Identification Information:Rinodina brodoana is a blue-gray to brownish-gray crustose lichen that can be recognized by its growth on the bases of mature oak trees and thick, overlapping areoles with irregularly shaped soralia that appear to bubble from the surface.
Rinodina brodoana is a crustose lichen that occurs on the bases of mature oak trees in remnant, mature low- and middle elevation forests within a small area of Great Smoky Mountains National Park in eastern North America. The species has likely been historically impacted by large scale habitat loss and degradation, phenomena which are inferred to continue in lands directly adjacent to all extant populations. Increased acquisition and protection of suitable habitat, monitoring of existing populations, and raising awareness of the species are recommended conservation measures for the species.
This species is categorised as Endangered based on the area of occupancy (AOO = 16 km²), small number of total locations (n=4), and the observed decline in habitat quality. The habitat that this species occurs in has been substantially impacted by logging activities in the past, as well as by flooding of lowlands for hydroelectricity. Although the species occurs within the borders of a protected management unit, the habitat quality in this area, including local climatic conditions, could be negatively impacted by proposed resource extraction as well as road/utility corridor construction on directly adjacent federal lands that are not afforded the same protected status.
Lendemer et al. (2014) ranked the species as Critically Endangered B1ab(iii); D, however that rank should be superseded by the one proposed here based on the subsequent discovery two additional populations, albeit within the already documented geographic range.
Assessor/s: Lendemer, J.; Reviewer/s: Scheidegger, C.; Contributor(s): Weerakoon, G.
Bibliography:
IUCN (2018) The IUCN Red List of Threatened Species. Version 2018-2. Available at: www.iucnredlist.org. (Accessed: 15 November 2018).
Lendemer, J.C., E. Tripp & J.W. Sheard (2014). A review of Rinodina (Physciaceae) in Great Smoky Mountains National Park highlights the growing significance of this “island of biodiversity” in eastern North America. The Bryologist117(3): 259-281.
Lendemer, J.C., R.C. Harris & E.A. Tripp (2013) The lichens and allied fungi of Great Smoky Mountains National Park: an annotated checklist with comprehensive keys. Memoirs of The New York Botanical Garden104( i-viii): 1-152.
Find out more about the IUCN Red List Categories and Criteriahere.
Diagnosis. Similar to R. brasiliensis by its orange-brown epihymenium and Pachysporaria-type I spores. The two species differ by the type of lichenized diaspores produced (isidia in R. brasiliensis vs. soredia in R. brodoana) and the immature ascospores of R. brodoana often develop apical canals (immature ascospores of R. brasiliensis have lumina surrounded by oil droplets). Rinodina brodoana is further distinguished from R. brasiliensis by the presence of cortical atranorin.
Type. U.S.A. NORTH CAROLINA: Swain Co., Great Smoky Mountains National Park, Lakeshore Trail 0–2.5 mi E of jct w/ Eagle Creek Trail at Horseshoe Bend in Eagle Creek, S slopes of Pinnacle Ridge, 2100 ft., acid forest with mixed hardwoods (Acer, Quercus, Liriodendron, Carya) and Pinus strobus, occasional non-calcareous rock outcrops, 13 March 2012, on large Quercus base, Lendemer 33109 & Tripp (holotype: NY!; isotype: COLO!).
Description.Thallus light gray, at first composed of scattered, plane areoles, ca. 0.30 mm in diam., then coalescing to form a more continuous, thicker thallus with minute marginal lobules 0.15–0.20 mm wide and therefore with a subsquamulose appearance, particularly when areoles overgrow each other; surface plane, matt; thallus margin indeterminate; prothallus absent; vegetative propagules present, first as corticated granules ca. 0.15 mm in diam., then erupting into pustulose soralia (for developmental sequence see). Apothecia broadly attached, scattered, sometimes becoming frequent but rarely contiguous, to 0.70–1.20 mm in diam.; disc dark brown and plane at first, often becoming convex and black; margin concolorous with thallus, narrow, ca. 0.05 mm wide, becoming excluded; excipular ring often present, raised or confluent with margin. Apothecialanatomy. Thalline exciple 70–100(–120) mm wide laterally, cortex ca. 15 mm wide; epinecral layer ca. 5 mm wide or absent; crystals present in cortex obscuring structure, absent in medulla; peripheral cortical cells 4.0–5.0 mm wide, not pigmented; photobiont coccoid, cells 12.0–14.5 mm wide; thalline exciple ca. 90 mm wide below; cortex 5–15 mm wide; epinecral layer 5–15 mm wide; proper exciple hyaline, 10–20(–30) mm wide laterally, often with an intricate structure and oil globules included, expanded to 40–50 mm wide above, concolorous with or darker than the epihymenium; hypothecium hyaline with oil globules, 100–110 mm deep; hymenium 120–140 mm high, not inspersed; paraphyses 1.5–2.5 mm wide, conglutinate, apices to 3.0–4.0 mm wide, rarely capitate but immersed in dispersed pigment forming an orange-brown epihymenium; asci 90–100 3 22–27 mm. Ascospores (Fig. 5) (4–)8/ascus, Type A development, Pachysporaria-type I (Sheard 2010), (24.0–)28.0–32.5(–35.5) 3 (13.0–)14.0–16.5(–18.0) mm (n 5 50), l/w ratio (1.7–)1.8–2.1(–2.3), lumina rounded, some polygonal or with apical canals at first, rarely with apical satellite lumina whenovermature; torus becoming well developed; walls not ornamented. Pycnidia not seen.
