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The Chinese jumping mouse Eozapus setchuanus (Pousargues, 1896) is endemic to the eastern border of the Tibetan plateau in China. It belongs to the Dipodidae family (Zapodinae sub-family) (Wilson and Reeder, 2005), among which the monotypic genus Eozapus is endemic to central China (Wilson and Reeder, 2005). Only about a dozen specimens are known to have been collected and deposited in Museums (Nowak, 1999). They come from elevations of 3,000–4,000 m, and stream bank in mountainous cool forests is the putative preferred habitat described by Nowak (1999). Still now, this species is reported to be rarely collected (Sung, 1998, in Amori and Gippoliti, 2003). Almost all published information concerns small mammal inventories or checklists at the regional scale, and atlases in which the presence of E. setchuanus is reported (Zhang, 1997; Wang, 2003; Qi et al., 2004; Zhang and Hu, 2004; Liu et al., 2005; Qi et al., 2005; Smith and Xie, 2008). To the best of our knowledge, no detailed information exists on its habitat requirements, life history traits, or population status. These data are however needed since the IUCN (World Conservation Union) designates E. setchuanus as vulnerable (category VU A1c), facing a high risk of extinction in the medium-term future because of human induced forest loss and degradation (Baillie, 1996). Its status was assessed in 1996, and its population trend is unknown (Baillie, 1996). Conservation actions towards this species must be grounded on a detailed knowledge about its ecology.
We report descriptive data on E. setchuanus which were collected by our research team as part of small mammal community surveys conducted in Central China between 1996 and 2005 (Giraudoux et al., 1998; Giraudoux et al., 2003; Giraudoux et al., 2006; Raoul et al., 2006). Details of trapping procedure are given by Giraudoux et al. (1998) and Raoul et al. (2006). Animals were sampled in July 1996, September 2003, June 2004, and September 2005. We compare these results with information available from the literature. Museum specimens were also used as information source. We provide information about life-history traits and habitat of E. setchuanus and present the first description of its karyotype.
Subfamily: Zapodinae Coues, 1875
Genus: Eozapus Preble, 1899
Species: Eozapus setchuanus (Pousargues, 1896)
Type locality: Tatsienlu (Kangding), Sichuan prov., China [102° 02′ E, 30° 03′ N]
Synonyms: vicinus (Thomas, 1912): 46 miles SE Taochow (Lintan) Gansu (= 3017 m), collected in 1911.
The most ancient form of the genus (early Miocene) was found in Mongolia and was attributed to Eozapus prosimilis (Lopatin & Zazhigin, 2000 in Wilson and Reeder, 2005). Eozapus similis, found in Inner Mongolia, China, is dated from late Miocene and could be the ancestral form of E. setchuanus (Fallbusch, 1992 in Wilson and Reeder, 2005).
The upper part of the body is tawny orangish or ochraceous with a darker and generally sharply defined large dorsal strip from the forehead to the tail. The lower part is white with (E. s. vicinus) or without an ochraceous median strip. The tail is dark above, white below and the tip is generally white. Upper incisors are grooved. Hind foot is over 24 mm. Table 1 describes the variability in colour patterns. Except the tail which is constantly bi-coloured, all other characters can vary.
Classical external body measurements are given in Table 2. The species is characterized by a long tail, which is generally 1.5 times longer than the head and body length. Among the four females captured, only one (HH9607JX01) had 6 embryos. No information is available from the literature about reproductive parameters.
Classical skull measurements are given in Table 3. Dental formula of E. setchuanus is: I 1/1; c 0/0; p 1/0; m 3/3, total 18. Upper incisors are grooved and molars show transversal lophs separated by lingual and buccal valleys. E. setchuanus might be the most primitive current form of the genus, with an occlusal morphology similar to that of Miocen forms (Eozapus intermedius ou E. similis). For a description of molars see Allen (1940).
Karyotype of the only male studied (MK0509ST01, see Table 2) has 71 chromosomes consisting of five pairs of middle to small sized meta-submetacentrics, 30 pairs of acrocentrics and one subtelocentric chromosome as large as the largest pair of acrocentric autosomes (Figure 1). All individual pairs were rather easily recognized by their specific G-banding pattern. Based on particular G-banding pattern shared by the odd chromosome and the Xs of other mammalian species, it was identified as X, thus suggesting X0 sex chromosomes constitution in the males of this species. However to exclude possibility of chromosomal aberration in the animal studied and to unambiguously assess the mechanism of sex determination in this species, chromosomal analysis of further individuals of both sexes is absolutely needed.
By chromosome number and morphology, E. setchuanus, the only representative of zapodines in the Palearctic, is very similar to the three earlier studied Nearctic species of the subfamily, namely Zapus hudsonius, Z. princeps and N. insignis (Meylan, 1968). Interesting that if both sexes of the former species have 2n=72 and an usual XX/XY sex chromosomes, the females in congeneric Z. princes displays X0 sex chromosomes and 2n=71 compared to normal XY males having 72 chromosomes (Meylan, 1968). Although a high karyotype similarity is a good indication on monophyletic origin of Palearctic and Nearctic zapodines, the absence of the chromosome banding data for other species of the same subfamily makes the discussion of the question premature. Another karyotypic feature of this species is the practical absence of C-bands onto all chromosomes.
The digestive tractus from stomach to caecum of five animals (HH9607JY06, HH9607JXO1, MK0510AZ01, MK0509ST01, RT0406AG10) were removed in the field and fixed in 10% formaline. Less than one month later, the digestive tractus were transferred into 70% ethanol and investigated for helminths at the Museum national d’Histoire naturelle (Paris).
