Taxonomic Relevance of Leaf Anatomy in Banisteriopsisc.B. Rob
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Acta Botanica Brasilica - 34(1): 214-228. January-March 2020. doi: 10.1590/0102-33062019abb0276 Taxonomic relevance of leaf anatomy in Banisteriopsis C.B. Rob. (Malpighiaceae) Josiane Silva Araújo1, 2 , Rafael Felipe de Almeida3 and Renata Maria Strozi Alves Meira1* Received: August 8, 2019 Accepted: December 12, 2019 . ABSTRACT We describe the leaf anatomy of 42 of the 60 species of the genus Banisteriopsis, one of the largest and most diverse genera of Malpighiaceae in the Cerrado domain. Our aim was to identify anatomical leaf characters useful for the taxonomy and systematics of this morphological diverse genus. Expanded leaves from herbarium specimens were rehydrated and processed according to usual anatomical methods for analysis under light microscopy. All characters were compared using the Unweighted Pair Group Method with Arithmetic Mean algorithm and expressed in dendrograms. The most useful leaf anatomical characters were petiole contour, presence/absence of vascular bundles in the petiole, the position of the vascular bundles in the petiole, shape of the midrib, presence/absence of sheath extension, mesophyll type, and both the presence/absence and shape of leaf glands. Our study indicates that the morphological groups proposed in the literature for Banisteriopsis are natural groups. Keywords: leaf glands, Malpighiales, multivariate analysis, plant anatomy, stigmaphylloid clade circumscribe Banisteriopsis sensu stricto. The morphological Introduction characters currently used to distinguish the species of Banisteriopsis are mostly restricted to inflorescence Banisteriopsis is one of the most diversified genera of architecture, flower, and fruit morphology (Gates 1982; Malpighiaceae in Neotropical savannas, comprising ca. Anderson & Davis 2006). As several floral characters are 60 species of shrubs and vines confined to the Americas not retained in fruiting specimens (e.g., color and floral (Gates 1982; Davis & Anderson 2010). The genus is easily display), correctly assigning newly collected specimens of recognized by its leaves bearing extra-floral nectaries on the Malpighiaceae to Banisteriopsis became one of the main leaf blades (Fig. 1), and by its greatly expanded glandular challenges for general botanists. connectives (Gates 1982). Even though Banisteriopsis was Leaf anatomy applied to taxonomic purposes has taxonomically revised in the early 1980’s (Gates 1982), it was historically been used as a useful tool for exploring additional evidenced to be polyphyletic in the first phylogenetic studies morphological characters in taxonomically convoluted for Malpighiaceae (Cameron et al. 2001; Davis et al. 2001; groups (Metcalfe & Chalk 1950; 1979). This approach Davis & Anderson 2010), leading to the segregation of some makes it possible to correctly identify fragmented or sterile species to Diplopterys or to the newly described Bronwenia plant specimens, besides pointing out evolutionary trends (Anderson & Davis 2006). After rendering Banisteriopsis in groups (Metcalfe & Chalk 1950; 1979). Nonetheless, monophyletic, these authors failed to morphologically re- few studies exploring the anatomy of specific genera in 1 Pós-Graduação em Botânica, Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-900, Viçosa, MG, Brazil 2 Universidade Estadual do Piauí, 64280-000, Campo Maior, PI, Brazil 3 Programa de Pós-Graduação em Biologia Vegetal, Departamento de Botânica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, 31270-901, Belo Horizonte, MG, Brazil * Corresponding author: [email protected] Diagramação e XML SciELO Publishing Schema: www.editoraletra1.com.br Taxonomic relevance of leaf anatomy in Banisteriopsis C.B. Rob. (Malpighiaceae) Malpighiaceae are available in the literature, such as Mamede The identification key was elaborated using the data (1993), Araújo et al. (2010), Possobom et al. (2015), Araújo from the matrix (Tab. 2) for all analyzed species, and a & Meira (2016), and Mello et al. (2019). reduced matrix comprising all 18 species sampled by Davis In order to search for additional leaf characters that & Anderson (2010) in the most recent molecular phylogeny might contribute to specific and generic delimitation in for Malpighiaceae. Leaf and floral characters for all species Banisteriopsis, we present a thorough survey of the leaf were compared among each other by converting the binary anatomy of 42 species of this genus. Additionally, we matrix into a symmetric matrix for Sorensen’s similarity. provide a multivariate analysis of all the analyzed species The Unweighted Pair Group Method with Arithmetic Mean to compare the dendrograms obtained with the most (UPGMA) was used in NTSYS-pc 2.2 software (Rohlf 2000; recent