Confirmation through genetic analysis of the existence of many local phyloclades of the genus Simocephalus (Crustacea, Cladocera) in China.

Xiaona Huang,Xinlu Shi,Alexey A Kotov,Fukang Gu,Donald James Colgan

doi:10.1371/journal.pone.0112808

Abstract

Previously, a series of Simocephalus taxa (Cladocera: Daphniidae) from China were described. Most were proposed to be junior synonyms in the last revision of the genus. Using original material from China and data from GenBank, we investigate the biodiversity and phylogeny of Simocephalus using sequences of the cytochrome c oxidase subunit I (COI) and the nuclear 18S genes. In both cases, neighbor-joining, maximum likelihood and Bayesian inference analyses led to highly congruent tree topologies. The grouping of the deeper clades agrees with the inter-generic classification of Orlova-Bienkowskaja (2001). Only the populations of S. serrulatus from Eurasia and North America seem to be closely related, and there are no other shared species between the two continents. Our study unambiguously confirms the existence of many lineages from the subgenera of Simocephalus (Echinocaudus) and Simocephalus s.str. in China, but their morphology needs to be reexamined by taking a wider range of characters (e.g., of female thoracic limbs and adult males) into consideration.

Highlights

Cladocera (Crustacea: Branchiopoda) is an important group of micro-crustaceans predominantly inhabiting continental water bodies of different, if not all, types [1]
The aim of this paper was to investigate the biodiversity and phylogeny of Simocephalus in China using the sequences of cytochrome c oxidase subunit I (COI) and nuclear 18S genes
The NJ, Maximum likelihood (ML), and Bayesian inferences (BI) phylogenetic analyses led to highly congruent tree topologies (Fig. 1)

Summary

Introduction

Cladocera (Crustacea: Branchiopoda) is an important group of micro-crustaceans predominantly inhabiting continental water bodies of different, if not all, types [1]. Among the most famous peculiarities of these animals are their sexually produced diapausing eggs, which are resistant to desiccation and other unfavourable conditions and are important propagules for passive dispersal by different modes, i.e. by birds [1], [2] Their strong ability to survive passive dispersal was one reason why cladoceran species’ distributions were for a long time accepted as cosmopolitan, but since the 1970’s this concept has changed radically to the so-called non-cosmopolitanism, or ‘‘continental endemism’’ [3], [4], [5], [6]. Many of the taxa were regarded by Orlova-Bienkowskaja [9] as junior synonyms of species described earlier

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Discussion

Conclusion