Phylogenetics of Gratioleae (Plantaginaceae): paraphyly of Stemodia and its implications for generic circumscriptions, with insights from floral evolution

Abstract

Gratioleae are the most species-rich tribe of Plantaginaceae in the tropics, spanning c. 30 genera and > 300 species, with a wide range of morphological variation and ecological strategies. As a first effort towards a phylogenetic classification of Gratioleae we generated a new phylogenetic hypothesis with improved taxa sampling, based on one nuclear and three plastid markers, using maximum parsimony and Bayesian inference approaches, and performed ancestral state reconstructions of ten morphological characters of flowers. The paraphyly of Stemodia s.l. was corroborated with members being retrieved in four clades; Bacopa, Conobea, Leucospora and Schistophragma are non-monophyletic. As actions towards recognizing only monophyletic genera in Gratioleae, we propose Stemodia s.s. as a monophyletic and morphological cohesive group, describe Umbraria as a new genus to accommodate two species segregated from Stemodia, transfer Stemodia vandelliodes to Darcya, merge Conobea with Bacopa and re-establish the names Chodaphyton ericifolium and Geochorda glechomoides. Traits used to define Stemodia s.l. are plesiomorphic in the tribe; the flower type (composed of seven floral characters) constitutes a good diagnostic set of traits for almost all genera in the tribe. Our study sheds light on the urgent need to reassess generic circumscriptions towards a unified classification in Gratioleae.

Plastid phylogenomics contributes to the taxonomic revision of taxa within the genus Sanicula L. and acceptance of two new members of the genus

“…In most angiosperms, plastids are usually considered to be inherited from the maternal parent and have low nucleotide substitution rates ( Wicke et al., 2011 ; Wataru and Tsuneaki, 2023 ). Thus, the plastid genomes (plastomes) have been widely and successfully used for plant phylogenetic analyses ( Duminil et al, 2012 ; Miller et al, 2014 ; Razafimandimbison et al, 2014 ; Zhang et al, 2018 ; Schneider et al, 2021 ; Xu and Hong., 2021 ; Ji et al., 2022 ; Scatigna et al, 2022 ; Xiang et al, 2022 ; Baldwin et al, 2023 ; Fu et al, 2023 ), especially for those taxonomically controversial taxa within the family Apiaceae ( Gou et al., 2020 ; Ren et al., 2020 , 2022 ; Cai et al., 2022 ; Liu et al., 2022 ; Guo et al., 2023 ; Liu et al., 2023a ; Lei et al., 2022 ; Gui et al., 2023 ; Peng et al., 2023 ; Qin et al., 2023 ; Song et al., 2023 ; Tian et al., 2023 ; Song et al., 2024 ). For example, Song et al.…”

Table_3.doc

“…In most angiosperms, plastids are usually considered to be inherited from the maternal parent and have low nucleotide substitution rates (Wicke et al, 2011;Wataru and Tsuneaki, 2023). Thus, the plastid genomes (plastomes) have been widely and successfully used for plant phylogenetic analyses (Duminil et al, 2012;Miller et al, 2014;Razafimandimbison et al, 2014;Zhang et al, 2018;Schneider et al, 2021;Xu and Hong., 2021;Ji et al, 2022;Scatigna et al, 2022;Xiang et al, 2022;Baldwin et al, 2023;Fu et al, 2023), especially for those taxonomically controversial taxa within the family Apiaceae (Gou et al, 2020;Ren et al, 2020Ren et al, , 2022Cai et al, 2022;Liu et al, 2022;Guo et al, 2023;Liu et al, 2023a;Lei et al, 2022;Gui et al, 2023;Peng et al, 2023;Qin et al, 2023;Song et al, 2023;Tian et al, 2023;Song et al, 2024). For example, Song et al (2023) transferred Peucedanum franchetii C.Y.Wu & F.T.Pu under the genus Ligusticopsis Leute based on phylogenetic analysis of ten plastomes.…”

Image_5.tif

“…In most angiosperms, plastids are usually considered to be inherited from the maternal parent and have low nucleotide substitution rates (Wicke et al, 2011;Wataru and Tsuneaki, 2023). Thus, the plastid genomes (plastomes) have been widely and successfully used for plant phylogenetic analyses (Duminil et al, 2012;Miller et al, 2014;Razafimandimbison et al, 2014;Zhang et al, 2018;Schneider et al, 2021;Xu and Hong., 2021;Ji et al, 2022;Scatigna et al, 2022;Xiang et al, 2022;Baldwin et al, 2023;Fu et al, 2023), especially for those taxonomically controversial taxa within the family Apiaceae (Gou et al, 2020;Ren et al, 2020Ren et al, , 2022Cai et al, 2022;Liu et al, 2022;Guo et al, 2023;Liu et al, 2023a;Lei et al, 2022;Gui et al, 2023;Peng et al, 2023;Qin et al, 2023;Song et al, 2023;Tian et al, 2023;Song et al, 2024). For example, Song et al (2023) transferred Peucedanum franchetii C.Y.Wu & F.T.Pu under the genus Ligusticopsis Leute based on phylogenetic analysis of ten plastomes.…”