RESEARCH ON THE REVISION OF G. SOROCARPUS LI ET DING BASED ON MORPHOLOGICAL OBSERVATIONS, EARLY DEVELOPMENT AND MOLECULAR ANALYSES
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Abstract
Grateloupia sorocarpus Li et Ding collected from Qingdao, Shandong Province was re-examined through morphological and early development observation followed by molecular analysis. The results showed that: (1) The thalli were upright, purplish red, single or clustered, up to 5—15 cm high, main branch width 1.5—2 mm, 1 mm thick. The texture was smooth and cartilaginous. The first branch was flat with pinnately branched 1—2 orders. Small plumes with flat or stick shapes. The branches were opposite, alternate or partial and usually constricted or tapered at the base. (2) Male gametophyte were not seen. The reproductive structure of the female gametophyte included carpogonial branch ampullae and auxiliary cell ampullae. The reproductive structure of female gametophyte showed representative Grateloupia-type; Carpogonial branch ampullae and auxiliary cell ampullae were composed of 6 cells and 5 cells (6cpb-5auxb type). Gametophytes dioecious, mature tetrasporangia originated from inner cortex cells and splited into cross. These characteristics were similar with those of G. asiatica Kawaguchi et Wang. (3) The early developmental type of G. sorocarpus Li et Ding were ‘mediate discal type’, consistent with that of G. asiatica. (4) Based on the phylogenetic tree constructed by gene (rbcL) sequences, there was no sequence divergence between the eight samples of G. sorocarpus and G. asiatica from Qingdao and Dalian, which formed an independent monophyletic subclade within the large Grateloupia clade of Halymeniaceae. The rbcL sequences differences between G. sorocarpus and G. asiatica from South Korea were 2 bp (0.124%) and the rbcL sequences differences between G. sorocarpus and G. asiatica from Japan were 3 bp (0.248%), belonging to intraspecific difference. Based on the phylogenetic tree constructed by COⅠ gene, there was no sequence divergence between the eight samples of G. sorocarpus and G. asiatica from Korea and Japan, which formed a single monophyletic subclade. Considering the morphological observations and molecular analysis, G. sorocarpus Li et Ding and G. asiatica Kawaguchi et Wang were proved to be the same species. According to the priority rule, G. sorocarpus Li et Ding was the synonym of G. asiatica.
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