Ulva adhaerens Matsumoto & Shimada

Lee, Hyung Woo & Kim, Eun Hee Bae and Myung Sook, 2022, The first record of Ulva adhaerens (Ulvaceae, Chlorophyta) from Jeju Island, Korea, Journal of Species Research 11 (4), pp. 266-277 : 270-272

Ulva adhaerens Matsumoto & Shimada ( Fig. 3A -N )

Holotype. TNS-AL183435; TNS ( Matsumoto and Shimada, 2015: 107, Fig. 60).

Type locality. Tenjin-jima, Sajima, Yokosuka, Kanagawa prefecture, Japan.

Korean name. ñģŭâ래 ( Ę ḑljḡ): The Korean specific epithet, yeonjeop, is means “connected each other” in reference to the adherence between blades by the haptera of bundles of rhizoidal filaments arising from the cells of the ventral layer of the upper blade.

Habitat. Epilithic or epiphytic from the intertidal area ( Matsumoto and Shimada, 2015) to the subtidal zone, up to 15 m deep (this study).

Distribution. Jeju Island, Korea (this study); Japan ( Matsumoto and Shimada, 2015).

Specimens examined. MSK-GA00073 ( Fig. 3B ) , MSK-GA00074 , MSK-GA00075 , Munseom, Jeju Island, Korea, Jan. 30, 2013 (deposited in JNUB) ; NIBR AL0000117920 , Munseom , Jeju Island, Korea, Feb. 11, 2009 , NIBR AL 00 00117921, Feb. 11, 2009 , NIBR AL0000118004 , Nov. 13, 2009 , NIBR AL0000118012 , May 13, 2009 (deposited in KB) .

Other examined specimens. MSKL160414-17-1, MSKL-160414-17-2, MSKL-160414-17-3, MSKL-160 414-17-4, and MSKL160414-17-5, Apr. 14, 2016 (deposited in JNUB).

DNA sequence data. rbc L, MSK-GA00073 (MT978111), MSK-GA00074 (MT978112), MSK-GA00075 (MT978 113); tuf A, MSK-GA00073 (MT978120), MSK-GA 00074 (MT978121), MSK-GA00075 (MT978122); 18S rRNA, MSK-GA00073 (MT978102), MSK-GA00074 (MT978103), MSK-GA00075 (MT978104).

Habit and vegetative morphology. Thallus growing on various substrates such as rocks, shells, small or heavy benthic invertebrates, and cartilaginous marcroalga or geniculate corallines in the subtidal ( Fig. 3A ). Thallus distromatic, foliose, and lobed ( Fig. 3B ); composed of several blades up to 5-7 one like a blossom; growing 5-6 cm in diameter up to 10 cm ( Fig. 3B ); attached by numerous minute discoidal plates without a distinct holdfast. Blade light-green to green in color ( Fig. 3A ). Blade margin slightly ruffled, entire, or slightly uneven without marginal denticulation ( Fig. 3C ). In the surface view, having polygonal to subspherical cell shape at the upper and middle part of blades, ranging 8-12 × 10-16 wide ( Fig. 3D ); more and more polygonal shape toward the basal region, ranging 10-22 × 20-40 wide ( Fig. 3E ). Each cell containing one or two pyrenoids ( Fig. 3E ), cells irregularly arranged throughout the thallus ( Fig. 3D, E ). In the transverse section, distromatic thallus composed of entirely cuboidal cells ( Fig. 3F- H ): 24-32 μm long× 6-15 μm wide, both dorsal and ventral at upper; 30-35 μm long × 6-15 μm wide, dorsal, and 25-30 μm × 6-15 μm wide, ventral, at middle; 40-50 μm long × 10-15 μm wide, dorsal, and 20-30 μm long × 15-25 μm wide, ventral at the base. Blade gradually thickened from upper to base, 48-64 μm at upper, 55-65 μm at middle, 60-80 μm at the base. At the basal blades, sequentially, numerous rhizoids budded off from the ventral-side cells ( Fig. 3L ); the interwoven rhizoidal bundle growing outside downwardly ( Fig. 3M ); a minute discoidal plate to attach on the substratum ( Fig. 3N ).

Figures

Fig. 3. Ulva adhaerens Matsumoto & Shimada. (A) Natural habit of U. adhaerens from Munseom, Jeju, growing blossom-like attached on benthic invertebrates, seaweeds or sands. (B) The voucher specimen (MSK-GA00073) of U. adhaerens from Munseom, Jeju, Korea, Jan 30, 2013. Thallus habit composed blossom-like and dorsiventral lobes having rounded and slightly ruffled blade. (C) Marginal part slightly uneven without marginal denticulations or microscopic protuberances. (D) Sub-roundish to polygonal cells at the surface view of upper part with irregular arrangement. (E) More angular cells at the surface view of basal part with irregular arrangement. Pyrenoids are one or two per cell (white arrows). (F) Transection of blade at upper part composed of cuboidal cells with solid cell profiles. The height of both dor- sal and ventral cells is similar. (G) Transection at middle part composed of cuboidal cells with solid cell profiles. Dorsal cells are slightly higher than ventral ones. (H) Basal transection composed of cuboidal cells with solid cell profiles. Dorsal cells are much higher than ventral ones. (I-K) Blade adherence by numerous and interwoven secondary rhizoids (black arrows). Blade adherence(black arrowheads) occurs at the basal part between dorsal plane of main blade and ventral plane of subsidiary one. Both secondary rhizoids originated from distromatic cells are fused to each other. (L-N) The development of minute rhizoidal holdfasts. Rhizoids are bud off from distromatic cells (black arrow) (L). Rhizoids are expanding through ventral cell plane downwardly (black arrows) (M). Fully expanded and interwoven rhizoids (black arrow) produce minute and disciform holdfast (black arrowhead) at the tips (N). Scale bars: B=1 cm; C-H, L=30 μm; I, J, N=150 μm; K=60μm; M=50μm.