Ramalina dictyota Dodge & Vareschi

Marcano, Vicente, Méndez, Antonio Morales & Prü, Ernesto Palacios, 2021, The genus Ramalina Acharius (Ascomycota, Lecanoromycetes, Ramalinaceae) in northern South America, Phytotaxa 504 (1), pp. 1-77 : 45-46

4. Ramalina dictyota Dodge & Vareschi (Fig. 33)

Acta Biol. Ven. 2: 8 (1956) . Type:― VENEZUELA. Mérida: Paramo La Negra , 3200 m, cloud forest of Polylepis, L. Vareschi & V. Vareschi 3958 (holotype VEN!).

Thallus corticolous, pendulous, reticulate, up to 50 cm high, Branches finely to widely perforated, sorediate. Lower cortex partly or fully absent. Pycnidia not seen. Apothecia rounded, lateral or laminal, disc flat or convex, up to 8 mm in diameter. Ascospores 1–septate, straight or curved ellipsoid, 10–11 x 4.5–5 µm.

Chemistry (TLC, HPTLC): Strain 1. Divaricatic acid (Vareschi 3294; Marcano et al. 7247, 7257, 7294; Martinez et al. 192). Strain 2. Sekikaic acid (Cleef & Rangel 10416).

Ecology and distribution: This species is found growing on bark, shrubs and Podocarpus branches in cloud forests and paramo at 2800–3500 m (Fig. 30). It is known only from northern South America ( Colombia and Venezuela).

Remarks: Ramalina dictyota is a rare species that is morphologically distinct from all other Ramalina species found in northern South America. Ramalina dictyota is very similar to R. menziesii Taylor (1847: 189) [≡ R. reticulata (Nöhden 1800: 237, nom. illegit., Art. 53) Krempelhuber (1869: 617)], known from North America (Howe 1914, Brodo et al. 2001). It is very difficult to distinguish the two species on morphological or anatomical features and it is possible that R. dictyota may be a synonym of R. menziesii ; however, the latter species contains only usnic acid ( Brodo et al. 2001). Molecular studies may help to elucidate if the two taxa should be distinguished at the species level. However, R. menziesii shows more widely reticulate branches and longer ascospores (11–20 x 4–7 µm) (Howe 1914, Brodo et al. 2001). Further, the geographical distribution of the two may indicate that they are vicariant species. Ramalina dictyota shows two strains, one containing divaricatic acid and a second with usnic and sekikaic acids. Morales et al. (1991) detected only sekikaic acid in specimens of this species by mass and 13CNMR spectroscopy techniques.

Specimens examined: COLOMBIA: Magdalena: Sierra Nevada de Santa Marta , between Rio Frio and Quebrada del Paramo, 2900 m, 20 August 1977, A . Cleek & O . Rangel 10416 ( B) . VENEZUELA: Mérida: Zanjon Hondo, Paramo de Mifafí , La Culata, 2800–3200 m, October 1994, V . Marcano , R . Vidal & A . Morales 7247, 7257, 7294 ( MER); Paramo La Negra , 2900 m, V . Vareschi 3294 ( VEN); Sierra Santo Domingo, around Mucubaji lake, 3500 m, 19 May 1993, D. Martinez , V . Marcano & L . Galiz 192 ( MER); Paramo La Victoria, Los Chorros valley , 26 December 2020, V . Marcano & L . Castillo 20–236 (herb. private V. Marcano) .