phylogenetic hypothesis and current infrageneric Sokal & Rohlf 1995) to generate dendrograms based on the classification for Banisteriopsis. Jaccard index, and using the species of Diplopterys A.Juss. , Peixotoa and Stigmaphyllon as outgroups. Results obtained from this analysis were also compared to the most recent Materials and methods molecular phylogeny study for Malpighiaceae (Davis & Anderson 2010). We analyzed leaves of 42 species of Banisteriopsis C.R. Rob , as well as leaves of closely related genera based on Davis & Anderson (2010) (Tab. 1, Fig. 1A-M). All leaves were Results obtained from exsiccates deposited in Brazilian herbaria (CEPEC, HUEFS, INPA, MBM, RB, SP, SPF, UB, UPCB, and Leaf anatomy of Banisteriopsis VIC; acronyms according to Thiers 2019). Fully expanded and well-preserved leaves were sampled from three specimens for each taxon, except for rare species (i.e., Banisteriopsis Petiole contour in transversal section displayed martiniana (A. Juss.) Cuatrec, and B. quadriglandula B. significant morphological variance (Fig. 2). In most species Gates). The leaves were rehydrated in boiling distilled water (29 species), the contour is plane-convex (Fig. 2A), while until complete submersion (within five to fifteen minutes, in 11 species (B. adenopoda, B. goiana, B. megaphylla, B. membranifolia, B. muricata, B. nummifera, B. oxyclada, B. in general), embedded in KOH 2 % for full distention (two hours in general), washed and dehydrated in ethyl alcohol prancei, B. paraguariensis, B. parviflora and B. quadriglandula) it is concave-convex (Fig. 2C). In the remaining two species series and stored in 70 % ethanol. All specimens were hand free sectioned using a shaving blade to obtain transversal (B. acerosa and B. scutellata), the contour is circular (Fig. 2B). and longitudinal sections from the leaf blade (base, middle, Two types of configurations of vascular bundles were margin, and apex) and petiole. We adopted the median observed in petioles: an open arch with convolute extremities, region for anatomical descriptions since there were not found in B. gardneriana and B. martiniana (Fig. 2E), significative differences among all sectioned portions of and an open arch in the remaining species (Fig. 2A-D, F). The the leaf blade. All sections were clarified in 20 % sodium occurrence of accessory bundles (Fig. 2A, C-F) was observed hypochlorite and stained in basic fuchsine – Astra blue, and in most analyzed species, except in B. acerosa (Fig. 2B) the slides were mounted in glycerin jelly and sealed with and B. stellaris, but the number of vascular bundles has also colorless varnish (Kraus & Arduin 1997). varied within the same species. Part of the samples was diaphanized according to a Sclerenchyma sheaths were recorded surrounding the modified Foster (1950) protocol. Samples measuring ca. 20 vascular bundles in petioles of eight species [B. anisandra, B. mm2 were kept in a solution of sodium hydroxide for two campestris, B. hatschbachii (Fig. 2F), B. irwinii, B. latifolia, B. hours, washed in distilled water several times, and then megaphylla, B. pulchra and B. schizoptera]. Disperse sclereids kept in 20 % sodium hypochlorite for 18 hours or until the were observed in petioles of nine species (Fig. 2A), B. arborea, tissue became translucid. After an additional wash, samples B. cipoensis, B. confusa, B. gardneriana, B. goiana, B. hirsuta, B. were dehydrated in a 50 % ethyl alcohol series overnight, muricata, B. sellowiana, B. malifolia var. apressa, B. malifolia and the slides were mounted in glycerin jelly and sealed var. malifolia), and were absent in the remaining species with colorless varnish. (Fig. 2B-E). Vascular bundles and vein patterns were classified Midribs presented a convex contour in both surfaces of according to Howard (1979) and to Ellis et al. (2009), leaf blades in most analyzed species (Fig. 3A-C, Tab. 2). Plane respectively. Hair types were classified according to Theobald midribs were observed in the adaxial surface of leaf blades of et al. (1979). Macromorphological data were obtained from eight species [B. anisandra (Fig. 3B), B. calcicola, B. gardneriana, Gates (1982) for elaborating a binary matrix (Tab. 2). B. irwinii, B. paraguariensis, B. prancei, and B. sellowiana]. All analyses and picture records were performed using a Concave midribs were observed in the adaxial surface of leaf photomicroscope (Olympus AX70TRF, Olympus Optical, blades of five species [B. andersonii, B. angustifolia, B. arborea, Tokyo, Japan) with a U-Photo system with a digital camera B. martiniana var. martiniana (Fig. 3C) and B. muricata]. The coupled (AxioCam HRc; Zeiss, Göttingen, Germany). epidermis is single-layered in most species (Fig. 3D), except Acta Botanica Brasilica - 34(1): 214-228. January-March 2020 215 Diagramação e XML SciELO