3 D X-ray microscopy (Micro-CT) and SEM reveal Zospeum troglobalcanicum Absolon, 1916 and allied species from the Western Balkans (Ellobioidea: Carychiidae) Author Jochum, Adrienne nne.jochum@senckenberg.de Author Michalik, Peter Author Inäbnit, Thomas 95F0148B-E147-4EB9-903A-6EEA7F55EB47 Institute for Biochemistry & Biology, University of Potsdam, Karl-Liebknecht-Strasse 24 - 25, House 26, D- 14476 Potsdam, Germany. inaebnit.thomas@gmail.com Author Kneubühler, Jeannette A42A773F-9C7C-4681-B861-B354A330DC4F Naturhistorisches Museum Bern, Bernastrasse 15, CH- 3005 Bern, Switzerland. & Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, CH- 3012 Bern, Switzerland. jeannette.kneubuehler@nmbe.ch Author Slapnik, Rajko 09E86269-966B-49E6-AB92-31B66968DC0D ZOSPEUM, Molluscs, Cave & Karst Biological Consulting, Drnovškova pot 2, Mekinje, SI 1240 Kamnik, Slovenia. rajko.slapnik@gmail.com Author Vrabec, Marko 00C5A26B-6E4A-41D9-BC9B-F36A2799E1AF Department of Geology, Faculty of Natural Sciences and Engineering, Aškerčeva 12, University of Ljubljana, 1000 Ljubljana, Slovenia. marko.vrabec@geo.ntf.uni-lj.si Author Schilthuizen, Menno 683D0AB7-CDD8-4FAA-94B6-436F3BFB8873 Naturalis Biodiversity Center and Leiden University, Vondellaan 55, NL- 2332 AA Leiden, The Netherlands. menno.schilthuizen@naturalis.nl Author Ruthensteiner, Bernhard 9A8A56B0-19FA-42AB-A85E-4FCA98BF4A6F SNSB - Zoologische Staatssammlung München (ZSM), 81247 München, Germany. ruthensteiner@snsb.de text European Journal of Taxonomy 2024 2024-03-20 926 1 62 https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2469/10973 journal article 10.5852/ejt.2024.926.2469 2118-9773 10847806 A00D7669-2151-46AE-A066-9AF4D0F2BEEE Zospeum njunjicae Jochum, Schilthuizen & Ruthensteiner sp. nov. urn:lsid:zoobank.org:act: F762D981-D8FB-4EE7-BB0F-489E3D596A04 Fig. 11 , 22A–B Diagnosis The smallest species of southern Balkan Zospeum , ca 1.2 mm , conical with 5 regularly coiled irregularly formed whorls; protoconch askew; peristome heavily callused on basal columellar side with a low, blunt, more or less conspicuous denticle some distance inside; columella centrally aligned, moderately thick, swollen at base; low lamella; well-defined umbilical depression. Etymology This species is dedicated to the biospeleologist and collector, Iva Njunjić. Type material Holotype MONTENEGRO • ( Fig. 11C–I ); Virpazar , Gornja Seoca , Golubova pećina ; 42.2093° N , 19.1306° E ; 26 Jun. 2018 ; M. Schilthuizen and I. Njunjić leg.; in cave entrance; NMBE 572617 . Paratypes MONTENEGRO • 2 specs ; same collection data as for holotype; NMBE 572616 • 2 specs ; same collection data as for holotype; SMF 349426 • 2 specs ; same collection data as for holotype; NHMW- MO-113651 • 3 specs ; same collection data as for holotype; TxEx-DU0018 . Description MEASUREMENTS . Holotype : sh: 1.271 mm ; sw: 0.914 mm ; ah: 0.560 mm ; aw: 0.578 mm ; hlw: 0.811 mm ; SA: 69.69 deg. Paratypes (N = 2): sh: 1.214 –1.248 mm ; sw: 0.944 –0.947 mm ; ah: 0.578 –0.588 mm ; aw: 0.507 –0.524 mm ; hlw: 0.764 –0.790 mm ; SA: 71.38–71.83 deg.; NMBE 572616. Shell minute, ca 1.2 mm , conical, with 5 regularly coiled convex whorls; transparent when fresh, opaque when older; protoconch leans slightly left (frontal view); aperture reniform; teleoconch sculpture with few irregular and occasional course growth lines, last whorl weakly crossed by radial banding; some weak axial ribbing present immediately behind palatal lip; palatal rim narrowly reflected; peristome thickly callused, notch indentation at upper parietal and palatal junction pronounced, upper palatal side thin and expanded, columellar side oblique and angular with a low, blunt, more or less conspicuous denticle inside; parietal shield thickly callused, long and straight, extending beyond half of height of last whorl; last whorl height about half of shell height ( Fig. 11E ), last whorl tightly coiled and almost disappearing under spire at last ⅓ of coiling (apical view); upper rim of peristome recedes ca 1/6 the width of the penultimate whorl (aperture facing left); columella centrally aligned, moderately thick ( Fig. 11E ), lamella loosely coiled on columella under penultimate whorl; umbilical depression callused, puckered; columellar side of peristome arches high over with curvature of whorl on top of umbilical depression, alignment of last 1/4 whorl is not compact. Fig. 11. Zospeum njunjicae Jochum, Schilthuizen & Ruthensteiner sp. nov. A–B . Light microscopic images of paratypes (NMBE 572616) showing aperture and dorsal views. C . Light microscopic images of holotype (NMBE 572617) showing aperture and dorsal views. D–I . 3D visualizations of X-ray microCT data of holotype (NMBE 572617). D . Aperture view. E . Aperture facing right view showing well defined lamella. F . Apical view. G . Dorsal view. H . Aperture facing left view. I . Ventral view. Distribution This species is only known from its type locality cave, Golubova pećina in southwestern Montenegro . Remarks This species differs from all others in that it demonstrates the smallest shells of the Southern Balkan region so far. The columella is more robust than that of Z. troglobalcanicum and the lamella comprises a low bulge rather than an incomplete thread atop of the columella directly under the penultimate whorl as in Z. troglobalcanicum . The columella of this species is also unevenly contoured with a few low humps due to the tight twisting of the inner coiling.