Relevance of leaf morphology and biometrics: a study with species of Aphelandra R. Br. (Acanthaceae)

Keyworks blade leaf structure variegation Morphological characteristics, as well as biometrics, govern the description of species. However, systematical comparative analyzes of these aspects between taxa are scarce. The aim of the work was to evaluate the relevance of these characteristics in species of Aphelandra. Leaves of A. longiflora, A. harleyi, A. espirito-santensis, A. nitida, A. sinclairiana and A. squarosa were collected and analyzed for morphologic patterns: phyllotaxis, texture, leaf blade form, symmetry, apex, base, margin, venation and coloring pattern; and for biometric parameters: total length, length and width of the leaf blade, length and diameter of the petiole. We calculated mean and standard deviations. Among the relevant morphological patterns are the shape of the blade, apex and base, and the biometric data showed differences. As conclusion, this analysis proposal proves to be an instrument of accuracy and detail for descriptions.

Morphological characteristics, as well as biometrics, govern the description of species. However, systematical comparative analyzes of these aspects between taxa are scarce. The aim of the work was to evaluate the relevance of these characteristics in species of Aphelandra. Leaves of A. longiflora, A. harleyi, A. espirito-santensis, A. nitida, A. sinclairiana and A. squarosa were collected and analyzed for morphologic patterns: phyllotaxis, texture, leaf blade form, symmetry, apex, base, margin, venation and coloring pattern; and for biometric parameters: total length, length and width of the leaf blade, length and diameter of the petiole. We calculated mean and standard deviations. Among the relevant morphological patterns are the shape of the blade, apex and base, and the biometric data showed differences. As conclusion, this analysis proposal proves to be an instrument of accuracy and detail for descriptions.

INTRODUCTION
Although plant taxonomic descriptions are predominantly morphological and also offer measurements indicating the dimensions of the structures presented, taxa comparative morphological and biometric approaches are scarce. This type of approach, in addition to giving more accuracy to taxa descriptions, can provide information and data usable for studies from autoecology to landscape ecology, and may also be of interest for cultivation (Stuessy, 2009).
Within Acanthaceae there are studies that evaluate leaf morphological aspects such as for species of Justicia L. (Aoyama and Indriunas, 2013) and Megaskepasma erythrochlamys Lindau (Jesus et al., 2020). However, addressing biometrics, these are restricted to reproductive structures such as in the work of Aoyama et al. (2015) on the morphology of mature fruits and seeds of Justicia scheidweileri V.A.W. Graham and, as well, in Ruellia furcata (Nees) Lindau (Monteiro et al., 2020), exclusively on seeds' morphology, we can cite the work with of Ruellia L. from an Atlantic Forest region of southeastern Brazil (Azevedo and Braz, 2018), of the Ruellieae tribe in Brazil (Azevedo and Moraes, 2020) and Ruellia elegans Poir seeds .
The genus Aphelandra R.Br. comprises shrubs or suffrutescent herbs; belong to Acanthaceae (ca. 3500 species) and include approximately 230 species of Neotropical distribution, ranging from southern Mexico to northern Argentina and Brazil, with some species being found also in western India (Wasshausen, 1975(Wasshausen, , 2013Profice and Andreata, 2011).
Since the morphological characteristics and biometric data are scarcely explored, the present guiding question of the study is whether these aspects are relevant in Aphelandra. The present study aims to analyze the leaf morphological characteristics of Aphelandra species. Morphological characters of the leaves such as phyllotaxis, texture, leaf blade form, symmetry, apex, base, margin, venation and coloring pattern were described using the terminology proposed by Hickey (1973) and Ellis et al. (2009). For the biometrical analyses we evaluated the following parameters: total length, length and width of the leaf blade, length and diameter of the petiole, all using a graded centimetre rule and a digital pachymetre. We calculated mean and standard deviations to all quantitative data.

RESULTS AND DISCUSSION
Similarly to most Acanthaceae species, Aphelandra leaves exhibit oposite decussate phyllotaxis, according to Bell and Bryan (2008, p. 262) "when sucessive pairs are oriented at 90º to each other, four rows of leaves will be visible from above", a typical pattern for the family, corroborating Wasshausen (1975). From the six species analyzed (Fig. 1-24), all exhibit a symmetrical lead base, except for A. squarrosa, where it is asymmetrical. All species have a smooth texture, except for A. squarrosa, in which it is cartaceous. Leaf margins and venation was equal to all species, with entire margins and the camptodromous-brachidodromous venation, a pattern in which the secondary veins get together forming a series of prominent arcs (Fig. 7-12).
Regarding the biometric data, A. espiritosantensis exhibited higher differences (Table 1) when compared to the others, with relatively small leaves, a distinctive character when compared to the other studied species. These biometric differences may be attributed to the herbaceous to reptant stem this species has (Profice and Wasshausen, 1993). This taxon deserves special attention, since it is endemic to the Reserva Natural Vale (Profice and Wasshausen, 1993). A. nitida has also shown biometric variations when compared to the other species, with the highest averages to all leaf parameter analyzed, which may be an environmental response, since this species occurs in a low light insulation conditions within the Atlantic rain forest. According to Martin et al. (2020) specimens occurring in places of high solar incidence exhibit shorter leaves, since they tend to be thicker than those growing under low solar incidence. Monteiro and Aoyama (2012) have also reported biometric differences in Ruellia furcata, with variations between specimens collected under shadows and bushes of higher insulation.

CONCLUSIONS
The most relevant morphological variations are the shape of the blade, the apex and the base and the biometric data point out differences between the analyzed species. Among them, A. espiritosantensis is the one that showed the most distinct results, since this taxon has a reptant habit and the others are subshrubs. Thus, the proposed question proves to be an instrument of greater accuracy and detailing for descriptions.

Species
Total length (cm)

ACKNOWLEDGMENTS
In the Reserva Natural Vale and to Museu de Biologia Professor Mello Leitão, at given way to realization of part of the collections made. The Geovane de Souza Siqueira curator of the herbarium CVRD, which contributed immensely to identifying, locating and gathering of species.