Gibbosporina, a new genus for foliose and tripartite,Palaeotropic Pannariaceae species previously assigned to Psoroma

Abstract

Reports of 'Psoroma sphinctrinum' from Palaeotropical areas are shown to instead represent species of the 17 genus Gibbosporina, which is described as new to science here. This genus is superficially similar to tripartite, austral 18 Pannaria species, such as the species now referred to as Pannaria sphinctrina (Mont.) Tuck. ex Hue. Phylograms based 19 on an analysis of the LSU and ITS loci show that Gibbosporina instead is a clade in a Pannariaceae branch referred to as 20 the 'Physma group', a most unexpected addition to Pannariaceae dealt with by several previous studies. Genera assigned 21 to this group have very contrasting general appearances. However, this diverse group shares distinctly ring-like thalline 22 excipular margins, strongly amyloid internal ascus structures, well-developed perispores which have irregular gibbae or 23 apicular nodulose or acuminate extensions, but not verrucae, lacks TLC-detectable secondary compounds and have 24 tropical distributions. Gibbosporina is the only tripartite genus in the group, with distinct, nodulose, placodioid, mini25 fruticose to mini-foliose cephalodia with a high diversity of Nostoc cyanobionts. The cyanomorphs can apparently exist 26 independently in some cases, although they have so far not been seen outside of the prothallus zone. In a sample from 27 Reunion, the apothecia on cephalodia were unexpectedly found to belong to the chloromorph. The genus and related genera in the 'Physma group' are probably evolutionary old, and their weak affinity to the 28 remaining part of 29 Pannariaceae, concentrated in the Southern Hemisphere, is discussed. The genus includes 13 known species, and the 30 generitype is Gibbosporina boninensis from the Japanese Ogasawara Islands, originally described as Psoroma boninense 31 and recombined here. The following 12 species are described as new to science here, seven of them with molecular 32 support: Gibbosporina acuminata (Australia, the Philippines), G. amphorella (New Caledonia), G. bifrons (Malaysia, 33 New Caledonia, the Philippines, Solomon Islands), G. didyma (Mauritius, Reunion), G. elixii (Australia), G. leptospora 34 (Australia, Papua New Guinea), G. nitida (Australia, Papua New Guinea, the Philippines), G. mascarena (Mauritius, 35 Reunion, Sri Lanka), G. papillospora (the Philippines), G. phyllidiata (Solomon Islands), G. sphaerospora (Australia, 36 Indonesia, Malaysia, the Philippines, Samoa, and with Psoroma sphinctrinum var. endoxanthellum as a new synonym), 37 and G. thamnophora (Australia and the Philippines). Except for the phyllidiate G. phyllidiata and G. thamnophora with 38 cephalodia adapted to vegetative propagation, the species are all primarily fertile. A key for determining the species is 39 provided