Melanelixia

Melanelixia is a genus of foliose lichens in the family Parmeliaceae. It contains 15 Northern Hemisphere species that grow on bark or on wood. The genus is characterized by a pored or fenestrate epicortex (a thin homogeneous polysaccharide layer on the surface of the cortex), and the production of lecanoric acid as the primary chemical constituent of the medulla. Melanelixia was circumscribed in 2004 as a segregate of the related genus Melanelia.

Melanelixia
Melanelixia glabra
Scientific classification
Kingdom: Fungi
Division: Ascomycota
Class: Lecanoromycetes
Order: Lecanorales
Family: Parmeliaceae
Genus: Melanelixia
O.Blanco, A.Crespo, Divakar, Essl., D.Hawksw. & Lumbsch (2004)
Type species
Melanelixia glabra
(Schaer.) O.Blanco, A.Crespo, Divakar, Essl., D.Hawksw. & Lumbsch (2004)

Taxonomy

Melanelixia was circumscribed in 2004 as a segregate of the genus Melanelia. Melanelixia originally contained eight species, including the type, M. glabra. The genus name combines Melanelia with the name of lichenologist John A. Elix, "for his immense contributions to lichen systematics and chemistry, especially in Parmeliaceae."[1]

Several species distributed in the Southern Hemisphere were removed from Melanelixia and transferred to the new genus Austromelanelixia in 2017. This group of species, which forms a distinct clade in Melanelixia, produces gyrophoric acid rather than lecanoric acid in their medullae.[2]

Description

Melanelixia lichens are foliose and have a loosely to moderately adnate attachment to their substrata. The thallus is made of plane to concave lobes with rounded tips that measure 1–6 mm wide. The upper surface of the thallus ranges in colour from olive-green to dark brown, and has a smooth or wrinkled texture. Features that are variably present on the thallus include maculae (spots or stains), soredia, isidia, and cortical hairs. Pseudocyphellae are not present. Cell walls contain the α-glucan compound isolichenan. The apothecia of Melanelixia have an abundantly fenestrated or pored epicortex. Ascospores are ellipsoid to ovoid in shape, thin-walled, and measure 9–15 by 5–11.5 μm.[1]

Lichens in the genus Pleurosticita are similar in appearance, but are distinguished from Melanelixia by their broader lobes, pores on the epicortex that are reticulated, a pigment that reacts violet in K and HNO3, and the presence of depsidones in the medulla.[1]

Habitat and distribution

Found in the Northern Hemisphere, Melanelixia species grow on bark or wood.[1]

Species
Melanelixia fuliginosa
  • Melanelixia ahtii S.D.Leav., Essl., Divakar, A.Crespo & Lumbsch (2016)[3]
  • Melanelixia albertana (Ahti) O.Blanco, A.Crespo, Divakar, Essl., D.Hawksw. & Lumbsch (2004)
  • Melanelixia californica A.Crespo & Divakar (2010)
  • Melanelixia epilosa (J.Steiner) A.Crespo, Divakar, Gasparyan, V.J.Rico, Essl., S.D.Leav. & Lumbsch (2016)[3]
  • Melanelixia fuliginosa (Fr. ex Duby) O.Blanco, A.Crespo, Divakar, Essl., D.Hawksw. & Lumbsch (2004)
  • Melanelixia glabra (Schaer.) O.Blanco, A.Crespo, Divakar, Essl., D.Hawksw. & Lumbsch (2004)
  • Melanelixia glabratula (Lamy) Sandler & Arup (2011)[4]
  • Melanelixia glabroides (Essl.) O.Blanco, A.Crespo, Divakar, Essl., D.Hawksw. & Lumbsch (2004)
  • Melanelixia hawksworthii S.D.Leav., Essl., Divakar, A.Crespo & Lumbsch (2016)[3]
  • Melanelixia huei (Asahina) O.Blanco, A.Crespo, Divakar, Essl., D.Hawksw. & Lumbsch (2004)
  • Melanelixia robertsoniorum S.D.Leav., Essl., Divakar, A.Crespo & Lumbsch (2016)[3]
  • Melanelixia subargentifera (Nyl.) O.Blanco, A.Crespo, Divakar, Essl., D.Hawksw. & Lumbsch (2004)
  • Melanelixia subaurifera (Nyl.) O.Blanco, A.Crespo, Divakar, Essl., D.Hawksw. & Lumbsch (2004)
  • Melanelixia subvillosella H.Y.Wang & J.C.Wei (2008)[5] – China
  • Melanelixia villosella (Essl.) O.Blanco, A.Crespo, Divakar, Essl., D.Hawksw. & Lumbsch (2004)

References
  1. Blanco, Oscar; Crespo, Ana; Divakar, Pradeep K.; Esslinger, Theodore L.; Hawksworth, David L.; Lumbsch, H. Thorsten (2004). "Melanelixia and Melanohalea, two new genera segregated from Melanelia (Parmeliaceae) based on molecular and morphological data". Mycological Research. 108 (8): 873–884. doi:10.1017/S0953756204000723. PMID 15449592.
  2. Divakar, Pradeep K.; Crespo, Ana; Kraichak, Ekaphan; Leavitt, Steven D.; Singh, Garima; Schmitt, Imke; Lumbsch, H. Thorsten (2017). "Using a temporal phylogenetic method to harmonize family- and genus-level classification in the largest clade of lichen-forming fungi". Fungal Diversity. 84: 101–117. doi:10.1007/s13225-017-0379-z. S2CID 40674310.
  3. Leavitt, Steven D.; Esslinger, Theodore L.; Divakar, Pradeep K.; Crespo, Ana; Lumbsch, H. Thorsten (2016). "Hidden diversity before our eyes: Delimiting and describing cryptic lichen-forming fungal species in camouflage lichens (Parmeliaceae, Ascomycota)". Fungal Biology. 120 (11): 1374–1391. doi:10.1016/j.funbio.2016.06.001. PMID 27742095.
  4. Arup, Ulf; Berlin, Emma Sandler (2011). "A taxonomic study of Melanelixia fuliginosa in Europe". Lichenologist. 43 (2): 89–97. doi:10.1017/S0024282910000678.
  5. Wang, Hai-Ying; Chen, Jian-Bin; Wei, Jiang-Chun (2008). "A new species of Melanelixia (Parmeliaceae) from China". Mycotaxon. 104: 185–188.
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