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 E2AD3AF2-ECC1-4DC3-BF5F-5C411AA946B3 Senckenberg Research Institute and Natural History Museum, Senckenberganlage 25, D- 60325 Frankfurt / M., Germany. nne.jochum@senckenberg.de Author Michalik, Peter FAEE4B6B-80F5-4452-9ED2-08CA38DFC1F9 Zoological Institute and Museum, University of Greifswald, Loitzer Strasse 26, D- 17489 Greifswald, Germany. michalik@uni-greifswald.de 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 4511b4bd-f026-49d3-9d4d-a39875e75cc5 2118-9773 10847806 A00D7669-2151-46AE-A066-9AF4D0F2BEEE 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). 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. 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.