Taxonomic study on eight Amphora species (Bacillariophyceae) in the Korean coastal waters

Abstract

Amphora Ehrenberg ex Kü tzing is a common and worldwide-distributed benthic diatoms genus, with high diversity in morphology. However, marine Amphora species have been rarely researched under modern microscopy techniques and molecular methods with complexity of cell structure and difficult on sampling. Also, a big problem limits the molecular research on Amphora is that cultures are hard to be acquired. In this study, for taxonomical study of Amphora, samplings were carried out in Korean coastal waters from September 2009 to August 2010. This thesis focused on morphological and molecular characteristics of eight Amphora species: A. eunotia, A. holsatica, A. marina, A. proteus, A. veneta, A. terroris, A. cf. costata and A. cf. coffeaeformis. Morphological characters were re-examined using scanning electron and light microscopy. Morphological characters were in good accordance with previous description of individual species and morphological details were provided as newly described information. A. marina and A. proteus belonged to subgenus Amphora Cleve with a smooth cingulum; the puncta of theirs were rather coarse and very distinct on the valve. While the other species: A. eunotia, A. holsatica , A. veneta, A. terroris, A. cf. costata and A. cf. coffeaeformis belonging to the subgenus Halamphora Cleve, had a plicate cingulum, puncta of theirs were not forming straight longitudinal lines, theirs valve were with ventral portion narrow, theirs apices were generally rostrate-capitate and recurved. In molecular analysis, eight Amphora species showed significant difference in small subunit (SSU) rDNA sequences according to each species. Furthermore, phylogenetic analysis base on the SSU rDNA showed that eight Amphora species were divided into two independent groups, which owned the morphological characteristics of two subgenera (Amphora Cleve and Halamphora Cleve) separately. In addition, in these re-described eight Amphora species, A. marina was recorded for the first time in the Korean coastal waters. For the reason that subgenera Halamphora Cleve were nearer to genus Entomoneis Ehrenberg than Amphora Cleve in SSU based phylogenetic tree, it showed that subgenera Amphora Cleve and Halamphora Cleve might be two independent genera probably.|국문요지

한국 연안의 저서 규조류 Amphora 속 8종의 분류학적 연구

한양대학교 일반대학원 생명과학과 왕펑빈

Amphora Ehrenberg ex Kü tzing속은 전 세계적으로 광범위하게 출현하는 저서성 규조류로서, 형태적으로 매우 다양하다. 따라서 본 연구에서는 한국 연안에 분포하는Amphora 의 분류학적 연구를 위하여2009년 9월부터 2010년 8월까지 한국연안해역에서 시료를 채집 분석하였다. 총 17개의 지역 중 5개의 지역에서 Amphora (A. eunotia, A. holsatica, A. marina, A. proteus, A. veneta, A. terroris, A. cf. costata와A. cf. coffeaeformis) 8종을 분리하였고, 주사 전자현미경과 광학현미경을 이용하여 형태적 특성을 관찰하여 선행연구와 비교 분석하고, 새로운 형태적 특징을 추가하였다. 본 연구에서 관찰한 종들은 뚜껑띠(cingulun)의 주름 유무에 따라 2개의 아속(subgenus)으로 나뉜다는 것을 확인하였다: A. marina와 A. proteus는 뚜껑띠에 주름이 없고 점무늬(puncta)가 거칠고 뚜껑(valve)이 매우 분명한 형태로 존재하여 Amphora Cleve 아속에 속하였으며, 다른 종 A. eunotia, A. holsatica, A. veneta, A. terroris, A. cf. costata and A. cf. coffeaeformis는 뚜껑띠에 주름이 있고 점무늬가 직선의 종선(longitudinal line)을 형성하지 않아 Halamphora Cleve 아속에 속하였다. Small subunit (SSU) rDNA 염기서열을 이용한 계통수 분석 결과에서도 8종은 크게 2개의 그룹으로 나뉘어 형태적 차이에 따른 분류와 동일한 결과를 나타내었다. 또한, Amphora속 내 두개의 아속을 다른 규조류 속과 비교해 보았을 때, 아속 Halamphora Cleve는 아속Amphora Cleve보다 다른 저서성 규조류 속인 Entomoneis Ehrenberg와 계통학적으로 더 가까운 것으로 나타났다. 이러한 결과를 보았을 때 아속 Amphora Cleve 및 Halamphora Cleve는 독립적인 속으로 분류 될 수 있을 것이라 사료된다.; the puncta of theirs were rather coarse and very distinct on the valve. While the other species: A. eunotia, A. holsatica , A. veneta, A. terroris, A. cf. costata and A. cf. coffeaeformis belonging to the subgenus Halamphora Cleve, had a plicate cingulum, puncta of theirs were not forming straight longitudinal lines, theirs valve were with ventral portion narrow, theirs apices were generally rostrate-capitate and recurved. In molecular analysis, eight Amphora species showed significant difference in small subunit (SSU) rDNA sequences according to each species. Furthermore, phylogenetic analysis base on the SSU rDNA showed that eight Amphora species were divided into two independent groups, which owned the morphological characteristics of two subgenera (Amphora Cleve and Halamphora Cleve) separately. In addition, in these re-described eight Amphora species, A. marina was recorded for the first time in the Korean coastal waters. For the reason that subgenera Halamphora Cleve were nearer to genus Entomoneis Ehrenberg than Amphora Cleve in SSU based phylogenetic tree, it showed that subgenera Amphora Cleve and Halamphora Cleve might be two independent genera probably.