Plagigeyeria pseudocostellina Grego 2020, sp. nov.
Creators: name: Grego, Jozef
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Littorinimorpha
Hydrobiidae
Plagigeyeria
Plagigeyeria pseudocostellina

description: Plagigeyeria pseudocostellina sp. nov.
urn:lsid:zoobank.org:act: 09A7B3DE-5B03-46E1-A0F9-A07BFEDBCA4B
Figs 7 G–H, 8 B
Type material
Holotype
BOSNIA AND HERCEGOVINA • 1 shell; Bosnian Federation, Mostar Municipality, Blagaj, left bank springs of Buna River 400 m from main Buna River Spring, Vrelo “Buna”; 43.256090° N, 17.900073° E; 36 m a.s.l.; 30 Mar. 2018; J. Grego, D. Angyal, G. Jakab and M. Olšavský leg.; HNHM-MOLL-104164.
Paratypes
BOSNIA AND HERCEGOVINA • 15 shells; same data as for holotype; SBMNH 626414 /10, coll. Grego /9 • 26 shells; Bosnian Federation, Mostar Municipality, Blagaj, spring at left bank of Buna River, under road, 500 m from main Buna River Spring; 43.256090° N, 17.900073° E; 36 m a.s.l.; 30 Mar. 2018; J. Grego, D. Angyal, G. Jakab and M. Olšavský leg.; HNHM MOLL 104177 /1, coll. Grego /24, coll. Glöer /1 • 5 shells; Bosnian Federation, Mostar Municipality, Blagaj, spring at left bank of Buna River, under road close to bridge towards mosque, 600 m from main Buna River Spring; 43.256518° N, 17.897381° E; 36 m a.s.l.; 30 Mar. 2018; J. Grego, D. Angyal, G. Jakab and M. Olšavský leg.; coll. Grego /5.
Dimensions
Holotype: H 2.34 mm; W 1.30 mm; BH 1.28 mm; BW 1.00 mm; AH 0.97 mm; AW 0.95 mm.
Paratype: H 2.10 mm; W 1.55 mm; BH 1.34 mm; BW 1.03 mm; AH 1.00 mm; AW 0.86 mm.
Etymology
Named after its resemblance to Costellina turrita (Kuščer, 1933), known from a small spring named Izvor in the valley of the Jadro near Split, Croatia.
Description
Elongate-pyramidal shell 2.3 mm high, with rounded blunt apex; milky-yellowish corneous translucent colour with five convex whorls separated by a deep suture. The shell surface is densely covered by lamellar ribs, the ribbing is absent at the nepionic whorl, where it is replaced by 24 densely set spiral ribs cross-sected by fine axial growth lines forming a cancellate structure. Spiral ribs fading down adapically, in pre-nepionic whorl forming faint transversal intercostal structures. Wavy spiral ribs continue towards the nucleus with intercostal granulation. Umbilicus open. Aperture elongate oval to rounded, expanded, shortly attached to the body whorl. Peristome blunt, and outward reflexed along the aperture outline. Outer lip lateral profile straight and flat as well as flat along the columellar lip. Aperture slightly, sometimes conspicuously protruded against the teleoconch and body whorl profile at basal view.
Differentiating features
The new species differs from P. mostarensis (Fig. 5 A–C) mainly by its straight labral and columellar margins and more open umbilicus. While possessing a similar shell morphology to Costellina turrita (Kuščer, 1933) (Fig. 5F) from the family Moitessieriidae, it differs by having a more open umbilicus and a more oval and more open aperture. Shell morphometry comparison with the related species is presented in the Table 1.
Habitat
The type specimens were found in sandy sediments washed out from the four small side springs at the right bank of Bunica River about 300–600 m from the main spring of Buna River (36 m a.s.l.). The position of sandy sediments and condition of the fragile shells suggest better adaptation of the new species to an interstitial habitat than we experienced in any other species of Plagigeyeria, which, in contrast, are more specialised to open phreatic cave habitats. The small springs likely draining the low karst plateau situated at the southern foot of the mountain range west of Blagaj without interconnection to the main karst conduit of the Buna.
Distribution
The new species is so-far known only from the four small springs of the type locality at the left bank of river Buna in Blagaj, while a local Buna form of P. mostarensis (Fig. 5 D–E) can be found in the sediment of the main spring of Buna River. The typical morphotype of P. mostarensis is found in the nearby spring of river Bunica near Hodbina (Fig. 5 A–C) and we suppose this is the type locality, which was erroneously confused with the Buna spring by Kuščer (1933).
Remarks
The shell morphology similarity to the moitessieriid Paladilhiopsis (Costellina) turrita could suggest an interlink towards Plagigeyeria mostarensis and other members of the genus Plagigeyeria, and its possible affiliation to the family Moitessieriidae.
description: Published as part of Grego, Jozef, 2020, Revision of the stygobiont gastropod genera Plagigeyeria Tomlin, 1930 and Travunijana Grego & Glöer, 2019 (Mollusca; Gastropoda; Moitessieriidae and Hydrobiidae) in Hercegovina and adjacent regions, pp. 1-56 in European Journal of Taxonomy 691 on pages 18-20, DOI: 10.5852/ejt.2020.691, http://zenodo.org/record/3961840