Introduction
Opegrapha Ach., recently reinstated into the Opegraphaceae (Ertz & Tehler Reference Ertz and Tehler2011), is a large genus with over 361 species of both lichenized and lichenicolous species (Kirk et al. Reference Kirk, Cannon, Minter and Stalpers2008). It is a complex genus, especially with regard to corticolous and lignicolous species, with many contradictions in the literature and some unsolved problems (Ertz & Egea Reference Ertz, Egea, Nash, Gries and Bungartz2007; Ertz Reference Ertz2009). The corticolous species of Opegrapha have recently been revised for the Paleotropics (Ertz Reference Ertz2009), but many of the lichenized and lichenicolous species in India are still insufficiently known. Based on Ertz (Reference Ertz2009), Singh & Sinha (Reference Singh and Sinha2010) enumerated 16 Opegrapha species from India, which was followed by four additional species (Jagadeesh & Sinha Reference Jagadeesh Ram and Sinha2010). Further studies on this genus, as part of a revision of the family Roccellaceae sensu lato in India, revealed a new species which is described below.
Material and Methods
The material studied is deposited in the ASSAM herbarium. Morphological details were examined using a Nikon SMZ 1500 stereomicroscope. Hand-cut sections of thalli and apothecia were studied mounted in distilled water and KOH. The amyloid reactions were tested in Lugol's iodine solution (I), with and without pre-treatment of KOH. Anatomical details were studied using a Leica DM 2500 compound microscope. Measurements of asci and ascospores were made on material mounted in distilled water whereas drawings were made from material in KOH. The chemistry was studied by spot tests and thin-layer chromatography following Orange et al. (Reference Orange, James and White2001).
The New Species
Opegrapha granulosa Siljo & G. P. Sinha sp. nov.
MycoBank No.: MB 563536
Thallus crustaceus, tenuis, albus, granulosus. Ascomata lirelliformia, discus rimiformis, epruinosus. Excipulum atrobrunneum, K+ olivaceum, infra clausum. Epihymenium I+ rubrum. Hymenium I+ rubrum (parte superiori), I+ caeruleum deinde rubescens vel violaceus (parte inferiori). Hypothecium I+ caeruleum-violaceus, K+ viridescens. Ascosporae hyalinae, 7–9 septatae, (39–)44–57(–60)×(3·2–)4·2–5·5 µm; perispora 0·9–1·5 µm lata. Conidia 3·5–4·8×0·7–1·2 µm.
Typus: India, West Bengal, Sundarbans Biosphere Reserve, Chamta National Park, on bark of Heritiera fomes Buch.-Ham, 25 February 2003, T. A. M. Jagadeesh Ram 13585 (ASSAM—holotypus; BSA—isotypus).
(Fig. 1)
Opegrapha granulosa. A, thallus; B, ascus, ascospores and conidia. Scales: A=1 mm; B=15 µm.
Thallus crustose, thin, continuous, rarely cracked, white, granular, matt, 30–45 µm thick (in section). Border line dark brownish, c. 0·3 mm wide.
Ascomata lirellate, sparse, scattered, straight to curved, simple, rarely forked, emergent, black, 0·4–2·0(–3·5)×0·2–0·3 mm. Disc always a slit, rarely± exposed, black, epruinose, 30–59(–202) µm wide. Excipulum dark brown, continuous below the hypothecium, K+ olivaceous green, N+ reddish brown, 30–61 µm thickened laterally, 60–89 µm thickened basally. Epihymenium hyaline to pale brownish, 16–26 µm thick, K± olivaceous, N−, I+ red. Hymenium hyaline, 75–96 µm high, I+ red (upper part), I+ blue turning red or blue-violet (lower part), K−, K/I+ blue. Paraphysoids branched, anastomosing, 0·8–2·0 µm wide, not or slightly thickened apically. Hypothecium hyaline to pale brownish, 24–27 µm thick, I+ blue-violet, K+ green. Asci cylindric, 8-spored, 52–90×12–22 µm, K/I+ apical blue ring distinct. Ascospores hyaline, (39–)44–57(–60) ×(3·2–)4·2–5·5 µm, 7–9 septate, ontogeny of type 2 (macrocephalic), not constricted at the septa; perispore distinct, hyaline, no brown pigmentation observed, 0·9–1·5 µm wide.
Pycinidia visible as small black dots, 150–200 µm wide. Conidia hyaline, bacilliform, 3·5–4·8×0·7–1·2 µm.
Chemistry. Thallus K+ pale yellow, C−, KC−, Pd−, UV+ pale yellow fluorescence with some pink spots. An unidentified UV+ red spot with Rf value 83 in C detected by TLC after treatment of the plate.
Etymology. The specific epithet ‘granulosa’ refers to the granular thallus surface of the new species.
Remarks. The new species can easily be distinguished from the similar O. apomelaena A. Massal., which has an inspersed hymenium, lacks pycnidia, and has a K− and UV− thallus. At present the species is known only from the type locality.
The authors thank Dr D. Ertz, National Botanical Garden of Belgium, for help in identification, and the Director, Botanical Survey of India, Kolkata and Dr A. A. Ansari, Head of Office, B.S.I, Allahabad for the use of facilities.
