A NEW SPECIES OF Microgale (LIPOTYPHLA, TENRECIDAE) FROM ISOLATED FOREST IN SW MADAGASCAR 



159 



ciput of the new species also resembles the condition in M. dobsoni 

 and M. talazaci. 



Microgale nasoloi shows slight similarities in dentition to M. 

 fotsifotsy and M. soricoides Jenkins, 1993. In M. nasoloi II is less 

 robust and less pro-odont than that of M. soricoides, but more so 

 than in M. fotsifotsy and much more so than in other species of 

 Microgale; 12 is scarcely smaller than C in M. nasoloi and M. 

 soricoides; 13 is very small relative to 12 in M. soricoides, small in 

 M. nasoloi and M. fotsifotsy; C is robust but short in crown height as 

 in M. soricoides; P2 is small and P3 notably smaller than P4, unlike 

 species of Microgale other than M. dobsoni and M. talazaci. 

 Microgale nasoloi differs from other species of Microgale in its 

 bucco-lingually elongated talons of P4 to M3, and anteroposteriorly 

 compressed, bucco-lingually elongated M3. Relative sizes of the 

 teeth of the lower anterior dentition are similar to that of M. 

 fotsifotsy, with il and i2 subequal in crown height and i3 small, 

 unlike M. soricoides which has i 1 larger than i2. 



Preliminary biomolecular analysis provides strong support for a 

 sister relationship between M. nasoloi and M. fotsifotsy and equally 

 strong support for their sister relationship with M. soricoides (Olson, 

 personal communication). 



DISCUSSION 



Fig. 4 Dentition of Microgale nasoloi (FMNH 156187). Buccal view of 

 left II - P2 (above), buccal view of left il - p2 (middle), lingual view of 

 left m3 (below). Scale = 1 mm. 



passionately interested in mammals and a keen scientist and natural- 

 ist. 



Comparison with other species. Externally Microgale nasoloi 

 is readily distinguished from all other species of Microgale by the 

 distinctive soft, grey pelage. While it is similar in body size to other 

 medium sized species such as M. cowani Thomas, 1882, M. taiva 

 Major, 1896a, and M. drouhardi G. Grandidier, 1934, larger speci- 

 mens of M. fotsifotsy Jenkins et al., 1997 (for dimensions see 

 Jenkins et al., 1996, 1997) and M. brevicaudata G. Grandidier, 

 1899, the thin, relatively short tail, serves to distinguish it from all of 

 these species with the possible exceptions of M. brevicaudata and 

 M. cowani. In the case of the latter two species, M. brevicaudata has 

 a shorter tail relative to head and body and skull length than M. 

 nasoloi, while M. cowani has a relatively longer tail (ratio of TL: 

 condylo-incisive length 1.47-1.85 mean 1.70 SD 0.11 n= lOinM. 

 brevicaudata; 2.28 in M. nasoloi; 2.7-3.1 mean 3.0 SD 0.13 n = 10 

 in M. cowani). 



Microgale nasoloi differs from all other species of Microgale in 

 its cranial morphology, particularly the flattened appearance of the 

 skull, in which the shallow braincase is scarcely deeper than the 

 rostrum, the long and very constricted interorbital region and the 

 reduction of some elements of the auditory region. The presence of 

 a well-marked lambdoid crest is a feature shared with M. brevicaudata 

 and, to a greater degree, M. dobsoni Thomas, 1884 and M. talazaci 

 Major, 1896b. The long interorbital region, angular braincase with 

 prominent supra-articular facets and short vertically inclined oc- 



Ecology 



Vohibasia ( 1 5,500 ha) is part of a complex of isolated forest blocks 

 that include Zombitse (14,200 ha) and several smaller satellite 

 forests (see Fig. 1; these surface area estimates are based on 1991 

 aerial photographs (Langrand and Goodman, 1997). These forests 

 are floristically transitional between eastern humid forest and west- 

 ern dry deciduous forest (Morat, 1973; Du Puy et al., 1994), yet 

 structurally they are closer to dry deciduous forest than humid forest 

 (Fig. 5). Other than these isolated fragments, which were once 

 contiguous, little remains of this transitional forest habitat in south- 

 western Madagascar, largely as a result of clearing and burning 

 forest for cattle pasture (Salomon, 1993). In 1998, these two forest 

 blocks and the smaller satellite site of the Isoky-Vohimena Forest, 

 were declared as a new reserve known as the Pare National (PN) de 

 Zombitse- Vohibasia. 



The Vohibasia Forest generally has a relatively dense understorey, 

 that may at least in part be the result of regeneration after selective 

 removal of hardwoods a few decades ago. Average tree height is less 

 than 10 m (Petignat et al., 1997). In general the woody vegetation is 

 not particularly spiny in comparison to sub-arid thorn scrub (spiny 

 bush) slightly further west and south. The soils are fine alluvial 

 sands from the Isalo Formation, surface water is highly seasonal, 

 and there is generally little or no soil humus. 



The vertebrate communities inhabiting the Zombitse- Vohibasia 

 forests are apparently typical of those found in other arid regions. 

 The known small mammal community consists of five tenrecid 

 lipotyphlans (Tenrec ecaudatus Schreber, 1778, Setifer setosus 

 (Schreber, 1778), Echinops telfairi Martin, 1838, Microgale nasoloi 

 and Geogale aurita Milne Edwards & G. Grandidier, 1872), one 

 soricid (Suncus madagascariensis [Coquerel,1848]), two exotic 

 murine rodents (Rattus rattus [Linnaeus, 1758] and Mus musculus 

 Linnaeus, 1758) and two nesomyine rodents (Eliurus myoxinus 

 Milne Edwards, 1885 and Macrotarsomys bastardi Milne Edwards 

 & G. Grandidier, 1898) (Goodman & Ganzhorn, 1994; Goodman & 

 Rasoloarison, 1997). 



To the west of the Zombitse-Vohibasia Forest, a region character- 

 ised by a dry climate and distinct deciduous vegetation, is the 



