Harpidium gavilaniae Amo, Pérez-Ortega & A. Crespo
Mycobank MB 517780
Thallus crustose, effigurated. Thallus rounded to ellipsoid, up to 2.5 cm in diam. Areoles independent, flat to bullate or sub-stipitate, affixed to substrate over most of lower surface; marginal zone usually free, maroon-purplish to copper-red. Peripheral areoles enlongated, forming lobes, 0.4–0.9(–1.23) mm in diam. Central areoles rounded, bearing immersed apothecia, 0.3–0.6(–0.8) mm in diam (n = 35). Areoles stratified in section, 0.2–0.4(–0.67) mm high. Upper cortex paraplectenchymatous, to 25 µm high; Photobiont layer continuous, 90–200 µm high; Photobiont chlorococcoid, Trebouxia-like, 6–15 µm in diam. Apothecia irregularly rounded, usually one per areole, immersed as in typical Aspicilia species, disc blackish, 0.1–0.3(–0.4) mm in diam. Thalline exciple up to 20 µm thick. Epihymenium reddish, K–, ca. 10 µm thick; hymenium 50–70 µm high; KI+ blue, paraphyses, moniliform, 4–6 µm wide, slightly wider at the apex. Asci unitunicate-rostrate, clavate, 8-spored, 24–27 x 11–14 µm (n = 30), ascus wall thick,. Ascospores hyaline, simple, crescent form with the two apices rotated 90º, 9–13 × 6–7 µm (n = 35), with thick wall (ca. 0.8 µm). Pycnidia frequent, laminal, immersed; 70–120 µm in diam. Conidia cylindrical to ellipsoidal, 3 x 1 µm. Secondary chemistry: no secondary metabolites detected by TLC.
Harpidium is a small genus, with only two species described so far. Harpidium rutilans is known from few localities in the Eurasian mountains (Sancho & Crespo, 1983) and H. nashii from four localities of SW North America (Schultz et al., 2000). Harpidium and Euopsis together comprose the family Harpidiaceae (Scheidegger & Schultz, 2004). The new taxon represents the first record of the genus in the Southern Hemisphere. The new species differs from the other two known species of Harpidium in its thallus shape. It forms effigurate thalli, up to 2.5 cm in diam. Harpidium rutilans is the most similar species but we have seen elongated areoles only in young thalli; subsequently the thallus becomes irregular with areoles dispersed over the surface. On the contrary, H. gavilaniae remains ellipsoid in shape and has elongated peripheral lobes. Harpidium nashii differs in having umbilicate areoles and a more dispersed thallus. These differences, together with the allopatric distribution and the genetic distance between populations (unpubl. data), in our opinion justify description of the South African population of Harpidium as a new species.
The name for this species is for Rosario Gavilán, Botanist at the Universidad Complutense de Madrid (Spain) who took part in our lichenologial expedition to South Africa in 2005.
Harpidium gavilaniae is so far only known from the type locality, growing on quartzites in vertical furrows (dihedral) with seasonal water flows. The area belongs to Namaqualand Hardevel biome (Mucina & Rutherford, 2006) and it is very dry (below 100 mm per year).
Type:—SOUTH AFRICA: North Cape Province: Namaqualand, 57 km E of Springbok, Kangna's Farm; 29º34’S, 18º20’E, 1036 m; quartzite creek area; Jun 2005, Crespo & Amo de Paz SA-80b (holotype MAF-Lich 16488; isotype MAF-Lich 16489).
Additional specimens examined (paratypes):—None.
Sicut Harpidium rutilans sed thallus effiguratus et areolae majores..