Cronisia weddellii (Mont.) Grolle

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 : 48

Cronisia weddellii (Mont.) Grolle

Figure 2A–E

Material examined. BRAZIL – Maranhão • Carolina, Parque Nacional Chapada das Mesas , Rio Farinha ; 06° 56′43″S, 047°20′31″W; alt. 179 m; 11 Mar. 2017; J. A. S Silva 020 col.; CCAA 1502 . • ibid.; J. A. S Silva 021 col.; CCAA 1553 .• ibid.; Cachoeira do Prata ; 06°59′41″S, 047° 09′53″W; alt. 197 m; 06 Jun. 2018; J. A. S Silva 218 col .;

CCAA 1532 . • ibid.; J. A. S Silva 222 col.; CCAA 1521 . • ibid.; J. A. S Silva 223 col.; CCAA 1539 . • ibid.; J. A. S Silva 227 col.; CCAA 1513 . • ibid.; Cachoeira São Ro- mão 07°04′25″S, 047°05′26″W; 7 Jun. 2018, J. A. S Silva 253 col.; CCAA 1517 . • ibid.; Riacho Buenos Aires; 06°56′43″S, 047°20′31″W; alt. 179 m; 08 Jun. 2018; J. A. S Silva 300 col.; CCAA 1589 . • ibid.; J. A. S Silva 302 col.; CCAA 1505 .

Identification. Plants terrestrial and rupicolous. Thallus dichotomous, light green, whitish, or violet, 0.9–0.20 × 0.8–1.1 mm, without central midrib; main axis wider; dorsal surface chlorophyllose; epidermal pores with 5 or 6 ring cells; thallus in cross-section with one layer of air chambers with chlorophyllose filaments; ventral surface whitish; margin entire, green hyaline; ventral scales violet, large (0.8 mm long), with a filiform appendage, not extending beyond the margin. Sporophyte on the dorsal surface; involucre covering the sporophyte; capsule spherical; spores spherical, brown to dark brown; elaters short, no more than twice as wide.

Cronisia weddellii can be confused with species of Riccia . However, C. weddellii differs by having the cavi- ties in the thallus containing antheridia, pores with ring cells, appendage scales filiform and sporophyte covered by the involucre (Bischler-Causse et al. 2005). Two species have been recorded from northeastern Brazil, C. weddellii and C. fimbriata (Nees) Whittem. , of which the latter occurs mainly in the Caatinga ( Yano and Porto 2006; Yano et al. 2009; Germano et al. 2016). Cronisia weddellii differs from C. fimbriata by having non-raised epidermal pores and scales that do not extend beyond the margins of the thallus.

Distribution and ecology. Neotropical (Bischler-Causse et al. 2005). In Brazil, it is known from Caatinga (Alagoas, Bahia, Ceará, Paraíba, Piauí and Pernambuco), Atlantic Forest (Espírito Santo), and Savanna biomes (Goiás, Maranhão, Mato Grosso, and Tocantins) ( Gradstein and Costa 2003; Yano 2009; Flora do Brasil 2020). It is a typical species of the Brazilian Cerrado and Caatinga and tolerant to drought and high temperatures. We collected this species on soil and rocks on riverbanks where it was growing with mosses of the family Bartramiaceae . We observed that young plants differ from adults in the color of the thallus and shape of the scales. The thallus in young is light green, with scales almost or entirely hyaline and with only the apex violet; in adults the thallus is whitish to violet.

Cyathodiaceae