Zospeum biokovoense 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 : 42-44

Zospeum biokovoense Jochum & Ruthensteiner sp. nov.

urn:lsid:zoobank.org:act:A976D460-68C4-460E-9023-E32539BE2C5B

Fig. 15

Diagnosis

Shell ca 1.4 mm, conical with 5¼ whorls; suture zone of penultimate and final whorl with irregular indentations succeeding into course growth lines with some crossing over parietal shield into the aperture; columella fat and short, almost 1/3 width of final whorl with lamellar bulge and an incomplete lamella; umbilical depression deep, callused with much puckering.

Etymology

This species is named after the Biokovo mountain range where it was found.

Type material

Holotype

CROATIA • ( Fig. 15B–H ); “Dalmatien, kl. Grotte beim Alpenvereinshaus, Biokovogebirge, kleine Grotte am Weg vom Alpenvereins zum Hegerhaus“ [Dalmatia, small cave by Alpine Club house, (today probably Biokovo Alpine Club Vosac ), Biokovo Mountains , small cave on the way from the Alpine Club house to Heger house]; [43.3091° N, 17.0473° E]; NHMW Mol.Coll. Edlauer 16.390.

Other material examined

CROATIA • 1 spec.; juvenile with damaged shell ( Fig. 15A ); same collection data as for holotype; NHMW Mol.Coll. Edlauer 16.390 .

Description

MEASUREMENTS. Holotype: sh: 1.37 mm; sw: 0.966 mm; ah: 0.680 mm; aw: 0.596 mm; hlw: 0.769 mm; SA: 66.39 deg. Other material: (N = 1): juvenile with damaged shell, not Micro-CT scanned or measured.

Shell ca 1.4 mm, conical, with 5¼ regularly coiled, convex whorls with penultimate and last whorl being irregularly formed and somewhat lopsided; height of last whorl greater than half of shell height; opaque; aperture reniform, slightly higher than wide; teleoconch sculpture with some irregular blunt growth lines and weak radial banding; suture zone of penultimate and final whorl with dense, deep indentations of course growth lines extending at irregular intervals showing tendency towards costateness; peristome thin at upper palatal side, columellar side thickly callused roundish in form and slightly expanded, callosity extends beyond plane of shell (aperture facing left), basal palatal side narrowly reflected with some low ribbing behind palatal side; parietal shield thins at mid-section with some irregular growth lines bisecting it and entering into the aperture on the columellar side; notch at upper parietal and palatal junction; upper rim of peristome recedes ca 1 / 7 the width of the penultimate whorl (aperture facing left); columella fat and short, almost ⅓ width of final whorl, centrally aligned and bulging at top with a thin, incomplete lamella; ventral side with deep, callused umbilical depression with much puckering and wrinkles; columellar side of peristome positioned directly above umbilical depression; alignment of last 1 / 5 whorl is not compact.

Distribution

This species is only known from its type locality cave located in the Biokovo region of the central Dinarides between the Cetina and the Neretva Rivers of Croatia.

Remarks

Absolon (1916a) noted that the Neretva River was a distinctive geographical barrier reflected in different morphological features in species of subterranean fauna between the central Dinarides and the southern Balkans. The species Z. biokovoense Jochum & Ruthensteiner sp. nov. differs from all other so far internally viewed (via Micro-CT) species by its remarkably fat columella. Though the lower side of the penultimate whorl shows some shell deformation directly above the columella, the columella itself bulges and demonstrates a threadlike lamella like that of Z. troglobalcanicum . The teleoconch however, differs in the lopsided formation of the penultimate whorl, the radial banding on the body whorl and the more numerous irregular growth lines extending in part across the parietal shield into the aperture of the species. The shell diameter is narrower, the aperture is taller and narrower, the height of the last whorl is shorter, and the spire is narrower in Z. biokovoense than in Z. troglobalcanicum . Ventrally, the last whorl is less swollen and the final coiling towards the aperture extends high above the umbilical depression such that is not compact versus that in Z. troglobalcanicum , which does not extend as far beyond the depression and is compact in relation to it. The umbilical depression is callused, puckered, and wrinkled in Z. biokovoense and differs significantly from the smooth and relatively uniform umbilical formation in Z. troglobalcanicum . Coiling of the final whorl (ventral side) is similar to that of Z. amplioscutum Jochum & Ruthensteiner sp. nov. but it does not extend as far up the shell as in that species. Though growth lines extend into the parietal shield and into the aperture also in Z. tumidum Jochum, Schilthuizen & Ruthensteiner sp. nov., the two species differ in aperture shape, whorl alignment, teleoconch structure, columellar configuration and size dimensions.

Figures

Fig. 15. Zospeum biokovoense Jochum & Ruthensteiner sp. nov. (NHMW Mol.Coll.Edlauer 16.390). A–B. Light microscopic images showing aperture and dorsal views and collection labels. A. Juvenile shell. B. Holotype. C–H. 3D visualizations of Micro-CT data of holotype. C. Aperture view showing gnarled deformation of the columella. D. Aperture facing right view showing fat columella and lamella. E. Apical view. F. Dorsal view showing lopsided spire and incomplete lamella on top of fat columella. G. Aperture facing left view. H. Ventral view showing puckered umbilical depression.