Collemopsidium elegans (R Sant.) Grube & B. D. Ryan
Pyrenocollema elegans R Sant.
Thallus superficial, very thin, translucent at first then greenish-brown and finally dark brownish but still translucent, dotted with small black excrescences or warts, 0.10-0.20 mm in diameter and black ridges 0.15-0.5 mm radiating mainly towards the margin, this thallus can, on thallus exposed to desiccation, divide by retraction into angular fragments and give the appearance of giraffe skin. Perithecia scattered more or less abundant, prominent with a depressed ostiole, 0.10-0.40 mm in diameter, blackish to blackish-brown (if wet) sometimes with small sinuous lip-shaped growths in the center which can give the appearance of short lirellae. Spores oblong, 1-septate but not depressed at this level, 12-20 x 4-7 µm. Pycnidia embedded in ridges, visible as black dots. Photobiont: Cyanobacterium (with brown-yellow cells). Species occuring to the surface of siliceous rocks with Verrucaria (Wahlenbergiella) striatula and Verrucaria (Wahlenbergiella) mucosa. Sometimes difficult to differentiate macroscopically from certain forms of Verrucaria (Wahlenbergiella) striatula whose spores are simple and the thallus very dark greenish with very angular perithecia with a very open apices. Collemopsidium halodytes s. l. very similar to a smooth thallus without excrescences or warts or black ridges on its thallus (but there are some difficult to name intermediates). NB Recent studies of molecular biology seem to show that this "species" is variously interpreted and still poorly defined and that there would probably be under this name many taxa, we present here examples which bring together the characters currently well defined for this species and adopted by a majority of lichenologists but see a lush rosette form: Collemopsidium elegans forme en rosette. N.B. Can be broadly defined in the field as a young Verrucaria (Wahlenbergiella) striatula with brown thallus.
Pyrenocollema elegans, a new marine lichen. R. SANTESSON. Lichenologist. 24 (1): 7-11 (1992).