A new species of hydrobiid snails (Mollusca, Gastropoda, Hydrobiidae) from central Greece

Abstract Anew minute valvatiform species belonging to the genus Daphniola Radoman, 1973, Daphniola eptalophos sp. n., from mountain Parnassos, Greece is described. The new species has a transparent valvatiform-planispiral shell, wide and open umbilicus, grey-black pigmented soft body and head and a black penis with a small colorless outgrowth on the left side near its base. A comparative table of shell dimensions and a key to the species known for this endemic genus for Greece are provided.


Introduction
Greece is a hot spot for hydrobioid gastropods both in terms of species richness and endemism Maassen 2009, Glöer et al. 2010). Hydrobioid gastropods include the family Hydrobiidae and several other families of Rissooidea that resemble these gastropods in general features (Hershler and Ponder 1998). To date, 72 hydrobioid species and subspecies belonging to 24 genera have been recorded in Greece (Bank 2006, inhabits most of mainland Greece, i.e., Peloponnesos, Attica except its easternmost part, the western part of Euboea, southeast Thessalia and east Macedonia.
Here a new Daphniola species is described from central Greece, i.e. Sterea Ellada, and compared with its congeners.

Materials and methods
Specimens of a minute valvatoid hydrobiid gastropod from a spring nearby Agoriani (Eptalophos, mountain Parnassos, Sterea Ellada, Greece), were collected alive. Since population abundance of this species seems to be low in the spring where it was found only eighteen specimens were collected. Thirteen of them were stored in 70% ethanol for morphological and anatomical studies and five specimens in deep freezing for future molecular analyses.
Shell morphometric variables (namely shell height and width, aperture height and width) were measured of all specimens collected using the micrometer of a Stemi 2000-C, Zeiss stereomicroscope. The ratios of shell variables were calculated as well.
The structure of protoconch and teleoconch of the shells were studied using scanning electron microscopy (Jeol JSM-35 operating at 25 kV) after being dehydrated in a gradient of ethanol dilution series (10-100%) and finally in pure acetone, critical point dried and spray coated in gold-palladium.
Six randomly chosen specimens were dissected (four of them were found to be mature males, one mature female and one immature female).
Shells and penes were photographed with a Canon Eos 1000D digital camera attached on a stereomicroscope Stemi 2000-C, Zeiss, Germany.
Abbreviations: ZMUA, Zoological Museum, National and Kapodistrian University of Athens.
Spire very low and blunt; 3-3.5 convex whorls, regularly growing, divided by a moderately deep suture, last whorl strongly developed.
Umbilicus open and very wide, the earlier whorls being visible inside. Aperture prosocline, almost circular with a sharp continuous peristome and thin margins, the upper part of columellar margin slightly leaned against to the shell wall, the outer margin simple. Operculum ( Fig. 3) ovate, dark orange, thin, thicker and more colored at the nucleus, thinner and colorless at the edges, circular to ovate with weakly convex inner face, paucispiral with subcentral nucleus without any outgrowth on inner face.
In living specimens epithelium of mantle darkly grey-black pigmented, the color being clearly visible under the transparent shell, head grey-black pigmented, large eye spots present and tentacles with a median longitudinal black stripe up to the half of their length.
Penis (Figs 4-6) black pigmented except the apex and the base, long, slender, gradually tapered towards the tip with a prolonged pointed apex, sometimes like an awl (Fig. 5), with a small unpigmented outgrowth on left side near its base (Fig. 6). Occasionally, this outgrowth is not well visible.
Type locality. Agoriani (Eptalophos), mountain Parnassos, Sterea Ellada, Greece, 22°3013.5"N, 38°35'35.5"W, 950 m a.s.l. All the specimens were found on the surface of small stones and dead leaves accumulated on the bottom of a spring covered by a thick snow layer. None other freshwater gastropod species was found to share the same spring.
Further localities. Known only from Agoriani (Eptalophos), Sterea Ellada, Greece. Etymology. The specific name is a noun in apposition taken from the type locality.

