Crocidura zaitsevi, 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 : 59-63

Crocidura zaitsevi sp. nov.

Holotype. ZIN 91224; collector’s number 31; female, body in ethanol, skull extracted, collected 11 April 2004 by A.V. Abramov.

Type locality. Ngoc Linh Mountain, west slope, 1–2 km west of apex, Central Highlands, Kon Tum Province, Vietnam, 15º05’ N, 107º57’ E, altitude 2300 m a.s.l.

Paratypes. ZIN 91214, female, collector’s number 6; ZIN 91215, male, collector’s number 8; ZIN 91216, female, collector’s number 9; ZIN 91217, female, collector’s number 16; ZIN 91218, male, collector’s number 17; ZIN 91219, male, collector’s number 20; ZIN 91220, male, collector’s number 21; ZIN 91221, female, collector’s number 25; ZIN 91222, male, collector’s number 26; ZIN 91223, female, collector’s number 27; ZIN 91225, male, collector’s number 33. All specimens are bodies in ethanol with skulls extracted, collected by A.V. Abramov from the same locality as the holotype, at altitudes from 1650 to 2300 m, between 2–13 April 2004.

Diagnosis. Very small in size, comparable only to C. kegoensis and an unnamed species (Lunde, in preparation), and smaller on average in external and cranial measurements than C. wuchihensis . Distinguished from these species by the moderately long tail and the long narrow rostrum and broad interorbital region relative to maxillary breadth of the skull. First upper incisor pro-odont. Third lower molar with a well developed talonid.

Description. Very small sized, head and body length 48–58 with a moderately long tail, ranging from 62– 81% of head and body length. Dorsal pelage gray with a slightly brownish hue, grading into the slightly paler ventral pelage, with individual hairs uniformly coloured from the base to the tips. The tail is similarly coloured to the body, being slightly paler on the ventral surface. The dorsal surfaces of the fore and hind feet are markedly paler than the body, with the lateral surfaces slightly darker brown than the inner surfaces. The dorsal surface of the feet is covered with short hairs. Ears dark gray. Bristle hairs are present on the proximal two thirds of the tail.

Skull (see Fig.1 ) with a long and moderately narrow rostrum, narrow maxillary region and relatively broad interorbital region. The interorbital region is long and increases gradually in breadth from anterior to posterior. The superior articular facets are at a shallow angle to the long axis of the skull so that the braincase broadens gradually from the orbital region; in lateral view there is a gradual increase from rostrum to the interorbital region then a change in degree of slope to the rounded and slightly domed braincase. Mandible slender.

First upper incisor (I1) pro-odont, projecting markedly beyond anterior border of the premaxillary, talon well developed approximately half the height of the first upper unicuspid (Un1). The upper unicuspids are well-spaced; Un1 is very large, equal to or slightly less in height than the principal cusp of I1 but less than the height of the paracone of the upper premolar (P4). The second upper unicuspid (Un2) is approximately half the height of Un1 but only slightly smaller than the third upper unicuspid (Un3). The parastyle of P4 is well defined, shorter than Un3, the paracone is robust, the protocone and hypocone are moderately prominent and the posterior border is concave. The talon of P4 projects beyond the protocone of the first upper molar (M1) but is approximately level with the hypocone. The third upper molar (M3) is moderately well developed with a broad talon. The first lower incisor (i1) has 2 low cusps and a well marked postero-buccal cingulum. The first lower premolar (p1) is elongated, approximately half the lower border of the tooth is in contact with i1, and its posterior border is slightly overlapped by the second lower premolar (p4). The third lower molar (m3) is approximately two thirds the size of the second lower molar (m2) with a well developed talonid. The talonid of m3 has a prominent entoconid, well developed entoconid ridge and talonid basin (see Fig. 2 ).

Comparisons. This is a very small shrew, comparable in size to the recently described Crocidura kegoensis and another undescribed species (Lunde, in preparation). It is smaller than most specimens of Crocidura wuchihensis , the other small sized shrew known to occur in Vietnam (see Table 1 ). It is considerably smaller than the other species of Crocidura that are found in Vietnam.

Note. All measurements of C. kegoensis and external measurements of C. wuchihensis are quoted from Lunde et al. (2004). All measurements of C. zaitsevi were taken by AA, cranial measurements of C. wuchihensis were taken by PJ.

The new species lacks the conspicuous blackish mystacial patches on the head characteristic of C. kegoensis and the body is grayer in coloration, similar to that of C. wuchihensis . All three species are small (see Table 1 ) with an overlap in head and body length between the smallest, C. kegoensis and C. zaitsevi , and between C. zaitsevi and C. wuchihensis which averages larger. Crocidura kegoensis has a shorter tail relative to head and body length (56.25%) than C. zaitsevi (61.82–81.25% mean 69.66%).

Crocidura zaitsevi differs in cranial and dental morphology from C. wuchihensis and C. kegoensis . The rostrum and maxillary region are broader, the interorbital region shorter (and more bulbous), in C. wuchihensis than C. zaitsevi . The cribriform is closer to mid-region of the interorbital in C. wuchihensis but positioned more posteriorly in C. zaitsevi . In dorsal view the superior articular facets of the braincase lie at a more acute angle to the long axis of the skull so that the braincase broadens more abruptly in C. wuchihensis than C. zaitsevi , and in lateral view the profile gradually increases from the rostrum to deep braincase in C. wuchihensis unlike C. zaitsevi .

