Hypnea tsudae M.O.Paiano F.P.Cabrera & A.R.Sherwood, 2022

Paiano, Monica O., Fumo, James T., Cabrera, Feresa P., Kosaki, Randall K., Spalding, Heather L. & Sherwood, Alison R., 2022, Calliblepharis yasutakei sp. nov. and Hypnea tsudae sp. nov. (Cystocloniaceae, Rhodophyta): novel diversity from the Hawaiian Islands, Phytotaxa 572 (1), pp. 74-86 : 82

Hypnea tsudae M.O.Paiano F.P.Cabrera & A.R.Sherwood , sp. nov. ( Fig. 4 A-H)

Holotype: — U.S.A. Hawai‘i, Pu‘ukohala Heiau National Park, Island of Hawai‘i 20.748°N, 24.384°W, 1.5 m depth, 03 August 2006, C. Squair (holotype BISH 740394 ).

Paratypes: — ARS 03115 ( BISH 786150 ) from U.S.A. Hawai‘i, Island of Maui , Hana, Kaihalulu Beach, 20.7589°N, 155.985°W, intertidal, 10 December 2007, K. Conklin ; ARS 03542 ( BISH 786151 ) from U.S.A. Hawai‘i, Island of Kauai , 22.2208°N, 159.583°W, intertidal, 17 March 2007, A. Kurihara .

Description: Thalli upright, terete, ranging from 1.2–4.5 cm in length ( Figs 4A–C ), usually rich red in color when living, drying to a light pink to orange when pressed ( Fig 4A ). Thalli are compressed with thorn-like branchlets that are often dichotomously branched at the apices and alternately branched in the mid to basal portions ( Figs 4D–E ). Branching most often in three-dimensional space ( Figs 4A–E ). In surface view, thallus is composed of small cortical cells, elongated, 4.0–7.5 μm in length and 2.0–10.8 μm in diameter ( Fig 4F ). Axes uniaxial, rounded. Transverse sections 310–440 μm in diameter ( Figs 4G–H ). Each axial cell surrounded by three to five periaxial cells ( Figs 4G–H ), 38–45 μm in diameter, surrounded by two to four layers of large, rounded to cuboidal medullary cells, 30–98 μm in length and 20–60 μm in width. Holdfast not observed. Only sterile plants observed.

Etymology:— This species is named in memory of our colleague, Dr. Roy Tsuda, who made many contributions to our understanding of the flora of the Western Pacific, and who collaborated with us extensively on the taxonomy of the mesophotic flora of the Hawaiian Islands and the Papahânaumokuâkea Marine National Monument.

Distribution and Habitat:— subtidal from Island of Hawai‘i, intertidal coastal waters of Maui and Kaua‘i, in the Main Hawaiian Islands, USA.

Identification using DNA sequence data:— GenBank accessions OL795917 (COI), OL795918 (rbc L) and OL828741 (SSU) for the holotype, ON704651 (ARS 03115) and ON704652 (ARS 03542) (rbc L) for the paratypes.

Figures

FIGURE 4. General morphology of Hypnea tsudae sp. nov. (BISH 740394). A. Pressed holotype, image provided by Bishop Museum (BISH 740394). B. Paratype ARS 03115 from a formalin voucher showing habit of the thallus. C. Stained paratype ARS 03542 from a formalin voucher showing apical portion of the branch. D. Detail of an apical branch (ARS 03115) E. Detail of a lateral branch (ARS 03542). F. Surface view of the apical portion of the thallus. G. Transverse section on the basal portion of the thallus. H. Transverse section of a middle portion of the thallus (ARS 03115).