Species Diversity Of Lecane、Brachionus And Trichocerca In Hainan Island, China

Only few zooplankton studies on Hainan island, and the rotifer fauna in particular is poorlyknown. We sampled134localities in Hainan island and investigated their rotifer fauna in2010.11,2011.5and2011.8.46(44%) species of the genera Lecane were identified, of which17species are new to Hainan island, and nine are new to China, L.papuana (Murray,1913), L.luna(Mülle,1776), L.bulla (Gosse,1851), L.quadridentata (Ehrenberg,1832), L.pyriformis (Daday,1905) and L.hamata (Stokes,1896) are the most common species in this genus;20species and22subspecies or formae (40%) of Brachionus were identified, with17species new to Hainanisland, and11are new to China, Several species are common:B.quadridentatus quadridentatusHermann,1783, B.quadridentatus f. cluniorbicularis Skorikov,1894, B.quadridentatus f.brevispinus Ehrenberg,1832, B.calyciflorus f. amphiceros Ehrenberg,1838, B.angularisangularis Gosse,1851;17(16%of the total) species of Trichocerca were identified, of whichfour are new to Hainan island and two new to China, T.pusilla (Jennings,1903), T.similis(Wierzjski,1893) and T.tenuior (Gosse,1886) are very common in Hainan island.The biographical affinities of Lecane, Brachionus and Trichocerca show that the majority ofspecies (or members of species complexes) on Hainan have a circumtropical or cosmopolitandistribution. There are16cosmopolitan taxa,18tropicopolitans taxa, two pantropical taxa ofLecane, and one endemic of Lecane for the Oriental Zone: L.kunthuleensis Chittapun,Pholpunthin&Segers,2003. The composition of Lecane is relative similar to the Australianregion. There are15cosmopolitan taxa, six tropicopolitans taxa, and four pantropical taxa ofBrachionus, the composition of Brachionus is relative similar to Oriental region. Most of theTrichocerca (77%) are cosmopolitan, with no endemid for Hainan, and the composition ofTrichocerca is relative similar to Austrilian region. We found six new records for Asia in thelatter three genera: L.cornuta (Müller,1786), L.rugosa (Harring,1914), L.margalefi De Manuel,1994, B.sericus Rousselet,1907, T. agnatha Wulfert,1939and T.intermedia (Stenroos,1898).Our preliminary study on the different composition of Lecane, Brachionus and Trichocercabetween Hainan and Thailand (the best studied country for rotifers in SE-Asia) shows that thereis a relative low endmism, but a high diversity in Hainan island. We attribute the low endemismto1. the undersampling of high altitude habitats,2. the low sampling frequency from hainan and3. taxonomic limitations: several widespread species could contain yet unknown cryptic species,undetectable by morphology.A key and drawings of the genera Lecane, Brachionus and Trichocerca are provided toallow future recognition of the Hainan rotifers. Species accumulation curves were used to assessthe sampling, to estimate the total number of species present in each genera. Jackknife1’s estimator was used to extrapolate the species number observed in134samples to total estimatednumber present. This S*amounted to58species in Lecane,50in Brachionus and20species inTrichocerca, with a low ration of variance/estimator. In conclusion, the rotifer fauna of Hainandeserves further study, perhaps focusing on inland regions at higher altitudes.