Plagigeyeria pseudocostellina, Grego, 2020

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, European Journal of Taxonomy 691, pp. 1-56 : 18-20

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 .

Figures

Fig. 7 (next page). A. Plagigeyeria mostarensis, Kuščer 1933, holotype, from Kuščer 1933, assigned to Izvor Buna in Blagaj but rather represents the form from near spring Bunica in Hodbina. B. P. mostarensis, hypotype of Schütt, 1970, from spring Bunica (SMF 221236). C. P. mostarensis, likely topotype from spring Bunica (JG F1146). D–E. P. mostarensis var., from spring of Buna assigned as type locality (JG F0536). Fa–Fb. Paladilhiopsis (Costellina) turrita (Kuščer, 1933) paratype and holotype from Kuščer 1933, spring Izvor in valley of river Jadro near Split. G. P. pseudocostellina sp. nov., left bank side spring of river Buna 400 m from main spring (holotype HNHM-MOLL-104164). H. P. pseudocostellina sp. nov., left bank side spring of river Buna 200 m from main spring (paratype JG F1140). I. Travunijana ovalis (Kuščer, 1933), holotype from Kuščer, assigned to Izvor Buna in Blagaj but not found in assigned locality, only in spring Bunica in Hodbina. J–K. T. ovalis (Kuščer, 1933), spring Bunica near Hodbina (JG F1145). L. T. robusta (Schütt, 1959), Trebinje district, Tučevac spring at right bank of Trebišnjica River (JG F1163). M. T. robusta, Trebinje district, Gorica, cave Vruljak 1 (JG F0831). N. T. robusta asculpta (Schütt, 1972), spring Ombla (Dubrovačka Rijeka) at Komolac near Dubrovnik (JG F1080).

Fig. 8. A. Plagigeyeria reischuetzorum sp. nov., Bjeljani, Dabarsko Polje, Vrelo Vruljak, paratype (SBMNH 632724). B. P. pseudocostellina sp. nov., Blagaj, side spring of Buna at left bank, paratype (SBMNH 626414). C. P. mostarensis Kuščer, 1933, Blagaj Izvor Bune (SBMNH 626411). D. P. mostarensis Kuščer, 1933, Hodbina, Izvor Bunice (SBMNH 626405). Scale bars = 1 mm (SEM SBMNH Vanessa Delnavaz).

Fig. 5 (next page). A. Plagigeyeria plagiostoma (A. J. Wagner, 1914), from Vrelo Bosne in Ilidža, (topotype JG F1116). B. Travunijana vruljakensis Grego & Glöer, 2019, Gorica near Trebinje, spring Studenac (holotype HNHM-MOLL-104416). C. P. inflata (A. J. Wagner, 1928), from Vrelo Bosne in Ilidža (topotype JG F1117). D. P. ljutaensis sp. nov., Konjic district, spring of River Ljuta (holotype HNHM-MOLL-104180). E. P. konjicensis sp. nov., small spring at left bank of Ljuta River, 600 m downstream of the main spring (holotype HNHM-MOLL-104174); F–G. P. olsavskyi sp. nov., Studenci, spring Kajtazovina F. Holotype (HNHM-MOLL-104178). G. Paratype (JG F1192). H–I. P. olsavskyi sp. nov., Ljubuški district, Donji Proložac, spring Mali Prokop (JG F1209).