Bacidina sorediata Seaward & Lücking
Mycobank MB 517735
Thallus foliicolous, 5–10 mm across and 15–20 µm thick, dispersed into minute, corticate, granulose to microsquamulose patches 0.05–0.1 x 0.05 mm large, giving the entire thallus a granulose appearance, pale olive green, sorediate; soredia at first discrete, maculiform, becoming in part confluent, farinose, 0.2–0.3(–0.5) mm diam., yellowish white. Photobiont chlorococcoid, cells 5–10 µm diam. Apothecia rounded, 0.25–0.5 mm diam. and 130–180 µm high; disc plane to slightly convex, pale yellow to orange-yellow; margin thin, evanescent, of same color as disc or somewhat paler. Excipulum paraplectenchymatous, 30–50 µm broad. Hypothecium 20–30 µm high, colourless to very pale yellow. Hymenium 40–50 µm high, colourless. Asci clavate, 35–45 x 6–7 µm. Ascospores arranged in bundle, bacillar to very narrowly clavate, tapering towards the proximal end, 25–35 x 1.2–1.7 µm, 17–22 times as long as broad, 3-septate. Pycnidia not observed. Secondary chemistry: no substances detected by TLC.
Bacidina is a small genus of crustose lichens with usually granulose to microsquamulose thallus and pale yellow to orange apothecia (Ekman, 1996; Lücking, 2008). In several species, including Bacidina varia S. Ekman, the farinose to granulose thallus can become diffusely sorediate. However, the combination of a distinctly microsquamulose thallus consisting of corticate squamules with discrete, maculiform soralia of a different color is not yet known from the genus. Bacidina sorediata otherwise combines features of three other common, foliicolous species: B. apiahica (Müll. Arg.) Vezda has the same type of ascospores but a farinose to granulose thallus lacking distinct soralia, whereas B. defecta Vezda and B. scutellifera (Vezda) Vezda have the same thallus squamules as in the new species and also share the apothecium and ascospore type, but instead of soralia produce scutelliform isidia (Lücking, 2008).
The epithet refers to the sorediate thallus, an unusual feature in the genus.
Known from a rich collection from the Seychelles.
Type:—SEYCHELLES. Mahé: Path to Le Niol Road; 70 m; Jan 1974, Norkett 18668B (holotype BM; isotypes F, hb. Seaward 115567).
Additional specimens examined (paratypes):—None.
Sicut Bacidina apiahica sed thallo sorediato differt.