Two new species of Hexasepalum (Rubiaceae: Spermacoceae) from the ʻcampo rupestreʼ of Brazil

  • João A.M. do Carmo Departamento de Biologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas – UNICAMP, CEP 13083-970, Campinas, São Paulo, Brazil https://orcid.org/0000-0002-7660-9918
  • Roberto M. Salas Facultad de Ciencias Exactas y Naturales y Agrimensura, Universidad Nacional del Nordeste – FaCENA–UNNE, Av. Libertad 5460, C.P. 3400, Corrientes, Argentina https://orcid.org/0000-0001-7799-9017
  • Elsa L. Cabral Instituto de Botánica del Nordeste – IBONE (UNNE–CONICET), Sargento Juan Bautista Cabral 2131, cc. 209, C.P. 3400, Corrientes, Argentina
  • Andrea A. Cabaña Fader Centro de Ecologia Aplicada del Litoral – CECOAL, Ruta Provincial Nº 5 Km 2.5 S/N, C.P. 3400, Corrientes, Argentina https://orcid.org/0000-0001-9258-6608
DOI: https://doi.org/10.5852/ejt.2026.1075.3302
Keywords: cerrado, conservation, endemism, Spermacoce clade, taxonomy

Abstract

The ʻcampo rupestreʼ is a montane vegetation mosaic associated with rocky outcrops, with outstanding levels of species diversity and endemism. Among its most diverse lineages, Rubiaceae ranks among the ten richest families. Hexasepalum Bartl. ex DC. is nested in the Spermacoce clade of Spermacoceae, the largest predominantly herbaceous tribe in the Rubiaceae. The genus comprises 14 accepted species and is distributed mostly in the Americas. Brazil is home to eight species, occurring mainly in the Caatinga and Cerrado (including the ʻcampo rupestreʼ) domains. The analysis of specimens collected in the ʻcampo rupestreʼ of Bahia (NE Brazil) and Minas Gerais (SE Brazil) revealed two species new to science. Hexasepalum bacigalupoae Cabaña Fader & E.L.Cabral sp. nov. and Hexasepalum motaviananum Cabaña Fader, J.A.M.Carmo & R.M.Salas sp. nov. are described and illustrated. We comment on their distribution, habitat, and taxonomy. We also provide an updated key to the species of Hexasepalum in the Americas. Hexasepalum bacigalupoae and H. motaviananum are preliminarily assessed as Endangered and Critically Endangered, respectively, underscoring the crucial importance of conserving the ʻcampo rupestreʼ.

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Published
2026-07-15
How to Cite
do Carmo, J. A., Salas, R. M., Cabral, E. L., & Cabaña Fader, A. A. (2026). Two new species of Hexasepalum (Rubiaceae: Spermacoceae) from the ʻcampo rupestreʼ of Brazil. European Journal of Taxonomy, 1075(1), 1–22. https://doi.org/10.5852/ejt.2026.1075.3302
Issue
Vol. 1075 (2026)
Section
Research article

Copyright (c) 2026 João A.M. do Carmo, Roberto M. Salas, Elsa L. Cabral, Andrea A. Cabaña Fader

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