A morphometric approach and recircumscription of the Stachytarpheta longispicata complex (Verbenaceae)

Abstract

The Stachytarpheta longispicata complex is a group of seven accepted infraspecific taxa endemic to the Brazilian Cerrado, defined by its pedicellate flowers with salmon or dark red corollas. Due to the great morphological variation and very brief original descriptions, these taxa have controversial circumscriptions. We evaluated the morphological variation through the morphometric analysis of 11 natural populations in addition to nomenclatural types to assess the current infraspecific circumscriptions and clarify the limits of these taxa. A set of 36 continuous vegetative and reproductive characters was measured for each of the 115 specimens sampled, encompassing the morphological variability in the group and its geographic distribution. A compiled data matrix formed the basis for the multivariate analysis (UPGMA, PCA, and DA). Our results recovered five consistent groups corresponding to the four subspecies, and all three recognised varieties treated in the same morphological group. Quantitative and qualitative characters not previously studied in detail are important to delimit the five groups. A taxonomic rearrangement is proposed for the complex, circumscribing five distinct species: Stachytarpheta brevibracteata, S. longipedicellata, S. longispicata, S. minasensis, and S. ratteri. The taxonomic treatment includes four new combinations and names at new rank, two new synonyms, and one lectotype. Descriptions, an identification key, geographical distribution map, illustrations, and provisional conservation assessments are also provided.

Still on the Stachytarpheta longispicata complex (Verbenaceae): two new narrowly endemic species from the Cerrado domain of Central Brazil

“…Furthermore, it was not possible to collect populations from Serra Dourada and Jalapão (Cardoso unpubl.). Still, after clarifying the limits of the S. longiospicata complex (Cardoso et al 2022), morphological analyses confirmed that the plants from Serra Dourada and Jalapão are distinct within Stachytarpheta , being proposed herein as new species.…”

“…Regarding the morphological characters of the Stachytarpheta inflorescence, almost all species present sessile flowers (inflorescences in spikes), except a small group endemic to the Brazilian Cerrado domain, characterised by having pedicellate flowers (inflorescences in racemes) (Atkins 2005, Cardoso and Salimena 2020, Cardoso et al 2022). This group of pedicellate flowers includes, according to Atkins (2005), seven infraspecific taxa (three varieties and four subspecies) of Stachytarpheta longispicata (Pohl) S.Atkins.…”

“…This group of pedicellate flowers includes, according to Atkins (2005), seven infraspecific taxa (three varieties and four subspecies) of Stachytarpheta longispicata (Pohl) S.Atkins. Recently, Cardoso et al (2022) detailed the taxonomic history of the group ( S. longispicata complex) and, based on population morphometry and morphological evidence, provided a new delimitation for this species complex. There are no phylogenetic studies comprising representatives of this complex.…”

“…According to Cardoso et al (2022), five species with particular geographic distribution are currently recognised: Stachytarpheta brevibracteata (Moldenke) Cardoso occurring in the State of Minas Gerais and near the limits with the State of São Paulo, mainly in the Serra da Canastra region; S. longipedicellata (Moldenke) Cardoso is found in the State of Goiás, mainly in the Chapada dos Veadeiros region; S. longispicata is endemic to the Serra dos Cristais region in the State of Goiás; S. minasensis (S.Atkins) Cardoso is restricted to the Serra do Cabral, State of Minas Gerais; and S. ratteri (S.Atkins) Cardoso is found mainly in Distrito Federal and within the State of Goiás, in the surroundings of the Serra dos Pirineus (Cardoso et al 2022). These species inhabit campos rupestres (rocky field) and campos cerrados (grassland) and have been suggested to be threatened with extinction (Cardoso et al 2022).…”

“…While preparing a taxonomic treatment of the S. longispicata complex, some undetermined specimens from the States of Goiás (Serra Dourada region) and Tocantins (Jalapão region) having pedicellate flowers called our attention due to their distinct morphology. These specimens were not included in the morphometric analyses of Cardoso et al (2022) because this study followed the circumscription and distribution of taxa presented by Atkins (2005). Furthermore, it was not possible to collect populations from Serra Dourada and Jalapão (Cardoso unpubl.).…”