Cryptic speciation in the herbaceous bamboo genus Piresia (Poaceae, Olyreae)

Abstract

Piresia, a small genus of herbaceous bamboos, has a geographical disjunction between the Caribbean and northern/western South America and the north-eastern Atlantic Forest in Brazil. Piresia leptophylla is reported from western Amazonia (WA) and the north-eastern Atlantic Forest (NAF), but its occurrence in western Amazonia is questionable. Using an integrative approach, we combined traditional morphological analysis, anatomy and niche modelling. The results revealed few macromorphological differences between WA and NAF specimens (only plant height, leaf length, lodicule dimensions, shape and position), contrasting with consistent differences in leaf anatomy (macrohairs and cruciform silica bodies in the costal zone of the adaxial/abaxial leaf surfaces, crenate silica bodies on the abaxial leaf surface, lack of panicoid hairs on the abaxial leaf surface, bicellular microhairs and lobed papillae over the abaxial leaf surface, and sparse but elongated fusoid cells in the mesophyll of WA specimens) and in niche patterns. The anatomical/micromorphological characters suggest environmental adaptations to the Amazonian and ‘restinga’ forests, respectively. We therefore propose the segregation of the WA populations into a new species, Piresia tenella sp. nov. We provide a formal description, photographs, a line illustration, a distribution map and discussion of the conservation status for the new species.

Notes on leaf micromorphology of the rare herbaceous bamboo Buergersiochloa bambusoides Pilg. (Olyreae, Poaceae) from New Guinea and its taxonomic implications

“…This subtribe is sister to the clade composed of the other two lineages ( Olyrinae and Parianinae ), which are essentially restricted to the Neotropics ( Oliveira et al 2014 ; Ferreira et al 2019 ). However, the recircumscription of Buergersiochloinae is in progress based on current phylogenetic studies ( Carvalho et al in press ).…”

Phylogenetics of Piresia (Poaceae: Bambusoideae) reveals unexpected generic relationships within Olyreae with taxonomic and biogeographic implications

“…Olyrinae is the most diverse subtribe of the three and currently includes 20 genera, of 24 total in the Olyreae, and approximately 89 species (of 124 in the tribe) that occur from Mexico and the West Indies to Argentina and Brazil, with one also reaching Africa (R.P. Oliveira & al., 2014, 2020; Clark & Oliveira, 2018; Ruiz‐Sanchez & al., 2019; Carvalho & al., 2020; I.L.C. Oliveira & al., 2020).…”

“…Oliveira & al., 2020), currently composed of six described species ( P. goeldii Swallen, the type, P. leptophylla Soderstr., P . macrophylla Soderstr., P. palmula M.L.S.Carvalho & R.P.Oliveira, P. sympodica (Döll) Swallen, and the recently described P. tenella M.L.S.Carvalho & R.P.Oliveira [Carvalho & al., 2020]). Carvalho (2013), however, provided evidence for the existence of additional, potentially cryptic and as yet undescribed species in this genus.…”

“…Carvalho (2013), however, provided evidence for the existence of additional, potentially cryptic and as yet undescribed species in this genus. Piresia is usually distinguished from the other genera of Olyrinae by the following combination of field characters: two types of culms, leafy ones, which are more numerous and bear many leaves toward the apex, producing a crowded pinnate‐to‐palmate‐appearing leaf complement, and reduced‐leafy ones (sensu Judziewicz & al., 1999), which grow decumbently, hidden under the litter, and bear reduced or vestigial leaf blades and single racemose synflorescences (these sometimes also present in the leafy ones); each raceme with a terminal female spikelet subtended by 2 to several male spikelets; and female floret with dark spots at maturity (Swallen, 1964; Soderstrom, 1982; Clayton & Renvoize, 1986; Judziewicz & al., 1999; Clayton & al., 2006–; Carvalho & al., 2012, 2020).…”

“…(1999), Piresia grows in wet lowland (less than 300 m) forest understories from Colombia, Venezuela, Trinidad, and the Guianas to Amazonian Ecuador, Peru, Bolivia and Brazil, often in periodically flooded sites (“várzea”) in Amazonia or in sandy “mata litorânea” on the Atlantic coast. Thus, this genus has a peculiar disjunct geographical distribution between the Caribbean and north/western South America and the northeastern Atlantic Forest in Brazil (Soderstrom & Calderón, 1974; Judziewicz & al., 1999) with no species shared between the two regions (Carvalho & al., 2012, 2020; Carvalho, 2013).…”