Riccia vitalii Jovet-Ast.

Riccia vitalii Jovet-Ast. View in CoL

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 GoogleMaps . • 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 GoogleMaps .

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.