Algae 2012, 27(4): 259-268 http://dx.doi.org/10.4490/algae.2012.27.4.259 Open Access Research Article Copyright © The Korean Society of Phycology 259 http://e-algae.kr pISSN: 1226-2617 eISSN: 2093-0860 Morphology and molecular study of Pterosiphonia arenosa sp. nov. (Rhodomelaceae, Rhodophyta) from Jeju Island, Korea Myung Sook Kim 1, * , Su Yeon Kim 2 , Mi Yeon Yang 1 , Byeongseok Kim 1 and Pilar Díaz-Tapia 3 1 Department of Biology and Research Institute for Basic Sciences, Jeju National University, Jeju 690-756, Korea 2 Department of Biology, Chungnam National University, Daejeon 305-764, Korea 3 Departamento de Bioloxía Animal, Bioloxía Vexetal e Ecoloxía, Facultade de Ciencias, University of A Coruña, Campus da Zapateira s/n, 15071 A Coruña, Spain The genus Pterosiphonia is composed of 22 species worldwide and four of these species have been reported in the North-East Asia. In Korea, P. pennata originally described from the Mediterranean Sea has been previously recorded from the southern coast as a widespread species. In order to confirm the same species from Korea and Mediterranean, we observed the morphology of Korean Pterosiphonia specimen and analyzed rbcL sequences for inferring phylogenetic re- lationships among similar congeners. Korean entity was recognized as a new species, Pterosiphonia arenosa sp. nov. The new species is characterized by ecorticate axes with 7-10 pericentral cells, branches formed every two segments, and co- alesced with main axis over 1-1.25 axial segments, and tetrasporangia formed in straight series on determinate branches of the upper parts of erect axes. A phylogenetic analysis of rbcL sequences demonstrated that P. arenosa was distinct from P. pennata found in Spain as well as other species. In conclusion, morphological and molecular sequence data indicated that P. arenosa sp. nov. has been previously misidentified as P. pennata in Korea. Key Words: morphology; Pterosiphonia arenosa sp. nov.; P. pennata; rbcL; Rhodophyta; taxonomy INTRODUCTION The genus Pterosiphonia Falkenberg in Schmitz et Falkenberg (1897) was established for a rhodomelacean species based on the type species, Pterosiphonia cloio- phylla, having the following characteristics: thallus bi- laterally symmetrical differentiated into prostrate and erect systems of indeterminate growth, erect axes with alternately distichous branches of determinate or inde- terminate growth, flattened to strongly compressed, and about 1-2 internodes congenital fusions of proximal parts in short laterals with main axes (Maggs and Hommer- sand 1993). To date, 22 species have been distinguished in Pterosiphonia, occurring in temperate to tropical regions of the Atlantic and Pacific Oceans (Guiry and Guiry 2012). Only four Pterosiphonia species have been reported in the North-East Asia: Pterosiphonia bipinnata (Postels et Ruprecht) Falkenberg (1901), P. pennata (C. Agardh) Sau- vageau (1897), P. pinnulata (Kützing) Maggs et Hommer- sand (1993), and P. tanakae S. Uwai et M. Masuda (1999). Pterosiphonia pennata is widely reported, but taxo- nomically confusing (Maggs and Hommersand 1993, Díaz Tapia and Bárbara 2004). This species was originally described by Agardh (1824) based on the materials col- lected from the warmer areas of the Mediterranean to At- lantic Sea. Pterosiphonia pennata is characterized by pin- Received August 18, 2012, Accepted November 15, 2012 *Corresponding Author E-mail: myungskim@jejunu.ac.kr Tel: +82-64-754-3523, Fax: +82-64-756-3541 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://cre- ativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.