Taxonomic notes on Scutellaria taipeiensis (Lamiaceae) from morphological and molecular data

Abstract

The genus Scutellaria comprises eight species distributed from 50 to 2000 m in Taiwan. Amongst them, S. barbata and S. taipeiensis are very similar on the basis of morphological and plastid DNA sequence information. Therefore, a comprehensive study of the taxonomic status of S. taipeiensis is necessary. We reviewed the herbarium sheets, related literature and protologues and compared morphologies of these two species, as well as their phylogenetic relationships. All evidence, including the diagnostic characters between S. taipeiensis and S. barbata, suggest that they belonged to a single species rather than two. As a result, S. taipeiensis is treated as a synonym of S. barbata.

The Role of In Situ Diversification in Island Endemism: Adaptive Introgression in Scutellaria in Taiwan

“…Hybrids that acquire new adaptive genes and subsequent mutations that function later in the speciation process (Bock et al, 2023) can widen their ecological potential, adapt to new habitats, and reduce vulnerability to climate change (Brauer et al, 2023). Chiang, Huang, and Liao (2012) established that S. barbata is the most divergent species (and a heterotypic synonym of S. taipeiensis (Chao et al, 2020;Hsiung et al, 2017)) in the phylogeny, followed by S. taiwanensis and the "indica group" (which includes S. indica , S. tashiroi , S. playfairii ,S. austrotaiwanensis (Chiang, Huang, & Liao, 2012), and the new species S. hsiehii (Hsieh, 2013)). Hybridization has occurred not only within the indica group but also between the indicagroup and S. barbata and S. taiwanensis , implying a lack of reproductive isolation between species.…”

“…1; Table S1). Species identification of the collected samples was based on Hsieh (2013), Hsieh and Huang (1995), Hsieh andHuang (1997), andChao et al (2020). Fresh leaves from 4-46 individuals per population were collected and dried in silica gel.…”

“…These three Taiwan-endemic species are thus cladogenetic or regional sympatric species. By contrast, S. taiwanensis and S. barbata (including its synonym S. taipeiensis (Chao et al, 2020)) colonized Taiwan independently during the Middle Pleistocene, i.e., 0.4 Mya (Chiang, Huang, & Liao, 2012), and are so-called anagenetic or regional allopatric species.…”

“…The demographic history of Scutellaria on Taiwan Island reveals frequent southward and northward dispersal and vicariance events (Chiang, Huang, & Liao, 2012), and their historical sympatric distribution has allowed interbreeding (Huang et al, 2017). Their morphological similarities (Chao et al, 2020;Hsieh, 2013;Hsieh & Huang, 1995, 1997 and relatively short speciation history (Chiang, Huang, & Liao, 2012) suggest that this group of species has only recently completed or is still undergoing the speciation process. Their adaptation to diverse environments and repeated secondary contacts allowing hybridization and introgression have likely played critical roles in maintaining their species and genetic diversities.…”