Racoplaca Fée, Essai Crypt Écorc. 1: LVIII, XCIV, XCIX (1825); Jiang et al., Fung. Div. 102: 285.
MycoBank number: MB 4640; Index Fungorum number: IF 4640; Facesoffungi number: FoF 08888; five morphologically delimited species (Jiang et al. 2020b); molecular data available for two species (Jiang et al. 2020b).
= Heterodothis Syd. in Sydow & Sydow, Philip. J. Sci. Bot. 9: 170 (1914).
Type species: Heterodothis leptotheca Syd. [= Strigula maculata (Cooke & Massee) R. Sant.].
Lichenized on leaves in terrestrial, lowland to montane, tropical habitats. Thallus (pseudo-)corticate, olive-brown to dark (olive-)green, usually with metallic glance, subcuticular and sometimes damaging the supporting leaf, laciniate, with a thin black, continuous or interrupted line along the margins of the laciniae. Photobiont Cephaleuros. Sexual morph: Ascomata perithecia, prominent, black or covered by thin thallus layer, wart-shaped or mostly conical, carbonaceous, ostiolate. Involucrellum present, carbonized. Excipulum prosoplectenchymatous, dark brown to brown-black. Hamathecium comprising 0.5–0.7 µm wide paraphyses, hyaline, flexuose, unbranched or very rarely branched and anastomosing. Asci 8-spored, bitunicate, fissitunicate, cylindrical to narrowly obclavate, shortly pedicellate, with narrow ocular chamber, non-amyloid. Ascospores irregularly arranged to biseriate, ellipsoid to fusiform, hyaline, 1-septate, with thin eusepta and rectangular lumina, smooth-walled, at least slightly constricted at the septa. Asexual morph: Pycnidia common, erumpent, visible as black dots. Conidia acrogenous, either macro- or microconidia; macroconidia aseptate or 1-septate, bacillar, with gelatinous appendages, hyaline; microconidia aseptate, ellipsoid to fusiform, small, hyaline.
Chemistry: No secondary substances known.
Type species: Racoplaca subtilissima Fée, Essai Crypt. Exot. (Paris): xciv, xcix (1825).
Notes: This newly recognized genus includes some of the prettiest foliicolous lichens, characterized by narrowly laciniate thalli bordered by a thin black line. It appears to be an early diverging clade within Strigula sensu lato but has no supported relationship with any of the other newly recognized genera (Jiang et al. 2020b). Five species are currently assigned to this genus (Jiang et al. 2020b).