Confirmation through Genetic Analysis of the Existence of Many Local Phyloclades of the Genus Simocephalus (Crustacea, Cladocera) in China

Cladocera) in China. PLoS ONE 9(11): e112808. doi:10.1371/journal.pone.0112808 Confirmation through Genetic Analysis of the Existence of Many Local Phyloclades of the Genus Simocephalus (Crustacea, Cladocera) in China Xiaona Huang 0 Xinlu Shi 0 Alexey A. Kotov 0 Fukang Gu 0 Donald James Colgan, Australian Museum, Australia 0 1 School of Life Science, East China Normal University , Shanghai, China, 2 Hangzhou Key Laboratory for Animal Adaptation and Evolution , Hangzhou Normal University , Hangzhou , China , 3 A.N. Severtsov Institute of Ecology and Evolution , Leninsky Prospect 33, Moscow , Russia 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 OrlovaBienkowskaja (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. - Competing Interests: The authors have declared that no competing interests exist. 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 1970s this concept has changed radically to the so-called non-cosmopolitanism, or continental endemism [3], [4], [5], [6]. The correctness of this idea is now confirmed for some genera and species groups [6], [7], [8], [9], although the real diversity and distribution of taxa in other groups needs to be accurately studied. Some cladocerans, such as species of the genus Simocephalus Scho dler, 1858 (family Daphniidae Straus, 1820), are used as environmental indicators and standard test objects in toxicological studies [10], [11]. Representatives of this genus are very common in vegetation, the open littoral zones of ponds and lakes, the semi-static affluents of rivers and pools and puddles of various types. Based on morphological characters, Orlova-Bienkowskaja [9] recognized 20 valid species in this genus belonging to five subgenera: Simocephalus s. str., Simocephalus (Coroncephalus), Simocephalus (Acutirostratus), Simocephalus (Echinocaudus), and Simocephalus (Aquipiculus). Many of the taxa were regarded by Orlova-Bienkowskaja [9] as junior synonyms of species described earlier. Several species of Simocephalus were identified and then redescribed by Chinese authors [12], [13], [14], [15], [16], [17], [18]. Only Simocephalus heilongjiangensis Shi & Shi, 1994, which is widely distributed in the tropics, was regarded as a valid species by Orlova-Bienkowskaja [9]. Among the taxa synonymized by Orlova-Bienkowskaja [9], there were several, earlier-described species from China, such as S. himalayensis Chiang & Chen, 1974 and S. beianensis Shi & Shi, 1994. In addition, S. himalayensis microdus Chen, Shi & Shi, 1992 was not discussed by OrlovaBienkowskaja [9], and its taxonomic status remains unclear. Therefore, there is a conflict that needs to be resolved in the understanding of the taxonomy of the genus between Western investigators, who mainly follow Orlova-Bienkowskaja [9], and Chinese researchers. Near the end of the 20th century, a powerful new tool for testing taxonomic hypotheses, molecular phylogenetics, became available. In cladocerans, it was mainly applied to species of different Daphnia groups [5], [19]. However, molecular phylogenetic studies were subsequently conducted for some other genera and families of the cladocerans [6], [20], [21], [22]. Simocephalus cf. vetulus Simocephalus cf. vetulus Simocephalus cf. vetulus Simocephalus beianensis Simocephalus vetuloides Simocephalus vetuloides Simocephalus himalayensis Simocephalus cf. congener S. sp. = Simocephalus serrulatus in Young et al. 2012 Simocephalus sibiricus Simocephalus sibiricus Simocephalus sibiricus Simocephalus heilongjiangensis Simocephalus serrulatus Simocephalus serrulatus Daphnia cf. similoides Daphnia cf. magna Simocephalus himalayensis microdus Longhe farm in Heilongjiang province, China Simocephalus himalayensis microdus Harbin Normal University, Heilongjiang province, China Boyang lake in Jiangxi province, China Near the railway station of Beian, Heilongjiang province, China Shangshan village, Fuyang, Zhejiang province, China Tongzigou, Muleng, Heilongjiang province, China The wetland in plateau from Xizang, China Sognsvan Lake, Norway Shangshan village, Fuyang, Zhejiang province, China Boyang lake, Jiangxi province, China. Qilin mountain, Jiangxi province, China Linhai reservoir in Heilongjiang province, China Longhe farm in Heilongjiang province, China Zhoushan in Zhejiang province, China Longhe farm in Heilongjiang province, China Wetland in plateau, Xizang, China Yuhang, Hangzhou,Zhejiang province, China Tongzigou, Muleng, Heilongjiang province, China Latitude, longitude, and altitude N44u23.1199, E130u27.4649, 516 m Shangshan village, Fuyang, Zhejiang N30u07.5999, province, China E119u46.7469, 98 m Haining of Zhejiang province, China N30u25.8169, E120u26.7769 Collection catalog numbers N indicates the North latitude, and E indicates East longitude. doi:10.1371/journal.pone.0112808.t001 COI barcoding studies for the Simocephalus genus were started by Elas-Gutierrez et al. [23]. These authors recognized eight taxa in tropical Mexico and Guatemala, including two species that are habitually similar to S. mixtus, two species habitually similar to S. exspinosus, and two species similar to S. punctatus. Then, Jeffrey et al. [24] detected six species in Arctic Canada including two different clades of S. cf. serrulatus and four clades of S. cf. punctatus. Young et al. [25], in contrast, found that all of the populations from Taiwan classified as S. vetulus, S. vetuloides and S. mixtus actually belonged to a single species, which compromises the taxonomy according to Orlov (...truncated)