Riccia vitalii Jovet-Ast.

Fernandes, Rozijane Santos, Silva, José Augusto dos Santos, Ottoni, Felipe Polivanov & Pinheiro Costa, Denise, 2021, Diversity of thalloid liverworts in Brazilian Savanna of Parque Nacional da Chapada das Mesas, Maranhão, Brazil, Check List 17 (1), pp. 45-58 : 55

Riccia vitalii Jovet-Ast.

Figure 8A–E

Material examined. BRAZIL – Maranhão • Carolina, Parque Nacional Chapada das Mesas, Cachoeira do Prata ; 06°59′37″S, 047°09′57″W; alt. 197 m; 12. Mar. 2017; J. A. S. Silva 073, 075, 079 col.; CCAA 1564 ; 1494; 1507 . • Estreito, Parque Nacional Chapada das Mesas, 06°59′39″S, 047°09′56″W; 12 Mar. 2017; J. A. S. Silva 085 col.; CCAA 1775 .

Identification. Plants rupicolous. Thallus dichotomous, dark green, 5–8 × 2–4 mm, without central midrib; dorsal surface with one deep, median groove with photosynthetic cells; pores absent; ventral surface whitish to violet, without photosynthetic cells; margin green to hyaline; ventral scales large, 0.05 mm long, violet, without filiform appendages, and extending beyond the margin. Sporophytes immersed in the thallus, without involucre; capsule spherical, brown; spores subspherical to subtetrahedral, reddish to dark brown, without elaters.

Riccia vitalii is terrestrial and differs from R. stenophylla in having the thallus with a deep median groove and large violet scales extending beyond the margin. In Brazil, R. vitalii when sterile can be misidentified as Riccia weinionis Steph. because both have a thallus with a deep median groove and dorsal cells with vertical bands of longitudinal thickenings which are seen in the thallus

cross-section). However, R. vitalii can be easily distinguished from R. weinionis by the form and ornamentation of the spores. In R. vitalii , the spores are subspherical to subtetrahedral, with a granular proximal face and an evident trilete mark, whereas in R. weinionis the spores are tetrahedral with a proximal face with few areolas and without a trilete mark ( Silva et al. 2018).

Distribution and ecology. Neotropical ( Costa Rica, Paraguay, Colombia, and Brazil) (Bischler-Causse et al. 2005; Gradstein et al. 2016). In Brazil, it occurs in the Amazonia (Amazonas), Atlantic Forest (Espírito Santo), Caatinga (Alagoas, Bahia, Ceará, Paraíba, Pernambuco, Piauí, Rio Grande do Norte and Sergipe), Pampas (Rio Grande do Sul), Pantanal (Mato Grosso do Sul), and Cerrado (Goiás, Maranhão, and Tocantins) biomes ( Flora do Brasil 2020). We found it growing in open, sunny habitats near waterfalls.