The red algal rhodomelacean genus
Of the genera belonging to the tribe Polysiphonieae recorded in Korea, Neosiphonia, which was separated from Polysiphonia (Kim and Lee, 1999), is most similar to Polysiphonia in habit and having polysiphonous branches and one tetrasporangium per segment in the stichidium. However, Polysiphonia differs from Neosiphonia by having only sporadically derived lateral branches, erect determinate and indeterminate branches developing from an extensive creeping base, rhizoids in open connection with pericentral cells, trichoblasts being scarce or absent, procarps with a 4-celled carpogonial branch,spermatangial branches born in the initial lateral branch, and tetrasporangia arranged in a straight row(Kim and Lee, 1999).
The specimens examined in this study were collected from Daejin on the east coast of Korea. Morphological observations were carried out using living materials and specimens preserved in 10% formalin-seawater. For anatomical observations, the material was cleared in 5-10% NaOH in distilled water for 2-7 days and then rinsed in distilled water. Branchlets dissected from cleared materials were hand-sectioned, transferred to a slide glass with a drop of distilled water, and mounted in pure glycerin. For permanent slides, the glycerin was exchanged with 50% Karo corn syrup. In some instances, the smearing method for microscopic examination was employed. Measurements are given as length and diameter. For photomicrographs, sections were stained with 0.5-1.0% aqueous methylene blue or hematoxylin and pictures were taken with a digital camera (C5050; Olympus, Tokyo, Japan), coupled to as BX50 microscope (Olympus).
Type: Lyall; BM (Womersley, 2003).
Type locality: Orcas Island, Washington, U.S.A.(Womersley, 2003).
Habitat: Epiphytic on other algae in the intertidal zone.
Korean name: Keun-bul-geun-sil nom. nov.
Specimens examined: N10070601~N10070603 (Daejin: 6.vii.2010).
Morphology:Thalli up to 20-45 cm high (Fig. 1A and 1C), decumbent; forming dense tufts,entangled with each other; coarse, very elongate,epiphytic on other algae; blackish red or black in color; cartilaginous and rigid in texture, with basal prostrate axes attached by rhizoids; rhizoids unicellular, derived from pericentral cells in open connection (Fig. 2B); 25-30-㎛ diameter; branching pseudodichotomous to alternate; main axis percurrent, with segments L/B 0.8-0.9, 200-300 ㎛ diameter, without cortication (Fig. 2A);vegetative axial segment with 4 pericentral cells(Fig. 2A), same length as pericentral cells; lateral branch initially mostly exogenous, produced sporadically on axial cells, developing into monosiphonous trichoblasts or polysiphonous branches; branches (Fig. 1B) cylindrical; polysiphonous,indeterminate, or determinate growth;indeterminate branches with conspicuous and 500 ㎛ Fig. 1.
[Fig. 2.] Polysiphonia senticulosa (Harvey 1862). (A) Vegetative axial segment with four pericentral cells(arrowheads) in transverse section of branchlets. (B) Rhizoid (arrowhead) connected with pericentral cells(arrow). (C-E) Details of vegetative branches showing flexuous laterals hooked backward below and axillary branchlets (arrowheads) (C) dome-shaped apical cell (arrowhead) (D) and cicatrigenous branchlets(arrowheads) (E). (F G) Details of stichidium with tetrasporangia (arrowheads) of straight arrangement.
dome-shaped apical cells 25 ㎛ diameter (Fig.2D); determinate branches with conspicuous and spinous apical cells 13 ㎛ diameter, flexuous,hooked backward below (Fig. 2C); cicatrigenous branches present (Fig. 2E); trichoblasts colorless,scarcely present, usually deciduous, sometimes leaving scar cells; stichidium (Fig. 1D) arising endogenously at axil of branches (Fig. 2F), 5-6 in one point and 1-3 tetrasporangia (Fig. 2G), with determinate growth; tetrasporangia tetrahedrally divided, borne singly in each segment in a straight row on a fusiform branch, 75-85 ㎛ diameter. Sexual plants were not found in this study.
Remarks: As previously reported (Segi, 1951, 1960; Kudo and Masuda, 1988; Kim et al., 1994), the
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