Halymenia malaysiana, Nguyen & Nguyen-Nhat & Nguyen & Nguyen & Truong & Dao & Do & McDermid, 2023

Nguyen, Xuan-Vy, Nguyen-Nhat, Nhu-Thuy, Nguyen, Xuan-Thuy, Nguyen, Trung-Hieu, Truong, Si Hai Trinh, Dao, Viet-Ha, Do, Anh-Duy & McDermid, Karla J., 2023, New record of Halymenia malaysiana (Halymeniaceae, Rhodophyta) from Viet Nam, and its genetic diversity in the western Pacific, Botanica Marina (Warsaw, Poland) 66 (2), pp. 113-123 : 116-119

Halymenia malaysiana P.- L. Tan, P.- E. Lim, S.- M. Lin et S.- M. Phang 2015.

References: Tan et al. (2015: 207–210, figs: 2–9).

Description: Thalli are foliose, pink to pinkish brown, gelatinous in texture, arising from a small discoid holdfast; stipe is not present; blades are oblong or suborbicular, broad with smooth surface, undulated margins; 10–30 cm long and 15–40 cm wide ( Figure 3A, B ). Cortex consists of 4–6 layers, and the cortical cells are subspherical to elongated or rounded, ellipsoidal to stellate in shape ( Figure 3C ). Medulla is filamentous, commonly consisting of refractive ganglionic cells, mostly with 6 arms ( Figure 3D, E ). Reproductive structures are distributed over the thallus. Cystocarps are deeply embedded in the medulla of the fertile blades. The auxiliary cell cuts off a gonimoblast initial terminally from a cup-shaped depression ( Figure 4C, D ). Gonimolobes differentiate into ellipsoidal or ovoid carposporangia ( Figure 4E ). Mature carposporophytes are spherical, 100–120 μm in diameter, bearing several gonimolobes ( Figure 4F ).

Type locality: Pulau Merambong , Johor, southern Peninsular Malaysia .

Distribution: Distributed in Pulau Besar, Malacca; Pulau Merambong, Johor; Tun Mustapha Park, Sabah ( Malaysia). Siargao Island, Catanduanes Island, Subic Bay, Busuanga Island ( Philippines), South Gam ( Indonesia).

R1 – R8 : names of haplotypes (Tan et al. 2018a). R9 – R11 : new haplotypes. Italic type indicates haplotypes from Vietnamese waters.

Vouchers: QTCC01 , 06 July 2018, 3 m depth at Con Co Island , Quang Tri province (17°151 N; 107°344°E), Viet Nam . NTh-H82, 28 September 1999, 8 m depth at Nui Thanh , Quang Nam province (15°499 N; 108°691°E), Viet Nam . LSQN-H3 , 17 February , 2022, 3 m depth at Ly Son Island, Quang Ngai province (15°393 N; 109°126°E), Viet Nam . CDNT-H15 , 25 February , 2022, 4 m depth at Cau Da, Nha Trang Bay, Khanh Hoa province (12°208 N; 109°216°E), Viet Nam . NH-H16, 01 March 2022, 4 m at Thai An , Ninh Hai, Ninh Thuan province (11°669 N; 109°179°E), Viet Nam . PQ-H17, 15 April 2022 at 5 m at Phu Quy Island , Binh Thuan Province (10°554 N; 109°955°E), Viet Nam . CDVT-H4 , 20 April 2022 4 m at Con Dao Island , Ba Ria Vung Tau province, (08°684 N; 106°625°E), Viet Nam .

Remarks: The herbarium voucher specimens were deposited in the Museum of Oceanography, Nha Trang City. Specimens at the Research Institute for Marine Fisheries, Hai Phong City, Institute of Marine Environment and Resources, Hai Phong City, Viet Nam were misidentified as H. dilatata .

Figures

Figure 3: Halymenia malaysiana from Viet Nam showing habit and vegetative morphology. (A) Thallus in Van Phong Bay (VPKH-H2). (B) Herbarium voucher specimen CDNT-H15 collected at Nha Trang Bay. (C) Cross section through middle part of a young blade showing densely arranged cortical cells and sparse.loosely arranged, filamentous medullary cells of CDNT-H15.(D) Magnification of cortex layers from (C). (E) Anomalous refractive ganglionic cell (arrow) with 6 arms from CDNT-H15. Scale bars in (C–E) = 20 µm.

Figure 4: Halymenia malaysiana from Viet Nam (CDNT-H15) showing cystocarp development. (A) Auxiliary cell and ampullar filaments (white arrowheads).(B) Young cystocarp showing auxiliary cell and medullary filaments (black arrowheads).(C–E) Development of other young cystocarps showing a basal fusion cell, gonimoblast initial (black arrow) and gonimolobe enveloped by elongated ampullar filaments and secondary medullary filaments. (F) Mature cystocarp showing gonimoblast initial (gi, black arrow), basal fusion cell (fc), and gonimolobe (g). Scale bars = 20 µm; aux, auxiliary cell; g, gonimolobe; gi, gonimoblast initial; fc, fusion cell.