Bahiana, a new Euphorbiaceae (Acalyphoideae) genus from seasonally dry forest in northeastern Brazil, corroborated by molecular and morphological evidence

Abstract

After discovering an unknown Euphorbiaceae with an unusual combination of morphological characters, molecular phylogenetic analyses were conducted to evaluate the phylogenetic position of the plant. Results of the analyses support the recognition of a resolved lineage sister to a clade comprising Caryodendron, which is sister to the Adenophaedra + Bernardia clade in subfamily Acalyphoideae. The phylogenetic position of this taxon is also supported by morphology, justifying the description of a new genus and species, Bahiana pyriformis, from the Caatinga seasonally dry forest, in Bahia State, Brazil. We compare morphological characters and discuss the phylogenetic relationships of these four genera, here treated as the Bernardia clade, as well as the possible relationship this clade has with genus Avellanita and tribe Plukenetieae.

A new, disjunct species of Bahiana (Euphorbiaceae, Acalyphoideae): Phytogeographic connections between the seasonally dry tropical forests of Peru and Brazil, and a review of spinescence in the family

“…Beyond biogeography there are clear morphological differences in staminate cymules, fruits, and leaves that serve to distinguish the two species of Bahiana, and additional differences may be discovered when flowering collections become available. Dissection of young staminate inflorescences found each cymule of B. occidentalis contained a single bud, while B. pyriformis is described as "cymules usually 3-flowered" with an early-developing central flower (Carrión et al 2022). Within the Bernardia clade, the fruits (and seeds) of B. occidentalis are closer in size to small-fruited Adenophaedra and most Bernardia (B. macrocarpa A.Cerv.…”

“…Adelia may not be monophyletic (De-Nova and Sosa 2007;Cervantes et al 2016), and the addition of A. cinerea to the 2-marker data set provides better context for the use of that outlier species as an outgroup in the 4-marker data set. The 4-marker data set of Carrión et al (2022) included Bernardia clade representatives for plastid matK (including 3' matK-trnK), petD, and trnL-F, and nuclear ribosomal ITS, and was modified here by my addition of the Peruvian Bahiana (two tips). Laboratory work on each of the two Peruvian samples occurred at very different times and under contamination-control protocols developed for degraded museum samples.…”

“…Seasonal rains typically fall (Dec-) Jan to Apr (85% of annual precipitation; Cueva-Ortiz et al 2020), after critically dry Sep to Nov. Flowering appears to coincide with the start of the rainy season (young staminate inflorescences present until mid-Nov) and mature fruit by Feb. The collections, although not diagnostic due to having only very young inflorescences or fruits, appear unisexual, which probably indicates dioecy as has been documented for B. pyriformis(Carrión et al 2022). The Tumbesian SDTF appears to have few other endemic Euphorbiaceae (e.g.,…”

“… Bahiana J.F.Carrión was recently described as a monotypic genus and narrow SDTF endemic, with a population of ca. 20 plants at the type locality in central Bahia of eastern Brazil ( Carrión et al 2022 ). A cryptic plant from the Peruvian SDTF , here described as a new species of Bahiana , that was first collected 40 years ago (1982) and is now represented by 35 collections, has lain unidentified to genus (or misidentified) among Euphorbiaceae in the Missouri Botanical Garden herbarium.…”

“…I recognized five years ago that these collections were united by leaf architecture and spinose stipules, and represented an unusual, potentially undescribed Euphorbiaceae - Acalyphoideae . However, an initial analysis of plastid trnL-F sequence data within the context of the family-wide phylogeny of Wurdack et al (2005) only yielded placement with New World members of Acalyphoideae tribe Bernardiaeae (clade A7; Bernardia clade, Carrión et al 2022 ; Bernardieae pro parte, Radcliffe-Smith 2001 ; Webster 2014 ), with no clear generic affiliation. The phylogenetic analysis and description of Bahiana pyriformis by Carrión et al (2022) expanded the sampling for the Bernardia clade and provided critical context for the Peruvian plant.…”