Hertella Henssen,
Type : Hertella subantarctica Henssen
Description : Thallus minute, filamentous, olive-green, fastened at base by a gelatinous attachment. Filaments 0.5 mm long or less, single or paired. Photobionts cyanobacterial, species of Scytonema or Tolypothrix. Hyphae extending in parallel, mainly within the gelatinous sheath of photobiont filaments, haustoria formed by short side branches. Ascomata apothecia adnate, hemiangiocarpous, olive or brown, with a pale, proper exciple. Hymenium strongly gelatinised, I+ dark-blue. Epithecium and hypothecium pale-brown. Hamathecium of paraphyses, septate, sparsely branched above. Proper exciple cupular, thick, pseudoparenchymatous. Asci cylindrical to clavate, with amyloid caps or indistinct amyloid ring structure, 8-spored. Ascospores simple, colourless, ellipsoidal to slightly curved. Conidiomata pycnidia, adnate. Conidiophores with a few short cells. Conidia bacillar, formed terminally and laterally.
Hertella, included in the family Placynthiaceae (Eriksson et al. 2004; Pennycook & Galloway 2004; Eriksson 2005) is a genus of three species occuring at high latitudes on moist, shady rocks in the Southern Hemisphere, with one species being known from Chile, one from Kerguelen and Prince Edward I. in the Indian Ocean and one species endemic to New Zealand (Henssen 1984b, 2004). Species are characterised by a minute, filamentous thallus forming tufts or rosettes with marginally spreading lobes, or the thallus may be almost crustose, with lobes densely aggregated and glued together by associated colonies of cyanobacteria. The lobe form corresponds largely to the morphology of the photobiont. Asci are 8-spored, with ascospores, colourless, ellipsoidal.
