[Modified from Degelius 1974] Thallus up to 7 cm diam. but usually somewhat less (often a few cm), membranous, thin, dark olive-green. Lobules broader than in var. pulcellum, generally 0.4-1.5 cm broad. Thickness of thallus: 40-130 (-150) (when moist). Typical pseudocortex observed. Apothecia 0.5-1.0(-2) mm diam. and 240-430 μm thick (when moist). Disk pinkish to red, in some specimens ± (white-) pruinose. Thalline margin smooth or somewhat crenulate. Thalline exciple sometimes with a primitive pseudocortex, seldom with a typical one; proper exciple as in the other varieties euparaplectenchymatous (centr. part 60- 150 μm thick, with cells up to 17, rarely 22 μm diam., marginal part thinner and with smaller cells); rarely more subparaplectenchymatous or euthyplectenchyrnatous (see below). Hymenium 85-120(-150) μm high. Paraphyses 1.5-2(-4) μm thick (KOH), with somewhat thickened apices (to ~4.5 μm). Spores (6-)8 per ascus. distichous to polystichous, imbricate, straight or curved or twisted in asci, straight or curved when free, (4-)6-8(-10)-celled (end cells or one end cell at times elongated), usually not constricted at septa but sometimes distinctly constricted, colorless, varying in size: 19-65(-73) x 4-8.5(-10.5) μm (somewhat narrower in KOH). Very seldom, immixture of submuriform spores. Pycnidia in some specimens abundant and dense in others sparse or lacking, for the rest = var. pulcellum. Pycnoconidia ~4-4.5 x 1.2-1.5 μm.
Chemistry. Not reported.
Substrate and Habitat. Most commonly on bark; rarely on rock or wood.
Distribution. Cosmopolitan (Asia, Africa, Americas/Caribbean); in North Carolina represented by a single specimen (F.W. Gray 2781, 11.VI.1928, UPS) in the Piedmont.
Literature
Degelius, G. (1974) The lichen genus Collema with special reference to the extra-European species. Symbolae Botanicae Upsaliensis20: 1-215.
Müller, J. (1882) Diagnoses lichenum Socotrensium novorum a participibus expeditionum Prof. Bayley Balfour et Dr. Schweinfurth lectorum. Proceedings of the Royal Society of Edinburgh11: 457-472 (original description as Synechoblastus flaccidus var. subnigrescens).