Ramicrusta fujiiana E. M. S. Pestana, G. N. Santos, Cassano & J. M. C. Nunes, 2020

Pestana, Edilene Maria Dos Santos, Lyra, Goia De Mattos, Santos, Gabriel Do Nascimento, Santos, Cibele Conceição Dos, Cassano, Valéria & Nunes, José Marcos De Castro, 2020, Integrative approach reveals underestimated Peyssonneliales diversity in Brazil: registering the first occurrence of Ramicrusta and Incendia, with the description of three new species, Phytotaxa 439 (1), pp. 39-55 : 43-45

Ramicrusta fujiiana E. M. S. Pestana, G. N. Santos, Cassano & J. M. C. Nunes sp. nov.

( Fig. 2 A-E).

Diagnosis: — Thallus crustose, prostrate, completely adherent to the substratum by unicellular rhizoids more than 110 μm long. Secondary pit connections restricted to upper perithallial cells. Hair cells absent. Elongate tetrasporangia are born laterally among simple paraphyses. Gametangia unknown. Distinguished from other species of the genus by COI- 5P sequence divergence above 6.0% and by rbc L sequence divergence above 7.8 %.

Type:— BRAZIL. Bahia: Maraú, Algodões, 14º04’15,06”S – 38º57’32,05”W, 29 September 2015, E. M. S. Pestana, G.N. Santos & J.M.C. Nunes ( ALCB 129839).

Etymology: — Named in honor of Dr. Mutue Toyota Fujii for her contributions to the taxonomy of Peyssonneliales in Brazil.

Description: — Thallus encrusting, reddish orange, completely calcified, strongly and completely adherent to the substratum, 500–650 μm ( Fig. 2A ). Rhizoids are unicellular, measuring more than 110 μm long, extending from the hypobasal cuticle ( Fig. 2C ). Hypothallus is monostromatic, the hypothallial filaments are parallel and composed of rhomboidal shaped cells giving rise to perithallial filaments at angles of 45º from their distal surfaces. Perithallus is composed by irregular cells, 18–30 μm long and 12–17 μm diameter ( Fig. 2B ). The upper portion of perithallus forms secondary pit connections between perithallial cells ( Fig. 2E ). Epithallus is thin and reduced to the uppermost 3 to 5 cell tiers. Cells are small, deeply pigmented and weakly calcified. Hair cells are absent. Tetrasporangial nemathecia up to 100 μm thick and irregularly distributed on thallus surfaces. Nemathecia are composed of short, simple paraphyses of 3 to 4 long cells. Tetrasporangia are elongated, 200–250 μm long and 40–65 μm diameter, decussately/cruciately divided and born terminally ( Fig. 2D ). Gametophytic specimens were not observed in the present study.

Habitat: — Epilithic specimens, growing over rocks in areas protected from wave exposure in the reef, emergent during low tide periods.

Examined Material:— BRAZIL, Bahia: Maraú, Três Coqueiros Beach , 28 September 2015, E. M. S. Pestana, G.N. Santos & J.M.C. Nunes ( ALCB 129838 ) ; Ponta do Mutá , 27 September 2015, E. M. S. Pestana, G.N. Santos & J.M.C. Nunes ( ALCB 129844 ) ; Salvador, Itapuã Beach , 11 July 2017, E. M. S. Pestana, C.C. Santos & J.M.C. Nunes ( ALCB 132952 ) ; Uruçuca, Pé de Serra Beach , 13 June 2018, E. M. S. Pestana & C. C. Santos ( ALCB 132953 ) ; Porto Seguro (Arraial d’Ajuda), Mucugê Beach, 15 May 18, E. M. S. Pestana & C. C. Santos ( ALCB 132954 ) ; Apaga Fogo Beach , 19 May 2018, E. M. S. Pestana & C. C. Santos ( ALCB 132955 ) .

Ramicrusta fujiiana is in agreement with the morphological characteristics described for the genus (Zhang & Zhou 1981, Dixon & Saunders 2013), with secondary pit connections in the upper perithallus and unicellular rhizoids. It is possible to differentiate R. fujiiana from R. paradoxa on the basis of size of perithallial filaments; crusts of R. fujiiana are 500–650 μm thick and formed by 14–17 layers of cells, whereas crusts of R. paradoxa are 200–400 μm thick, with more than 20 cell layers.

Figures

FIGURE 2. Ramicrusta fujiiana. (A) Habit. (B) Radial vertical section of thallus, evidencing perithallus. (C) Unicellular rhizoids. (D) Radial vertical section of tetrasporangial nemathecium, evidencing tetrasporangia. (E) Upper perithallus with secondary pit connections (arrows). Scale bar:A, 1 cm; B, 100 μm; C, D and E, 30 μm.