Novel classification and biogeography of Leptolejeunea (Lejeuneaceae, Marchantiophyta) with implications for the origin and evolution of the Asian evergreen broad‐leaved forests

Abstract

Although recent molecular phylogenetic analyses have greatly improved our understanding of the classification of the large liverwort family Lejeuneaceae, the frequent incongruencies between morphology‐based taxonomy and molecular phylogeny have hindered our understanding of evolutionary diversification within the group. Here we focus on Leptolejeunea (Spruce) Steph., a pantropical epiphyllous genus in Lejeuneaceae with 40 species. Phylogenetic studies on the genus have been hampered by insufficient taxon sampling, leaving the deep phylogenetic relationships within this group unresolved. We present the most comprehensive phylogenetic analysis of the genus to date with sampling of over 80% of species, including the enigmatic Leptolejeunea spinistipula (Mizut.) X.L.He endemic to Borneo. Based on data from three molecular markers with representatives of Leptolejeunea and its allies, Leptolejeunea appeared to be monophyletic following the exclusion of L. spinistipula and its transfer to Soella R.L.Zhu, L.Shu, Qiong He & Y.M.Wei. A total‐evidence approach was taken to resolve the backbone phylogeny of Leptolejeunea and a first infrageneric classification of Leptolejeunea, including a new subgenus and three new sections, is proposed based on integrated molecular and morphological evidence. Reconstruction of the evolutionary history showed a wide ancestral area of Leptolejeunea during the Paleogene that arose in mainland Asia, followed by an accelerated speciation rate. Across the biogeographical history of Leptolejeunea, long‐distance dispersal had profound effects on population expansion. Our findings suggest that Australasia is a source of biodiversity of Asian evergreen broad‐leaved forests that have been established since the Oligocene and rose after the early Miocene.

Taxonomic notes and range extension of several complex thalloid liverworts

“…DNA extraction and sequencing: The isolation of plant tissues and extraction of total DNA followed protocols previously described by Xiang et al (2016) and Shu et al (2022). Three DNA loci ( rbc L, rps 4, and trn L–F) were sequenced by Jie Li Biology Inc., China (http://www.genebioseq.com).…”

An updated checklist of liverworts and hornworts of Malaysia

“…Steph. – Herzog (1942 as L. serrulata ), Inoue (1967a as L. serrulata ), Kitagawa (1969c as L. serrulata ), Thiers (1986 as L. serrulata ), Pócs et al (2020) , Shu et al (2021) . Penang, Selangor, Pahang, Sabah.…”

“… Soella spinistipula (Mizut.) R.L.Zhu et L.Shu – Mizutani (1970 as Pycnolejeunea spinistipula ), Bi et al (2019 as Leptolejeunea spinistipula ), Shu et al (2021) . Sarawak, Sabah.…”

“… Leptolejeunea elliptica auct. (Asian plants; non typus) = L. subacuta A.Evans ( Bechteler et al 2017 , Shu et al 2021 )…”