A molecular approach to the phylogeny of the moss genus Pseudocrossidium (Pottiaceae, Bryopsida) and its taxonomic implications

Abstract

Pseudocrossidium is a genus of 21 species belonging to the Pottiaceae with the highest concentration of taxa and morphological variation found in South America. To investigate the evolutionary relationships among the species of Pseudocrossidium and other members of the Pottioideae, molecular phylogenetic reconstructions, using the nuclear ITS1-5.8S-ITS2, and the plastid atpB-rbcL, trnG, and trnL-F, has been performed because this genus has only been partially tested using molecular markers. Bayesian and maximum likelihood topologies show that the genus, as presently circumscribed, is polyphyletic. Consequently, the circumscription of Pseudocrossidium is amended and numerous taxonomic changes resulting from the molecular, morphological, and nomenclatural studies are proposed. The phylogenetic and morphologically divergent Pseudocrossidium mendozense is renamed as Gertrudiella mendozensis. Pseudocrossidium linearifolium and P. porphyreoneurum are representatives of the new genera Barbulastrum and Helicobarbula, respectively. Pseudocrossidium carinatum and P. santiagense are accommodated in a new genus Austrobarbula. Aloinella, nested in a paraphyletic Pseudocrossidium, is maintained at generic rank, apparently derived from Pseudocrossidium. Barbula integrifolia, B. riograndensis, and Tortula jaffuelii are transferred to Pseudocrossidium. The remaining species of Pseudocrossidium are maintained in this genus, pending further studies. Conflicts of the trees observed could be evidence of interspecific or intergeneric gene flow in various lineages in the Pottioideae.

Circumscription and Phylogenetic Position of Two Propagulose Species of Syntrichia (Pottiaceae, Bryophyta) Reveals Minor Realignments within the Tribe Syntricheae

“…(2), S. erythrodontus (Taylor) Wilson ex Mitt. (3) and Willia brachychaete (Dusén) R.H. Zander (2); also, we selected some more distantly related Pottiaceae members according to Cano et al [ 6 ] and Jiménez et al [ 29 ], including four representative Pottieae sensu Zander [ 1 ]: Bryoerythrophyllum recurvirostrum (Hedw.) P.C.…”

“…To understand the position of S. amphidiacea and S. gemmascens in relation to other members of the genus, we included 1-4 specimens of: Syntrichia amphidiacea (3), S. angustifolia (Herzog) M.J. Cano (3) and Willia brachychaete (Dusén) R.H. Zander (2); also, we selected some more distantly related Pottiaceae members according to Cano et al [6] and Jiménez et al [29], including four representative Pottieae sensu Zander [1]: Bryoerythrophyllum recurvirostrum (Hedw.) P.C.…”

“…According to Casado [26], the generic characters that unify Streptopogon include: (1) scabrous and mitrate calyptrae, (2) short and twisted setae, (3) exserted or emergent, wide, and cylindrical capsules, (4) absence of a stem central strand (Figure 2G), (5) a strong costa with a single stereid band (Figure 2D,E), and (6) smooth leaf cells (Figure 2F). Other distinguishing characteristics of the genus according to Zander [3] are: (1) laminal KOH reaction usually red, (2) basal cells little differentiated from the upper cells (Figure 2H), (3) the presence of clavate propagula on leaves or costae (Figure 2A,B), (4) leaves entire to denticulate or serrate in the upper third (Figure 2C), ( 5) lack of hydroids in the costa, (6) transverse section of the costa with the dorsal stereid band round to semicircular, (7) costal dorsal epidermis present or occasionally absent (Figure 2D), and (8) perichaetial leaves not or little sheathing. Salmon [28], in his excellent monograph on Streptopogon emphasized its similarity to Syntrichia, but highlighted its generic differentiation on the basis of the smooth laminal cells and mitrate and scabrous calyptrae, although pointing out that some species of Streptopogon have glabrous calyptra.…”

“…The Pottiaceae, characteristic of harsh habitats [ 1 ], are one of the most complex and diverse family of mosses and are widely distributed around the world [ 2 , 3 , 4 , 5 ]. The taxonomy of Pottiaceae has been complicated and its generic circumscriptions are the subject of ongoing debate [ 6 ]. The genus Syntrichia Brid.…”

“…With all this research, the taxonomy of Syntrichia and its allied genera becomes tremendously exciting, encouraging new collections and studies in Pottioideae. According to Cano et al [ 6 ], most genera included in the Pottiaceae have not been the subject of extensive study using molecular data, and part of the studied genera have been resolved as paraphyletic or polyphyletic molecular entities. This situation can be assumed to be advantageous, as molecular paraphyly provides important information about evolutionary processes and, therefore, should not be suppressed by phylogenetic practices to preserve strict monophyly [ 24 ].…”