Systematic Study On The Ganesella(Gastropoda: Camaenidae) From China

Ganesella was established by Blaford in1863, is a member of Camaenidae,Gastropoda, Mollusca, the type species is Helix capitum Benson. Because of the taxon ofGanesella were based on the character of the shell, which are often confused withPlectotropis, Aegista and Bradybaena, so they can be distinguished by reproductivesystem have stylophore and mucus glands or not. In recent years, this genus whichdistributed in East Asia had been moved to Satsuma. The main purpose of this paper is tobuild the phylogenetic tree of Ganesella and related groups according to the shellmorphology, anatomy and molecular systematics; to revise the taxon of ChineseGanesella in genus and species taxon; to re-describe, clarify and merge the taxons andnew taxon, solve problems of name chaos in this genus. The result mainly includes twoparts.1. The study of classification system on Ganesella from Chinese.(1) Species clarification and re-description. By collecting and checking up theGanesella samples in museum home and abroad, with other literatures,26species ofGanesella from China (including Satsuma) were clarified. Every species werephotographed and described the character of the shell, and established the informationdatabase of Ganesella.(2) Genus taxon revision. According to the results of anatomy and molecularsystematics analysis, Ganesella of China is divided into2groups: Ganesella and Satsuma,Satsuma is the new genus in China.(3) Species taxon revision. By dissecting the suspicious samples of Bradybaena, wefound that Bradybaena stenozona (Moellendorff,1884), B. meridionalis (Pfeiffer,1850), B.uncopila (Heude,1882), which belong to Bradybaena originally, have not stylophore ormucus glands, and close to Satsuma in phylogenetic tree, so they are revised to S.meridionalis (Moellendorff,1884) and S. uncopila (Heude,1882), respectively.Bradybaena stenozona (Moellendorff,1884), Ganesella citrina (Zilch,1940) and Satsumamellea (Pfeiffer,1866) no only difficult to distinguish in the shell, but also pairwisedistances less than0.08, so they are revised to one species, named Satsuma mellea(Pfeiffer,1866). By dissecting the samples of Ganesella, there are stylophore and mucusglands in the reproductive system of Ganesella brevibarbis (Pfeiffer,1859), G. trochacea(Gredler,1885), G. virgo (Pilsbry,1926), and G. saurivonga (Bavay&Deutzebory,1900),and they are close to Bradybaena in the phylogenetic tree, combine with their shell characteristics, we revise them to Plectotropis brevibarbis (Pfeiffer,1859), Bradybaenatrochacea (Gredler,1885), B. virgo virgo (Pilsbry,1926) and B. saurivonga (Bavay&Deutzebory,1900), respectively.(4) The new species. In the study of Ganesella, we found a new species: Plectotropisyonganensis sp. nov., which is similar with Ganesella brevibarbis (Pfeiffer,1859); andfound a new subspecies: Bradybaena virgo mongolia subsp. nov., which is similar withGanesella virgo (Pilsbry,1926) in shell characteristic. We contrasted and discussed thenew species and subspecies in this paper.2. The molecular characteristics and systematics research of Ganesella from China.Use the universal primer of invertebrate chondriosome cytochrome oxidaseⅠ(COⅠ),with PCR method amplified the COⅠin Ganesella and related groups, obtained710bpfragment sequences were analyzed by software including Squencher4.1.4、ContigExpress、ClustalX1.83、MEGA5.0. The conclusions are showed as follows:(1) Nucleotide and amino acids component. The A+T content of COⅠgenes of24samples in the group is62.8%, while the G+C content of them is37.2%, which shows astrong A+T bias. Though analyze of codon, we found the bias in codon usage of the24samples sequences. In the study,18kinds of amino acids (besides Lys and Gln) are codedin COⅠgenes, and shows strong bias in amino acids contents.(2) The base substitutions. In these24sequences, transitions less than transversions.Most transitions occur between T and C, while most transversions occur between A and T.Substitution of the second position of codons is the lowest: transition is1.8%of alltransitions, while transversion is5.9%. And substitution of the third position of codons isthe highest: transition is75.0%, while transversion is82.4%.(3) The phylogenetic analysis. We constructed the phylogenetic trees of24samplesby using Neighbor-Joining (NJ), Maximum Parsimony (MP) and Maximum Likelihood(ML). The results indicated that topologies of the trees are almost identical. It is the samewith morphology and anatomy. The phylogenetic tree was divided into2branches firstly,Satsuma and Bradybaena. The Bradybaena branch was divided into3branches: Cathaicafasciola fasciola, Aegista and Plectotropis, Bradybaena. G. brevibarbis, G. saurivongaand G. trochacea which belong to Ganesella originally in the Bradybaena group now, thisresult is the same with the research of anatomy. The Ganesella group is divided into3branches: Satsuma largillierti, Satsuma in Taiwan and Satsuma in mainland of China.Satsuma in mainland of China including S. uncopila, S. meridionalis (which two are sinistrorse) and S. mellea. Among them, the pairwise distance of Bradybaena stenozona(Moellendorff,1884) from Fuzhou Drum Mountain, Ganesella citrina (Zilch,1940) fromFujian Wuyi Mountain and Satsuma mellea (Pfeiffer,1866) from Taiwan less than0.08,so they are the same species. In Ganesella group there are3species belong to Bradybaenaoriginally (S. mellea Gushan, S. uncopila and S. meridionalis), there are no stylophore ormucus glands, can be affirmed as Satsuma.