Nephromopsis melaloma (Nyl.) A. Thell & Randlane
Nomenclatural data
Mycol. Progress 4(4): 311, 2005. – Platysma melalomum Nyl., Syn. Lich. 1: 303, 1860. – Type: [India] Sikkim, Jongri, regione alpina, supra mare alt. 13 000 ft, inter Cladonias et muscos, J. D. Hooker 2665 (BM! – lectotype, H-NYL 36 072! – isolectotype). – Cetraria melaloma (Nyl.) Kremp., Verh. Zool.-Bot. Ges. Wien 18: 315, 1868. – Cetraria pallida D. D. Awasthi, Proc. Indian Acad. Sci. 45: 130, 1957. – Type: Nepal, Topkegola, Thaglabhanjyang, alt. 4200 m, 29.05.1953, D. D. Awasthi 2347 (Herb. Awasthi – holotype)
Morphology
Thallus dorsiventral, suberect to erect, 2–3.5 cm high, irregularly branched; lobes plane or involute, of medium size, 2–6 mm broad, with undulate margins; both surfaces pale yellow up to brownish yellow, often with brown margins and always with black marginal projections; pseudocyphellae laminal, round or oval, ca. 0.5 mm in diameter, grey in colour, surrounded by a black or brown rim, may be present on both surfaces but more usual on the lower surface only; rhizines, isidia and soredia absent. Medulla white. Apothecia unknown. Pycnidia black, on short marginal projections; pycnoconidia not seen.
Typical characters. Thallus dorsiventral, pale yellow to brownish yellow on both surfaces. Lobes rather wide (up to 6 mm). Pseudocyphellae – laminal, round or oval, grey, surrounded by a dark rim – may be present on both surfaces but are more common on the lower surface.
Chemistry
Contains usnic acid in the cortex; lichesterinic and protolichesterinic acids in the medulla. According to Awasthi (1983), stictic acid has also been detected occasionally.
Remarks
The species is morphologically rather similar to another rare Asian Cetraria – 'C.' leucostigma Lév. However, the latter is darker in colour (usually yellow on the upper and brown on the lower surface), with white pseudocyphellae only on the lower surface. Apothecia have not been observed in 'C.' melaloma, and have only been reported once in 'C.' leucostigma (Awasthi 1983) but have not been thoroughly studied. Pycnidia have been observed in both species but pycnoconidia have not been detected in either taxon. We agree with Thell (1996) that 'C.' leucostigma and 'C.' melaloma do not belong to the genus Cetraria s. strict. According to the revised definition of the genus (Kärnefelt et al. 1993), all the cetrarioid lichens containing usnic acid have been excluded from Cetraria s. strict. Presence of one-layered palisade plectenchymatous cortex with anticlinally arranged hyphae in 'C.' leucostigma and 'C.' melaloma (Thell 1996) is not characteristic of Cetraria s. strict. either. The systematic position (generic location) of these two species has yet to be determined (Randlane et al. 1997), and will be dependent upon a detailed investigation of ascomata or upon molecular analysis.
Ecology and distribution
A rare species, known from India (Awasthi 1983, 1988), Nepal (Awasthi 1983) and China – Shaanxi and Xizang provinces (Wei 1991); and now also from Bhutan. Grows on soil among mosses or on rocks in alpine meadows at altitudes of 3500–4800 m.
Literature
Randlane, T. & Saag, A. 1992. | Randlane, T. & Saag, A. 1998. |Randlane, T. & Saag, A. 2004. | Randlane, T., Saag, A. & Obermayer, W. 2001. | Randlane, T., Saag, A., Thell, A. & Kärnefelt, I. 1994. | Randlane, T., Thell, A., & Saag, A. 1995. | Thell, A., Randlane, T., Saag, A. & Kärnefelt, I. 2005.
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