Crocidura sokolovi, Jenkins, Paulina D., Abramov, Alexei V., Rozhnov, Viatcheslav V. & Makarova, Olga V., 2007

Jenkins, Paulina D., Abramov, Alexei V., Rozhnov, Viatcheslav V. & Makarova, Olga V., 2007, Description of two new species of white-toothed shrews belonging to the genus Crocidura (Soricomorpha: Soricidae) from Ngoc Linh Mountain, Vietnam, Zootaxa 1589, pp. 57-68 : 63-65

Crocidura sokolovi sp. nov.

Holotype. ZIN 91232; male; body in ethanol, skull extracted; collector’s number 11; collected 5 April 2004 by A.V.Abramov.

Type locality. Ngoc Linh Mountain, west slope, 1–2 km west of the apex, Central Highlands, Kon Tum Province, Vietnam, 15º05’ N, 107º57’ E, altitude 2400 m a.s.l.

Paratypes. ZIN 91233; male; collector’s number 12; collected 5 April 2004 at altitude 2400 m a.s.l.; ZIN 91234; male; collector’s number 30; collected 12 April 2004 at altitude 2300 m a.s.l. Both bodies in ethanol, skulls extracted, collected by A.V.Abramov from the same locality as the holotype.

Diagnosis. Similar in size to C. attenuata but pelage brown and with a long tail relative to head and body length and to skull length; maxillary breadth narrow relative to interorbital and braincase breadth; braincase deep and comparatively short; first upper incisor small.

Description. A medium sized shrew with a long tail relative to head and body length (see Table 2 ). Pelage long, dense and soft; dorsal and ventral coloration brown with grayish hue; tail brownish dorsally, somewhat paler ventrally but without distinct differentiation. Dorsal surfaces of fore feet and hind feet pale buffy brown. Tail enlarged at the base, with bristle hairs covering less than the proximal third of the tail.

Ratio of Interorbital breadth to maxillary breadth at M2 0.8 ± 0.01 0.72 ± 0.04

0.79–0.82 (3) 0.65–0.76 (17) Ratio of maxillary breadth at M2 to braincase breadth 0.62 ± 0.001 0.68 ± 0.05

0.62 (3) 0.64–0.77 (17) Ratio of braincase height to braincase length 0.68 ± 0.02 0.62 ± 0.02

0.66–0.7 (3) 0.59–0.64 (16) Skull medium in size (see Table 2 ). Anterior region of skull (see Fig. 3 ) slender in appearance; maxillary region of skull relatively narrow; zygomatic plate broad and posteriorly positioned; lacrymal foramen level with parastyle of M2 or sulcus between the parastyle and mesostyle of M2; interorbital region relatively broad and short; braincase broad, rounded and domed in appearance; anterior region of sinus canal rises steeply and continues in a shallow curve towards the tabellum; superior articular facets sloping and rounded, inferior articular facets narrow; distance between superior and inferior articular facets short; occiput deep and rounded; palate narrow between first premolars; palatal suture posterior to protocone of M2. Mandibular corpus and ascending ramus slender.

Dentition. First upper incisor small, with shallow alveolar region and comparatively short, slender principal cusp. Talon of P4 broad, sub-oblong in shape with a shallowly concave posterior margin. Talonid of m3 large, with distinct talonid basin.

Comparisons. Similar in head and body size to C. attenuata , but with a longer tail relative to head and body length (see Table 2 ). The pelage of C. sokolovi is longer, softer and brownish gray in coloration in contrast to that of C. attenuata which has a dark gray pelage.

The skull of C. sokolovi is similar in overall size to that of C. attenuata but differs in shape and proportions (see Fig. 3 and Table 2 ). The maxillary region of C. sokolovi is narrower relative to the interorbital region, with a correspondingly more vertically and posteriorly positioned zygoma in comparison to the broad, angular and flared maxillary region of C. attenuata and more sloping and anteriorly positioned zygoma; the lacrymal foramen is level with the metastyle of M1 or the junction of M1 and M 2 in C. attenuata but level with the parastyle or sulcus between the parastyle and mesostyle of M 2 in C. sokolovi . The braincase of C. sokolovi is comparatively broad, deep and rounded in appearance in contrast to the angular, comparatively narrower, shallower and long braincase of C. attenuata . In dorsal and lateral view the occipital condyles project obviously posteriorly to the occiput, whereas in C. sokolovi they are only slightly evident. The palatal distance between anterolingual regions of first upper premolars is less in C. sokolovi than in C. attenuata . The palatal suture lies posteriorly to the protocone of M 2 in C. sokolovi , anterior to the protocone in C. attenuata .

