Plekocheilus (Eurytus) Albers, 1850

Breure, Abraham S. H., 2009, New Orthalicidae (Mollusca, Gastropoda) from Venezuelan Guayana: unravelling secrets from the Lost World, Zootaxa 2065, pp. 25-50 : 29-32

Subgenus Plekocheilus (Eurytus) Albers, 1850

Type species: Helix pentadina Orbigny, 1835

Plekocheilus (Eurytus) sophiae spec.nov. ( Figs 5 A─C, 9C)

Plekocheilus (Plekocheilus) blainvilleanus linterae, Breure 1978 : fig. 2. Genitalia.

Diagnosis. Shell sculptured on the last whorl with horizontal threads of various length, often anastomosing; colour uniform reddish-brown; aperture ovate, slightly descending in front, peristome somewhat thickened and reflexed.

Description. Shell 44 mm (further dimension given in Table 1 ), 1.9 times longer than wide, imperforate, sides slightly convex, thin. Colour reddish-brown, with indistinct spots and tent shaped markings of darker brown; a golden hue on the ventral side of the last whorl and a line of the same colour behind the reflexed lip; upper whorls lighter, purplish, eroded. Surface shining, upper whorls with spirally incised lines, faintly crossed by vertical incisions; on the last whorl this sculpture is more conspicuous, resulting in horizontal threads of various length, often anastomosing; axial growth wrinkles at irregular spaces. Protoconch smooth (eroded). Whorls 4.8, the upper whorls hardly convex, the last whorl much more convex; suture well impressed, somewhat crenulated, slightly descending in front. Aperture elongate-ovate, hardly pointed above, 1.8 times longer than wide, 0.53 times the total length; peristome somewhat thickened and reflexed, whitish. Columellar margin straight, entering the aperture with a hardly noticeable fold. Parietal wall with a thin, translucent callus.

Type material. Venezuela, Estado Bolívar, Yuruaní-tepui, 2300 m, R.W. McDiarmid leg., 11.i.1977, amoungst the leaves of a Heliamphora species. Holotype UF 24413.

Comparison with other taxa. This species may be compared to Plekocheilus (Eurytus) mundiperditi Haas, 1955 , from which it differs in (1) being stouter; (2) the different sculpture on the last whorl; (3) having the aperture more ovate, less pointed above. It also resembles closely P. (E.) nebulosus spec. nov., from which it differs in (1) having the last whorl more inflated; (2) the aperture more ovate; (3) the less descending last whorl.

Remarks. This specimen appeared to be misidentified in the UF-collection as Plekocheilus (P.) blainvilleanus linterae . When Breure (1978) dissected the animal he had not received the shell and the misidentification remained unnoticed. Only the penial complex could be studied and shows the same characteristics as other P. ( Eurytus ) species from this area, viz. contortions and a vas deferens shorter than the length of penis and epiphallus. The sculpture of the last whorl (Fig. 9C) is the same as in P. (E.) nebulosus spec.nov.

Ethymology. This attractive species is named after my wife Sophie, as a token of my gratitude for her continued support of my research.

Figures

FIGURE 5. Shells in Plekocheilus (Eurytus). A ─ C. P. (E.) s o p h i a e spec. nov., holotype UF 24413. Photos R. Lasley. D ─ F. P. (E.) juliani Haas, 1955, holotype FMNH 49737. G ─ I. P. (E.) nebulosus spec. nov., holotype UF 284723. J ─ M. P. (E.) huberi spec. nov. J ─ L. Holotype UF 284764; M. Paratype RMNH 112027. Scale bar— 1 cm.