Diagnosis. Similar to Cora hymenocarpa, with distinct sutures, a completely adnate, initially spot-like but soon confluent hymenophore and lower medullary papillae; differing from the latter in the smaller thalli and lobes and in the reddish brown pigment bleeding from rewetted herbarium specimens; differing from the closely related C. casanarensis in substrate (epiphytic vs. rock-dwelling) and color of hydrated thalli (aeruginous vs. olive-grey to grey-brown), and from the closely related C. itabaiana in the larger thallus and lobe size, the color of hydrated thalli (aeruginous vs. green-grey) and the presence of lower medullary papillae, and from both also in the bleeding pigment.

Type. USA. Florida: [Seminole County], Oviedo; [28º40' N, 81º12' W], [15 m]; without data on habitat and substrate; May 1923, S. Rapp 581 (us-1034276!, holotype; fh-00394661!, isotype).

ITS barcoding sequence. MT908260 (Florida, Rapp 581, US-1034276; holotype; Illumina); MT908272 (Florida, Thaxter s.n., US-1034207; paratype; Sanger).

Description. Thallus epiphytic on stems, branches and twigs of shrubs, foliose, 2.5–7 cm across, composed of (1–)3–5 semicircular, adjacent to subimbricate lobes; individual lobes 1–3(–4) cm wide and 1–3 cm long, moderately to frequently branched, with long, radial branching sutures, surface aeruginous green when rewetted, with slight concentric color zonation, olive-green to olive-brown towards or along the margins, with thin, involute, grey to grey-green or grey-brown margins, becoming grey in the herbarium; margins upon rewetting often yellowish to reddish brown and bleeding a reddish brown pigment. Upper surface shallowly and broadly undulate when rewetted, undulate-rugose when dry, glabrous; involute margins glabrous but becoming pilose near the sutures; lower surface ecorticate, felty-arachnoid (representing the exposed medulla), green-grey when rewetted, becoming light grey in the herbarium. Thallus in section 200–250 µm thick, with upper cortex, photobiont layer, and medulla; upper cortex distinctly viaduct-shaped, formed by a 20–30 µm thick layer of densely packed, periclinal, 4–6 µm thick hyphae supported by a 30–50 µm high 'medullary' layer of spaced groups of more or less anticlinal, 4–6 µm thick hyphae; photobiont layer 60–100 µm thick, aeruginous; medulla 30–50 µm thick, hydrophobic; clamp connections absent, but lower medullary hyphae with numerous short, unbranched to shortly coralloid, straight to hooked, papilliform hyphae. Hymenophore developed as initially rounded to irregular, resupinate, completely adnate, emarginate patches soon becoming confluent and covering the entire lobe underside, then usually with irregular to concentric cracks, patches at first 0.5–1 mm diam. before becoming confluent, with whitish to cream-colored, smooth surface and indistinct margins; hymenophore in section 70–80 µm thick, resting on a dense layer of medullary hyphae, strongly hydrophobic; hymenium composed of numerous, palisade-like basidioles and scattered basidia; basidioles 20–30 ´ 4–6 µm; basidia 25–35 ´ 4–6 µm, 4-sterigmate; basidiospores not observed.

Chemistry. No substances detected by TLC, but lobe margins upon rewetting bleeding with a reddish brown pigment.

Etymology. The epithet is a noun in apposition, referring to the Native American Timucua people, which occupied a large territory covering the northern Florida peninsula and southeasternmost Georgia. With an estimated population of approximately 200,000 at the onset of European colonization, the Timucua became extinct towards the second half of the 18th century due to infectious diseases brought from Eurasia, warfare and the slave trade (Ehrmann 1940; Hann 1996; Milanich 1996; Stojanowski 2005). We selected this epithet to symbolize the problem of extinction of natural habitats, species, and indigenous ethnicities as result of the modern colonization of the Americas.

Distribution and ecology. The new species is presumably endemic to the southeastern United States (Florida). According to label information, which frequently mentions "white sand scrub" as habitat, the reported phorophytes, and the reconstructed distribution of known specimens (see below), the species was chiefly collected as epiphyte on shrubs in the Florida (sand pine) scrub vegetation, specifically Florida peninsula inland scrub and oak-dominated hardwood forest, at an elevation range of 90–120 ft (about 25–35 m). Identified phorophytes were mostly Lyonia ferruginea (Walter) Nutt. (rusty staggerbush) and Quercus virginiana Mill. (southern live oak), and thalli of this lichen were found associated with bryophytes and other lichens, including Coccocarpia erythroxyli (Spreng.) Swinscow & Krog, Dictyonema spp., Leptogium spp., Normandina pulchella (Borrer) Nyl., Sticta beauvoisii Delise, and various parmelioid taxa including Parmotrema reticulatum (Taylor) M.Choisy. Given the number of historical collections, it is difficult to ascertain whether this species was (or is) genuinely rare and was relatively frequently collected due to its unique morphology, or once was more common (see below).

Notes. The material here recognized as a new species, Cora timucua, had previously been identified with the names C. glabrata, C. pavonia, Dictyonema glabratum, or D. pavonium (Hale & Culberson 1956, 1970; Parmasto 1978; Esslinger 2019). The earliest collections date to 1885 and the species was accepted, as C. pavonia, in Fink's (1935) The Lichen Flora of the United States (listed for Florida) and in the first checklist of North American lichens (Hale & Culberson 1956). However, in the two subsequent editions of the checklists it was excluded, given as "... apparently not in our area ..." (Hale & Culberson 1960: 167; Hale & Culberson 1966: 173), without any explanation. Moore (1970) confirmed the presence of the species, as C. pavonia, in Florida and it was then again listed for North America in the fourth checklist (Hale & Culberson 1970) and up to the most recent version (Esslinger 2019).

