Sylvaemus group. Previously listed as a subspecies of A. sylvaticus (Corbet, 1978c; Ellerman and Morrison-Scott, 1951; Pavlinov and Rossolimo, 1987), but now recognized as the oldest name for a distinctive small-bodied species formerly called A. microps (Musser and Carleton, 1993; Pavlinov and Rossolimo, 1998; Pavlinov et al., 1995a). Synonymy of European microps with Asian uralensis has been documented by results of a variety of molecular and morphological studies (Bellinvia et al., 1999; Filippucci et al., 1996; Macholán et al., 2001b; Mezhzherin, 1997a; Mezhzherin and Mikhailenko, 1991; Mezhzherin and Zykov, 1991; Mezhzherin et al., 1992; Reutter et al., 2003). Mezhzherin (1997b:309) summarized historical literature indicating the presence of a species different from A. sylvaticus that corresponded to A. uralensis. Pertinent systematic treatments cover chromosomal and allozymic variation (as microps; Gemmeke, 1983; Mezhzherin, 1997b; Vorontsov et al., 1989, 1992); morphological data presented in context of distinguishing species of Apodemus (Tvrtkovic and Dzukic, 1977); variation in banded chromosomes between A. uralensis (as microps) and A. alpicola (Reutter et al., 2001); morphology (skin, skull, and dentition) of northern Turkish samples (Filippucci et al., 1996), and results of discriminant function analyses separating samples of E Turkish A. uralensis from Turkish and Iranian A. flavicollis, A. witherbyi (reported as hermonensis), and A. hyrcanicus (Frynta et al., 2001); comparison of isozymic, chromosomal, and molecular divergence among A. uralensis, A. witherbyi (reported as A. fulvipectus), and A. ponticus (Chelomina et al., 1998a); and morphological traits distinguishing A. uralensis and A. sylvaticus in E Ukraine (Naglov, 1995). Electrophoretic analysis of allozymic data indicated a recent separation of A. flavicollis, A. alpicola, A. uralensis, and A. witherbyi (reported as hermonensis) from a common ancestor (Filippucci, 1992; Filippucci et al., 1966), and a closer link between A. uralensis and A. hyrcanicus than between A. uralensis and A. flavicollis, A. sylvaticus, or A. witherbyi (reported as hermonensis), the other species sampled (Macholán et al, 2001b). However, analyses of sequences from mtDNA cytochrome b and 12S rRNA identify A. uralensis as a sister-species to A. alpicola (Michaux et al., 2002a), as did cytochrome b haplotype divergences (Reutter et al., 2003), but not complete mtDNA cytochrome b sequences (Liu et al., 2004). Allozymic variation and morphology suggest a close alliance with A. pallipes from the Pamirs and Himalayas (Mezhzherin, 1997a). In Reutter et al’s (2003) analyses of cytochrome b haplotype divergences, a a sample from GenBank labeled "sylvaticus 2" from Pakistan (specimen in FMNH) used by Jansa et al. (1999) and Liu et al. (2004) clustered with samples of A. uralensis; "sylvaticus 2" represents A. pallipes as that is the most common species in Pakistan and the one usually found in museum collections (Musser’s identifications). Results derived from "sylvaticus 2" reinforces the close phylogenetic allicance between A. pallipes and A. uralensis indicated by Mezhzherin’s (1997a) study; this alliance is also substantiated by qualitative observation of specimens (Musser’s research), and phylogenetic analyses of mtDNA cytochrome b and nuclear IRBP sequences (Suzuki et al., 2003; sample identified as A. wardi, but see account of P. pallipes). Hille et al. (2002) summarized the various cladistic trees involving A. uralensis and other Apodemus, highlighting similarities and incongruences among them.

Species-boundaries are far from resolved. Using only chromosomal banding data, Orlov et al. (1996a, b) separated mosquensis and ciscaucasicus as separate species within what they referred to as the superspecies Sylvaemus uralensis; two forms of A. uralensis from the Caucasus were also detected by Hille et al. (2002). Based on morphological and allozymic data, Mezhzherin (1997a) recognized a clade containing uralensis, kastschenkoi, and pallipes (which had been listed as a synonym of A. uralensis; e.g., Musser and Carleton, 1993) and applied each name to a separate species. Mezhzherin explained that kastschenkoi was proposed by Kuznetzov for the small-bodied species in the Siberian Altai that had been identified as tscherga. The original description of tscherga suggested a composite of A. sylvaticus and A. peninsulae, but Kuznetzov studied the type series and identified all members as A. peninsulae (Russians use A. major instead of peninsulae). Mezhzherin noted that kastschenkoi has dark brown upperparts, gray belly, and is readily distinguished from A. uralensis, and that the names microtis, tokmak, and balchaschensis are probable synonyms of A. uralensis. We are not impressed with the degree of genetic distance separating Mezhzherin’s samples of A. uralensis and kastschenkoi or the slight morphological differences between specimens we studied from the Siberian Altai and those representing A. uralensis from the west. On the other hand, species-status for pallipes, which occurs to the south in the Pamirs and Himalayas, and is larger-bodied with generally paler upperparts and white or whitish gray underparts (see that account), is supported by genetic-distance measurements and morphology, as Mezhzherin indicated. The NW Chinese nankiangensis (from Aksu in Xinjiang) was described as a subspecies of A. sylvaticus and compared with tscherga from farther north in Xinjiang and the Siberian Altai from which it differs primarily in color (sandy brown upperparts instead of grayish brown; Corbet, 1984; Wang, 1964); we include it as a synonym of A. uralensis. An isolated population in NW Bohemia in the Czech Republic was extensively documented by Vohralík (2002) under cimrmani (as a new subspecies of A. microps).

European populations reviewed by Steiner (1978, under microps) and Mitchell-Jones et al. (1999), Russian range and taxonomy reviewed by Gromov and Erbajeva (1995). Recent faunal studies incorporating distribution, taxonomy, ecology, and other information are available for: E Germany (Feiler and Tegegn, 1998), Austria (Bauer and Spitzenberger, 1996, as microps), Baltic region (Miljutin, 1997, 1998; Timm et al., 1998; Zagorodnyuk and Mezhzherin, 1992, as microps), Lithuania (Juškaitis et al., 2001), Serbia and Montenegro (Petrov, 1992, as microps), E Carpathians (Kyselyuk, 1993, as microps), Czech Republic (Krška, 1996, under microps; Vohralík, 2002, as microps; Zima and And�ra, 1996), Slovakia (Mosansky, 1994; Stanko and Mosansky, 1994, 2000; Stanko et al., 1994), Bulgaria (Peshev, 1996, as microps), and NW China (Ma et al., 1987).