Leptogium tectum
Leptogium tectum is a species of saxicolous rock-dwelling jelly lichen in the family Collemataceae, found in the maritime Antarctic. The thallus forms packed, ascending and short scales whose edges can be slightly wrinkled and warted; tiny clonal outgrowths occur on one or both surfaces. Unlike many related species, it does not have hairs on the underside; instead, it anchors by a mesh of interwoven fungal hyphae that spread through fine sediments beneath the thallus.Taxonomy
Leptogium tectum was described as a new species in 2018 by Aline Lorenz, Marcos Kitaura, and Mayara Scur. The holotype is from Clearwater Mesa, James Ross Island, where it grew in a small wind-scoured hollow in basaltic rock. The epithet is from Latin tectus, reflecting that both known specimens were collected inside hollows. The authors note that L. tectum is similar to L. puberulum but differs in its agglomerated, ascending lobes bearing marginal isidia and, crucially, in its attachment by interwoven hyphae rather than hairs.Description
The thallus of L. tectum is about 1.5–2.0 cm across and 75–150 μm thick, appearing blackish-grey to dark brown-grey; or are 2–4 mm wide, crowded and slightly attached, with rounded, ascending tips. Margins range from smooth to irregularly ornamented and may look a little "crisped". Wart-like outgrowths occur mainly along the margins, and isidia are granular to short-cylindrical, grouped on the broader lobes and found on one or both surfaces; are absent. The upper is a single cell layer; the lower cortex is non-, light brown to yellowish, and one to three cell layers thick. In section, the medulla shows scarce, short pillar-like "columnar" hyphae standing between tightly packed cyanobacterial cells—the partnership that swells and softens when wet and gives "jelly lichens" their texture. No apothecia or pycnidia were seen in the available material. Rhizines and true hairs were not observed; attachment is by interwoven hyphae that originate near the lobe bases and mingle with sand grains or organic matter beneath the thallus.Similar species
Within Antarctic Leptogium, the combination of a hairless, non-tomentose lower cortex and firm interwoven hyphae used for attachment separates L. tectum from the common L. puberulum and from the Antarctic species L. antarcticum and L. crispatellum.Habitat and distribution
Both known collections of L. tectum are from James Ross Island. The lichen was found inside small hollows formed by wind erosion in basaltic rock, growing on rock with fine sediments at around 200 m elevation. The original account lists the species as known only from James Ross Island.