Ochrolechia: Notes on O

Opuscula Philolichenum, 11: 120-134. 2012. *pdf effectively published online 10July2012 via (http://sweetgum.nybg.org/philolichenum/) On the perplexing variability of reproductive modes in the genus Ochrolechia: Notes on O. africana and O. arborea in eastern North America 1 2 IRWIN M. BRODO & JAMES C. LENDEMER ABSTRACT. – Notes on the discovery of several rare, reproductively atypical populations of Ochrolechia africana and O. arborea in eastern North America are presented. Sorediate fertile populations of the typically esorediate and fertile species O. africana were found in the Coastal Plain of southeastern North America. Conversely fertile sorediate populations of O. arborea, a species that is typically sterile and sorediate, were found in Maine and Pennsylvania, U.S.A. The unusual populations are described in detail and their geographic distributions mapped within the context of the reproductively typical populations of each species. A discussion of the labile nature of reproductive modes in Ochrolechia species is presented. The positive hypochlorite reaction in the amphithecial medulla and presence of 4,5-di-O-methylhiascic acid in the apothecia, together with the presence of lichexanthone in all tissues, point to a close relationship of O. arborea with O. mexicana. KEYWORDS. – Ochrolechia mexicana, sterile crusts, hiascic acids. INTRODUCTION Many sorediate crustose lichens that are typically found in their sterile state (i.e., without apothecia or perithecia) are occasionally encountered with fruiting bodies (Lendemer & Knudsen 2010; Tønsberg 1992). This phenomenon can be quite rare, however, and a non-trivial proportion of sterile asexually reproducing lichens have never been found in a fertile state (Fryday & Coppins 1997; Lendemer 2011). Such lichens have either been left undescribed, and thus obscured from the scientific dialogue, or have been classified provisionally in a genus based on correlated chemistry or superficial resemblance to known fertile species (Timdal 2001). In the event that these taxa have later been found in a fertile state, they have frequently had to be reclassified since the higher level taxonomic scheme for lichen-forming fungi relies largely on sexual characters. Such was the case with Ochrolechia arborea (Kreyer) Almb., a species that is common and widespread in some parts of temperate eastern North America (Brodo 1991). Originally the taxon was described as a variety of Variolaria lactea (L.) Pers. (= Pertusaria lactea (L.) Arnold). Later, Almborn (1952) combined it in the genus Ochrolechia based on the discovery of apothecia in Russian specimens, adding that he did not find them in Scandinavian material. Verseghy (1962) did not mention apothecia in her description of the species, and neither Tønsberg (1992) nor Brodo (1991) report seeing any fertile material in Norway and North America, respectively. In describing the apothecia in Russian specimens, Kopaczevskaja et al. (1971:253) said only that they were “encountered very rarely” and the discs were flat, reddish and naked, with thalline margins that are quite thin and entire (no spores were observed). Recently, Kukwa (2011) reported the occurrence of apothecia in two specimens of O. arborea, one each from Russia and Sweden. The anatomy of these specimens was not studied in detail however, due to the few apothecia present on the thalli. 1 IRWIN M. BRODO − Canadian Museum of Nature, P.O. Box 3443, Station ‘D’, Ottawa, ON K1P 6P4, Canada. – e-mail: [email protected]. 2 JAMES C. LENDEMER – The New York Botanical Garden, Institute of Systematic Botany, Bronx, NY 10458, U.S.A. – e–mail: [email protected] 120 When both of the authors of the present contribution independently discovered fertile populations of Ochrolechia arborea in eastern North America, we decided to study the material in detail and report our findings in the hope of better understanding the relationships of this species to its congeners. Concurrently, the second author (JCL), together with Richard Harris, uncovered the existence of a handful of sorediate populations of the usually esorediate and fertile species, O. africana Vain., from southeastern North America. Since sorediate populations of O. africana do not appear to have previously been reported from this portion of the continent, we decided to also detail this discovery in the present contribution. The present reports of reproductively atypical populations of normally sterile sorediate and fertile esorediate species fit well within the context of Ochrolechia, where the phenomenon appears to be widespread (for discussion see Brodo (1991) and Kukwa (2011)). However, these reports nonetheless highlight the difficulties in working with sterile asexually reproducing crustose lichens. METHODS Specimens were examined with standard microscopic techniques. Spores and soredia were examined and measured in water. Microtome sections (10-15 µm) were made of a mature apothecium using a Physitemp BFS Series freezing stage with an AO Spencer microtome. The sections were mounted in lactophenol with cotton blue cytoplasmic stain. Anatomical features were examined and