Type. U.S.A. ARIZONA. Santa Cruz Co., Santa Rita Mountains, vicinity of Bellows Springs, 31o42'N 110o51'W, on boulder face, 7 600ft, 10 October 1981, T.H. Nash 18541 (holotype! - ASU).
Description.Thallus thick, light to dark grey, consisting of dispersed or contiguous, verrucose areoles to 0.40‑0.60 mm wide; surface convex, matt; margin determinate; prothallus sometimes dark, fimbriate; vegetative propagules absent. Apothecia narrowly attached, becoming narrowly attached, frequent, contiguous or not, to 0.60-1.00 mm in diam.; disc dark brown to black, concave at first becoming plane; thalline margin concolourous with thallus, prominent, 0.10‑0.15 mm wide, entire, flexuose and/or verrucose in old apothecia, persistent. ApothecialAnatomy. Thalline exciple 60‑110 µm wide laterally; cortex 10‑20 µm; epinecral layer absent; crystals present in cortex, absent in medulla; cortical cells to 4.5-5.5 µm wide, not pigmented; algal cells to 11.5-15.5 µm long; thalline exciple 90‑140 µm below, cortex 20-40 µm wide, cellular; excipular ring absent; proper exciple 10‑15 µm wide laterally, expanded to (10-)20‑30 µm above; hypothecium colourless, 50‑80 µm deep; hymenium 120‑140 µm high, not inspersed; paraphyses 2.5‑3.0 µm wide, strongly conglutinate with apices lightly pigmented, to 4.0‑7.0 µm wide, immersed in dispersed pigment, forming an orange-brown epihymenium; asci 70‑80 x 22‑25 µm. Ascospores 8/ascus, developmental type A, Pachysporaria-type I, (18.5-) 22.5-24.0(-28.0) x (10.5-)13.0-14.0(-16.5) µm, average l/b ratio 1.6-1.8, lumina first rounded, then irregularly polygonal, finally rounded at maturity with persistently thick walled, often developing satellite apical lumina, more rarely additional lateral lumina, often slightly constricted; torus narrow, lightly pigmented; walls not ornamented. Pycnidia prominent, dark brown to black, 0.05-0.10 mm in diam., mostly on small verrucae 0.20-0.30 mm in diam.; conidiophores type I; conidia bacilliform, 3.5-4.5 x ca. 1.0 µm.
Substrate and Ecology. Collected on siliceous rock, sandstone and rhyolite at 1 700-2 560 m
Distribution. A North American endemic species found in southern Arizona and the state of Chihuahua, Mexico. It is the only saxicolous species belonging to the Madrean element.
Notes.Rinodina verruciformis has a similar habit to the eastern Rinodina tephraspis (Tuck.) Herre, including its association with filamentous cyanobacteria (paracephalodia, Poelt & Mayrhofer 1988). It differs in its significantly larger Pachysporaria-type I spores with small satellite lumina and its chemistry. The polygonal shape of the immature spore lumina indicate a relationship with the corticolous R. dalmatica (see Figure 2C, Giralt et al. 1995) of Mediterranean-Atlantic Europe and with the North American R. perreagens. Rarely, some spores at later stages of development, possess smaller lumina (perhaps oil globules) surrounding the main lumina which are similar to those of R. dolichospora (Figure 10c, Mayrhofer et al. 1999). Mature spores with the very distinctive satellite, apical lumina are similar to the extreme oceanic European species R. confinis Samp. (Figure 5D, Giralt & Mayrhofer 1995).
Two sorediate species which have similar spores and chemistries, including the stictic acid complex, are R. stictica (mostly corticolous) and the R. algarvensis (saxicolous), the latter known only from Portugal. Together with R. verruciformis, these two species appear to be closely related despite some chemical differences such as the chloroatranorin in R. stictica being in higher concentrations than atranorin when present, and the variable presence of menegazziaic acid in R. algarvensis.
Specimens examined. MEXICO. CHIHUAHUA. Barranca del Cobre, 1 km S Rio Urique, T.H. Nash 36759, 36772; M.A. Herrera-Campos 4175; 20 km S Cusare, T.H. Nash 37410 (all ASU). U.S.A. ARIZONA. Gila Co., Pine Canyon, T.H. Nash 39462 (ASU); Pima Co., Spud Rock, C.M, Wetmore 54470 (ASU, MIN); Santa Cruz Co., near Bellows Springs, Santa Rita Mountains, T.H. Nash 18541, 18542, 19544 (all ASU).
Reference. Sheard & Mayrhofer (2002 Fig. 26), Sheard (2004).
Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.
Thallus: crustose, thick, consisting of dispersed or contiguous verrucae, up to 0.4-0.6 mm wide surface: light to dark gray, dull; margin: determinate; prothallus: sometimes present, dark, fimbriate; vegetative propagules: absent Apothecia: sessile, frequent, contiguous or not, up to 0.61 mm in diam. disc: dark brown to black, concave at first, becoming plane thalline margin: concolorous with thallus, prominent, 0.1-0.15 mm wide, entire and persistent; excipular ring: absent thalline exciple: 60-110 µm wide laterally; cortex: 10-20 µm; cells: up to 4.5-5.5 µm wide, not pigmented; algal cells: up to 11.5-15.5 µm in diam.; thalline exciple: 90-140 µm below; cortex: 20-40 µm wide, cellular proper exciple: hyaline, 10-15 µm wide laterally, expanded to (10-)20-30 µm at periphery hymenium: 120140 µm tall; paraphyses: 2.5-3 µm wide, often conglutinate, sometimes with oil paraphyses, with apices lightly pigmented, up to 4-7 µm wide, immersed in dispersed pigment, forming orange-brown epihymenium; hypothecium: hyaline, 50-80 µm thick asci: clavate, 70-80 x 22-25 µm, 8-spored ascospores: brown, 1-septate, broadly ellipsoid, type A development, Pachysporaria-type, (18.9-)22.5-24(-28) x (10.5-) 13-14(-16.5) µm, lumina irregularly polygonal when immature, lumina often developing satellite apical lumina, more rarely additional lateral lumina, spores persistently thick walled, often slightly waisted at maturity; torus: narrow; walls: not ornamented Pycnidia: prominent, dark brown to black, 0.05-0.1 mm in diam., on small verrucae; conidiophores: type I conidia: bacilliform, 3.5-4.5 x c. 1 µm Spot tests: K+ yellow, C-, KC-, P+ lemon yellow (rarely P+ red) Secondary metabolites: atranorin, zeorin and unknown substance 3-4/4-5/3 (or stictic acid replacing unknown). Substrate and ecology: on siliceous rock and rhyolite World distribution: endemic to southwestern North America Sonoran distribution: southern Arizona and Chihuahua, at elevations of 1700-2560 m. Notes: Rinodina verruciformis is characterized by its rock growing habit and large, Pachysporaria-type spores with small, apical, satellite lumina, and by its chemistry. The polygonal shape of the immature spore lumina indicate a relationship to R. algarvensis Giralt, Barbero & v.d. Boom (1996), another species on rock described from maritime southern Portugal. This latter species, however, lacks satellite apical spore lumina, and is sorediate, possessing discrete soralia.