The Pseudamnicola spp. from Greece (Gastropoda: Hydrobiidae) with the description of four new species

Four species of the genus Pseudamnicola (Gastropoda: Hydrobiidae Stimpson, 1865), i.e. P. stasimoensis n. sp., P. lesbosensis n. sp., P. samosensis n. sp. and P. skalaensis n. sp are described as new to science. The type localities of 13 Pseudamnicola spp. and 1 subspecies hitherto known from Greece, including the Greek part of Cyprus, are presented on a map.

In 2015 Szarowska et al. (2015) sequenced numerous samples from Greece and found 16 main mitochondrial clades, most of them endemic to their type localities. This paper is intended to describe another four Pseudamnicola spp. from Greece which were collected in 2007, 2008 and 2010 by Robert Reuselaars in the Peleponnesos and on the islands of Samos and Lesbos.

Material and methods
The snails have been collected by Robert Reuselaars and fixed in 80% ethanol. Unfortunately the alcohol evaporated during the long period of storage so we could not study the anatomy. The specimen were taken by hand or with a tweezers in the springs of Pnaka (figure 1), Stassimo, Tripi and the spring between Argenos and Lepetymnos. On these localities only a few specimen were collected to avoid disturbing these small populations too much. A sieve has been used in the strong running water of the Vasilopotamus river near Skala. Of the three new species, two are living in a habitat of about only 1-1,5 m 2 and in relatively low densities (see figures 3 and 6).
The measurements of the shells were carried out using a stereo microscope (ZEISS) with an eyepiece micrometer; the photographs were made with a digital camera system (Leica R8). The type material is stored in RMNH (Rijskmuseum van Natuurlijke Historie Naturalis Leiden, The Netherlands) and in the collection of Robert Reuselaars.

Study Area
Greece is a hotspot for land and freshwater molluscs (Strong et al. 2008). Despite the fact that Greece is visited by many malacologists in the past, there is a continuous flow of new discoveries (Radea et al. 2015, Szarowska et al. 2015, Falniowski 2015, Glöer & Hirschfelder 2019, Glöer & Reuselaars 2020, Glöer & Hirschfelder 2020. In this article we present our findings on the freshwater genus Pseudamnicola. As shown on the map, the destribution of this genus is concentrated in the Aegean area, except for the islands in the central part. It seems to be absent in the northern and western part of continental Greece and the northern and central part of the Peleponnesos. On many visits in Greece in the past 20 years, no Pseudamnicola sps were discovered in those areas.  Habitat (type locality): Small artificial basins and gutter below the outflow of the spring where the species was found on the sandy gravel and old leaves. Habitat is less than 1.5 m 2 .

Genus
Etymology: Named after the town Stasimo. Description: The shell is ovate with 4-4.5 slightly convex whorls with a deep suture. The aperture is ovate, slightly angled at the top. The peristome is sharp, thickened at the columella and somewhat reflexed, The umbilicus is closed. The body whorl takes 0.8 of shell height. The aperture is 0.8 mm high and 0.8 mm broad. The ratio of shell height to shell width is 1.5. The shell is 2.0 mm high and 1.3 mm broad.
Differentiating characters: The body whorl is broader than in the other Pseudamnicola spp. Distribution: Greece; only known from type locality.  Habitat: Artificial basin of about 1 m2 below outflow of the spring where the species was found on sandy gravel. Etymology: Named after the island of Lesbos. Description: The shell is ovate with 4.5-5 slightly convex whorls which are separated by a deep suture. The aperture is ovate, angled at the top. The peristome is slightly thickened at the columella, The umbilicus is closed. The body whorl takes 0.8 of shell height. The aperture is 0.8 mm high and 0.7 mm broad. The shell is 2.0 mm high and 1.2 mm broad. Distribution: Greece; only known from type locality.
spring where they live in and which is already under human pressure. Pseudamnicola stasimoensis is known of two springs with a very small habitat. This species is also considered as critically endangered due to human pressure. We do not consider Pseudamnicola skalaensis as endangered because it is living in in the spring in Tripi and the Vasilopotamos river near Skala town. However if someone decides to clean the gutter of the spring in Tripi this species most likely will be eradicated from this location. Our contribution to the knowledge of springsnails in Greece is important if we want to protect these species. Springs are very sensitive ecosystems (Cantonati et al. 2006, Savić et al. 2019. Most species in Greece are serious under stress where springs are used for drinking water or irrigation purposes. Human impact has led to the extinction of many springsnail species in the past and will lead to more extinctions if they will not be protected. But this is not only the case with springs. During a field trip in september 2019 we noticed the very low water levels in the lakes Prespa, Kastoria, Zirou and Pamvotis (see figure 9). Most of these lakes are used as water reservoir for irrigation and/or drinking water and a combination of long droughts and closing the water supply from springs (i.e. the springs at the east bank of lake Pamvotis) have led to these very low water levels. At the eastern bank of lake Pamvotis we saw hundreds of fresh shells of Sinanodonta woodiana (introduced) and Viviparus hellenicus in the mud, all died during the summer. At lake Zirou this was the case with Unio crassus. All these species also live in deeper water of these lakes, so most likely they will survive, for now. This is just another example of human impact on freshwater ecosystems which can lead to the extinction of species.