DESCRIPTION OF A NEW SUBSPECIES OF PSEUDAMNICOLA PAULUCCI, 1878 (CAENOGASTROPODA: TRUNCATELLOIDEA: HYDROBIIDAE)

A new subspecies of Pseudamnicola (P.) moussonii is described for the Pseudamnicola populations inhabiting the Maltese Islands. Key WorDs: Pseudamnicola, Maltese Islands, new subspecies


INTRODUCTION
Boeters (in BecKmann 1987) discovered a species of Pseudamnicola from Gozo, one of the Maltese Islands, and misinterpreted it as P. melitensis (Paladilhe, 1869).Giusti et al. (1995) identified this species from Malta and Gozo as P. moussonii (Calcara, 1841).Moreover, they proved that Amnicola melitensis Paladilhe, 1869 belonged to Mercuria Boeters, 1971.In view of the fact that the type locality of P. moussonii is situated in Sicily, it seemed reasonable to compare the Pseudamnicola from the Maltese Islands not only with P. moussonii, but also with all other Sicilian species of Pseudamnicola.
The following updated description of the species of Pseudamnicola inhabiting the Maltese Islands gives a comparison not only with P. moussonii, but also with P. conovula, P. sciaccaensis and P. orsinii.Finally, also Amnicola cocchii Benoit, 1882 is taken into consideration, since its type locality is also situated on Sicily: "un piccolo laghetto presso Mazzara" (Benoit 1882: 165).
Finally, the Pseudamnicola sp.inhabiting the Maltese Islands, misinterpreted by Boeters (in BecKmann 1987) and occasionally co-occurring with M. melitensis, is described as a new subspecies of P. moussonii, assuming that the Sicilian populations represent the nominotypical subspecies P. m. moussonii.

MATERIAL AND METHODS
The snails were collected with a sieve and preserved in 75% ethanol.Specimens of the new subspecies were found on Gozo, one of the Maltese Islands (Fig. 1).Dissections and measurements of the shells (Figs 2-14) as well as of the male (Figs 15-19) and female (Figs 20-25) genital organs were carried out using a stereo microscope, the photographs were taken with a Leica digital camera system.In addition we used literature sources and materials listed in the text.

SYSTEMATIC PART
Female genitalia (Fig. 21): Proximal section of renal oviduct black pigmented, distal section unpigmented.Receptaculum (RS1) oval with a negligible duct.Large bursa like a bent, slightly folded sac, on its convex side entered by the bursal duct.Both ducts originate adjacent to each other.The bursal duct broadens gradually to its junction with the bursa.
Penis (Figs 18,19): Elongated, flattened cylindrical with few accordion-like folds and a black pigmented area accompanying the penial duct in the core of the penis; penis tip blunt; vas deferens opening at a papilla of the penis tip.(2) Versus P. conovula (Figs 4-6: shells, 15: penis, 20: female genitalia).The females of this species are characterised by a duct of receptaculum which is about as long as the bursal duct (raDoman 1972(raDoman : 198, figs 4A-B, 1978(raDoman : 49, fig. 7, 1983: 36, fig. 11) : 36, fig. 11) and not half as long as the bursal duct in P. m. magozensis n. subsp.Giusti et al. (1995) and BoDon et al. (1995) raised doubts regarding the species status of P. conovula versus P. moussonii.However, it should be remembered that the distance between their type localities is about 750 km.Furthermore, on Sicily the differences between P. moussonii and the species identified as P. cf. conovula (Figs 7-9: shells, 17: penis, 22: female genitalia; BOE 0519) are so great that the two taxa can be easily distinguished.
(3) Versus P. sciaccaensis.This species can be distinguished based on its elongated conical shell with a considerable height of 5.2-5.8mm and diameter of 3.1-3.5 mm.Whereas P. m. magozensis n. subsp.belongs to Pseudamnicola s. str., it is assumed that P. sciaccaensis rather belongs to Corrosella Boeters, 1970
The following description is based on the two above types and two samples from Calatafimi (Trapani, Sicily)(Giusti 1976: 106, figs 1N-O and T-U).Shell (Figs 2,

Fig. 1 .
Fig. 1.Localities of Pseudamnicola m. magozensis n. subsp.: 1 -Xlendi Valley; 2 -Sara Valley; 3 -Lunzjata Valley; 4 -Fontana 107) possibly widespread in Southern France, Spain and north-western Africa, a view which is shared byGirarDi et al. (2009: 135), but doubted byFalKner  & Boeters (2003: 26).Remarks: (1) It should be borne in mind that according to BoDon (inGiusti et al. 1995: 142)   Sicilian specimens vary considerably in the length of seminal receptacle and in the length and shape of bursa copulatrix duct.This may have ledGiusti et  al. (1995)  to assigned also Pseudamnicola populations with characters deviating from those listed above for Sicily, especially populations from the mainland of Italy(Giusti & Pezzoli 1980) and from the Maltese Islands, to P. moussonii.It is consistent with the fact thatGiusti et al. (1995: 142)  speak of doubts thrown "on the validity of other classical species confirmed on the basis of anatomical study.This is the case of Pseudamnicola conovula (Frauenfeld, 1863; type locality: Insel Pag, Croatia), an alleged Transadriatic species …".szaroWsKa et al. (2006: 187), dealing with P. conovula on morphological and genetic basis, seem to confirm this view in expressing their "skepticism considering [at least] shell-based taxonomy in Pseudamnicola".(2)Paludina moussonii was described as having corneus-brown shell tending to yellowish [di color corneo tendente al biondetto] (calcara 1841).However, the shell of the lectotype is opaque white (cf.Glöer & BecKmann 2007: 123, fig.2.2).Furthermore, its height is distinctly smaller than that of the shells figured byGiusti (1976: 106, fig.1N-O).Thus, the identification of the taxon in question needs clarification.It should, however, be added that shells of P. m. magozensis n. subsp.from the Xlendi Valley on Gozo and of, for example, P. cf. conovula from Minareto on Sicily (BOE 0519), are opaque white and resemble shells of Mercuria.(3)Recenly DelicaDo et al. (2015: 408, for "Tra, MSc, Bal, Sig") published DNA data for P. moussonii from Sicily, but without any morphological characters.

Table 1 .
Pseudamnicola The values for figs1N-O (see Giusti 1976: 106, fig. 1) are not calculated with the use of 2 mm scale, but according to fig.1G measuring 3.25 mm.