Bithynia danubialis, Glöer & Georgiev, 2012

Glöer, P. & Georgiev, D., 2012, Bithynia Danubialis, A New Species From The Bulgarian Danube (Gastropoda: Rissooidea: Bithyniidae), Acta Zoologica Academiae Scientiarum Hungaricae 58 (2), pp. 193-197 : 194-196

publication ID	https://doi.org/ 10.5281/zenodo.5735795
persistent identifier	https://treatment.plazi.org/id/9E352638-FFA3-FFEF-FDBE-FC012155FC50
treatment provided by	Felipe
scientific name	Bithynia danubialis
status	sp. nov.

Treatment

Bithynia danubialis View in CoL sp. n.

( Fig. 2 View Fig )

Material examined: 30 ex., DILIAN GEORGIEV leg. 14.05.2009 and 21.07.2011 (10 specimens dissected).

Holotype: shell height 6.5 mm, width 4.4 mm, ZMH 79308.

Paratypes: 5 ex., ZMH 79309 , 5 ex. coll. GLÖER , rest coll. GEORGIEV

Locus typicus: Bulgarian sector of the Danube River at the village of Marten (Russe town area) N43° 56’ 19.4”; E26° 05’ 20.7”

Habitat. Littoral zone of the Danube River.

Distribution. Only known from the type locality as yet. But it possibly will be dispersed by the current in most of the Bulgarian and Romanian Danube River sectors down to the Danube Delta.

Associated gastropods. Theodoxus danubialis (C. PFEIFFER, 1828) , Viviparus sp. , Bithynia tentaculata (LINNAEUS, 1758) , Lithoglyphus naticoides (C. PFEIF- FER, 1828), and Esperiana daudebartii (PREVOST, 1821).

Etymology: named after the Danube River were the species was found.

Description. Shell glossy and light yellowish to horn-coloured, surface finely striated, 4.5–5 whorls which are slightly convex with a clear visible but not deep suture, umbilicus closed, the aperture height takes 0.5 of the shell height, edge of aperture sharp, thickened at the columella ( Fig. 2.1 View Fig ), outer margin of aperture slightly sinuated ( Fig. 2.2 View Fig ). The females are as large as the males, thus a sexual dimorphism is not visible. The operculum is oval and slightly angled at the top ( Fig. 2.3 View Fig ). Shell height 6.46± 0.4 mm (s = 0.35), width 4.51± 0.4 mm (s = 0.17).

Morphology of the penis. The distal part of the penis is as long as the penial apendix ( Fig. 2.5 View Fig ). The flagellum is approximately four times longer than the penis ( Fig. 2.6 View Fig ).

pendix, pp = pseudopenis, s= snout, t = tentacle

Differentiating features. From Bithynia tentaculata , which also occurs in Bulgaria, the new species can be distinguished by the deeper suture, the more convex whorls and the sinuated margin of the aperture, which is in B. tentaculata straight. The penis morphology is similar to that of Bithynia transsilvanica BIELZ, 1853 ( GLÖER & FEHÉR 2004, = B. troschelii ), which occurs in Romania ( GLÖER & SÎRBU 2005), but the whorls of B. transsilvanica are more convex, the suture is deeper and the operculum is rounded. In addition B. danubialis sp. n. is, however, smaller in height than B. tentaculata and B. transsilvanica .

Notes on the ecology. The species was found on sandy bottom at the littoral zone of the Danube, the river banks were dominated by Salix sp. , and Populus sp. Maybe this new species survives short periods of desiccation on the banks under wet water vegetation, and mud, like other Bithynia spp. do.

Remarks. In some females we found specimens with a pseudopenis ( Fig. 2.4 View Fig ), a very small, not completely developed penis. This phenomenon can be found in species of the genus Pseudamnicola , too (GLÖER et al. 2010).