Cueva de La Herrería. Main entrance (1), two views of the Zospeum biotope (2, 3) and cave plan (4) (red dots: Zospeum sites). Photos and plan: S. Quiñonero-Salgado / A. Alonso.

Zospeum percostulatum sp. n. Different views of the holotype (A–C) and a paratype 1.58 mm height (D–G). Note the inner whitish/yellowish mass in the holotype corresponds to their soft parts and the different orientation of the longer aperture axis between A and D.

Zospeum percostulatum sp. n. Frontal view of a paratype (A, 1.42 mm height) [MHNS] and some partial views (B–G): B protoconch C microsculpture of the protoconch D detail selected in C E suture and costulae of the last whorl F shape of costulae G microsculpture of the teleoconch.

Zospeum percostulatum sp. n. Frontal views of three paratype shells (A–C 1.41, 1.80, 1.58 mm) and a shell from Cueva Collubina (D 1.49 mm) [ZUPV]. Note the robust, smooth columella through the window opened in the body whorl (C) and closer, smaller riblets in D.

Tridimensional plot of main conchological parameters (SH, SW and BWH) of Zospeum vasconicum, Z. zaldivarae and Z. percostulatum sp. n. (data in Excel files of C. Prieto). Note the holotype (violet dot) and the smaller shells from Cueva Collubina (orange). Note also that a large shell of Z. zaldivarae (described in Prieto and Gómez 1985) and a slender, teratological shell of Z. vasconicum lie outside their circumscribing ellipses.

Map (above) and virtual aerial view (below, from the North) with mentioned caves for Asturian-Cantabrian Zospeum species: Z. percostulatum (♦); Z. schaufussi / suarezi (●). Map made with Dmap; aerial view of Digital Globe (screen shot of Google Earth).