Orcula Held 1837

Pall-Gergely, Barna, Deli, Tamas, Irikov, Atanas & Harl, Josef, 2013, Subgeneric division of the genus Orcula Held 1837 with remarks on Romanian orculid data (Gastropoda, Pulmonata, Orculidae), ZooKeys 301, pp. 25-49 : 27

Genus Orcula Held 1837

Orcula Held, Isis: 919. (1837)

Type species.

Pupa dolium Draparnaud 1801, by subsequent designation Gray: 1847: 176.

Diagnosis.

Shell yellowish–greenish to dark brown; cylindrical to conical and elongated; 8-10 weakly convex whorls; sculpture of first 0.5-1.0 protoconch whorl usually smooth, but may be of fine spiral lines, which may be extremely weak; teleoconch axial sculpture variable, ranging from irregular growth lines to equally spaced, conspicuous radial structure; apertural barriers: one parietal and 1-3 columellar lamellae; palatal side of the aperture smooth or with strong tooth or thickening parallel to the apertural lip; parietal callus weak, subangularis sometimes present; palatalis plicae missing.

Penis cylindrical, penial caecum of variable length and shape; penial appendix absent; interior of penis, epiphallus and caecum with longitudinal folds; retractor muscle attaches to the penis-epiphallus junction on the opposite side of the penial caecum; diverticulum absent; distal part of vas deferens sometimes slightly swollen, entering epiphallus terminally; bursa copulatrix long, club-like.

Habitat.

Orcula species occur in humid limestone areas, usually forests, or rocky boulder fields at high altitudes. Animals live under stones, leaf litter or decaying wood, or at the base of large rocks.

Remarks.

Detailed anatomical and conchological diagnoses were provided by Gittenberger (1978) and Schileyko (1998). According to Hausdorf (1996), the genera Orcula , Orculella Steenberg 1925 and Schileykula Gittenberger 1983 cannot be distinguished from each other based on conchological characters alone.

Some African genera, such as Fauxulus Schaufuss, Fauxulella Pilsbry and Anisoloma Ancey have very similar genital tracts but usually possess sinistral shells with several apertural lamellae and denticles (see Schileyko 1998, 2012).

In general, species of Schileykula and Orculella usually inhabit dry limestone areas in the Mediterranean. The only exceptions known are the closely related Orculella bulgarica (Hesse) and Orculella aragonica (Westerlund) which both prefer very humid, marshy stream banks ( Garrido et al. 2005, Arrébola et al. 2012).