Plagigeyeria lukai, Glöer & Pešić, 2014

Glöer, Peter & Pešić, Vladimir, 2014, New subterranean freshwater gastropods of Montenegro (Mollusca: Gastropoda: Hydrobiidae), Ecologica Montenegrina 1 (2), pp. 82-88 : 85-87

Plagigeyeria lukai n. sp.

( Figs. 3 A-C)

Type series. Holotype ( ZMH 79705 ): Shell height 1.3 mm, shell width 0.9 mm; Montenegro, Podgorica, spring in village Pričelje, 39 m asl., 20.iv.-25.v. 2014 Pešić . Paratypes: 1 ex. ( ZMH 79706 ), same data and locality as holotype .

Locus typicus. Montenegro, Pogorica , spring in the Pričelje village, 42°30'17.52'' N, 19°13'17.93'' E .

Etymology. The species is named after Luka Pešić, the four-year old son of the author.

Description

Shell. Shell elongated conical with a large and broad apex ( Figs. 3 A-B). The regularly growing 4.5 whorls are convex with a deep suture. Shell surface ribbed ( Fig. 3C), with thin and sharp ribs with broad interspaces. The aperture is large, the lower edge of the aperture is moved forwards, and the outer margin is sinuated from lateral view. The outer margin of the aperture is flanged. The umbilicus is open and deep. The shell height 1.3 mm, shell width 0.9 mm, apertural/shell height ratio 0.4.

Body: unknown.

Differentiating features. Plagigeyeria lukai n. sp. is the smallest species of this genus in Montenegro. The dimensions of other Plagigeyeria species from Montenegro varying in height from 2.0 to 2.8 mm (Schütt 1960). The lower edge of the aperture in the new species from Pričelje is moved forwards stronger than in all other Plagigeyeria spp. known so far. In addition only in Plagigeyeria lukai n. sp. the lower border of the aperture is on the right side attenuated. From P. zetaprotogona Schütt, 1960 and its subspecies known from several springs along Zeta river, the new species differs by the lower apertural/shell height ratio, which is in P. zetaprotogona 0.54 and in P. zetadidyma 0.64.

Distribution. Montenegro; known only from the type locality.

Discussion

For Montenegro a total of 28 freshwater hydrobiid gastropods are reported ( Table 1). Three species are listed as Extinct by Regnier et al. (2009): Antibaria notata (Frauenfeld, 1865) , Bracenica spiridoni Radoman, 1973 and Vinodolia gluhodolica (Radoman, 1973) . The two latter species, presumed to be subterranean forms, recently have been re-discovered by Pešić and Glöer (2013) so the statement of Regnier et al. (2009) should be partially rejected.

The most diverse genera are Plagigeyeria with 7 taxa (3 species and 5 subspecies), followed by Vinodolia Radoman, 1973 with 6, and Radomaniola Szarowska, 2006 with 4 species. Schütt (1972) made a taxonomic revision of the genus Plagigeyeria based on conchological features and divided Plagigeyeria zetaprotogona into four subspecies (P. z. zetaprotogona , P. z. zetadidyma , P. z. zetatridyma, P. z. pageti). However these subspecies could be found living syntopically in several springs along Zeta river (the spring near Straganik and Tunjevo, spring near Studeni near Danilovgrad and spring between Slap and Bog in the upper Zeta valley) suggesting that they represents separate species. However, taxonomic status of these taxa should be clarified by checking additional material. The systematic status of Radomaniola curta and its subspecies is still problematic. Falnowski et al. (2012) studied the morphology of the shell, penis, and female reproductive organs, as well as the mitochondrial COI and ribosomal 18S in 17 populations of Radomaniola from Skadar Lake drainage and shows that the molecular differentiation was not reflected in morphology. They postulated morphostatic evolution, as a result of non-adaptive radiation characterized by the rapid proliferation of species without morphological and ecological differentiation ( Gittenberger 1991).

At the species level, 92 % of the total hydrobiid fauna appears to be endemic for Montenegro. Most of endemic species are found in Adriatic Sea catchment area, and only three species (all of the genus Bythinella ) occur in the Black Sea catchment area. Members of the latter genus are absent from Adriatic drainage area, with the exception of one locality in the upper part of Morača river, close to the watershed of the two drainage sea areas ( Glöer and Pešić 2010). The Skadar lake basin is the region with the highest number of endemic species, the adjusted rate of gastropod endemicity estimated at 37.5 % ( Pešić and Glöer 2013). The endemism occurs also at genera level and Montenegro harbors three endemic and monotypic hydrobiid genera, Karucia Glöer & Pešić, 2013 , Montenegrospeum Pešić & Glöer, 2013 , and Zeteana n. gen.

The IUCN Red List of Threatened Species ( Cuttelod et al. 2011) includes 19 hydrobiid species from Montenegro. Five of them are assessed as Critically Endangered, 8 as Endangered, 2 as Data Deficient and 5 as Least Concern in the IUCN Red List of endangered species (see: Table 1). Furthermore, the six species: Vinodolia zetaevalis , V. scutarica , V. matjasici , Radomaniola lacustris , R. elongata and Bracenica spiridoni are protected in Montenegro by national legislation (Službeni list RCG, br. 76/06, 2006).