Isalonactis

Isalonactis is a monotypic fungal genus in the family Roccellaceae. It contains the single species Isalonactis madagascariensis, a saxicolous (rock-dwelling), crustose lichen found in Madagascar. Both the genus and species were described as new in 2014 by Damien Ertz, Anders Tehler, Eberhard Fischer, Dorothee Killmann, Tahina Razafindrahaja, and Emmanuël Sérusiaux. The type was collected on the Isalo Massif (in Isalo National Park) at an altitude of 851 m; there, it was found growing on sheltered mesozoic sandstone cliffs. The genus name alludes to both Isalo Massif, the type locality, and the phylogenetic relatedness to genus Lecanactis.

Isalonactis madagascariensis has a thin, smooth thallus lacking a cortex, and with fine surface cracks, sometimes to the point of being areolate. The photobiont partner is trentepholioid (i.e., green algae in the genus Trentepohlia). The lichen contains psoromic acid.