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A study on the distribution of Ingerana borealis was carried out in Mizoram. Based on morphological comparison with type species of the genera Ingerana, Occidozyga and Phrynoglossus and data on behaviour, Micrixalus borealis is allocated to the genus Ingerana Dubois, 1987. The study also reveals its occurrence up to 1000 m asl, previously unrecorded for this species. The species lives in lotic habitat and is well adapted not only to the slow-moving waters, but also to the fast flowing permanent streams in and near forests. The holophoront of Micrixalus borealis is redescribed and recently collected specimens from Mizoram allocated to this species are described.
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Introduction
Annandale (1912) described Micrixalus borealis from the collections of the Abor Expedition based on 11 specimens. It was only Dubois (1987) who reconsidered generic allocation of this species using the character states given in original description. He allocated the species to Phrynoglossus Peters, 1867 as it shares with this genus the absence of vomerine teeth, the enlarged, rounded finger and toe tips without grooves and the indistinct tympanum. Morphological data and recent phylogenetic studies showed that Phrynoglossus and OccidozygaKuhl& Van Hasselt, 1822 are members of a monophyletic clade(Marmayou et al., 2000; Kosuch et al., 2001) transcribed by Fei et al. (1990) and Dubois (2005) as the subfamily OCCIDOZYGINAE Fei, Ye & Huang, 1990, and by others (Inger, 1993; Frost et al., 2006) by synonymisation of Phrynoglossus with Occidozyga. Thus, Micrixalus borealis was listed as Occidozyga borealis by Frost et al. (2006). The OCCIDOZYGINAE might include further ranoid groups as molecular data (Bossuyt et al., 2006) indicate close relationship of Occidozyga lima (Gravenhorst, 1829), O. laevis (Günther, 1859) and Ingerana tenasserimensis (Sclater, 1892).
In the last decade, more specimens of Micrixalus borealis from a large range including Bangladesh, Bhutan, NE India and Myanmar have been collected and observed in the wild and the onomatophore deposited in the collection of Zoological Survey of India, Kolkata, has been studied. At present, M. borealis is known from several north-eastern states of India, including Arunachal Pradesh, Meghalaya (Matthew&Sen, 2003) and Nagaland (Ao et al., 2003). Outside India, it has also been recorded from Bhutan (Dubois, pers. comm.) and from the Rangamati Hill district in Bangladesh and the Arkan...