Data from: Systematics of Oxalis subg. Thamnoxys (Endl.) Reiche sect. Holophyllum Progel (Oxalidales, Oxalidaceae)

Oxalis sect. Holophyllum (Oxalidaceae) is a small group of species that
are endemic to the Brazilian Atlantic Forest in the states of Rio de
Janeiro, Minas Gerais, Espírito Santo, and Bahia. Species of the section
can be recognized by the unifoliolate leaves, one-seeded carpels, and the
common presence of dorsiventrally flattened (and sometimes winged)
peduncles and/or petioles. Circumscriptions of the currently accepted
species needed to be revaluated, as the overlap in several features have
blurred limits among morphologically similar taxa. In this study we
evaluate the monophyly and phylogenetic relationships among species of O.
sect. Holophyllum, and provide an updated taxonomic study of the section,
aiming at improving species circumscriptions and facilitating
species-level identification. For this task, we analyzed samples from
herbaria and carried out fieldwork to observe the plants in loco, collect
samples, and gather material for DNA extraction, amplification, and
sequencing. Bayesian and Maximum Likelihood phylogenetic analyses were
performed using sequences from three markers: nrITS, and plastid
trnL-trnF, and petA-psbJ from 13 of the 17 currently accepted species,
which corroborate the monophyly of the section. Among the species of O.
sect. Holophyllum, ten are newly described here at species level: O.
adpressipila Fiaschi & Bilk (based on O. kuhlmannii Lourteig var.
adpressipila Lourteig), O. capixaba Fiaschi & Bilk, O. cornicarpa
Fiaschi, O. inopinata Fiaschi & Bilk, O. itamarajuensis Fiaschi
& Bilk (based on O. alata Mart. ex Zucc. var. hirta Lourteig), O.
leonii Fiaschi & Bilk, O. occulta Fiaschi & Bilk, O.
retrorsa Fiaschi & Bilk, O. sciophila Fiaschi & Bilk, and
O. septentrionalis Fiaschi & Bilk. Lectotypes are chosen for nine
names, and an epitype for O. impatiens Vell. An identification key to all
species is provided, as well as descriptions, illustrations, geographic
distribution maps, and preliminary conservation statuses following IUCN
guidelines.

全叶组酢浆草（Oxalis sect. Holophyllum，酢浆草科Oxalidaceae）是一个小型物种类群，特有分布于巴西大西洋森林的里约热内卢州、米纳斯吉拉斯州、圣埃斯皮里图州及巴伊亚州。该组物种可通过以下特征识别：单小叶、具单种子的心皮，以及普遍存在的背腹扁平（有时具翅）的花序梗和/或叶柄。由于多个性状的重叠模糊了形态相似类群间的界限，当前被接受的物种界定亟需重新评估。本研究对全叶组酢浆草的物种单系性及系统发育关系进行了评估，并对该组开展了更新的分类学研究，旨在优化物种界定并推动物种水平的鉴定工作。为此，我们分析了标本馆馆藏样本，并开展了野外考察以原生境观察植株、采集样本并收集材料用于DNA提取、扩增及测序。研究采用核核糖体内部转录间隔区（nrITS）、质体trnL-trnF及质体petA-psbJ三个分子标记的序列，对当前被接受的17个物种中的13个进行了贝叶斯法（Bayesian）与最大似然法（Maximum Likelihood）系统发育分析，结果支持该组为单系类群。在全叶组酢浆草中，本次研究共新描述10个物种：O. adpressipila Fiaschi & Bilk（基于O. kuhlmannii Lourteig var. adpressipila Lourteig）、O. capixaba Fiaschi & Bilk、O. cornicarpa Fiaschi、O. inopinata Fiaschi & Bilk、O. itamarajuensis Fiaschi & Bilk（基于O. alata Mart. ex Zucc. var. hirta Lourteig）、O. leonii Fiaschi & Bilk、O. occulta Fiaschi & Bilk、O. retrorsa Fiaschi & Bilk、O. sciophila Fiaschi & Bilk及O. septentrionalis Fiaschi & Bilk。本研究为9个学名指定了后选模式，并为O. impatiens Vell.指定了新模式。我们还提供了所有物种的检索表、形态描述、插图、地理分布地图，以及遵循世界自然保护联盟（IUCN）指南制定的初步保护等级评估。