Lichens marins

Stictis radiata (L.) Pers.

Description

Presence of a thallus discussed, the species of this genus being able to be saprophytic or lichenized depending on the case, here frequent presence of green algae and in particular of Trentepohlia seeming to constitute a thin, grayish, greenish gray thallus. Globose apothecia 0.4-0.8 mm in diameter, totally immersed in the substratum, opening at the surface at maturity by a star-shaped tear leaving multiple small lobes on the edges of a circular opening (flower-like appearance ), these lobes disappear quickly and the opening appears smooth and slightly raised, snow-white, under the microscope it contains very many crystals. At the bottom of the cavity one can observe, on very fresh samples, the orange-brown, olive-brown hymenium (N.B. this hymenium typically separates from the walls as it dries!). Octosporous asci, long cylindrical 250-300 x 8-10 µm, the spores are arranged in parallel and when mature the asci twist (corkscrew appearance) and the spores are expelled through an orifice located at their top which gives the whole thing an 8-armed squid look. Very elongated hyaline spores, multiseptate with individual cells of 4-5 µm (Taenia look !), 150-200 x 2-3 µm according to the literature, 120-180 x 3 (4) µm according to our measurements. Paraphyses simple or slightly forked at the top. No significant color chemical reactions but asci tips typically react blue to iodine. Rare and seasonal species (winter) from the base of trees on bark and even bare wood, conifers (Cupressus) or deciduous trees (Populus, Fraxinus...) in humid oceanic woods.

N.B. Species very often associated in our prospecting area with Gyalecta truncigena and Thelopsis corticola.

N.B. To be differentiated from Stictis stellata which grows on herbaceous plants and whose ends of the asci are I-.

_ For the problem of knowing if the species of Stictis are lichenized or not one can consult:

Mats WEDIN, Heidi DÖRING, Gunnard GILENSTAM. "Saprotrophy and lichenisation as options for the same fungal species on different substrata: environmental plasticity and fungal lifestyles in the Stictis-Conotrema complex". New phytologist december 2004. Volume 164, issue 3, p 459-465.