarmid leg., 31.i ─ 10.ii.1985 ( RMNH 112027 /1, UF 284746/1 + 1 juv.).

Comparison with other taxa. This novelty seems closely related to Plekocheilus (Eurytus) juliani Haas, 1955 , but differs in (1) the weaker sculpture on the last whorl; (2) being somewhat smaller (47.9 vs. 54.2 mm); (3) the less shining surface. It may also be compared to P. (E.) tatei Haas, 1955 , from which it differs in (1) being more slender; (2) the less conspicuous sculpture on the last whorl; (3) the slightly less shining surface. Etymology. Named in honour of Otto Huber (Merano, Italy), who has devoted his career to augment our knowledge of the Guayana region and the conservation of its biodiversity.

Figures

FIGURE 2. Genitalia in Plekocheilus (Eurytus). A. P. (E.) t a te i Haas, 1955, FMNH 50346; B ─ D. P. (E.) huberi spec. nov., UF 284746; E ─ F. P. (E.) nebulosus spec. nov., UF 284723. Scale bar— 5 mm.