Tricharia nigriuncinata Yeshitela, Eb. Fischer, Killmann & Sérus.
Mycobank MB 517815
Thallus epiphyllous, continuous, smooth, lacking crystals, thin, greyish green, up to 5 mm wide, furnished with abundant sterile setae. Photobiont chlorococcoid with cells green and globose, 5–8 µm diam. Setae setiform, black, simple or usually furnished with 1–2(–6) horizontal or usually downwards bending hooks near their middle, slightly bending, up to 1.5 mm long and 0.04 mm thick at their base, black. Hyphophores not found. Apothecia usually absent, sometimes abundant, sessile, round, 0.1–0.2 mm diam., ca. 75 µm high; disc light orange to almost translucid, opaque, plane without pruina; margin thin, non or slightly prominent, smooth, pale brown, usually darker than the disc. Excipulum gelatinized, prosoplectenchymatous, 20–30 µm thick, light brown. Hypothecium ca. 10 µm thick, hyaline. Epithecium 5–8 µm high, pale brown. Hymenium hyaline, 40–50 µm thick. Paraphyses branched and anastomosing, 1 µm thick. Asci broadly clavate, 1(–2)-spored, 50–65 x 35–50 µm. Ascospores muriform with numerous cells, ellipsoid, 40–55 x 15–25 µm, hyaline.
Within the very diverse lichen family Gomphillaceae, the genus Tricharia is a well-delimited and coherent taxon (Lücking et al., 2005), with black setae as a distinct character. Indeed, black setae are otherwise known only in Gyalectidium nashii, Paratricharia paradoxa and in rare forms of Arthotheliopsis floridensis (Lücking et al., 2007; Lücking, 2008). Tricharia nigriuncinata is easily recognized by its long and rather stiff setae usually furnished with 1–2(–6) hooks near their middle. Tricharia demoulinii Sérus. (known from Papua New Guinea and Thailand), T. elegans Sérus. (known from Papua New Guinea), and T. substipitata Vezda (known from Congo RDC) are the only other three species in the genus with hooked setae (Sérusiaux, 1984; Vezda, 1979; Papong et al., 2007). However, the hooks of these species are at the tip of the setae; in T. substipitata, the hooked setae may represent immature hyphophores as the thallus is otherwise furnished with very long, black hairs. The setae of T. nigriuncinata are similar to the white setae of Aderkomyces armatus (Vezda) Lücking, Sérus. & Vezda (Vezda, 1975). Tricharia nigriuncinata is very similar with the widespread and pantropical T. vainioi R. Sant. and differs only in the hooks on the setae. We first considered it might be an aberrant form of the latter, but we finally came to the conclusion that it represents a different species as both are sympatric in a restricted area in the Tropics (e. g. pristine forests in the Albertine Rift in Africa) and as T. nigriuncinata has never been observed in the large collections examined either from the Neotropics (Lücking, 2008) or from Papua New Guinea (E. Sérusiaux, unpubl. data).
The epithet refers to the characteristic hooks on the setae.
Tricharia nigriuncinata is typically a foliicolous species in the understory of dense rainforests; it is confined to undisturbed forests along the Albertine Rift, a major biodiversity hotspot in East Africa (Plumptre et al., 2007). It seems to be most common on the Western side of the Rift in Congo RDC.
Type:—UGANDA: Budongo forest; 01°43’N, 31°32’E, ca. 1000 m; on living leaves on Argomuellera macrophylla; Oct 2005, Yeshitela 16 (holotype LG).
Additional specimens examined (paratypes): CONGO RDC: South Kivu: Irangi, rainforest by river Luhoho; Lambinon 78/263, 269, 272, 273 (all LG). Kahuzi-Biega National Park, km 58 of Bukavu-Walikale road; Lambinon 78/320 (LG). RWANDA: Nyungwe Forest National Park, near Kamiranzovu swamp; Lambinon s.n. (LG). Gisakura waterfall; Dec 2009, Fischer s. n. (KOBL). UGANDA: Budongo forest; Yeshitela 65, 66, 71 & 75 (KOBL), Sérusiaux s.n. (LG).
Ab omnibus speciebus generis Trichariae differt nigris setis in medio uncinatis.