Plekocheilus (Eurytus) paraguas, Borrero, Francisco J. & Breure, Abraham S. H., 2011

Borrero, Francisco J. & Breure, Abraham S. H., 2011, The Amphibulimidae (Mollusca: Gastropoda: Orthalicoidea) from Colombia and adjacent areas, Zootaxa 3054, pp. 1-59 : 40-42

Plekocheilus (Eurytus) paraguas spec. nov.

(Figs 12A, 17E–F)

Diagnosis. A medium-sized species of Plekocheilus (Eurytus) characterized by a dense, fine granulated sculpture throughout, overall yellow-brown coloration interrupted by obliquely arranged irregular bands of darker reddish brown and a weak columellar fold.

Description. Shell up to 48 mm (mean 42.7, n = 9), about 1.58 times longer than wide, imperforate, ovate, sides convex, relatively thick. Periostracum honey yellow to amber in color, with descending oblique bands of darker reddish-brown which radiate from the suture between the penultimate and the body whorls; the edges of the axial bands irregular, with a zigzag appearance stronger in the upper part of the body whorl. Upper whorls usually lacking the axial (oblique) banding, but exhibiting a spiral sub-sutural reddish-brown band which is interrupted with equally spaced blotches of yellow. Surface shining, upper whorls with growth striae as the dominant sculpture, also including fine granules. Body whorl with oblique growth striae, the dense, fine granulation as the dominant sculpture. Granules spherical in shape, more densely on (but not restricted to) the obliquely arranged axial growth lines. Protoconch eroded. Whorls 4.2, slightly convex; suture impressed, neither descending nor ascending in front. Aperture elongate-ovate, about 1.65 times as long as wide and about 0.7 times the total shell height; plane of aperture slightly oblique to axis of shell; color within a uniform cherry to purple. Columellar margin oblique to axis of shell, with a weak, but long fold midway. Peristome somewhat expanded, reflexed, white to slightly tinted with (very) light brown; dorsally, the expanded portion ranges from white to a salmon color. Parietal wall with a thin, white-edged callus, colored purple from about midway to the upper part of the aperture.

Dimensions in mm: H 37.2–48.0, D 23.0–30.0, HA 27.2–34.2, WA 17.1–21.0, LW 34.0–44.5, 4.2–4.6 whorls; holotype H 43.0, D 27.0, HA 27.9, WA 17.1, LW 39.5, 4.5 whorls.

Type locality. Colombia, Valle del Cauca, Serranía de Los Paraguas , Corregimiento El Boquerón, Vereda Las Amarillas, ca. 20 km NW Municipio El Cairo, near Cerro El Inglés, [04°46’N 076°17’W], ~ 2160 m.

Type material. Colombia, Valle del Cauca. Holotype: UVZ 97015 (L.A. Osorio leg., iii.1996). Paratypes: Serranía de Los Paraguas , Corregimiento El Boquerón, Vereda Las Amarillas, ca. 20 km NW Municipio El Cairo, Cerro El Inglés: UVZ 97012/7, UVZ 97013/11 (both 7400–8200 ft [2222–2460 m], M.S. Alberico et al. leg., ii.1987), UVZ 97014/2 (~ 2160 m, F. Castro leg., ii.1996, subadults), UVZ 97019/2 (2120–2160 m, W. Bolívar leg., ix.1996); Alto de Galápagos, road Ansermanuevo [Valle del Cauca]–San José del Palmar [Chocó], 2000 m, J.H. Restrepo leg., v.1985: UVZ 85024/1.

Additional material. Two additional, uncatalogued lots are available at Universidad del Valle, Cali, but no locality information is available for these lots. They are likely collected at or near the same localities as the type material: UVZ sn004/1, UVZ sn006/1 (subadult).

Altitudinal range. The localities range from 2000–2460 m.

Remarks. This new taxon resembles P. (P.) glandiformis in its overall shape and size, and some specimens exhibit similar coloration. It differs from P. glandiformis in that P. (E.) paraguas (1) is larger (mean 42.7 mm versus 38.2 [n = 25, range 32–43.2]), (2) has a granulated sculpture (rather than malleated with granules), and (3) while the color elements of both species are the same (yellow and brown), P. paraguas has zigzag bands of reddishbrown that radiate from the suture, whereas P. glandiformis has an irregular distribution of both colors, giving it a blotchy appearance.

Shell coloration is somewhat variable, but this may be an artifact of preservation; fresh specimens exhibit an overall yellow-brown color. Some specimens, preserved in alcohol for extended time (i.e., several years) exhibit an overall honey color, with little or no banding. The color within the aperture is uniform cherry to purple, but exterior bands and mottling shining through in immature specimens; in alcohol-bleached specimens the shells appear completely white. Field notes associated with UVZ 97019 state that in life the foot is a cream color, with no additional remarks.

Plekocheilus (E.) castaneus co-occurs at its type locality with P. paraguas ; the two species are quite different and are easily separated by size, shape, sculpture and coloration. The distribution of P. (P.) glandiformis includes the nearby higher elevation areas of Riofrio (Páramos del Duende), located SW of Serranía de Paraguas at a linear distance of approximately 50 km. Both P. castaneus and P. glandiformis have wider distributions in Colombia (see elsewhere in this paper).The region of the Serranía de Paraguas has not been extensively studied, but several species of plants and animals have been described recently from the same general area (Harvey 2008, Lynch 1992, Pedraza-Peñalosa 2008, Ramos-Tafur 2006). This novelty and several other species of terrestrial mollusks currently awaiting description (Breure & Borrero, in preparation) suggest that this region—nestled in the middle of the Biogeographic Chocó Region—may harbour an abundant novel biota. However, our opinion is that collecting efforts have not been sufficient to assess levels of endemism.

Ecology. All known material comes from cloud forests in the border area between Departments of Valle del Cauca and Chocó, from 2000 to 2460 meters elevation. Lots UVZ 85024, 97013–97014 were collected alive in “secondary forest.” Lot UVZ 97019 was collected alive in “primary forest from which the largest trees had been taken,” attached to vegetation; one specimen was found at about 1.5 m from the forest floor. The latter annotation suggests that the species may exhibit at least partly arboreal habits, which has been observed in other species of the subgenus Eurytus ( Breure 2009 for P. nebulosus ; Breure & Schlögl 2010 for P. breweri ; Borrero, unpublished observations, 2010 for P. coloratus ).

Etymology. Named after the Serranía de Los Paraguas , Valle del Cauca/Chocó, the general region from which all known material was collected. The specific epithet is used as a noun in apposition.