Eriocaulaceae: A new classification system based on morphological evolution and molecular evidence

Abstract

Paepalanthus, in its current sense, is the most diverse genus of Eriocaulaceae in the Neotropics, comprising about 400 species. Previous studies have consistently found that the genus is not monophyletic, also being morphologically heterogeneous and diagnosable by a set of homoplasies; thus, the current circumscription needs to be revised. The new classification proposed here uses a comprehensive phylogeny of Paepalanthus and closely related genera as a framework and an evaluation of a set of morphological characters using ancestral state reconstruction, which allowed the recognition of strongly supported clades with morphological diagnosability. We propose the recognition of 12 genera in the clade encompassing Paepalanthus and allied groups, including six new genera (Coracoralina, Floralia, Giuliettia, Gnomus, Hydriade, Nisius), two new statuses (Cryptanthella, Monosperma), the reestablishment of Actinocephalus, Lachnocaulon, and Tonina, and a recircumscription of Paepalanthus. In this new circumscription, Paepalanthus comprises 257 species, most of them restricted to the Brazilian campos rupestres. Among the proposed genera, nine have potential morphological synapomorphies, one has a restricted geographical distribution, and the other two can be recognized by a combination of characters. Newly generated seed morphology data is consistent within the different genera and plays an important role in their recognition. A total of 136 new combinations are hereby proposed. We provide a genus-level identification key, as well as generic descriptions, diagnostic features, photos illustrating their morphological diversity, maps and notes on distribution, and lists of species by genus.

Global analysis of Poales diversification – parallel evolution in space and time into open and closed habitats

“…In Bromeliaceae, centres of palaeoendemism occur in the Guayana Shield -the site of putative origin of the family -whereas centres of neoendemism are restricted to the Brazilian Shield, where Bromelioideae subsequently radiated (Givnish et al, 2011). Eriocaulaceae mirror this pattern (Andrino et al, 2023), with the added area of super-endemism in India, where nearly 20% of the family occurs in the Western Ghats region alone (Sunil et al, 2015).…”

Global analysis of Poales diversification – parallel evolution in space and time into open and closed habitats

“…In Bromeliaceae, centres of palaeoendemism occur in the Guayana Shield – the site of putative origin of the family – whereas centres of neoendemism are restricted to the Brazilian Shield, where Bromelioideae subsequently radiated (Givnish et al ., 2011). Eriocaulaceae mirror this pattern (Andrino et al ., 2023), with the added area of super‐endemism in India, where nearly 20% of the family occurs in the Western Ghats region (Sunil et al ., 2015). In Restionaceae, Western Australia, the ancestral home of the family, hosts palaeoendemics, while neoendemics are restricted to South Africa (Linder et al ., 2003).…”

A missing piece is found: a new species of Paepalanthus (Poales, Eriocaulaceae) and the puzzling relations of the campos rupestres mountaintop floras of eastern Minas Gerais, Brazil

“…Subsequent investigations and consultations of materials deposited in herbaria ( Reflora 2024 ; SpeciesLink 2024 ) yielded no previous collections of this species. The collected material underwent analysis using a stereomicroscope, considering both reproductive and vegetative characters according to specific terminology for describing Eriocaulaceae ( Andrino et al 2015 ; Andrino et al 2023 ).…”

“… Eriocaulaceae Martinov is a monocotyledon family belonging to the Poales (APG IV 2016), which comprises around 1400 species divided into 18 genera ( Giulietti et al 2012 ; Andrino et al 2023 ; Sano et al 2024 ) and two subfamilies: Eriocauloideae Ruhland and Paepalanthoideae Ruhland ( Ruhland 1903 ). It has a pantropical distribution, but an important center of diversity is found in the campos rupestres of east Brazil, especially in the Espinhaço Range (ER), where the family represents around 10% of the diversity of vascular plants, with an endemism rate of 85% ( Costa et al 2008 , 2018 ).…”

“…In this new classification, Paepalanthus is delimited as a monophyletic genus comprising 256 species, and the remaining species were segregated into eight new genera, in addition to Actinocephalus (Körn.) Sano, Tonina Aubl., and Lachnocaulon Kunth, previously nested within Paepalanthus ( Andrino et al 2023 ). According to the new circumscription, Paepalanthus is characterized by having trimerous and isostemonous flowers, the pistillate flowers with free petals and free stigmatic branches, and the seed coat presenting rectangular or narrow hexagonal cells with appendices with truncate apex or with a “T” form along the periclinal walls, and lacking micropapillae ( Andrino et al 2023 ).…”