All the tractus were negative for helminths (cestodes and nematodes). The low sample size prevent any definitive conclusion, but two points can be highlighted: (1) 10 Allactaga sibirica and 1 Stylodipus telum, also belonging to the family Dipodidae, collected in Xinjiang in 1995 were also negative; (2) the Arvicolinae and Murinae sampled in the same sites than Eozapus were strongly parasitized by helminths (42 out of 55 Murinae harboured helminths and 19/47 Arvicolinae).
Country-scale mammal distribution atlas (Zhang, 1997; Smith and Xie, 2008) as well as recent regional fauna checklists (Wang and Xu, 1992; Wang, 2003; Qi et al., 2004; Zhang and Hu, 2004; Liu et al., 2005; Qi et al., 2005; inter alia) report the presence of E. setchuanus throughout Central China: E and S Qinghai, S Gansu, S Ningxia, SW Shaanxi, W Sichuan, and NW Yunnan (Figure 2). This distribution covers around 1 million km2 (Zhang, 1997) in mountainous areas of the eastern part of the Tibetan plateau, and belongs to the Palaearctic biogeographical zone, at the limit of the Indo-Malayan zone (Dobrov and Neronov, 1995; Xiang et al., 2004).
Literature suggests that the habitats of E. setchuanus are beside streams in cold forests of elevation between 3,000 and 4,000 m (Corbet and Hill, 1992), and mountains forest scrub, shrub-steppe and meadow (Zhang, 1997; Smith and Xie, 2008). Allen (1940) for E. s. vicinus gives mixed spruce, vicinity of small brooks at 3017 m, and Poussargues for the co-type gives alpine habitat at 3657 m. Local checklists generally report the presence of the species for broad altitudinal classes, without precise information within each class, and without data on habitat: in Shaanxi, Li and Wang (1996) report the trapping of E. setchuanus in Qinling-Dabashan mountains (Shaanxi district) in three classes, ie 780–2300m, 2300–2800m and 2800–3400m. In Sichuan, Wang (2003) report the species between 3800 and 4200 m in Shiqu county, and Qi et al. (2004) gives the two following classes in Meigu county: between 1500 and 2800m, and above 2800m. To our knowledge, only one published study (Giraudoux et al., 1998) has provided detailed information about the habitat characteristics of E. setchuanus (see below).
Table 4 reports habitats where we trapped the species. All individuals were trapped according to a standard protocol using small break-back traps (wood snapping traps 4.5 × 9 cm) and/or sheet metal INRA live traps (5 × 5 × 15 cm) baited with a mix of flour and peanut butter (Giraudoux et al., 1998; Raoul et al., 2006), except MK0509ST01 which was caught alive by hand. All individuals were humanely killed. In Ningxia, E. setchuanus was found specifically in association with Ochotona huangensis in tall grasslands, along with the ubiquitous Apodemus agrarius, Cricetulus longicaudatus and Tscherskia triton (Raoul et al., 2008). In Gansu, the species belonged to a small mammal assemblage characterised by Apodemus draco and Apodemus peninsulae (Giraudoux et al., 1998). In MaErKang (Sichuan), E. setchuanus was specifically associated with Micromys minutus in cultures, where this latter species dominated (Vaniscotte et al., 2009). In RangTang (Sichuan), E. setchuanus belonged to an assemblage dominated by Apodemus peninsulae (Vaniscotte et al., 2009). E. setchuanus was never found to be a dominant species in the various small mammal assemblages, and density was low in comparison with species of the Murinae, Cricetinae and Arvicolinae sub-families (Giraudoux et al., 1998; Raoul et al., 2008; Vaniscotte et al., 2009). The species was never recorded in low vegetation habitats (eg grazed grasslands), suggesting specific requirements in terms of shelter against predators and/or food. Its altitudinal distribution ranges from 780–2300 m (minimum altitude of our study: 2500m) to 3800–4200m (maximum altitude of our study: 3825m).
Fox faeces content analysis on a sample of 7 faeces collected in South Ningxia [35.928 N, 105.681 E] revealed the presence of E. setchuanus skulls in 3 faeces.
This paper provides original information on the biology and ecology of a threatened Chinese small mammal endemic species. Our data suggest that E. setchuanus can exploit a wider range of habitats than previously anticipated (Corbet and Hill, 1992; Zhang, 1997; Smith and Xie, 2008): high vegetation habitats ranging from secondary forest to tall grassland via intermediate stages of deforestation, and agricultural landscapes (eg crop cultures). To reduce environmental problems due to soil erosion and to decrease biodiversity loss, Chinese authorities have recently promoted conservation and restoration of forest ecosystems through a set of measures including tree plantation over large areas (National Forest Conservation Programme launched in 1998, Wenhua, 2004). This new situation may provide in the near future habitats potentially favourable to E. setchuanus.
This work was supported by the European Community Programme (TS3-CT94-0270, “Hydatid and Alveolar Echinococcosis in Northwest China: Community screening, patient treatment/follow-up and transmission studies”), by the French-Chinese Programme of Advanced Research (PRA E95-01, “Landscape management and rodent community structure: consequences on transmission of alveolar echinococcosis”), by grants number RFATW-00-002 and RO1 TW001565 from the Fogarty International Center. The content is solely the responsibility of the authors and does not necessarily represent the official views of the Fogarty International Centre or the National Institutes of Health. The authors express special thanks to people who participated to field work during the different small mammal surveys (Nadine Bernard, Michaël Coeurdassier, Pierre Delattre, David Pleydell, Dominique Rieffel, Kenichi Takahashi, Amélie Vaniscotte, Junli Wang, Jean-Christophe Weidmann), and to Vitaly Volobouev for his contribution to cytogenetic analysis.
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