Hypnea wynnei Nauer, Cassano & M.C. Oliveira, sp. nov (Figs 3–7)

Plants sub-erect, epilithic, dark-red when fresh, terete at basal and middle portions and flattened at apical portions, fleshy in texture, 1–1.5 cm long (Figs 3, 4), forming an entangled basal portion attached to the substratum by several discoid holdfasts and by secondary discoid holdfasts at the apices of lateral branches. Anastomoses absent. Multiple main axes are often distinguishable, 300–500 μm in diameter in the middle portions. Branching irregular to alternate at acute or right angles, with 1 (–2) orders of branches. First-order branches more slender than the main axis, 200–375 μm wide. Apices straight without hooks or tendrils. Spiny-like branchlets straight, at acute or right angles, sparse, irregular to alternately scattered throughout the thalli, 90–500 μm long and 50–200 μm in diameter. Thalli with one layer of pigmented cortical cells and 1–2 layers of hyaline medullary cells (Fig. 6). Cortical cells rounded, 7–12 μm long and 5–12 μm in diameter. Axial cells rounded, smaller than periaxial cells, 30–45 μm long and 50–62 μm in diameter. Each axial cell is surrounded by 4–5 periaxial cells (Fig. 6); periaxial cells rounded to elliptical, 65–150 μm long and 75–97 μm in diameter. Lenticular thickenings not observed. Tetrasporangial branchlets disposed throughout the thalli, mainly in their upper third part, 750–1500 μm long and 375–425 μm in diameter. Tetrasporangia in sori surrounding the apical portions of branchlets. Tetrasporangia zonately divided, cut off from the cortical cells, 31–35 μm long and 13–20 μm in diameter (Fig. 7). Male and female plants not observed.

Type:— BRAZIL. Rio de Janeiro: Angra dos Reis, Ilha Grande Island, Lagoa Verde, 23.100°S, 044.200°E, 5–7 m depth, coll. F. Nauer, tetrasporangial plant, 18 April 2012 (holotype SPF 57515), GenBank accession numbers for rbc L KX426553, COI-5 P KX426547, and UPA KX426556.

Distribution and habitat:— Brazil: Rio de Janeiro:Angra dos Reis, Ilha Grande Island, Laje Branca 18April.2012, F. Nauer (SPF57516). Plants growing in subtidal areas of island.

Etymology:—The specific name honors Dr Michael J. Wynne, Professor Emeritus at the University of Michigan for his important contribution to the knowledge of marine benthic algae of the Atlantic Ocean.