Myosorex meesteri, Taylor & Kearney & Kerbis Peterhans & Baxter & Willows-Munro, 2013

Taylor, Peter John, Kearney, Teresa Catherine, Kerbis Peterhans, Julian C., Baxter, Roderick M. & Willows-Munro, Sandi, 2013, Cryptic diversity in forest shrews of the genus Myosorex from southern Africa, with the description of a new species and comments on Myosorex tenuis, Zoological Journal of the Linnean Society 169 (4), pp. 881-902 : 897-898

MYOSOREX MEESTERI SP. NOV.

MEESTER’ S FOREST SHREW

Holotype

DM 4693, an adult female collected by Teresa Kearney, Albert Kumirai, Peter Taylor, and Peter Wright on 10 December 1995. The specimen is represented by a skin and skull in good condition. The external measurements are as follows (in mm): total length 120; tail length 40, hindfoot length (cum unguis) 15; ear 10. Body mass was 12 g. The extremely small cranial size is indicated by cranial measurements (in mm) as follows (see abbreviations under Material and methods): CI 20.6; PPL 9.46; UTR 8.82, LIW 4.05; BW 6.22; GW 10.3; LTR 8.1; M3L 1.48; M3 W 0.8; P4–M3 5.11. The skull, dentition, and mandible are illustrated in Figure 7 . The anterior margin of the medial palatal foramen overlaps with the posterior margins of the two lateral foramina ( Fig. 7 ). The fourth upper unicuspid is tiny and bordered by teeth, which are almost touching because of the curved extension of the parastyle of the third upper unicuspid ( Fig. 7 ). The pelage coloration is brownish rather than blackish above and below, with pale hindfoot and bicoloured tail, similar to M. varius .

Type locality

Chingamwe Estates, 15 km south-east of Juliasdale, Inyanga Mountains, eastern Zimbabwe (18.4625°S, 32.753°E). The specimen was trapped with a Sherman trap in tall grassland bordering a young pine plantation.

Paratypes

An additional 21 shrews were collected from the same series ( DM: 4641, 4642, 4643, 4644, 4645, 4646, 4647, 4648, 4651, 4652, 4655, 4656, 4664, 4665, 4678, 4679, 4680, 4688, 4694, 5003, 5004).

Referred specimens: See the Appendix.

Etymology

This species is named after J.A.J. ‘Waldo’ Meester who made a significant contribution to African mammalogy, most particularly through his authorship of two landmark volumes: Mammals of Africa: an Identification Manual (1971–1977) and Classification of Southern African Mammals (1986). He was a shrew specialist whose early work drew attention to the enigmatic taxonomic status of Myosorex from Zimbabwe ( Meester, 1958), which we now name in his honour.

Diagnosis

Individuals of this species can be readily distinguished from South African Myosorex species by the presence of a ‘tiny’ fourth upper unicuspid tooth, bordered by teeth that are touching or almost touching because of a curved extension of the parastyle of the anterior premolar ( Fig. 6 ; Table 7). This feature, together with small cranial size ( Fig. 4 ; Table 3), is shared with Tanzanian species ( M. geata and M. kihaulei ); however, M. meesteri sp. nov. is clearly distinguished on molecular and biogeographical grounds from the Tanzanian species ( Fig. 2 ).

Description

This is a small species of Myosorex , particularly in cranial dimensions ( Table 3). In its pelage colour it is most like M. varius , having brownish rather than blackish dorsal pelage and relatively pale hindfeet and a bicoloured tail. Similarly, in its predominantly overlapping medial and lateral palatal foramina it is most like M. varius ; however, in a few cases (13%) the foramina do not overlap or the medial foramina may be missing (8%; Table 7).

Distribution and biology

The species is endemic to the Eastern Zimbabwean montane forest–grassland mosaic ecoregion of the Eastern Highlands of Zimbabwe and of Mount Gorongosa, Gorongosa National Park of Mozambique. The type series from Inyanga Mountains of Zimbabwe were all collected in moist grasslands, sometimes bordering a dam or pine plantations, but never in forest. On Mount Gorongosa, it was by far the most common small terrestrial mammal caught, comprising almost 50% of all captures. It is restricted to the moist montane forest (1120–1580 m a.s.l) and alpine meadows (1680–1700 m a.s.l.), and is not found in the drier scrubbier areas, nor even amid the gallery forest below (elevation 790–940 m a.s.l.).

Figures

Figure 2. Maximum-likelihood phylogeny (left) and maximum clade probability tree (right), inferred from the combined analysis of molecular data (mitochondrial DNA control region, 16S rRNA, and the nuclear intron STAT). The newly resurrected or described species Myosorex tenuis and Myosorex meesteri sp. nov. are in bold. Maximum-likelihood bootstrap and posterior probability (in that order) values are shown for nodes of the maximum-likelihood tree. Values above nodes of the maximum clade probability tree indicate the posterior mean divergence dates in millions of years before present. Shaded bars indicate the 95% highest posterior density (HPD) credibility intervals. Values below the nodes indicate posterior probability values generated during the BEAST dating analysis.

Figure 4. Canonical variate analysis (CVA) of ten logtransformed craniometric variables in six operational taxonomic units (OTUs) of Myosorex from southern and eastern Africa; ○, Zimbabwe–Mozambique; ●, Myosorex kihaulei and Myosorex geata (Tanzania); ▲, east Soutpansberg; △, north Drakensberg + west Soutpansberg; ×, Myosorex varius; +, Myosorex cafer (topotypic). The first two canonical vectors explained 72.7 and 14.7%, respectively, of the total variance.

Figure 6. Photographs of the fourth unicuspid and adjacent molars in the upper tooth rows of: (A) TM 10448, Myosorex sclateri (Ngoye Hills, KwaZulu-Natal); (B) TM 41824, Myosorex varius (Karkloof, KwaZulu-Natal); (C) TM 793, Myosorex cf. tenuis (Wakkerstroom, Mpumalanaga); (D) TM 25843, Myosorex cf. tenuis (Entabeni, Soutpansberg Range, Limpopo); (E) TM 34613, Myosorex meesteri sp. nov. (Mount Selinda, Chirinda Forest, Zimbabwe).

Figure 7. Dorsal, ventral, and lateral views of the cranium and lateral view of the mandible of the holotype of Myosorex meesteri sp. nov. (DM 4693). Scale bar: 2 mm.