Lichenologist 6: 106 (1974).
Protolog: Thallus minutissimus, fruticulosus, cum rhizinis substrato affixus,olivaceo-nigricans, nitidulus. Thalli rosula singularis 2-6 mm lata vel confluens aliquot centrimetra tegens. Rami forte ramosissimi, teretes, erecti vel deflexi, usque 0.4 mm longi et 0.05 mm lati. Apothecia typo pycnoascocarpio usque 0.3 mm lata, hymenium 130-190 µm altum, superne fuscum, paraphyses (=conidiophorae elongatae) fortiter gelatinosantes. Asci cylindracei, 80-115 x 6-7 µm. Sporae octonae, eseptatae, incolores, ovales vel ellipsoideae (in asco) 10.0-11.5 x 4.5-5.5 µm. Conidia bacilliformia, circiter 2 x 1 µm. Alga symbiotica ad Scytonema pertinens, trichomata 4-7 mm lata.
Protolog type data: Holotypus: United States, Alabama, St. Clair Co., Cook Springs, near Leeds, 1963, A. Henssen 15155a (Herb. Henssen).
Type locality: USA, Alabama, St. Clair County, Cook Springs, near Leeds, 1963, A. Henssen 15155a (Henssen - holotype).
Type locality coordinates: 33°35'24"N, 86°23'40"W; 33.59°, -86.394444°.
Thallus: fruticose, very small, blackish olive, shining, attached to the substrate by tufts of rhizoid-like hyphae. Thallus rosettes singly 2-6 mm in diameter or, aggregated covering several cm of the substrate. Lobes cylindrical, richly branched, erect or decumbent, about 0.4 mm long and 0.05 mm thick in the dry state, sections 55-80(-100) µm high. Hyphae longitudinally arranged, forming a limiting outer layer of one to three cells at the periphery. Apothecia lateral, pycnoascocarps, up to 0.3 mm broad, with a thalline margin, disc brown. Hymenium 130-190 µm high in section, paraphyses (=elongated conidiophores) strongly gelatinized, becoming evanescent. Asci cylindrical, 80-115 x 6-7 µm. Spores 8, simple, colourless, ovoid or ellipsoid, 10.0-11.5 x 4.5-5.5 µm (in the ascus). Conidia rod-shaped, slightly tapered at the ends, c. 2 x 1 µm, produced terminally on simple, long-celled conidiophores (Henssen 1974: 106).
Photobiont: Scytonema, trichomes 4-7 µm broad, more or less contorted within the thallus, especially towards the basal area of the lobes (Henssen 1974: 106).
Chemistry: No lichen substances (Henssen 1974).
Ecology: On slightly inclined faces of sandstone rock in an open area, occasionally overgrowing adjacent thalli of other lichens, such as species of Lecanora sect. Aspicilia.
Distribution type: Endemic in Alabama. Known only from the type locality.
Taxonomy: The four Lichinodium species are remarkably alike in their external and internal morphology. With regard to the size of the lobes, L. saxicola comes closest to L. canadense, but in habit, the new species, in the dense clustering of its richly branched lobes more closely resembles L. ahlneri. While L. saxicola grows typically on stone, occasionally spreading to adjacent lichens, L. sirosiphoideum is primarily an epiphyte on other lichens only occurring secondarily on mosses or even more rarely on stone. The two other species of Lichinodium, L. ahlneri and L. canadense, are exclusively bark lichens (Henssen 1974: 107).
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