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 simplex Inäbnit, Jochum & Neubert, 2021 Figs 18–19 Original diagnosis Shell usually ca 1.3 mm in height, transparent, conical, peristome thickened, roundish, with a differentiated parietal shield, lamellae not present. Type material Holotype BOSNIA AND HERZEGOVINA • municipality of Tomislavgrad , Gornji Brišnik , Jama Dobravljevac ; 43.6347° N , 17.2328° E ; 25 Aug. 2019 ; R. Slapnik and J. Valentinčič leg.; NMBE 568060 (ex RSC 3760). Other material examined (via Micro-CT and SEM) BOSNIA AND HERZEGOVINA • 2 specs ( Fig. 18 , MicroCT); same collection data as for holotype; NHMW-MO-113642 (ex RSC 3760) • 2 specs ( Fig. 19 , SEM); same collection data as for holotype; SMF 349425 (ex RSC 3760) . Emended diagnosis considering Micro-CT and SEM Data Shell ca 1.4 mm and 5½–6 whorls; conical with narrow spire; peristome bears slight indentation at upper junction of parietal and palatal sides; low, hump-like callus on the inner columellar side of peristome; teleoconch with dense rows of microscopic, radially aligned, elongated pits; medium-sized columella with either two weak, loosely coiled low incomplete lamellae or a single incomplete lamella. Fig. 18. 3D visualizations of Micro-CT data of Zospeum simplex Inäbnit, Jochum & Neubert, 2021 , (NMHW-MO-113642 ex RSC 3760) from Dobravljevac jama, Gornji Brišnik, Bosnia and Herzegovina. A–F . Specimen 1 (spm1). A . Aperture view. B . Aperture facing right view. C . Apical view. D . Dorsal view. E . Aperture facing left view. F . Ventral view. G–L . Specimen 2 (spm2). Same perspectives as Specimen 1. Enhanced description with Micro-CT and SEM Data MEASUREMENTS (N = 2). sh: 1.40–1.41 mm ; sw: 0.93–0.96 mm ; ah: 0.57 mm ; aw: 0.61–0.62 mm ; hlw: 0.83–0.84 mm ; SA: 56.46–59.45 deg., NHMW-MO-113642 (ex RSC 3760). Shell ca 1.4 mm , conical, with 5½–6 regularly coiled, convex whorls with height of last whorl slightly greater than half of shell height; spire angle narrow; protoconch bulbous with microstructure of dense pitting and some irregular raised bands extending to the suture; the second and third whorls bear rows of interrupted dashes of radial pitting; teleoconch sculpture includes blunt irregular growth lines and weak radial banding on all whorls; density of blunt striations varies, showing a tendency towards costateness at the suture zones; high magnification of shell surface (5 μm) shows tiny pinpoint perforations; aperture reniform, wider than high; peristome slightly oblique on columellar side with a low, hump-like thickening on the inner columellar side ( Fig. 18A ), palatal side narrowly reflected with low ribbing extending some distance beyond the lip; parietal shield well defined, long and angular, with a slight indentation at upper parietal and palatal junction; upper rim of peristome recedes ca 1 / 5 the width of the penultimate whorl (aperture facing left) ( Fig. 18E ); columella centrally aligned and slender; a low lamella is present under penultimate whorl (aperture facing right) ( Fig. 18B ) which then turns into either two incomplete loosely coiled low lamellae (dorsal view) ( Fig. 18D ) or constitutes one well pronounced one ( Fig. 18J ); ventral side with small, umbilical depression with no puckering; columellar side of peristome arches slightly over and oblique to umbilical depression, alignment of last 1/4 whorl somewhat compact ( Fig. 18F ). Remarks Differs from Z. troglobalcanicum in that it bears at least one additional or ½ whorl; the upper parietal and palatal junction has a slight indentation in contrast to a well-defined notch; protoconch is more bulbous and somewhat elevated; the shell spire angle is narrower than that of Z. troglobalcanicum but within the spectrum of the narrowest spire measurements of two shells of Z. constrictum Jochum & Ruthensteiner sp. nov. (57.5–59.2 deg.); width of the shell is narrower than that of Z. troglobalcanicum ; Fig. 19. Zospeum simplex Inäbnit, Jochum & Neubert, 2021 , (SMF 349425) Scanning Electron Microscopy images. A . Protoconch and upper teleoconch showing microstructure of superficial pitting. B . Close up view of pitting microstructure. C . Last whorl with axial ribbing extending beyond peristome lip. D . Close up view of second whorl showing rows of interrupted dashes of radial pitting. E . Growth lines and radial banding on teleoconch. F . Close up view of growth lines and shell microstructure. the low, hump-like thickening of callus (not a denticle) a short distance inside the columellar side of the peristome is so far distinctive for this species. When compared to its molecularly closest congener, Z. kolbae Jochum, Inäbnit, Kneubühler & Ruthensteiner sp. nov. , Z. simplex Inäbnit, Jochum & Neubert, 2021 shows a significantly lower apertural height of an almost equal width with that of Z. kolbae as well as a narrower spire angle than that of Z. kolbae . Shell height shows more range in Z. kolbae than in Z. simplex . Though Z. simplex Inäbnit, Jochum & Neubert, 2021 resembles Z . amplioscutum Jochum & Ruthensteiner sp. nov. , it differs by its reduced extension onto the body whorl and less heavily callused parietal shield. Z. simplex is larger, has a narrower spire angle and a markedly less textured teleoconch in comparison to that of Z. amplioscutum . Zospeum simplex does not have a second lamella on the columella (aperture facing right) ( Fig. 18B ) but rather, weak ripples of a potential double one ( Fig. 18D ) or a stronger, incomplete single one in dorsal view ( Fig. 18J ). The narrow columella ( Fig. 9C–D ) and the elongation of the last whorl further beyond the umbilical depression (ventral side) additionally differentiate Z. amplioscutum from Z. simplex . The incidence of the one solid lamella versus the two incomplete low lamellae occurred in one of the two shells scanned. In sync with Inäbnit et al . (2021) , the shell height:shell width ratio is the most effective way to differentiate Z. simplex Inäbnit, Jochum & Neubert, 2021 from morphs of Z. troglobalcanicum . The low, hump-like callus on the inner columellar side of the peristome is consistent in the three shells from the type locality.