A new species group from the Daphnia curvirostris species complex (Cladocera: Anomopoda) from the eastern Palaearctic: taxonomy, phylogeny and phylogeography

Abstract

The eastern Palaearctic is a centre of diversity for freshwater cladocerans (Crustacea), but little is known about the evolution and taxonomy of this diversity. Daphnia curvirostris is a Holarctic species complex that has most of its diversity in the eastern Palaearctic. We examined the phylogeography, rates of evolution and taxonomic status for each clade of the D. curvirostris complex using morphological and genetic evidence from four genes. The cybertaxonomical and morphological evidence supported an eastern Palaearctic clade, with at least four species (described here as the Daphnia korovchinskyi sp. nov. group) having diagnostic morphological characters. We also detected convergent morphological characters in the D. curvirostris complex that provided information about species boundaries. Two of the new species (Daphnia koreana sp. nov. and Daphnia ishidai sp. nov.) are known from single ponds and are threatened by human activity. Divergence time estimates suggested an ancient origin (12–28 Mya) for the D. korovchinskyi group, but these estimates are complicated by the small number of calibration points.

One More “Living Fossil”: Mesozoic Lineage Differentiation, Morphological Stasis and Weak Phylogeographic Structure in Eurasia in the Bosminopsis Deitersi Group (Crustacea: Cladocera: Bosminidae)

“…For Cladocera, Pleistocene mass extinction in the Holarctic due to glaciation and aridization [122] also has phylogeographic support [123,124]. But phylogeographic publications referring to previous epochs with non-Holarctic samples are rare [7,54]. For Bosminopsis, our results suggest a Mesozoic differentiation of the lineages and then survival of only two main lineages in the mid-Caenozoic.…”

“…Groups "Eurasia", "Thailand", and "Americas" are well-differentiated, while differences between two sub-clades of Eurasia are less than 0.5%. The two subclades may result from moderately separated mitochondrial lineages, which are common in cladocerans [53,54]. Again, North and South American populations may be separate species, but more sequences are needed to test this hypothesis.…”

“…Most probably, the Paci c Coast Region ("Far East") was the center of B. zernowi diversi caton, as this region is the richest in mitochondrial haplotypes (Fig. 3), and is often a center of diversity for cladoceran taxa [54].…”

“…This divergence involves ne-scaled characters such as the mucro-like spine number, male basal spine, and antenna I appearance and armature. Such subtle differences among species are known in other cladoceran groups [54] but can only rarely be associated with a timescale.…”

“…Our approach to cybertaxonomic taxon delimitation was described in a previous paper [54]. An integrated approach based on genetic species delimitation combined with "traditional" morphological taxonomy was used to estimate the species richness.…”