Zospeum intermedium Jochum & Ruthensteiner, 2024

Jochum, Adrienne, Michalik, Peter, Inäbnit, Thomas, Kneubühler, Jeannette, Slapnik, Rajko, Vrabec, Marko, Schilthuizen, Menno & Ruthensteiner, Bernhard, 2024, 3 D X-ray microscopy (Micro-CT) and SEM reveal Zospeum troglobalcanicum Absolon, 1916 and allied species from the Western Balkans (Ellobioidea: Carychiidae), European Journal of Taxonomy 926, pp. 1-62 : 28-30

Zospeum intermedium Jochum & Ruthensteiner sp. nov.

urn:lsid:zoobank.org:act:5F135CC4-5DCF-4CD0-9EDF-D694561E37D8

Fig. 6

Zospeum troglobalcanicum – Maier in Gittenberger 1975: 26: fig. 3.

Diagnosis

A tall shell ca 1.6 mm, conical or elongate-conical with ca 5½ regularly coiled, slightly shouldered whorls; columella bears a well-formed lamella forming a conspicuous and short parietalis visible in umbilical view ( Fig. 6H ); ventral side swollen with small umbilical depression.

Etymology

This species is named after its mixture of significant shell characteristics in four species of Zospeum from nearby caves described in this study, making for a composite, intermediary form of these species.

Type material

Holotype

MONTENEGRO • Cetinjska pećina [= Cetinska pećina] near Cetinje, Crna Gora [= Montenegro] behind monastery; 15 May 1974; E. Gittenberger leg.; RMNH.MOL.234132 .

Description

MEASUREMENTS. Holotype: sh: 1.57 mm; sw: 1.08 mm; ah: 0.58 mm; aw: 0.66; hlw: 0.95 mm; SA: 66.35 deg.

Shell conical or elongate conical, height ca 1.6 mm with 5½ whorls; transparent. Whorls convex, and slightly shouldered, spire regularly and tightly coiled; suture moderately deep; aperture reniform, almost elliptical ovate; aperture wider than high, columellar side slightly rounded; slight notch at upper parietal and palatal junction; parietal callus (shield) well defined, straight, long and angular; palatal rim thin; palatal-basal lip narrowly reflected; teleoconch smooth with irregular growth lines; weak radial banding on body whorl; course irregular growth lines present immediately behind palatal-basal lip; height of last whorl less than half of shell height; apertural rim thin and receding 1 / 5 width of penultimate whorl (in aperture facing left view), exposing deeply set parietalis ( Fig. 6G ); columella centrally aligned, moderately thick, not swollen at base; low lamella under penultimate whorl forming a conspicuous, short parietalis reaching up as high as the umbilical depression in umbilical view; umbilical depression small; umbilicus callused at junction of peristome and base of columella, columellar side of peristome positioned above and to the right of the umbilicus, base swollen with little puckering; upper palatal rim not reflected (as seen from umbilical view); alignment of last ¼ whorl compact with a slightly rightward tendency (seen in umbilical view).

Remarks

It is not known from which section of the cave this shell derived except that it was amidst a larger sample (RMNH.MOL.234134) comprising 64 shells from a part of the cave “with absolute darkness” ( Gittenberger 1975). The species represents an intermediary form between Z. troglobalcanicum , Z. tortuosum Jochum & Ruthensteiner sp. nov., Z. dubokidoense Jochum & Ruthensteiner sp. nov. and Z. simplex . It is significantly larger than these species in shell height, shell width, aperture height, aperture width, height of the last whorl and narrower in spire angle. The columella shows similarity with that of Z. dubokidoense in turning angle, its slightly off-centered alignment, and superficial irregularities. In dorsal and aperture facing left views, the columella is similar to that of Z. troglobalcanicum and Z. dubokidoense . However, Z. intermedium Jochum & Ruthensteiner sp. nov. differs from these species in that the umbilical depression grades from a pronounced umbilical depression in Z. troglobalcnicum and Z. simplex to that of a slight umbilical depression in Z. intermedium to that of no umbilical depression in Z. dubokidoense , which is largely covered by the columellar side of the peristome directly above it. Z. intermedium differs from the rest of the Southern Balkan species in this study in that it bears a pronounced lamella forming a deeply set, conspicuous parietalis. Only Z. dubokidoense shows a very slight but visible parietalis ( Fig. 8L ). Z. troglobalcanicum bears a threadlike partial lamella that does not form a visible parietalis.

Figures

Fig. 6. Zospeum intermedium Jochum & Ruthensteiner sp. nov. (RMNH.MOL.234132) from Gittenberger (1975). A. Light microscopic images of apertural and dorsal views. B. Sample labels. C–H. 3D visualizations of X-ray Micro-CT data. C. Aperture view. D. Aperture facing right view. E. Apical view. F. Dorsal view. G. Aperture facing right view. H. Umbilical view showing slight umbilical depression and lamella projecting from the columellar side.

Fig. 8. 3D visualizations of Micro-CT data of shells from the caves Lipska pećina and Duboki do (Montenegro). A–F. Zospeum troglobalcanicum Absolon, 1916 (MCSMNH-PMSL-Moll.-FVelkovrh 29603) (Fig. 7A). A. Aperture view. B. Aperture facing right view. C. Apical view. D. Dorsal view. E. Aperture facing left view. F. Ventral view showing reduced umbilical depression. G–L. Zospeum dubokidoense Jochum & Ruthensteiner sp. nov., holotype (MCSMNH-PMSL-Moll.-FVelkovrh 30360[spm1]). G. Aperture view. H. Aperture facing right view. I. Apical view. J. Dorsal view. K. Aperture facing left view. L. Ventral view showing no umbilical depression.