There has been no critical revision of this species throughout its range, and D. nitedula may actually contain two or more species. An allozymic and biometric study by Filippucci et al. (1995) of southern populations indicates that the Israeli population probably represents a separate species, a conclusion supported by ecological data (Nevo and Amir, 1961b) and phallic and bacular morphology (Simson et al., 1995). It would have been treated as a species here, but unfortunately no name has been given to this population. Historically, the Israeli population has been included in D. n. phrygius (described from Murat Dagi, W Turkey), but Filippucci et al. (1995) showed that the two populations are morphologically different, and topotypes of D. n. phrygius clustered with the European population from Turkish Thrace. Mursalo—lu (1973b) suggested that the E Anatolia (Turkey) population represents a separate species, D. pictus, originally described from Kohrud, south of the Caspian Sea, Iran (Krystufek and Vohralík, 2001). Documented comparisons with representative geographic samples of D. nitedula are critical, as are comparisons with the NC Iranian population from the type locality of pictis to determine if that name applies. For synonyms see Ellerman and Morrison-Scott (1951) and Corbet (1978c).

Rossolimo et al. (1990) reviewed D. nitedula, including illustrations of live animal, distributional, morphological, ecological, behavioral and other characteristics. Taxonomy of subspecies occuring in the independent republics of the former USSR studied by Rossolimo (1971). Taxonomic study and key to subspecies in Europe provided by Roesler and Witte (1969), in Serbia and Montenegro by Kryštufek (1985a), in Greece and SE Europe by Ondrias (1966), and in the independant republics of the former USSR by Ognev (1947). Morphometric study of Bulgarian populations given by Mitev et al. (1994), Peshev and Delov (1995b), and Markov (2001b). Markov found significant sexual dimorphism within Bulgarian populations, an uncommon finding within the family, whereas Mitev et al. (1994) found no significant sexual dimorphism. Comparison of dental pattern with fossil Dryomys from Poland given by Daoud (1993). Chromosomal data, and review of past cytogenetic studies provided by Zima et al. (1995), additional karyotypic data from Bulgaria reported by Peshev and Delov (1995a), Markov et al. (1997); from Macedonia by Zima et al. (1997b); from Turkey by Do—ramaci and Kefel¥o—lu (1990); from Italy, Israel and Turkey by Civitelli et al. (1995b); and from Kazakhstan, Russia, and Turkmenistan by Graphodatsky and Fokin (1993). Allozyme variation analyzed by Filippucci and Kotsakis (1995). Phallic and bacular structure and variation studied by Hrabe (1969) and Simson et al. (1995). Illustrations and taxonomic implications of the os and glans penis, and stomach anatomy provided by Kratochvil (1973). Patterns of daily activity, winter activity, and importance of air temperature studied by Nowakowski (1998, 2001b). Detailed maps of European distribution, and discussion and review of distribution and ecology for each European country reported by Kryštufek and Vohralík (1994). Documented in faunal studies made in N Italy (Locatelli and Paolucci, 1996a; Paolucci et al., 1993) and S Italy (Cagnin and Aloise, 1995). Status in the E Baltic region reviewed by Timm et al. (1998) and discussed in a review of ecological strategies of Baltic rodents by Miljutin (1998). Recorded from Pleistocene sediments in Europe (Horacek, 1987; Kowalski, 2001).