The first upper incisor of C. sokolovi is markedly smaller than that of C. attenuata which has a large principal cusp and deep alveolar region. The anterior face of P4 lies at a shallow angle relative to the midline of the palate in C. sokolovi in contrast to the steeper angle in C. attenuata . The shape of the talon of P4 differs between the two species (see Fig. 2 ), being sub-oblong in C. sokolovi whereas in C. attenuata the hypocone is set further towards the midline so that the lingual edge is more curved and the posterior border of the tooth is markedly concave.

Distribution. Currently known only from Ngoc Linh Mountain, Kon Tum Province, Vietnam. The specimens were collected in different localities on the west slope of Ngoc Linh at high altitudes of 2300–2400 m.

Habitat. The specimens were collected in high montane broadleaf evergreen forest and in elfin forest.

Etymology. The new species is named in honour of the late Academician Vladimir E. Sokolov (1928– 1998), the famous Russian zoologist. He initiated collaborative Russian-Vietnamese zoological studies in Vietnam and founded the Joint Russian-Vietnam Tropical Research and Technological Centre.

Figures

FIGURE 2. Upper row: teeth of Crocidura zaitsevi ZIN 91224. Left: semi-oblique occlusal view of left upper premolar and first molar; right: lingual view of right lower third molar. Lower row: Comparison of left upper premolar and first molar of Crocidura sokolovi ZIN 91232 (left) and Crocidura attenuata ZIN 91229 (right). Scale 1 mm.

FIGURE 3. Comparison of dorsal and ventral views of skulls and lateral views of skulls and mandibles of Crocidura sokolovi ZIN 91232 (on the left of each view) and Crocidura attenuata ZIN 91229 (on the right).

Tables

TABLE 2. Comparison of external, cranial measurements, and ratios of Crocidura sokolovi and C. attenuata from Vietnam. Measurements are given as mean, followed by standard deviation, range and number of specimens in parentheses.

	Crocidura sokolovi	Crocidura attenuata
Head and body length	72.67 ± 3.77 70–78 (3)	74.9 ± 8.19 62–91 (15)
Tail length	66 ± 1.41 65–68 (3)	49.87 ± 5.35 41–61 (15)
Hindfoot length	14 ± 0 14 (3)	13.44 ± 0.90 11–15 (14)
Condylobasal length	19.6 ± 0.64 18.8–20.36 (3)	19.65 ± 0.61 18.27–21.2 (16)
Upper toothrow length	8.75 ± 0.37 8.32–9.22 (3)	8.82 ± 0.28 8.19–9.45 (17)
Incisor to 3rd unicuspid length	3.86 ± 0.26 3.55–4.19 (3)	3.95 ± 0.20 3.53–4.52 (16)
Maxillary breadth at M2	5.91 ± 0.09 5.82–6.03 (3)	6.21 ± 0.25 5.74–6.79 (17)
Least interorbital breadth	4.74 ± 0.14 4.59–4.93 (3)	4.45 ± 0.18 4.09–4.72 (17)
Postglenoid breadth	6.14 ± 0.11 6.04–6.29 (3)	6.36 ± 0.22 6.01–6.83 (16)
Braincase breadth	9.52 ± 0.14 9.37–9.71 (3)	9.12 ± 0.35 8.21–9.63 (17)
Braincase height	5.2 ± 0.09 5.12–5.32 (3)	4.79 ± 0.26 4.3–5.24 (17)
Braincase length	7.63 ± 0.15 7.48–7.84 (3)	7.81 ± 0.31 7.39–8.57 (17)
Anterior width of M2	2.03 ± 0.06 1.95–2.09 (3)	2.14 ± 0.1 1.96–2.31 (16)
M3 length	0.72 ± 0.01 0.71–0.73 (3)	0.68 ± 0.06 0.59–0.78 (16)
Mandible length	12.73 ± 0.6 11.94–13.38	12.82 ± 0.45 12.13–14.01 (16)
Mandible toothrow length	8.14 ± 0.4 7.66–8.63 (3)	8.23 ± 0.29 7.6–8.95 (16)
Mandible height	4.76 ± 0.21 4.47–4.94 (3)	4.89 ± 0.2 4.52–5.34 (16)
Ratio of tail length to head and body length	0.91 ± 0.03 0.87–0.93 (3)	0.67 ± 0.1 0.47–0.81 (15)
Ratio of tail length to condyloincisive length	3.27 ± 0.06 3.2–3.35 (3)	2.47 ± 0.22 2.13–2.87 (14)