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Page number:54 
Remarks (internal):According to Hansen et al. (1987) and Poelt & Hinteregger (1993), C. chalybaea belongs to Chalybaeae group, comprising species characterized by a crustose to poorly effigurate grayish thallus, brown to black apothecial disc without anthraquinone crystals but with diffused gray-violet pigments, and widely ellipsoid spores with a tendency of reduced septum. Later Wetmore (1994) placed this species in a group of taxa characterized by brown or black-fruited apothecial disc, K-/K+ yellow thallus, and K-/K+ purplish epihymenium. This rather large group includes species representing mostly all ecological groups, e.g., corticolous, lignicolous, and saxicolous (Massalongo 1853; Wetmore 1994). Five other members of this group previously reported from India (Singh & Awasthi 1978; Poelt & Hinteregger 1993; Joshi & Upreti 2007a; Joshi et al. 2009) include three corticolous species - C. atrosanguinea (G. Merr.) I.M. Lamb, C. pollinii (A. Massal.) Jatta, C. rinodinopsis Poelt & Hinter. - and two saxicolous species - C. transcaspica (Nyl.) Zahlbr., C. variabilis (Pers.) Müll. Arg.
Caloplaca chalybaea is characterized by a crustose areolate to coarsely rimose-areolate grayish thallus with a dendritic black prothallus, numerous small apothecia, a brownish-red to blackish apothecial disc with a concolorous proper margin, and numerous pycnidia with brownish-black to black ostioles. Superficially it resembles Aspicilia in habit but is easily distinguished by the polarilocular spores and K+ purple epihymenium. It is close to C. atroflava (Turner) Mong., which differs from it in having a dark gray to black, cracked areolate thallus with a brownish-orange apothecial disc lacking a thalline margin and broadly ellipsoid spores. Another related species, C. concilians (Nyl.) H. Olivier, is differentiated by bigger apothecia, branched paraphyses, and lack of dendritic prothallus.
 
Description type:Non-original description 
Description:Caloplaca chalybaea (Fr.) Müll. Arg., Mém. Soc. Phys. Hist. nat. Genève 16: 38, 1862.
Thallus crustose, saxicolous, appearing as spotted grayish patch on a dark black hypothallus, areolate to coarsely rimose-areolate, olivaceous gray to brownishgray to lead gray to pale gray. Cortex paraplectenchymatous. Medulla white. Prothallus black, dendritic.
Apothecia numerous, scattered to ± clustered, immersed in the thallus at first, later on sessile, round, 0.2-0.3 mm in diam.; disc brownish-red to brownish-black to black, flat to subconvex; proper margin thin to moderate, smooth, entire, persistent, concolorous or slightly darker than disc, glossy, in cross-section of indistinct to small oval cells; thalline margin thin, at maturity ± restricted to the base of apothecia, concolorous with the thallus. Epihymenium brownish to golden-brown. Hymenium hyaline, 40-60 µm high. Hypothecium hyaline, of paraplectenchymatous cells, impregnated with crystals, oil globules absent. Amphithecium with algae. Paraphyses simple to furcated, with upper 1-3 cells swollen. Asci 8-spored, spores polarilocular, ellipsoid, (6-)8- 14 x 3-6 µm, isthmus 1-3 µm. Pycnidia numerous, 1-3 per areolae, ostiole brownish-black to black, conidia bacilliform, 1-2 x 0.5-0.7 µm. [n = 20 for all measurements.] For further descriptions see Wunder (1974).
Chemistry - Spot test reactions: Thallus K+ yellow, C-. Medulla K-, C-. Apothecial disc K+ purple or K-. Epihymenium K+ faint purple. Secondary metabolites: atranorin.
Ecology and distribution - Caloplaca chalybaea was found growing over boulders (quartzite) in tropical regions between 510-1050 m. It was accompanied by Caloplaca subsoluta (Nyl.) Zahlbr. and C. cinnabarina (Ach.) Zahlbr.
Wade (1965) and Wunder (1974) reported this species growing over dolomite and calcareous rocks from Central Europe. Later, Fletcher & Laundon (2009) reported this species growing over hard limestone, natural boulders, buildings, and chest tombs from Europe, Macaronesia, Asia, and Africa. Wetmore (1994) reported it from North and Central America. The present study extends its distribution in India
 
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