     Given the findings of recent phylogenetic revisions of the genus Cora and the substantial level of previously unrecognized phenotypic and ecological divergence of species-level clades in this genus, together with the inferred high level of regional endemism (Lücking et al. 2014a, 2017), the finding that the North American material from Florida does not represent C. pavonia or C. glabrata is not surprising. Lücking et al. (2014b) argued that C. pavonia is likely a Caribbean endemic, thus far only known from Jamaica. Likewise, C. glabrata is considered a Caribbean endemic thus far only known from Guadeloupe (Lücking et al. 2013). Morphologically and ecologically, C. glabrata differs in being terrestrial, the brownish color when hydrated, the thicker, revolute lobe margins and the absence of distinct branching sutures, and the more or less concentric, corticiform hymenophore composed of small, sessile, irregular to elongate patches with slightly upturned margins (Lücking et al. 2013). Cora pavonia is similar to C. timucua in size, but it grows over bryophytes mostly on rock and soil, its branching sutures are less conspicuous, the fresh color is more greyish green without a strong aeruginous tinge, and the hymenophore is similar to that of C. glabrata, forming concentric circles of small, irregular to elongate patches with slightly upturned margins (also based on topotype material recently collected by MDF; unpublished).

     Compared to many other recently described species in the genus (Lücking et al. 2017b), a rather large number of collections is available for this taxon. The morphology of these specimens is remarkably uniform, characterized by epiphytic growth, mid-sized thalli and lobes with distinct branching sutures, a strong aeruginous tinge of rehydrated thalli with a reddish brown, bleeding pigment, lower medullary papillae, and the adnate hymenophore, at first forming rounded, whitish patches similar to ascomata of Cryptothecia but then becoming confluent and covering the entire lower surface (Fig. 4). Therefore, even if only two collections have sequence data available, we conclude that a single species is present. Based on the above features, and adding the undulate lobes, the absence of soredia and trichomes, and the presence of a viaduct-like cortex, the binning analysis identified Cora hymenocarpa as closest morphological match to C. timucua. However, C. hymenocarpa forms much larger thalli (up to 20 cm across) with broader lobes (5–15 cm broad) and a bleeding reddish brown pigment upon rewetting was not observed in that species (Lücking et al. 2017). Cora hymenocarpa is only distantly related to C. timucua.

     Another phenotypically similar, also distantly related species is C. galapagoensis Dal-Forno, Bungartz & Lücking, which agrees in the branching sutures and anatomical details. However, like C. hymenocarpa, C. galapagoensis also forms much larger thalli with a much branched, partly imbricate lobes that take a grey-brown to olive-grey color when fresh, and its hymenophore is formed by well-delimited, concentrically arranged patches (Dal Forno et al. 2017).

     Based on our ITS-derived phylogeny, C. timucua is most closely related to C. casanarensis from Colombia and C. itabaiana from Brazil. The first is a rock-dwelling species that agrees with C. timucua in size and in the distinct branching sutures, but its fresh color is olive-grey to grey-brown, without any aeruginous tinge (Vargas et al. 2014). The epiphytic C. itabaiana is overall smaller than C. timucua and lacks an aeruginous tinge (green-grey when fresh), and it also lacks lower medullary papillae (Lücking et al. 2017). Overall, the distinctiveness of C. timucua is thus demonstrated both phylogenetically and phenotypically, and our data suggest that this is the only species present in Florida (and all of North America north of Mexico) and that is likely endemic to that region.

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Common name(s): Timucua Heart Lichen.

ASSESSMENT JUSTIFICATION [criteria: A2c; B1ab(iii)+2ab(iii); D]

This species is at least Critically Endangered due to the decline of the Florida sand pine scrub vegetationin Florida (United States of America), which has been gravely affected by land conversion through urban development and citrus groves. The potential current range for this species includes only areas in Ocala National Forest, with a maximum area of occupancy and extent of occurrence of 12 km² and 73 km² respectively. However, all recent attempts to verify its existing subpopulations throughout the state have been unsuccessful in relocating this taxon, and it may now be extinct. Indeed, over the past three generations (90 years), the population size has potentially decreased by >99%. The sand pine scrub ecoregion is endemic to Florida and itself endangered with only 10–15% remaining. The scrub habitat includes 32 species federally listed and 100 at the state level; nonetheless, only approximately 35% of this scrub remnants are in protected areas (Hoekstra et al. 2010). Therefore, based on surveys there is a high probability that the species may be extinct, and also a relatively high chance that it may have disappeared based on the threats too. Further survey work is required to confirm that the species is no longer extant, but even if it does persist the population will be extremely small and highly restricted.Therefore, Cora timucua is assessed as Critically Endangered (Possibly Extinct).

Date last seen: 1985

Assessor/s: Dal Forno, M., Kaminsky, L. & Lücking, R.; Reviewer/s: Lendemer, J.; Facilitator/s & Compiler(s): Bishop, G., Allen, J. & Chandler, A.

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