Diagnosis. Shell c. 1.72 mm in height, opaque, elongate-pupiform with an entire, elliptically shaped and thickened peristome, with a palatal callus, columellar-basal cal¬lus and a moderately sized, parietal denticle.
Description. Measurements are provided in Table 2. Shell minute, elongate-pupiform, opaque, very thin, with about 4.25 convex whorls and a deeply incised suture; with irregular striations or blunt growth lines on the body whorl. Protoconch bulbous. Teleoconch is smooth with glossy sheen. Peristome elliptical and thickly doubled by callus below the palatal bulge (not denticle), only slightly higher than wide, taking up more than one third of the shell height, moderately reflected and curved back at the base. Columellar margin has a parietal-columellar callus. Parietal denticle deeply set and moderately thick, slightly downward projecting and prominently visible from the umbilical perspective . Internally, C. zarzaae sp. n. has a very thin sinuous lamella starting at the upper third of the penultimate whorl and forming a moderate tongue-like configuration in the body whorl in dorsal perspective. Under the sinuous lamella, the elongated columellar spindle twists smoothly, forming the columellar basal callus at its proximal end. In dorsal and side-ventral perspectives, the columellar lamella forms an oblique, elongated S form with its thickest part forming the rim of the distal portion and projecting moderately from the columella.

Differs from C. hardiei by its very thin shell, rounder whorls and general reduction of marked striation on the teleoconch. In side view aperture-left profile, the body whorl of C. zarzaae projects c. 1/8 beyond the rim of the peristome. The shell of C. zarzaae is smaller and thinner than C. costaricanum and larger and thinner than C. mexicanum. The parietal denticle and the parieto-columellar callus on the peristome of C. zarzaae are not prominent as in C belizeense but larger than in C. hardiei and most similar to those in C. mexicanum (Puebla). The increasing sinuosity of the lamella as it continues into the body whorl in the uppermost part of the penultimate whorl (in the dorsal perspective) of C. zarzaae is similar to that of C. hardiei and not to C mexicanum nor to C. costaricanum . However, in C. zarzaae-, the thickness of the lamella and the degree of horizontal lamellar extension is reduced in comparison to this structure in C. hardiei (aperture right and left views; differs from C. mexicanum by the fatter shell and the reduced parieto-columellar callus seen in some shells from the Puebla C. mexicanum population, by the uneven thickness of callus on the peristome at the palatal mid-section and where it curves back at the basal palatal margin; from C. costaricanum by the greatly reduced robustness of the shell and the imbalanced distribution of callus on the peristome. The elongated S-shaped lamella in C. zarzaae is most similar to that in C. mexicanum. The shell of C zarzaae is homogeneously compact in contrast to the elegantly slender, tapered form of C. jardineanum, which also bears nearly six whorls compared to the 4.25 in Z. zarzaae.

Holotype: Panama. Chiriqui Province, Boquete, path near Boquete.