Cimaria vargasi, Høisaeter, Tore, 2012

Høisaeter, Tore, 2012, Cimaria vargasi n. gen, n. sp. (Gastropoda: Pyramidellidae: Odostomiinae) from the Pacific Coast of Costa Rica, Central America, Zootaxa 3178, pp. 63-67 : 65-66

Cimaria vargasi sp. nov.

Figs 2 and 3 A, B.

Type material: Holotype (adult, empty shell) MZUCR 8955 and one paratype (living juvenile) MZUCR 8956 (both on same SEM-stub), and 32 paratypes, ZMBN 87909, 87912–87916.

Type locality: Punta Morales, 10°04'N, 84°58'W, Golfo de Nicoya, Pacific coast of Costa Rica.

Material examined ( Table 1 ): The holotype and 33 paratypes from Punta Morales; two worn shells from the Estero Cocorocas, about 500 m east of Punta Morales ( ZMBN 87917), and two juveniles found alive at Puerto Jiménez in Golfo Dulce, 8°32'N, 83°18'W ( ZMBN 87910).

Etymology: The species is named for José Antonio Vargas, former director of CIMAR, and dedicated marine biologist, who has studied the fauna of the mud flats at Punta Morales for more than a decade.

Description: Shell ( Fig. 2 ) is globose-conical, with inflated body whorl. Whorls slightly shouldered, with marked and deep suture. Just below the suture a distinct constriction. Whorls regular and round in young specimens, but tends to get slightly irregular in fully grown shells. Sculpture of teleoconch whorls characteristic, consisting of opisthocline, slightly irregular rows of circular, close-set pits, covering entire surface of the teleoconch except for the subsutural ridge ( Fig. 2 D). Pits increase in diameter with growth of shell, to approximately 40 µm in fully grown specimens. Except for occasional growth lines at about 30° angle to rows of pits, no other sculpture visible. Shell unusually thick, when alive translucent bluish white. Empty, worn shells white and opaque. Protoconch ( Fig. 2 C) small, smooth and glossy, with a distinct demarcation line to first postnuclear whorl. Obliquely immersed (almost 180°) in the following whorl, with only its base visible. Protoconch probably of less than one full whorl, and measures roughly 300 µm across. Aperture broadly ovate, rather spatulate in young specimens. Inner lip fairly straight, with a distinct columellar fold near upper edge, sometimes somewhat retracted into the mouth. No real umbilicus, but a distinct chink where inner lip meets the shell. In fully grown shells, outer lip thickened and varix-like ( Fig. 3 A,B).

Dimensions: Of 40 shells found, the largest was c. 2.7 × 1.5 mm, with a little more than four teleoconch whorls. Body whorl very large, 1.95 mm long, aperture 1.3 mm. Holotype 2.2 × 1.25 mm, body whorl 1.75 mm, aperture almost 1.2 mm long.

Soft parts: The snails were not observed alive, but through the partly transparent shell in alcohol preserved specimens the eyes were seen to be very close together. Distance between the small eyes less than their diameter. Digestive gland tends to be dark brown, filling almost 1 ½ teleoconch whorls. Rest of body dirty yellowish white after preservation. A fuzzy darkish spot on the base, somewhat to the left (in ventral view) of the columella, could be interpreted as the remnants of the pigmented mantle organ (which usually fades quickly in alcohol). Operculum thin and shiny, with no visible apophysis.

Figures

FIGURE 2. Cimaria vargasi, scanning electron microscopy. A, D - Holotype (MZUCR 8955); 2.2 × 1.3 mm. A. Whole shell in apertural view. D. Detail of sculpture. B, C - Paratype, juvenile (MZUCR 8956); 0.8 × 0.6 mm. B. Semiapertural view, showing shell scar. C. Apical view. Scale bars = 100 µm.

FIGURE 3. Light microscopy. A & B - Cimaria vargasi. Two views of largest shell found (ZMBN 87909); 2.7 mm long. Showing the thickened outer lip in fully grown shells. C - Cimaria sp. Shell from Macau, Brazil (ZMBN 87911); 1.4 mm long.