Type. ANTARCTICA. East Graham Land, James Ross I., Sidney Herbert Sound, 30 m, loose piece of limestone, 60.00S 57.38W, 23 Nov., 1945, A. Taylor s.n. (BM - holotype!).
Description. Thallus thick, dark grey or ochraceous to dark brown, rimose‑areolate with sublobate margins; areoles to 0.70‑1.20 mm wide, becoming loosely attached to substrate, subsquamulose at margin; surface plane or rugose, matt or shining; margin determinate or not; prothallus absent; vegetative propagules absent. Apothecia erumpent at first, becoming broadly attached to narrowly attached, frequent, contiguous or not, to 0.50‑1.10 mm in diam.; disc black, plane, becoming convex, sometimes half‑globose, frequently cracked in larger apothecia; thalline margin concolourous with thallus, entire, 0.05‑0.10 mm wide, sometimes becoming partly excluded; excipular ring sometimes present, confluent. ApothecialAnatomy. Thalline exciple (65‑)100-120 µm wide laterally; cortex 10‑20 µm wide; epinecral layer 10-20(‑30) µm wide; crystals absent in cortex and medulla; cortical cells to 4.0‑6.0 µm diam., usually pigmented; algal cells to 9.5‑26.0 µm long; thalline exciple 100-120 µm wide below when apothecia narrowly attached, 10‑20 µm wide; proper exciple hyaline, 10‑15 µm wide laterally, expanding to 20‑50 µm wide above, hypothecium colourless, 60‑180 µm deep, sometimes inspersed; hymenium 70‑100 µm high, inspersed or not; paraphyses 2.5‑3.0 µm wide, conglutinate, apices to 4.5‑6.5 µm wide, darkly pigmented, forming a dark brown epihymenium; asci ca. 50‑70 x 19‑26 µm. Ascospores 8/ascus, Type A development, Bicincta‑type, (16.0-)18.5-19.5(-22.5) x (8.5-)10.5-11.0(-12.5) µm, average l/b ratio 1.7-1.9, inflated at septum at first, becoming constricted when overmature, light pigmented bands across cells of some spores, sometimes becoming refractive with age; torus absent; walls not ornamented. Pycnidia not seen.
Chemistry. Spot tests all negative; secondary metabolites, zeorin.
Substrate and Ecology. Calcicolous on limestone and basalt.
Distribution. A bipolar species which is rare or under collected in the high arctic. The species is also known from West Greenland and northern Scandinavia (Mayrhofer and Moberg 2002). The specimen from Kluane National Park, Yukon (Scotter 20071 CANL) listed by Mayrhofer and Sheard (1988) probably belongs to a different species.
Notes.Rinodina endophragmia is closely related to R. straussii from the southwestern states but tends to have a brownish (never chalky-white) thallus, more prominent apothecia, conglutinate paraphyses and slightly smaller spores. As presently understood, these species are allopatric. Nevertheless, there is a possibility that the two species will yet prove to be synonymous. The thallus habit and colour of R. endophragmia are also reminiscent of young stages of R. castanomela, a species which develops a subumbilicate thallus with lobate margins and possesses slightly smaller spores. Both of these species may contain zeorin. Mayrhofer and Sheard (1988) consider similarities with other arctic species. Thomson (1997) refers to R. diskoensis Sheard ined. and R. lyngei Sheard ined., both from west Greenland and which are included here in R. endophragmia.
Specimens examined. CANADA. NUNAVUT. Bathurst Island, Polar Bear Pass, I.M. Brodo 19378a, c. GREENLAND. Disko Island, Asuk, P. Gelting 18853a, b, d, e (C); Godhavn, 1982, J. Poelt; Marmorilik, 1983, J. Poelt; Umanuq, 1983, J. Poelt (all GZU).
Selected References. Mayrhofer & Sheard (1988 Fig. 3); Thomson (1997 as R. diskoensis Sheard ined. and R. lyngei Sheard ined.), Mayrhofer & Moberg (2002 p. 103).
Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus light to dark gray, ochraceous, or brown, chinky-areolate with sublobate margins or larger with verruciform areolae and subsquamulose at the margins, the areolae 1-1.2 mm broad, dull or shining; with no visible hypothallus. Apothecia erumpent, becoming broadly attached, to 1.1 mm broad; margin of same color as thallus, entire; thalloid exciple with green than brown and is more developed than that of R. archaea, being continuous or composed of discrete flat or rugose areolae rather than chinky-areolate or disappearing or of small granules (despite the name, which was based on the superposed thallus of a granular lichen in the type specimen, according to J. W. Sheard).