The rostrum and the length of the anterior dentition (I-Un3) are shorter, the maxillary and postglenoid broader, and the relative interorbital to maxillary breadth less in C. kegoensis (76.6%) than C. zaitsevi (80.0– 85.95% mean 83.12%) The braincase of C. kegoensis is noticeably more angular and flattened in comparison with the domed, rounded braincase of C. zaitsevi .

The markedly projecting I1 of C.zaitsevi with its large talon differs from the falciform or sickle-shaped I1 of C. kegoensis in which the talon is smaller. The first upper unicuspid is very large in both species but Un2 is smaller relative to Un1 and Un 3 in C. kegoensis than in C. zaitsevi . The two species differ markedly in the morphology of P4 (see Figs. 1–2 and Lunde et al. 2004): the parastyle is well defined in both species but while obviously shorter than Un 3 in C. zaitsevi , it is nearly as tall as the preceeding tooth in C. kegoensis ; the paracone (of Dannelid, 1998, the metacone of Meester, 1963) is tall and thin, the hypocone barely perceptible and the posterior border deeply concave in C. kegoensis , while in C. zaitsevi the paracone is robust, the protocone and hypocone are moderately prominent and the posterior border is moderately concave. This deep concavity of the posterior border of P4 of C. kegoensis , and a similar but less marked emargination of the succeeding molars reveals the underlying bone between each of the teeth, whereas in C. zaitsevi the posterolingual region of the talon of each tooth is in contact or nearly so with the antero-lingual region of the succeeding tooth. The second upper molar (M2) is broader and M3 slightly longer in C. kegoensis than C. zaitsevi . The dorsal surface of i1 of C. zaitsevi has two cusps, whereas that of C. kegoensis is acuspulate. In C. kegoensis m3 is slightly larger than half the size of m2 and the talonid is reduced to a minute entoconid and hypoconid, in contrast to that of C. zaitsevi which is larger relative to m2 and with a well developed talonid.

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 altitudes from 1650 to 2300 m.

Habitat. The specimens were collected in medium to high montane broadleaf evergreen forest.

Etymology. The new species is named in honour of the late Dr. Mikhail V. Zaitsev (1954–2005) of the Zoological Institute RAS (Saint-Petersburg, Russia), important for his studies of the taxonomy of Recent and fossil insectivores. He began the investigation of these Vietnamese shrews but unfortunately did not have time to finish it.

Figures

FIGURE 1. Dorsal, ventral and lateral views of the cranium of Crocidura zaitsevi ZIN 91224.

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.

Tables

TABLE 1. Comparison of external and cranial measurements of Crocidura kegoensis, C. zaitsevi and C. wuchihensis. Measurements in millimetres are presented as the mean and standard deviation, range and number of specimens in parentheses.

	Crocidura kegoensis	Crocidura zaitsevi	Crocidura wuchihensis
Head and body length	48	53 ± 3 48–58 (12)	58.9 ± 3.3 55–65 (9)
Tail length	27	37 ± 2 33–41 (12)	38.6 ± 2.3 35–42 (9)
Hindfoot length	10	10 ± 1 8–11 (12)	11.3 ± 0.8 10–13 (9)
Ear length	5	7 ± 1 5–8 (12)	7.7 ± 0.8 6–9 (9)
Condylobasal length	14.9	14.79 ± 0.34 14.19–15.3 (12)	15.57 ± 0.23 15.32–16.01 (6)
Upper toothrow length	6.5	6.51 ± 0.16 6.23–6.78 (12)	6.88 ± 0.21 6.58–7.52 (6)
Incisor to 3rd unicuspid length	2.6	2.79 ± 0.08 2.64–2.95 (12)	3.12 ± 0.14 2.95–3.29 (6)
Maxillary breadth at M2	4.7	4.38 ± 0.11 4.22–4.55 (12)	4.75 ± 0.11 4.59–4.89 (6)
Least interorbital breadth	3.6	3.64 ± 0.1 3.4–3.75 (12)	3.69 ± 0.14 3.46–3.85 (6)
Postglenoid breadth	5.2	4.78 ± 0.14 4.46–5.0 (12)	5.21 ± 0.14 4.95–5.39 (6)
Braincase breadth	7.4	7.51 ± 0.18 7.21–7.78 (6)	7.51 ± 0.18 7.21–7.78 (6)
Braincase height	3.8	3.75 ± 0.12 3.53–3.96 (11)	3.9 ± 0.12 3.73–4.12 (6)
Braincase length	6.2	6.16 ± 0.16 5.9–6.36 (11)	6.77 ± 0.17 6.44–6.9 (6)
Anterior width of M2	1.6	1.44 ± 0.05 1.36–1.56 (12)	1.58 ± 0.07 1.5–1.67 (6)
M3 length	0.6	0.54 ± 0.04 0.47–0.59 (12)	0.54 ± 0.08 0.44–0.65 (6)
Mandible length		9.29 ± 0.21 8.77–9.59 (12)	9.72 ± 0.2 9.46–10.04 (6)
Mandible toothrow length		6.06 ± 0.14 5.73–6.22 (12)	6.37 ± 0.18 6.12–6.6 (6)
Mandible height		3.49 ± 0.12 3.28–3.65 (12)	3.74 ± 0.1 3.55–3.9 (6)