Tephromela atrocaesia (Nyl ex Cromb.) Fryday comb. nov.
MycoBank No.: MB519204
Basionym: Lecanora atrocaesia Nyl. ex Cromb., J. Bot.13: 334 (1875); type: Kerguelen, Swain’s Bay, [January 1875,] A. E. Eaton (H-Nyl. 25774—lectotypus!, hic designatus; BM—probable isolectotypus!).
Description
Thallus white to pale grey, effuse, from less than 1 cm to several cm across, thin to moderately thick (0·7–1·0 mm); areolate, areoles flat to slightly convex, 0·3–0·4 across; not corticate although upper 10 µm cells with blue-black pigment (H+ blue, N+ red; cinereorufa-green); inspersed with numerous, minute (< 1µm across) crystals that do not dissolve in K. Photobiont chlorococcoid, 12–15(–17) µm diam.
Apothecia lecanorine, adnate to slightly raised, 0·8–1·4 mm diam.; disc black, thalline margin thick, grey-white, non corticate, 0·1 mm wide, not raised above the level of the disc and becoming almost excluded in larger apothecia. Hymenium c. 170–250 µm tall, hyaline with purple-brown streaks or completely purple-brown (atra-red); epihymenium purple (atra-red); paraphyses 3 µm thick, sparingly branched and anastomosing, septate, with a gelatinous sheath, widening at the apex (5–8 µm) with a distinct, purple (atra-red), rarely blue-black (H+ blue, N+ red; cinereorufa-green) cap. Hypothecium 75–100 µm tall, golden brown with a narrow upper hyaline band (15–20 µm). Asci Bacidia-type, 35 × 15 µm (but immature; no mature asci seen), cylindrical to slightly clavate; ascospores simple, hyaline 10– 11 × 6–8 µm. Thalline exciple with numerous, with larger, angular crystals, 3–5(–10) µm across that do not dissolve in K; differentiated cortical cells lacking but surface cells with blue-black pigment (H+ blue, N+ red; cinereorufa-green), algal layer composing all but the upper 40–50 µm.
Conidia not seen.
Chemistry. Atranorin, α-collatolic acid, ± alectoronic acid, 4-O-methylphysodic acid (minor) and physodic acid (trace), ± unknown by TLC.
Notes.Tephromela atrocaesia is similar to T. atra but differs in having a greyish thallus and less prominent apothecia with a thick, non corticate thalline margin. This gives the surface of the thalline margin a rough appearance that contrasts with that of T. atra that is always corticate and smooth. Tephromela atrocaesia was described from Îles Kerguelen in the southern Indian Ocean, where it appears to be frequent, but also occurs in southern South America, including the Falkland Islands, and South Georgia.