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| Crassicaulis Lei Cai & Mich.Möller gen. nov. Crassicaulis guiliangii Lei Cai & F.M.Yang, in F. Yang, Ling, R. Yang, Wen, Gu, Hu, Lin, Wang, J. Cai, Ren, Möller et L. Cai, 2025. 粗茎苣苔属 || DOI: doi.org/10.1111/cla.70010 |
Abstract
The subtribe Leptoboeinae (Gesneriaceae) has undergone numerous taxonomic revisions due to ambiguous generic boundaries, complicating conservation and utilization efforts. In this study, we employed transcriptomes from a representative clade within the subtribe to construct a low-copy nuclear (LCN) gene data set. Plastid genomes and LCN genes, assembled from 66 samples, were used to investigate the phylogenetic structure, reticulate evolution and divergence times among the species of this subtribe. Firstly, phylogenetic analysis revealed that Boeica is polyphyletic and identified a new genus, Crassicaulis, which forms a sister group to the remaining genera within the subtribe. Secondly, complex cytonuclear conflicts and gene tree incongruence at genus-level nodes were identified. Multiple lines of evidence revealed two reticulate evolutionary events within this lineage, suggesting that Boeica porosa and B. stolonifera, as well as Boeica enpingensis, underwent hybridization during their speciation processes. Finally, divergence time estimation revealed that most genera emerged between 17 and 12 Ma. This study provides a well-resolved phylogenetic framework for the subtribe Leptoboeinae, describes a new genus and elucidates the subtribe's intricate reticulate evolutionary history. Furthermore, we propose that the mid-Miocene East Asian monsoon played a pivotal role in the diversification of this lineage.
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| Crassicaulis guiliangii Lei Cai & F.M.Yang, sp. nov. (a) Habitat. (b) Stem showing petiole and peduncle. (c) Adaxial leaf surface. (d)Abaxial leaf surface. (e–g) Inflorescence. (h) Infructescence. (i) Front view of flower. (j) Opened corolla and pistil. (k) Opened corolla and pistilwith calyx. (l) Opened young fruit. |
Crassicaulis Lei Cai & Mich.Möller gen. nov.
Diagnosis: Crassicaulis Lei Cai & Mich.Möller most resembles Boeica C.B.Clarke and Leptoboea Benth. according to the morphological evidence but can easily be distinguished from Boeica by its opposite leaves, and a corolla tube that is slightly longer than the limb, from Leptoboea by the habit of its species (subshrubs without woodiness), and the 20–35 flowers on each inflorescence, and from both by the pedicel, calyx and corolla all being glandular-pubescent, the two ridges at the lower part of the corolla throat and the thicker stem.
Etymology: The genus name “Crassicaulis” was chosen to reflect the relatively thick stems, a rare character in the Gesneriaceae, of the only known species ofthis genus. The Chinese name is 粗茎苣苔属.
Type species: Crassicaulis guiliangii Lei Cai & F.M.Yang.
Fengmao Yang, Shaojun Ling, Ruxuan Yang, Fang Wen, Wei Gu, Xiangzhou Hu, Liewen Lin, Yizhi Wang, Jie Cai, Mingxun Ren, Michael Möller and Lei Cai. 2025. Phylogenomic Reconstruction reveals deep reticulate Evolutionary History and Polyphyletic Genus Boeica in the subtribe Leptoboeinae (Gesneriaceae), with description of A Novel Genus. Cladistics. DOI: doi.org/10.1111/cla.70010 [08 October 2025]
