| Summary: | 碩士 === 國立臺灣海洋大學 === 海洋生物研究所 === 107 === Members of the “Plesionika martia” species group are deep-sea shrimps and can be found world-wide. In some areas they are rather abundant and of commercial importance. Four species are currently recognized in this species groups, namely P. martia (A. Milne-Edwards, 1881), P. semilaevis Bate, 1888, P. orientalis Chace, 1985 and P. parvimartia Chace, 1985. However, there are still many controversies in the taxonomy of this species group. This works successfully sequenced the mitochondrial cytochrome oxidase (COI) and 16S rDNA genes of 48 specimens from eight localities in the western Atlantic, Western Pacific and Indian Ocean. Together with the sequences of two specimens from the type locality eastern Atlantic of P. martia in the GenBank, the present analysis includes topotypic material of all the four species in this group. The highest COI sequence divergence in this group is revealed to be 23.0%. Moreover, intraspecific COI sequence divergence can be as high as 18.6% in P. martia, 11.7% in P. orientalis and 16.8% in P. semilaevis. Analysis using the species delimitation model Species Tree and Classification Estimation, Yarely (STACEY) reveals that the P. martia group actually consists of 11 species. Except for P. parvimartia, there are cryptic species in the other three species. There should be five species within the material currently identified as P. martia, two species in P. orientalis and three species in P. semilaevis. Nevertheless, distinguishing morphologically differences have so far only been found amongst the cryptic species in P. orentalis and P. semilaevis.
Keywords: Plesionika、"Plesionika martia" group、STACEY、Molecular taxonomy
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