Diorygma is a genus of lichen-forming fungi in the family Graphidaceae. The genus was circumscribed by Franz Gerhard Eschweiler in 1824.[2] Species of the genus are widely distributed in tropical and subtropical regions of the world. These lichens form paint-like crusts on bark and rock that range from chalky white to light green, with elongated, pencil-like slits containing their spores that may flex and branch across the surface. The genus was established in 1824 for tropical script lichens with large, many-celled spores, but molecular studies in the 2000s and 2010s expanded it significantly by transferring species from other genera and revealing new diversity.
The name Diorygma was coined by Franz Gerhard Eschweiler in 1824 for a group of neotropical script lichens in the family Graphidaceae that have large, many-celled ( muriform ) spores and a thin, naked hymenium.[2]Elias Fries accepted the genus in 1825—likening it to what is now Arthonia—but made no additional combinations. Eschweiler himself broadened the concept in 1833 by adding several species that subsequent work has reassigned to Fissurina and Platythecium. Towards the end of the nineteenth century, Johannes Müller Argoviensis erected the genus Graphina for muriform -spored taxa, retaining a handful of Diorygma species within his sectionsPlatygraphina and Platygrammina, thereby narrowing the scope of Eschweiler's original taxon.[3]
Interest in the group revived in the twentieth century. Dharani Dhar Awasthi and Mamta Joshi, while revising Helminthocarpon in 1979, recognised that these lirellate lichens formed a discrete lineage, but instead of resurrecting Eschweiler's name they introduced Cyclographina. In a comprehensive monograph of 2002, Bettina Staiger restored Diorygma for this assemblage and, on the basis of its rather unusual tissue organisation, suggested that it might fall outside the core Graphidaceae. Subsequent molecular analyses have confirmed that Diorygma does indeed belong within that family and have expanded its limits to include species with either single-spored, muriform asci or with spores divided only by transverse walls.[3]
Description
Species of Diorygma form a crustose (tightly adherent, paint-like) thallus that ranges in hue from chalky white or cream to light olive-grey or green. The surface is generally dull and may be uneven, slightly wrinkled, or minutely warted; fine cracks are common. Unlike many other script lichens, the thallus lacks special powdery propagules (soralia or isidia). A true outer "skin" ( pseudocortex ) is poorly developed or absent, while the interior medulla is white and often riddled with conspicuous crystal deposits. The embedded partner alga is Trentepohlia, a filamentous green alga that imparts a faint orange tinge when exposed.[4]
The sexual fruit-bodies are lirellae —elongate, pencil-like slits that may flex and branch across the thallus. Their margins can be thick and swollen or remain almost flush with the surface, and the exposed disc is usually brown, sometimes dusted with a whitish or yellowish bloom ( pruina ). Internally, the lateral wall ( exciple ) may be pale or blackened (" carbonised ") and often shows fine striations produced by repeated regrowth events. The hymenium—the spore-producing layer—is clear and oil-free but stains bluish-violet in iodine at its upper and outer portions. At its roof lies a tangle of gelatinous, net-like paraphyses that carry nodular tips and brown or colourless granules . Club-shaped asci have the so-called "Graphis-type" apex with a thickened inner cap, and they bear one to eight colourless ascospores. These spores are oblong with rounded ends, occasionally spindle-shaped, and show transverse walls (sometimes with additional vertical walls to give a brick-like, muriform pattern); they measure roughly 15–250 × 5–60μm and may turn blue-violet in iodine.[4]
↑ Joshi, Santosh; Jayalal, Udeni; Oh, Soon-Ok; Koh, Young Jin; Nguyen, Thi Thuy; Dzung, Nguyen Anh; Hur, Jae-Seoun (2013). "New species and new records in the family Graphidaceae (Ascomycota: Ostropales) from Vietnam". The Lichenologist. 45 (5): 599–609. Bibcode:2013ThLic..45..599J. doi:10.1017/s002428291300025x.
↑ Kalb, K. (2020). "New or otherwise interesting lichens. VII, including a world key to the lichen genus Heiomasia". Archive for Lichenology. 15: 1–18.
1 2 3 Feuerstein, Shirley Cunha; Cunha-Dias, Iane Paula Rego; Aptroot, André; Eliasaro, Sionara; Cáceres, Marcela Eugenia da Silva (2014). "Three new Diorygma (Graphidaceae) species from Brazil, with a revised world key". The Lichenologist. 46 (6): 753–761. Bibcode:2014ThLic..46..753F. doi:10.1017/s002428291400036x.
↑ de Lima, Edvaneide Leandro; Maia, Leonor Costa; Aptroot, André; da Silva Cáceres, Marcela Eugenia (2013). "New lichen species from Vale do Catimbau, Pernambuco, Brazil". The Bryologist. 116 (4): 327–329. doi:10.1639/0007-2745-116.4.327.
↑ Papong, Khwanruan Butsatorn; Lücking, Robert; Kraichak, Ekaphan; Parnmen, Sittiporn; Konrat, Matt Von; Lumbsch, H. Thorsten (2014). "Twenty-three new species in the lichen family Graphidaceae from New Caledonia (Ostropales, Ascomycota)". Phytotaxa. 189 (1): 204–231. Bibcode:2014Phytx.189..204P. doi:10.11646/phytotaxa.189.1.15.
↑ de Lima, Edvaneide Leandro; Maia, Leonor Costa; Barroso Martins, Mônica Cristina; da Silva, Nicácio Lima; Lücking, Robert; da Silva Cáceres, Marcela Eugenia (2019). "Five new species of Graphidaceae from the Brazilian Northeast, with notes on Diorygma alagoense". The Bryologist. 122 (3): 414–422. doi:10.1639/0007-2745-122.3.414.
↑ Archer, A.W.; Elix, J.A. (2017). "A new species of Diorygma (Graphidaceae, lichenized Ascomycota) from Australia containing neotricone". Australasian Lichenology. 81: 93–95.
↑ Sipman, H.J.M. (2018). "Diorygma upretii spec. nov., a poleotolerant lichen in the tropics". Cryptogam Biodiversity and Assessment. Special volume (2018: 1–5.
↑ Archer, A.W.; Elix, J.A. (2008). "Three new species in the Australian Graphidaceae (lichenized Ascomycota)". Australasian Lichenology. 63: 26–29.
Cited literature
Kalb, K.; Staiger, B.; Elix, J.A. (2004). "A monograph of the lichen genus Diorygma – a first attempt". Symbolae Botanicae Upsalienses. 34 (1): 133–181.
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