Tuesday, May 30, 2023

[Botany • 2023] Stigmatodon lemeanus (Bromeliaceae: Tillandsioideae: Vrieseinae) • A New epilithic Bromeliad from Pedra dos Três Pontões, Espírito Santo, Brazil, with An emended Combination for the Genus

Stigmatodon lemeanus D.R.Couto, A.P.Fontana & Fraga,
in Couto, Fontana, da Costa & de Fraga, 2023. 

Background and aims – Stigmatodon (Bromeliaceae) is a monophyletic genus currently comprising 33 species, all endemic to rocky outcrops, mainly inselbergs, from the Atlantic Forest and campos rupestres of the Espinhaço range, Brazil.

Material and methods – Our fieldwork in the inselbergs of the Atlantic Forest of the state of Espírito Santo led to the discovery of a new Stigmatodon species with a tubo-laciniate stigma type. Standard herbarium taxonomy practices were adopted to study the novelty. Morphological data were obtained from herbarium specimens and fresh material collected in the field.

Key results – Stigmatodon lemeanus is here described and illustrated. Diagnostic characters and affinities of the new species are discussed, accompanied by notes on its ecology, geographic distribution, and conservation status. A key to the species of Stigmatodon from Espírito Santo state is provided. The novelty is similar to S. goniorachis from coastal inselbergs of Rio de Janeiro and S. attenuatoides, another inselberg endemic from southern Espírito Santo. Stigmatodon lemeanus is preliminarily assessed as Vulnerable (VU) according to the IUCN Red List criteria. Additionally, we present a new combination of Tillandsia oligantha in Stigmatodon, correcting a nomenclatural error.

Keywords: Atlantic Forest, Brazilian endemics, campo rupestre, inselbergs, taxonomy, Vrieseinae

Stigmatodon lemeanus.
A. Habit. B. Leaf. C. Peduncle bract. D. Inflorescence before anthesis. E. Flower, frontal view with detail of the stamens arranged in two groups of three on each lateral side of the corolla. F. Flower, lateral view. G. Floral bract, adaxial side. H. Floral bract, abaxial side. I. Floral bract, detail of the thickest part at the base. J. Petal with two basal appendages. K. Basal appendages, details. L. Stamen. M. Pistil.
From the holotype D.R. Couto & C.N. Fraga 4926 (MBML). Drawn by Joelcio Freitas.

Stigmatodon lemeanus.
 A–B. Plants in situ at the type locality. C. Flowering individual in cultivation. D. Lateral view of the flower and floral bract. E. Frontal view of the flower. F. Details of the tubo-laciniate stigma and anthers.
Photographs: A, C–F by Dayvid R. Couto, B by André P. Fontana.

Stigmatodon lemeanus D.R.Couto, A.P.Fontana & Fraga, sp. nov.

Diagnosis: Similar to Stigmatodon goniorachis (Baker) Leme, G.K.Br. & Barfuss but distinguished by the suberect to patent peduncle (vs erect to suberect) that is more robust with a diameter of 6.5–7.8 mm (vs 3.5–6.2 mm), the main axis with shorter internodes (8.5–9.5 mm vs 15–25 mm long) that supports fewer flowers (11–13 vs 14–32), the longer flowers (56–60 mm vs 35–40 mm long), the larger petals (38–39 × 17–21 mm vs 22–28 × 13–15 mm), the basal appendages with irregularly acute-dentate apex (vs irregularly bidentate), and the shorter stamens (19–22 mm vs 26–28 mm long).

Habitat and ecology: The plant is epilithic, heliophilic, living on bare and vertical rock walls of inselbergs, where it forms large populations (Figs 2A, 4C), surrounded by Atlantic Forest fragments and farmland. In the type locality, Stigmatodon lemeanus grows on vertical rock walls (Fig. 2A–B), including on the large and pointed peaks of the mountain, from which the name “Pedra dos Três Pontões” is derived (Fig. 4B). In some places, they grow alongside sparse individuals of Pitcairnia diversifolia (Bromeliaceae), Mandevilla declinata (Apocynaceae), and the orchids Bulbophyllum weddellii Rchb.f., Bifrenaria harrisoniae (Hook.) Rchb.f., and Pseudolaelia dutrae Ruschi.

Etymology: The specific epithet honours our friend Dr Elton Martinez Carvalho Leme (1960−), from Rio de Janeiro, Brazil, whose personal efforts have substantially contributed to the knowledge of the diversity, taxonomy, and systematics of Brazilian bromeliads. In addition, Dr Elton Leme is one of the authors of the genus Stigmatodon and has greatly contributed to the knowledge of these plants.

Stigmatodon lemeanus.
 A–B. General view of the landscape at the type locality, highlighting the large and vertical pointed peaks of Pedra dos Três Pontões. C. Detail of the population on a vertical rock wall alongside sparse individuals of Pitcairnia diversifolia; some individuals grow close to the base of the slope, which facilitated the collection of some specimens for the study and description of the new species.
Photographs: A by André P. Fontana, B–C by Claudio N. Fraga.


 Dayvid Rodrigues Couto, André Pavioti Fontana, Andrea Ferreira da Costa and Claudio Nicoletti de Fraga. 2023. A New epilithic Bromeliad (Stigmatodon, Tillandsioideae) from Pedra dos Três Pontões, Espírito Santo, Brazil, with An emended Combination for the Genus. Plant Ecology and Evolution. 156(2): 215-224. DOI: 10.5091/plecevo.98904