Hypnea yamadae Tanaka 1960: 94
Type locality: Uji Islands, Kagoshima Prefecture, Japan (Yamagishi and Masuda 1997)
Korean name: Mit-eong-kin-ga-si-u-mu nom. nov. (신칭: 밑엉킨가시우무)
Specimens examined: NIBRAL0000146496, MGARBb000744, MGARBb000745, MGARBb000746 (Daebori: 07.viii.2014)
Habitat: Epilithic in upper to lower intertidal
Morphology: Thalli up to 10–15 cm high, epilithic, subcompressed or subterete to terete, somewhat entangled at base, without iridescence, light brown to dark brown in color, cartilaginous in texture (Fig. 1a); main axes more or less percurrent, issuing irregularly or alternately branches with wide angle and proliferations; branches bearing a few branchlets in alternate to spiral manner (Fig. 1b); branchlets short, spinous, slender, rarely hooked, without constriction near base, 5–20 mm long (Fig. 1d); apical cells distinct at the apices of axes (Fig. 1c); lenticular thickenings usually absent in the wall of medullary cells; cortex 2–3 cell layers thick; medullary cells round to elliptical in transverse section, linear to cylindrical shape in longitudinal section, with many pit connection between adjacent cells; tetrasporangia produced from cortical cell (Fig. 1f), restricted in ultimate branchlets (Fig. 1e), zonately divided, 25–35 × 55–70 μm. Sexual plants were not collected during the present study.
Hypnea cenomyce J. Agardh 1851: 452
Type locality: ad oras Novae Hollandiae (Silva et al. 1996)
Korean name: God-eun-ga-si-u-mu nom. nov. (신칭: 곧은가시우무)
Specimens examined: NIBRAL0000146479, MGARBb000747, MGARBb000748, MGARBb000749 (Sacheonjin: 03.vii.2014)
Habitat: Epilithic in upper to lower intertidal
Morphology: Thalli up to 10–15 cm high, epilithic, terete, somewhat entangled at basal part, without iridescence, dark red to brown in color, cartilaginous in texture (Fig. 2a); main axes often more or less percurrent, issuing irregular or alternate branches and proliferations; branches bearing abundant branchlets in alternate to spiral manner (Fig. 2b); branchlets short, spinous, usually with constriction near base, 5–15 mm long; apical cells distinct at the apices of axes (Fig. 2d); lenticular thickenings occasionally present in the medullary cell walls (Fig. 2c); cortex 2–3 cell layers thick; medullary cells round to elliptical in transverse section, linear to cylindrical shape in longitudinal section, with many pit connection between adjacent cells; tetrasporangia produced from cortical cell (Fig. 2f), restricted in ultimate branchlets (Fig. 2e), zonately divided, 10–20 × 20–40 μm. Sexual plants were not collected during the present study.
Hypnea nidulans Setchell 1924: 161
Type locality: Tutuila Island, American Samoa (Silva et al. 1996; Setchell 1924)
Korean name: Gi-neun-ga-si-u-mu nom. nov. (신칭: 기는가시우무)
Specimens examined: NIBRAL0000146497, MGARBb000741, MGARBb000742, MGARBb000743 (Sachenjin: 20.vii.2017)
Habitat: Epilithic or occasionally epiphytic in upper to lower intertidal
Morphology: Thalli up to 5–10 cm high, interwoven, loosely entangled, terete to subterete, without iridescence, red to brown in color, cartilaginous in texture (Fig. 3a); main axes erect, often percurrent, issuing irregularly branches and proliferations; branches bearing numerous branchlets in alternate to spiral manner (Fig. 3b); branchlets short, linear to lanceolate, usually with constriction near base, 2–10 mm long; apical cells distinct at the apices of axes; lenticular thickenings present in the wall of medullary cells (Fig. 3c, d); cortex 2–3 cell layers thick; medullary cells round to elliptical in transverse section, linear to cylindrical shape in longitudinal section, with many pit connection between adjacent cells; tetrasporangia produced from cortical cell (Fig. 3f), restricted in ultimate branchlets (Fig. 3e), zonately divided, 20–30 × 45–60 μm. Sexual plants were not collected during the present study.