Study On The Molecular Phylogeny Of The Genus Periclimenes Costa,1844and Its Related Genera (crustacea, Decapoda, Palaemonidae)

The genus Periclimenes Costa,1844has become the most speciose genus of thePontoniinae, Palaemonidae, Decapoda, Crustacea. Up to date, there are still155species included in this large genus despite many species having been separated fromit and given generic status over recent years. It has been suggested that Periclimenesis a polyphyletic taxon, however, the morphological study couldn’t resolve well theorigin and phylogenetic relationships of the Periclimenes and its related genera as thegenus Periclimenes owns a great diversity of morphological characters and themajority of the species are considered as the associates of an variety of marineinvertebrates.Nucleotide sequences of the mitochondrial16S rRNA gene from extant genera ofthe Pontoniinae were used to reconstruct the phylogeny of the Periclimenes and itsrelated genera, and Macrobrachium japonicum was selected as the outgoup.According to the Phylogenetic trees constructed based on the three methods,parsimony (MP), maximum likelihood (ML) and Bayesian inference (BI), the mainconclusions of the present study were shown as follows:According to this study, the genus Periclimenes and its related genera clustertogether and form a monophyletic group within the Pontoniinae; Crinotonia Marin,2006, the first genus separated from the truck of the phylogenetic trees ofPericlimenes and its related genera of the Pontoniinae, should be the most primitivegenus; the remaining genera excluding Periclimenes are divided into two distinctclades, with the first clade consisting of Philarius, Cuapetes, Palaemonella, and Vir,and the second clade including Harpiliopsis, Brucecaris, Ancylomenes, Unguicarisand Laomenes; the species of Periclimenes Costa,1844are scattered in the two clades,implying this genus Periclimenes is a polyphyletic group; Palaemonella Dana，1852and Vir Holthuis,1952are clustered together in the first clade supported strongly bythe bootstrap (BP) and posterior probabilities (PP), but the analysis result does notsupport that they are the most primitive group in the subfamily Pontoniinae; species of Periclimenes foresti species group， Periclimenes alcocki species complex andPericlimenes hertwigi species group are clustered together separately, but whetherPericlimenes brevicarpalis species group is a valid species group still needs furtherstudy; Ancylomenes Okuno&Bruce,2010, which was established to cover thePericlimenes aesopius species group of the genus Periclimenes Costa, is a valid genus,and the monophyly of this genus was supported by the molecular analysis; thepolyphyly of the crinoid-associated fauna of the Periclimenes and its related generademonstrates that the very diverse morphology are the consequence of the convergentand parallel evolutions.The phylogenetic analysis of Periclimenes and its related genera of thePontoniinae reveals the phylogenetic relationships among these genera, enriches theapplication of the mitochondrial16S rRNA gene sequences on the molecularphylogenetic studies and provides molecular information for the study on thephylogenetic study of the decapod Crustacea.