Análise morfométrica e filogenética do complexo Asplenium claussenii no Rio Grande do Sul-RS

Abstract

Pteridophytes are known to be the first vascular plants and the most diverse of vascular plants after the bryophyte group. The Aspleniaceae family is one of the most numerous of the leptosporangiate ferns, the sixth most diverse in Brazil (having two genera) and the seventh with the highest number of endemism. The genus Asplenium L., being richly numerous, presents several lineages (morphological and phylogenetic) resulting in many complexes of difficult circumscription. The polyploidy and hybridization events of plants create these taxonomic uncertainties, such as the Asplenium claussenii complex, with six species recognized for Brazil, namely Asplenium claussenii Hieron., A. kunzenanum Klotzsch ex Rosenst., A. mourai Hieron., A. regulare Sw., A. sellowianum C. Presl ex Hieron.) Hieron. and A. ulbrichtii Rosenst. This complex has a morphological homogeneity, where the characters overlap, and in the state of Rio Grande do Sul there are three of these species of the complex: Asplenium ulbrichtii, Asplenium sellowianum and Asplenium claussenii. Their most significant differences are based on the overall size of the plant. Also noteworthy is the lack of molecular information. In this way, it is proposed whether morphometric and molecular analyzes can delimit biological differences capable of distinguishing between these species. Twenty-five exsiccates per species, previously selected through the databases, were evaluated. A list of quantitative and qualitative morphological characters (85) was assembled, from these filtered the most delimiting between the rates to assemble a data matrix in the Mesquite v. 3.6 and analyzed by Maximum Likelihood and Maximum Parsimony. For the morphometric analysis, 10 fronds, 10 apices and 50 pinnae of each species were measured in the MorphoLeaf software. Spores and scales were observed by scanning electron microscopy (SEM). Non-fertile leaflets were used for flow cytometry on the BD Accuri™ C6 Plus Flow Cytometer. For DNA extraction, the CTAB 2% method was used, later for the sequences alignments (Blast) were searched against the GenBank database, the alignments of the regions CRY2, rbcl-ESRBCL, gapCpSh, rbcl-atpB, atpA and TRNG were analyzed by Maximum Likelihood. Also submitted to site selection pressure analysis with the GARD, FEL and FUBAR algorithms on the datamonkey platform. The size of the frond, pinna and serum and the presence of prolific bud are the biggest morphological differences between the three species. Even having different dimensions, they share the same proportions for the fronds, with this character having a considerable 10 variation, related to the level of ploidy. A. sellowianum was separated into two taxonomic variations based on the shape of the apex of the blade, the pina radicante variation, which presents morphological measurements closer to A. ulbrichtii; the pina pinatífida variation, closer to A. claussenii. The perine presents greater ornamentation and fenestration in A. claussenii and A. ulbrichtii than that observed in A. sellowianum. Through morphological analysis a taxonomic key was elaborated. In the analysis of molecular data of plastids the AtpA and TRNG regions, A. ulbrichtii appears as a sister branch of the other two species, for the gapCPSH and gapCS regions, A. claussenii is observed as a sister branch. The rbclESRBCL region presented the highest number of sites under diversifying pressure. A. claussenii and A. sellowianum have half the genome (15pg each) of A. ulbrichtii, which may be a hybrid of the other two species, leading to inconsistencies in the topologies. However, due to the variations observed in morphological characters and phylogenies, we did not find much evidence about the relationship between the three species in this study.