Rusavskia is a
genus of
lichen-forming
fungi in the family
Teloschistaceae. It has 12 species.[1] It is a member of the subfamily Xanthorioideae.[2] The
thallus of Rusavskia is characterized by its
foliose (leaf-like) structure with distinct and typically narrow
lobes that curve outwards.
Taxonomy
The genus Rusavskia was proposed by lichenologists
Sergey Kondratyuk and
Ingvar Kärnefelt in 2003, with Rusavskia elegans assigned as the
type species. The initial
circumscription of the genus relied predominantly on an evaluation of
morphological, anatomical and chemical characteristics, with a notable absence of
molecular phylogenetic analysis.[3] For this reason, the reception of the Rusavskia by lichenologists was initially met with cautious appraisal. As several molecular studies in the subsequent years showed, the Rusavskia elegans-group occupies a separate
monophyletic branch in the Teloschistaceae;[4][5][6] the growing body of molecular evidence led to the acceptance of the genus Rusavskia.[7]
Description
Rusavskia is characterized by its
foliose (leaf-like) structure with distinct and typically narrow
lobes that curve outwards. These lobes often feature
pseudocyphellae – tiny, white porous areas on the lichen's surface. The lichen adheres to surfaces using short, root-like structures called
hapters. Its reproductive structures, known as
apothecia, are
zeorine in form and display a noticeable orange hue. The
ascospores produced are
ellipsoid in shape, and polardiblastic, with a moderately divided central region (
septa). Additionally, Rusavskia may possess
pycnidia, which are embedded reproductive structures, and produce ellipsoid-shaped
conidia (asexual spores).[7]
Rusavskia was distinguished from Xanthoria due to several unique characteristics. Unlike Xanthoria, Rusavskia has a mesodermate
paraplectenchymatous cortex, which contrasts the earlier belief of it being
scleroplectenchymatous. While it was believed to lack attachment organs, it was later found that species like R. elegans and R. sorediata have hapters, albeit short ones. The
conidia (asexual spores) of Rusavskia are primarily ellipsoid, with only a minority being
bacilliform, contrary to earlier descriptions.[7]
In terms of morphology, Rusavskia predominantly differs from Xanthoria by its narrower lobes. When compared to Dufourea, Rusavskia stands out due to its narrow lobes that adhere more closely to surfaces. Although some experts hesitated to accept the distinct classification of Rusavskia, genetic evidence firmly sets it apart from Xanthoria and other related groups.[7]
^Fedorenko, Natalya M.; Stenroos, Soili; Thell, Arne; Kärnefelt, Ingvar; Kondratyuk, Sergey Y. (2009). "A phylogenetic analysis of xanthorioid lichens (Teloschistaceae, Ascomycota) based on ITS and mtSSU sequences". In Thell, Arne; Seaward, Mark; Feuerer, Tassilo (eds.). Diversity of Lichenology – Anniversary Volume. Bibliotheca Lichenologica. Vol. 100. J. Cramer in der Gebrüder Borntraeger Verlagsbuchhandlung. pp. 49–84.
ISBN978-3-443-58079-7.
^Fedorenko, Natalya M.; Stenroos, Soili; Thell, Arne; Kärnefelt, Ingvar; Elix, John A.; Hur, Jae-Seoun; Kondratyuk, Sergij Y. (2012). "Molecular phylogeny of xanthorioid lichens (Teloschistaceae, Ascomycota), with notes on their morphology". In Kärnefelt, Ingvar; Seaward, Mark R.D.; Thell, Arne (eds.). Systematics, biodiversity and ecology of lichens. Bibliotheca Lichenologica. Vol. 108. pp. 45–64.
ISBN978-3-443-58087-2.
^Gaya, Ester; Högnabba, Filip; Holguin, Ángela; Molnar, Katalin; Fernández-Brime, Samantha; Stenroos, Soili; Arup, Ulf; Søchting, Ulrik; Boom, Pieter Van den; Lücking, Robert; Sipman, Harrie J.M.; Lutzoni, François (2012). "Implementing a cumulative supermatrix approach for a comprehensive phylogenetic study of the Teloschistales (Pezizomycotina, Ascomycota)". Molecular Phylogenetics and Evolution. 63 (2): 374–387.
doi:
10.1016/j.ympev.2012.01.012.
PMID22306043.
^
abcdArup, Ulf; Søchting, Ulrik; Frödén, Patrik (2013). "A new taxonomy of the family Teloschistaceae". Nordic Journal of Botany. 31 (1): 16–83.
doi:
10.1111/j.1756-1051.2013.00062.x.