measured in the stained sections. Thin layer chromatography was performed using solvents A, B’ and C as given in Orange et al. (2001) guided by Table 3 in Brodo (1991), where the depsides found in Ochrolechia are compared. With the fertile specimens of O. arborea, the apothecia, carefully cleaned of attached thalline material, were analyzed separately from fragments of thalli bearing no apothecia in order to determine the location of the various secondary compounds. Similarly, with the sorediate specimens of O. africana, soraliate fragments of the thallus were chromatographed separately from the apothecia. Light micrographs (LMs) were produced following Lendemer (2011a). Specimens cited in this contribution are deposited in NY and/or CANL. Label data for the former specimens have been digitized and are available via the C.V. Starr Virtual Herbarium of The New York Botanical Garden (http://sciweb.nybg.org/science2/hcol/lena/index.asp.html). RESULTS I - DESCRIPTIONS OF THE SPECIES Detailed accounts of the unusual populations of Ochrolechia arborea and O. africana are provided below. Additionally, a key is provided in order to facility the identification of corticolous sorediate Ochrolechia populations from eastern North America. Discussion of the relationships between the species, and others in the genus, is provided in a section following the descriptions and key. 1. Ochrolechia africana Vain., Ann. Univ. fenn. Aboënsis, ser. A, 2(3): 3. 1926. TYPE [fide Brodo (1991)]: SOUTH AFRICA: “Durban Trunk of tree. 1921, van der Bijl 136” (TUR-V 34315!, holotype). DESCRIPTION OF SOREDIATE THALLI (FIG. 1). – Thallus well developed, thin to thick, continuous and rugulose to rimose, bearing discrete soralia, mostly round but some irregular in shape, excavate to hemispherical; soredia greenish, very fine, 7.5-12(-17) µm in diameter. CHEMISTRY OF SOREDIATE THALLI. – Thallus cortex C-, UV± yellow; medulla and soralia C+ pink, UV± yellow. Apothecial cortex C-, UV± yellow; amphithecial medulla and epihymenium C+ pink, UV± yellow. All four cited specimens contain gyrophoric acid (major), 5-O-methylhiascic acid (major), lecanoric acid (minor). Three of the four (all except Harris 43419) also contained major or minor amounts of lichexanthone (thallus UV+ yellow). All of these substances were found in both the apothecia and the thallus (including soralia). 121 Figure 1, morphology of sorediate populations of Ochrolechia africana (left [A, C, E], UV- chemotype from Harris 43419; right [B, D, F], UV+ chemotype from Harris 39972). A-B, gross morphology of the thallus and apothecia (scales = 1.0 mm). C-F, detail of the soralia (scales = 0.5 mm in D & F, 0.25 in C & E). 122 Figure 2, geographic distribution of Ochrolechia africana in North America based on specimens examined for this study (yellow dots = populations with lichexanthone detectable by UV; red dots = populations with lichexanthone not detectable by UV; arrows point to sorediate populations). ECOLOGY AND DISTRIBUTION. – This species is common and widespread throughout the subtropical and tropical regions of North America, especially in the southeastern Coastal Plain (Brodo 1991; and fig. 2 herein). The distribution extends northward up the Mississippi River embayment into the Ozarks, and as far north as Massachusetts in the Coastal Plain. The sorediate populations are scattered throughout the range of the species and are found on a variety of deciduous trees (figure 2, see arrows). NOTES. − Although the soralia found on specimens of Ochrolechia africana vary from round and hemispherical, virtually capitate, to irregular in shape and somewhat excavate, the soredia within the soralia are uniformly tiny and powdery, no more than 20 µm in diameter. Because we observed some variation in soralium shape even on the same thallus, this character does not seem to be a fundamental feature of this rare morphotype. Nonetheless, the fine soredia and C- reaction of the thallus cortex should readily distinguish the sorediate morphotype of O. africana from both O. arborea and O. mexicana. Sorediate specimens examined. – U.S.A. ALABAMA. MARION CO.: North Fork Creek, on W side of US 43, 4.x.1993, on Prunus, R.C. Harris 43419 (NY, UV- chemotype). GEORGIA. CANDLER CO.: Fifteenmile Creek Preserve, uplands above E shore of Fifteenmile Creek, 22.xii.2009, on Quercus, J.C. Lendemer et al. 21652 (NY, UV+ chemotype). COLUMBIA CO.: Burks Mountain, ~3.5 mi E of US 221 from Pollards Corner on road through Rosemont, 12.iii.2010, on vine, R.C. Harris 55917 (NY, UV+ chemotype). SOUTH CAROLINA. RICHLAND CO.: Fort Jackson Army Base, Buffalo Creek Natural Area, 13.iii.1997, on Acer, R.C. Harris 39972 (NY, UV+ chemotype). 123 Selected esorediate specimens examined (UV+ populations). – U.S.A. ALABAMA. BALDWIN CO.: Shelbey’s, 17.iii.1925, on trees, A.W. Evans 296 (NY). CHEROKEE CO.: Wolfden Flats, off CR45, 3.x.1999, on bark, W.R. Buck 36391 (NY). ESCAMBIA CO.: Little River State Forest, 12.iv.2007, on Liriodendron, R.C. Harris 53340 (NY). MARION CO.: North Fork Creek, on W side of US43, 4.x.1999, on bark, W.R. Buck 36437 (NY).

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