A mitochondrial genome phylogeny of voles and lemmings (Rodentia: Arvicolinae): Evolutionary and taxonomic implications

Arvicolinae is one of the most impressive placental radiations with over 150 extant and numerous extinct species that emerged since the Miocene in the Northern Hemisphere. The phylogeny of Arvicolinae has been studied intensively for several decades using morphological and genetic methods. Here, we sequenced 30 new mitochondrial genomes to better understand the evolutionary relationships among the major tribes and genera within the subfamily. The phylogenetic and molecular dating analyses based on 11,391 bp concatenated alignment of protein-coding mitochondrial genes confirmed the monophyly of the subfamily. While Bayesian analysis provided a high resolution across the entire tree, Maximum Likelihood tree reconstruction showed weak support for the ordering of divergence and interrelationships of tribal level taxa within the most ancient radiation. Both the interrelationships among tribes Lagurini, Ellobiusini and Arvicolini, comprising the largest radiation and the position of the genus Dinaromys within it also remained unresolved. For the first time complex relationships between genus level taxa within the species-rich tribe Arvicolini received full resolution. Particularly Lemmiscus was robustly placed as sister to the snow voles Chionomys in the tribe Arvicolini in contrast with a long-held belief of its affinity with Lagurini. Molecular dating of the origin of Arvicolinae and early divergences obtained from the mitogenome data were consistent with fossil records. The mtDNA estimates for putative ancestors of the most genera within Arvicolini appeared to be much older than it was previously proposed in paleontological studies.

Leaf venation patterns in Saxifraga L. species (Saxifragaceae) of Indian Western Himalaya and its taxonomic implications

In the present study leaf venation types of 30 Saxifraga L. species, found in Indian Western Himalaya, were studied. Out of these, leaf venation patterns of 20 species were not previously studied. In total, five major types of leaf venations- acrodomous (perfect-basal; perfect-suprabasal; imperfect-suprabasal), camptodromous (eucamptodromous), campylodromous, hyphodromous, and palinactinodromous – were recorded. Section Micranthes show palinactinodromous; section Ciliatae show mainly acrodromous; section Mesogyne show palinactinodromous; and sect. Porphyrion show acrodromous, eucamptodromous and hyphodromous types of venation. Palinactinodromous appear as the ancestral venation type.