Algae. 1986; 1(1): 3-86.

A Taxonomic Study of Genus Polysiphonia (Rhodophyta) from Korea

Ha-Yong Yoon

Department of Science, Jinju Teachers College

A taxonomic study of the members of genus Polysiphonia (Rhodophyta) in Korea was carried out morphologically and ecologically with the materials collected during 1980-1986, and of herbarium specimens. The members investigated are P. morrowii, P. subtilissima, P. atlantica, P. tongatensis, P. yendoi, P. sphaerocarpa, P. harlandii, P. decumbens, P. japonica, P. japonica var. savatieri, P. japonica var. forfex, P. japonica var. teradomariensis, P. crassa, P. notoensis, and P. brodiaei, Among them, P. japonica var. savatieri, P. japonica var. forfex, and P. japonica var. teradomariensis are newly combined during this study. Among the species, P. morrowii and P. subtilissima are cool temperate members achieving maximum growth and reproduction in winter-spring. P. harlandii, P. sphaerocarpa and P. notoensis are warm temperate species achieving maximum growth in summer-autumn. P. decumbens and P. japonica are eurythermal species, occurring throughout the year. Life history of this genus agrees with triphasic alternation of generations, but the species collected are, in general, prominent in tetrasporic phase, especially in P. morrowii and P. subtilissima. The average height of the species is less than 10 cm in general, except P. morrowii and P. japonica which are normally large, and sometimes reach to 25 cm. Attached substrata are relatively constant according to species, e. g., prostrate species (P. morrowii, P. subtilissima, P. atlantica, P. tongatensis, P. yendoi, and P. sphaerocarpa) are commonly inhabiting on rocks, whereas erect species (P. harlandii, P. decumbens, P. japonica, P. crassa, and P. notoensis) are commonly found on other algae, except P. harlandii, erect species, is commonly found on rocks. Saxicolous algae are more densely tufted than that on other algae. Shape, length and abundance of rhizoids can not be significant as taxonomic characters, because they vary largely due to substrata. The origin of rhizoid can be accepted as a most significant taxonomic character in this paper, because it is related to the other characters of the species; e. g., in the species bearing rhizoids connected with the pericentral cell, trichoblasts are not developed and spermatangial branches replace th whole trichoblast, while in the species bearing rhizoids separated from the pericentral cell except pit-connection between them, trichoblasts are well developed and spermatangial branches are arising as primary fork of trichoblast. The main axes are relatively slender in prostrate species whereas those in erect species are thick. The proportions of length to breadth in pericentral cells can vary markedly depending on the size of fronds. The origin of branches is significant as taxonomic character. Branches can be divided into endogenous and exogenous ones. The latter is also divided into trichoblast-replacing branch, trichoblast-connecting branch, and cicatrigenous branch, of which the pattern is species-specific. In Korea, however, the species which have trichoblast-connecting branches have not been found. Ramification is characteristic in certain species. P. morrowii, P. subtilissima, P. harlandii, and P. yendoi have an alternate pattern, and P. atlantica, P. tongatensis, and P. japonica, have a dichotomous pattern. The interval of segments is also significant in distinguishing P. subtilissima from P. atlantica, and P. yendoi from P. sphaerocarpa. respectively. Absence or presence and occurring frequency of trichoblasts are also related to the origin of rhizoid in Korean species. Even in the developed species, large variation within species lessens the diagnostic value. According to the concept that the number of pericentral cells was constant when they are 4, the genus was divided into two subgenera; Oligosiphonia which had four pericentral cells and Polysiphonia which had more than 4. However, this concept is not applicable to the present study. For instance, P. japonica var. forfex, which has 4-6 pericentral cells, proves that the criterion is not valid. Presence or absence, and degree of cortication are largely dependent on the conditions under which the plant, P. japonica var. savatieri, is growing. In the plants growing under the severe environment, cortication is well developed to erect the frond. Therefore, the degree of cortications seems to be related to the degree of erectness, size of frond, strength of wave action, and the degree of exposure in the intertidal zone, etc. Stichidia in P. morrowii and P. crassa are a typical character to identify them from the other species. The origin of spermatangial branch and the number of sterile cells on the branch tip are related to the origin of rhizoids. Shape of cystocarp varies in relation to the degree of growth, and the shape of pedicellate cell also changes according to the growing stage of cystocarp. Phylogenetic relation can be established according to the degree of differentiation of the vegetative structure. Species in which rhizoids are not cut off by cross walls from pericentral cells, trichoblasts are not developed, and spermatangial branch replaces trichoblast, are considered as primitive, whereas the species in which rhizoids are cut off, trichoblast are well developed, and spermatangial branch arises as primary fork of trichoblast, are more advances. Among the latter, erect species are believed to be more advanced than prostrate species. The foreign species, however, in which rhizoids are not cut off, trichoblast are developed. and spermatangial branch arises as primary fork of trichoblast, seem to rank between two groups mentioned above, and the species which have trichoblast-connecting branch are considered to be differentiated from the species which have trichoblast-replacing branch.

Keywords : monographic study, of polysiphonia, Rhodophyta, Ceramiales