Zospeum schaufussi von Frauenfeld, 1862

Jochum, Adrienne, E. Prieto, Carlos, Kampschulte, Marian, Martels, Gunhild, Ruthensteiner, Bernhard, Vrabec, Marko, D. Doerge, Dorian & J. de Winter, Anton, 2019, Re-evaluation of Zospeumschaufussi von Frauenfeld, 1862 and Z. suarezi Gittenberger, 1980, including the description of two new Iberian species using Computer Tomography (CT) (Eupulmonata, Ellobioidea, Carychiidae), ZooKeys 835, pp. 65-86 : 65

Zospeum schaufussi von Frauenfeld, 1862 Figures 2, 3, 4, 7, 8, 9

Zospeum schaufussi von Frauenfeld, 1862.

Zospeum suarezi Gittenberger, 1980: 204. Syn. n.

Material.

Von Frauenfeld collection, a single undamaged syntype shell (NHMW 71837); 4 broken syntype shells (NHMW 71836). Terra typica: ".. einer neuen Art, welche ich von Hrn. Schaufuss in Dresden erhielt, die darum von Interesse ist, dass er sie in einer Höhle in Spanien auffand, daher die erste Art, welche das geographische Gebiet dieser Gattung mächtig erweitert." [.. a new species that I received from Mr. Schaufuss in Dresden, which is significant by the fact that he obtained it from a cave in Spain, ... which considerably expands the geographic range of this genus.]. Fischer (1887) narrowed the provenance of Z. schaufussi to the greater historical region of Asturias and Cantabria (i.e. Asturia de Oviedo and Asturia de Santillana), but this was apparently overlooked by later authors.

Lectotype designation and rationale.

Von Frauenfeld’s (1862) original description [Z. minutissima, vix umbilicata, conica, hyalina, nitida, laeve, anfractibus 5, convexis, apertura rotundata, edentata, peristomate continuo, reflexo] was not detailed enough to recognize the species and lacks an illustration, which in his day, was perhaps deemed unnecessary as no other Iberian congeneric species were known. In Vienna, one of us (AJ) could study five original syntype shells of Z. schaufussi (NHMW 71836 - 71837), as was previously done by Gittenberger (1980). The syntypes are firmly glued on two pieces of cardboard (Figs 2-3). Von Frauenfeld mentions that he viewed "some damaged specimens .., without the slightest hint of dentition, such that I cannot doubt the consistent lack of teeth in this species" [translated from German]. All surviving shells, except one (NHMW 71837), are seriously damaged. Gittenberger (1980) concluded that the four damaged syntype shells could not be Z. schaufussi because internal barriers are clearly discernible and that the syntypes of the true, edentate, Z. schaufussi were missing or lost. We can confirm Gittenberger’s observation of the damaged syntypes (see Fig. 3). Gittenberger (1980) attributed the single undamaged syntype shell to his new species, Z. suarezi (as a paratype), rather than to Z. schaufussi . We cannot concur with his view. Von Frauenfeld (1862) stressed the similarity with Z. amoenum von Frauenfeld, 1856, as the only other toothless Zospeum species; in fact, all other Zospeum species known by the end of the 19th Century have apertural teeth conspicuously present in frontal view, but the deeper, internal dentition, was often unknown or not specifically addressed in descriptions (see e.g. Kobelt 1899, pls 218-219). We therefore, assume that von Frauenfeld referred to the externally visible dentition in the “apertura”; “Mündung”. The apertural dentition in the intact syntype shell is not, or barely, visible externally (Fig. 2). We conclude that this shell, bearing the label notation "Orig [inal] Ex [emplar]!" (Fig. 2), is the only remaining undamaged syntype of Z. schaufussi and thus, designate it here as the lectotype. The purpose of this lectotype designation is the fixation of a taxon name to a specific morphology and to stabilize nomenclature rather than reconstructing the historical course of events.

Lectotype description.

Shell minute, ca. 1.3 mm, elongate-conical, with at least 5½ regularly coiled, convex whorls, suture deep; teleoconch smooth; aperture roundish-lunate; peristome thickened, elongate-roundish (not angular), closely adhering to spire; peristome height ca. 36% of shell height; umbilicus closed, umbilical depression deep, wrinkles behind apertural lip leading to umbilicus (seen in SEM-EDX Fig. 9B). Externally, no apertural dentition is visible apart from a rather low lamella (appearing as a barely visible denticle) in the parietal-columellar corner, discernible only in a rather oblique apertural view. Internally, the columella appears as a short, slightly twisted stem, compressed-dilated at its base (Fig. 7 C–F), circumscribed by a conspicuous, inclinate lamella that changes in extension along its course. In addition, there may be a hint of secondary lamellar growth at the base of the penultimate whorl (Fig. 7E).

Zospeum schaufussi is easily separable from Z. biscaiense and Z. zaldivarae in shell and peristome shape and apertural characters, whereas Z. percostulatum is distinctly ribbed. Zospeum vasconicum and Z. bellesi are more similar, but the latter has no apertural barriers or even a suggestion of any. The former has a much less prominent columellar lamella and is clearly less tightly coiled. The species described here as Z. gittenbergeri , differs by its angular rather than rounded peristome and slightly developed lamella on the columella.

Clearly, the lectotype of Z. schaufussi strongly resembles Gittenberger’s topotypic Z. suarezi , to the extent that Gittenberger (1980) considered the lectotype shell a paratype of his species. The shell described below as Z. praetermissum sp. n., is distinct in its less elongate shell with less tightly coiled whorls and the presence of a second lamella on the base of the columella (Fig. 11G, I, K). Shells of Z. suarezi from the type cave agree with the Z. schaufussi lectotype in their elongate-conical shell and coiling tightness (see Table 1), rounded peristome, and barely visible dentition in the aperture. Internally, they have a similar columellar lamella configuration.

Remarks.

Although our SEM-EDX analyses revealed no significant evidence linking the lectotype to a specific cave or potential cave region, this method, however, revealed some ecological information derivable from the sediment encrusting the shell. The sediment reflects a granitic context and minerogenetic processes ( Onac and Forti 2011) acting in the cave environment. Detectable, are different concentrations of calcium (Ca), aluminum (Al), silicon (Si), magnesium (Mg), oxygen (O), carbon (C), iron (Fe), potassium (K), phosphor (P) and lead (Pb).