Holotype. SPAIN Cueva del Puente de Inguanzo, Inguanzo, Concejo de Cabrales, Asturias, MGRS 30TUN4897097640; N43.315574, W4.860905; 230 m a.s.l.; 19 Feb 1979; G. Favre & R. Emery leg.; RMNH.MOL.55391 [55386]. Paratypes. SPAIN locus typicus: 2 shells; data as the holotype; RMNH.MOL.339954 [55386]. Other material.MHNG 96219/1 shell (now lost).

Shell ca. 1.1–1.2 mm, conical with a roundish and moderately thick peristome, lacking apparent apertural barriers but with a small distinct lamella (denticle) in the parietal-columellar corner; internally, columella robust with a central lamella, a low upper columellar bulge and a basal umbilical ridge.

Measurements of holotype and paratypes are presented in Table 1. Shell minute, fresh shells transparent, variable in shape (SH:SD ratio 1.41–1.57) with ca. 5 whorls, regularly coiled, suture deep, whorls convex, more or less strongly shouldered; teleoconch sculpture consists of occasional blunt growth lines; robust columella with an inclinate, central lamella (Fig. 11F); an upper lamellar bulge swells from the base of the inner penultimate whorl above the central lamella (Fig. 11G, I, K); a distinct, short, ridge projects from the base of the columella above the umbilical indentation (Fig. 11G, I, K); aperture more or less circular; peristome adhering to spire, reflected, moderately thickened, roundish; umbilicus closed; apertural barriers absent apart from the low lamella that appears externally as a small, but distinct denticle on the parietal-columellar corner visible in oblique apertural view (Figs 5M, 10D).

Differs from Z.schaufussi externally by its more conical shell with less tightly coiled whorls – adult shells having around 5 rather than 6 whorls of the same size – and a more pronounced lamella/denticle visible in the parietal-columellar corner in oblique view; internally by its robust columella and by its pronounced basal columellar ridge (above umbilical indentation). Zospeumpraetermissum is easily distinguished from Z.biscaiense and Z.zaldivarae in shell and peristome shape and apertural characters, whereas Z.percostulatum is distinctly ribbed. Zospeumgittenbergeri differs by its broad, angular peristome and barely developed lamella on the columella. Zospeumvasconicum has a more rounded aperture with an almost uniformly-thickened peristome. Z.bellesi has no apertural barriers nor a columellar lamella.

The name, praetermissum, refers to the situation that the holotype shell was originally not recognized as distinct from Z.suarezi.

Only known from the type locality.

According to the records of the speleologist Gérald Favre (pers. comm. 2017), the collection site was located ca. 200 m from the cave entrance (also noted on the data label NHMG-Moll 96219 (978.363)). His field notes document that the collection area consisted of sandy substrate, some chestnut fragments and that the humidity level was low. The total length of the cave is 1500 m.

The label to the shell material Gittenberger (1980) assigned as Z.suarezi paratypes (NHMG-Moll.96219/1 shell), bore Gittenberger’s apparent ambivalence “Zospeum schaufussi Frfld Gitt. det. 1979” (Fig. 5L). Although currently lost, this shell was most likely conspecific with Z.praetermissum. We consider the paratype Z.suarezi shell (NHMW-MO 75000-E-48815) from Cueva Hernialde, Guipuzcoa to be Z. cf.vasconicum (Fig. 6).