Discussion
The new species collected in the Parnassos Mts. belongs to the genus Daphniola because it has the characteristics of this genus as defined by , Schütt (1980), Radoman (1983) and Bodon et al. (2001): 1) shell very small valvatiform 2) operculum without peg 3) penis narrow, slender and elongated with a prominent apex and one outgrowth on left side 4) female genitalia with two seminal receptacles, oviduct loop and ovate bursa copulatrix well-developed. The macrosculpture of protoconch and teleoconch of D. eptalophos is quite similar to those described by Szarowska (2006) and Falniowski et al. (2007) for D. exigua and D. louisi respectively. The shell of D. eptalophos is light horn-colored to whitish in contrast to the shell of D. louisi, which is brightly yellowish (Falniowski and Szarowska 2000), and of D. exigua, which is whitish to greenish-whitish (Schütt 1962).
D. eptalophos has a flatter valvatoid shell with lower spire if compared to those of D. exigua and D. louisi (Figs 14-16, Falniowski and Szarowska 2000). Additionally, the dimensions of its shell are different if compared to those of the other known species and subspecies of Daphniola (Tables 1-2).
The color of the operculum in D. eptalophos is dark orange while in D. exigua is yellowish brown (Schütt 1980) and in D. louisi light yellowish.
Body and head of D. eptalophos are dark pigmented like that of D. exigua (Falniowski et al. 2007); in D. louisi, the pigmentation of the soft parts is limited to the delicate spots on the visceral sac covering the digestive gland and gonad while the head is unpigmented (Figs 14-16, Falniowski and Szarowska 2000). The soft body of D. hadei is pigmentless .
The eye spots of D. eptalophos are large like in D. louisi (Falniowski and Szarowska 2000), whereas the eye spot of D. hadei are rather small .
The penis of D. eptalophos is more slender and elongate than that of D. louisi (Falniowski and Szarowska 2000: page 184, Figs 18-25). D. eptalophos differs from its congeners in the lateral outgrowth on the left side of penis: this outgrowth is small, rather triangular and located near its base in D. eptalophos, it is long, slender and located at half the penis length in D. exigua (Radoman 1983: page 84, Fig. 45) and it is small, blunt and located at half the penis length in D. louisi and D. hadei Szarowska 2000: page 184, Figs 18-25, andSzarowska 2011: page 135, Figs 16-18). Finally, the penis of D. eptalophos is almost entirely black pigmented, a characteristic not observed in any other Daphniola species.
Some of the specimens collected were observed to be carrying a single hemispherical egg capsule inside the umbilicus or attached to the body whorl with an embryo at different stage of maturation (Fig. 2). The attachment of egg capsules to the shells of the same species has not been referred in literature for any other Daphniola species but it has been recorded in some other hydrobiid taxa with wide umbilicus such as Tarraconia gasulli (Boeters, 1981) and Boetersiella wolfi Boeters & Glöer, 2007(Ramos et al. 2000, Boeters and Glöer 2007. Figures 11-13. Female genitalia of Daphniola species. D. eptalophos sp. n. female genitalia drawn from the only one female individual found among dissected specimens 11 D. louisi female genitalia re-drawn from Falniowski and Szarowska (2000) 12 D. exigua female genitalia re-drawn from Radoman (1983) 13 Scale bar 0.5 mm.

12 13
To date, Daphniola eptalophos sp. n. has been found in only one spring. This fact in combination with its low population density indicates that the new species will be highly sensitive towards any kind of change of its biotope. Obviously, a monitoring of the new species is immediately required and the assessment of its population status and trends is of high priority. Unfortunately "hydrobioid" localities in Greece, most of them springs, are prone to changes (Szarowska andFalniowski 2004, Szarowska andFalniowski 2011b) due to urbanization, water pollution, waste accumulation, tourism and agricultural practices. Many of these localities have been destroyed, and a decline or even loss of endemic hydrobiid taxa has already been recorded (Ryan and Griffiths 2001, Szarowska and Falniowski 2004, Albrecht et al. 2006, Regnier et al. 2009, Szarowska and Falniowski 2011a.
Effective conservation measures must be urgently taken to protect "hydrobioid" localities in Greece, among them the spring nearby Agoriani, before their unique gastropod fauna disappears.