Molecular Phylogenetics and Trait Evolution in Stigmatodon (Bromeliaceae, Tillandsioideae), an Endemic Genus to Brazilian Rocky Outcrops

Abstract

Abstract— The genus Stigmatodon occurs in vertical and bare granite slopes, typical of the inselbergs of the Brazilian Atlantic Forest. Here, we present the first broad phylogenetic analysis focused on Stigmatodon, sampling a total of 83 terminals, including 16 of the 20 species of the genus and the morphologically similar species of Vriesea. We conducted a phylogenetic analysis using two plastid markers (matK and rps16-trnK) and the nuclear gene PHYC to infer phylogenetic relationships and reconstruct ancestral states for ecological and morphological characters. Our results suggest the monophyly of Stigmatodon as originally circumscribed is only possible with the inclusion of morphologically and ecologically similar Vriesea species. In addition, the morphological and anatomical traits led us to propose a new circumscription for the genus, combining eight species of Vriesea to Stigmatodon as S. andaraiensis, S. freicanecanus, S. lancifolius, S. limae, S. oliganthus, S. pseudoliganthus, S. vellozicolus, and S. zonatus. The stomata positioned above the ordinary epidermal cells, the adaxial water-storage parenchyma with axially elongated cells, the stamens positioned in two groups of three on each side of the corolla, and the tubo-laciniate stigma are exclusive to Stigmatodon in its new circumscription. These new morphological and phylogenetic results constitute a relevant contribution to the taxonomy and evolution of Bromeliaceae, one of the most diverse and ecologically important families of flowering plants of the Neotropics.

Comparative phylogeography reveals the demographic patterns of neotropical ancient mountain species

“…Nonetheless, the Espinhaço Range is one of the main BQM areas, where biogeographic regionalization areas (bioregions hereafter) have been proposed mainly based on plant endemism (Campos et al, 2019; Colli‐Silva et al, 2019; Echternacht et al, 2011). Thus, to test for congruent phylogeographic patterns in the Espinhaço Range, we selected four species that occur along these mountains, two eudicots, Richterago discoidea (Asteraceae) (Barres et al, 2019) and Euphorbia attastoma (Euphorbiaceae) and two monocots, Neoregelia bahiana and Stigmatodon oliganthus (= Vriesea oligantha ) (Bromeliaceae) (Couto et al, 2022; Dantas‐Queiroz et al, 2021). The phylogeographic congruency between species were tested using the phylogeographic concordance factors (PCFs), an index developed by Satler and Carstens (2016).…”

Hyperepilithics—An overlooked life form of vascular plants on tropical vertical rock walls

“…In this region, hyperepilithic bromeliads stand out, especially the genera belonging to the subfamily Tillandsioideae. Within the hyperepilithic specialist members, the most remarkable example is Stigmatodon , with most species being restricted to VRWs (Couto et al, 2022). Equally important are species of Tillandsia subgenus Anoplophytum (e.g.…”

“…V. saundersii and V. botafogensis ) are also examples of hyperepilithic specialists. Of these genera, Stigmatodon and Alcantarea are almost exclusively epilithic (but see exceptions in Couto et al, 2022), while Vriesea and Tillandsia are highly important in epiphytic communities in Neotropical Rainforests (Zotz, 2013). On the contrary, Orchidaceae genera, such as Bulbophyllum, Cattleya and Epidendrum (similarly important as lithophytes and epiphytes), preferentially grow on flat to somewhat inclined slopes in inselbergs, and are not notable in VRWs.…”

“…Mainly in Stigmatodon and Tillandsia , we note that they: (i) are small or medium in size (ca. 5–110 cm tall when flowering; Couto et al, 2022; Tardivo, 2002) and display water‐impounding tanks or non‐impounding; and (ii) have xeromorphic leaves that are densely lepidote on both surfaces, which in many cases, are completely covered with a dense layer of cinereous trichomes, giving the leaf blade a silvery colour. On the contrary, larger hyperepilithic bromeliads (ca.…”

“…In particular, mining and the destruction and degradation of the flanking vegetation in the surrounding region for agriculture and urban development (Porembski et al, 2016) are particularly damaging to VRW species. Also, despite the difficult access to VRWs, recreational activities such as rock climbing can result in damage to the vascular hyperepilithic flora (Couto et al, 2022) as occurs for non‐vascular plants (Clark & Hessl, 2015). Thus, climbers and mountaineering societies should be aware of this specialized plant group in the tropics and avoid opening new routes in regions rich in hyperepilithics.…”