Morphological and molecular evidence support the intertidal barnacle Octomeris intermedia Nilsson-Cantell, 1921 (Thoracica, Chthamalidae) as a valid species in Indo-Pacific waters.

Octomeris is a chthamalid intertidal barnacle with eight shell plates. There are currently two species of such barnacles: O. brunnea Darwin, 1854 (type locality in the Philippines), common in the Indo-Pacific region, and O. angulosa Sowerby, 1825, only recorded in South Africa. Octomeris intermedia Nilsson-Cantell, 1921, identified from the Mergui Archipelago in Myanmar, was considered to be conspecific with O. brunnea by Hiro (1939) based on samples collected in Taiwan. The morphological differences in shell and opercular plates between O. brunnea and O. intermedia are believed to be intra-specific variations due to different degrees of shell erosion. In the present study, the genetic and morphological differentiations of Octomeris in the Indo-Pacific region were examined. This study found two molecular clades (with inter-specific differences) based on the divergence in the COI genes, and the species also have distinct geographical distributions. The Octomeris brunnea clade covers samples collected from the Philippines and Taiwan waters and the other clade, which we argue is O. intermedia, is distributed in Phuket and Krabi, Thailand and Langkawi, Malaysia. Phuket and Krabi are located approximately 300 km south of the Mergui Archipelago, the type locality of O. intermedia. The morphology of samples collected from Thailand fits the type description of O. intermedia in Nilsson-Cantell (1921). Our study concludes that O. intermedia is a valid species based on morphological and molecular evidence.

Phylogeography, Historical Demography, and Genetic Structure of the Rose Bitterling, Rhodeus ocellatus (Kner, 1866) (Cypriniformes: Acheilognathidae), in East Asia.

Yao-Feng Tsao, Wen-Wen Lin, Chia-Hao Chang, Takayoshi Ueda, Nian-Hong Jang-Liaw, Ya-Hui Zhao, and Hsiao-Wei Kao (2016) Rose bitterling, Rhodeus ocellatus, is a small cyprinid fish distributed in East Asia. To infer its phylogeography and genetic structure, specimens from Taiwan, China, and Japan were collected, and complete mitochondrial cytochrome b (cyt b) DNA sequences were amplified and sequenced. Phylogenetic analyses identified seven mitochondrial lineages (A-G). Among them, three lineages (A, B, and C) distributed in mainland China. Lineages D, E, and F distributed in Japan, Korea, and Taiwan, respectively. Lineage G distributed in both China and Japan. The results of the Bayesian Binary MCMC analysis (BBM) suggested that the most recent common ancestor of R. ocellatus was from Lower Yangtze region. Divergence times among lineages inferred by molecular clock ranged from 7.55 to 1.44 million years ago. We propose that topography and climate changes by uplift of the Tibetan Plateau in the Late Miocene-Pliocene and the glacial-interglacial cycles in the Pleistocene might account for population expansion and genetic differentiation. Divergence times among lineages A, B, and C in Yangtze River basin ranged from 7.55 to 2.27 million years ago that might result from changes of flow directions of rivers from westward to eastward driven by the uplift of the Tibetan Plateau. The glacial-interglacial cycles in the Pleistocene might further cause population expansion to the northward of lineage G at about 0.19 million years ago. Lineage D in Japan was dispersed from the mainland China before the opening of the Sea of Japan, and lineage F in Taiwan was dispersed from the mainland China through the land bridge in the Pleistocene. Because of the genetic differentiation is statistically significant among populations, protection of genetic diversity and distinctness of R. ocellatus should be considered in the future conservation management.