Etymology. The species is named in honor of Irwin (Ernie) M. Brodo (1935–present), internationally acclaimed scientist who has done much to promote the study of lichens in North America.
Ecology and distribution.Rinodina brodoana is presently known from two populations that were found on old growth hardwood trees (Acer and Quercus) at two localities in GSMNP. Both localities are middle- to low-elevation mature hardwood forests with little evidence of previous human disturbance in the form of logging or settlement. Comparable examples of middle to low elevation intact forests are rare in eastern North America, with GSMNP hosting some of the most extensive remaining tracts of this habitat type. Unfortunately, middle to low elevation habitats in the southern Appalachian Mountains have been relatively unexplored lichenologically, especially with respect to ‘more charismatic’ upper elevations (Lendemer & Tripp 2008; Lendemer et al. 2013).
Discussion.Rinodina brodoana is a distinctive and charismatic member of the southern Appalachian lichen biota that is not likely to be confused with any other species. The combination of a corticolous habit with production of thick, sorediate, thalline areoles that become lobed with age and the production of atranorin distinguishes it from all other sympatric crustose lichens that are typically sterile and reproduce asexually through the dispersal of lichenized diaspores. The same features, together with the large, Pachysporaria-type I ascospores (when ascospores are present) readily distinguish R. brodoana from all other species of Rinodina that are known from the southern Appalachians. The ascospore type and size of Rinodina brodoana as well as the orange-brown epihymenium suggest a relationship to the recently described Brazilian species R. brasiliensis Giralt, Kalb and H. Mayrhofer (Giralt et al. 2009; Figs. 6 & 7). Rinodina brodoana is nevertheless well separated from R. brasiliensis by its light gray thallus (vs. dark gray-brown in R. brasiliensis), the presence of pustulose soralia (vs. isidia), and the production of atranorin in the cortex (vs. no substances in R. brasiliensis). Absent from R. brodoana are the oil droplets surrounding the spore lumina that are characteristic of R. brasiliensis (Giralt et al. 2009: Fig. 2C–E). Another distinction between Rinodina brasiliensis and R. brodoana is the frequent development of apical canals in the spore lumina (and later and very rarely, satellite apical lumina) of R. brodoana. These same structures are known also from the Pachysporaria-type I spores of R. flavosoralifera Tønsberg (Giralt et al. 2010; Sheard 2010). Although the latter species is sorediate, it has a very different chemistry (anthraquinones) compared to R. brodoana. When describing Rinodina brasiliensis, Giralt et al. (2010) provided a detailed comparison with R. dolichospora (syn. R. confinis Sampaio). We agree that the two are closely related and thus the relationship of both to R. brodoana merits further study. The new species nonetheless differs from R. dolichospora in the production of soralia (lichenized diaspores are absent in R. dolichospora) and the production of atranorin (vs. no substances in R. dolichospora). Rinodina megistospora is a species that was recently described from the Pacific region of Oregon. This taxon may also be related to R. brodoana. Like the new species, R. megistospora has cortical atranorin, apothecia with brown discs that become convex, and a hypothecium that contains oil droplets. Rinodina megistospora also has very large spores belonging to Pachysporaria-type I, but the species differs markedly from R. brodoana in lacking lichenized diaspores. A relationship among all of the abovementioned species is suggested by their possession of Pachysporaria-type I ascospores and an orange-brown epihymenium (of varying intensity).