Bronwenia

Vilarinho, Milena Pereira, Santos, João Victor Da Costa, Santos-Filho, Francisco Soares & Araújo, Josiane Silva, 2023, Contributions of leaf morphoanatomy to the taxonomy of Bronwenia (Malpighiaceae Juss.), Phytotaxa 599 (4), pp. 252-264 : 258-260

Bronwenia species identification key

1. Presence of malpighiaceous trichomes on the leaf blade ( Fig.2F ).....................................................................................................2

- Absence of malpighiaceous trichomes on the leaf blade....................................................................................................................6

2. Presence of bundle sheath extension in the mesophyll ( Fig.3F, G )....................................................................................................3

- Absence of bundle sheath extension in the mesophyll.......................................................................................................................4

3. Plane-convex contour of petiole ( Fig. 2E ); absence of accessory bundles on the petiole; conformation of the vascular system in an open arch on the petiole ( Fig. 2G ); conformation of the vascular system in an open arch with convoluted ends in the midrib ( Fig. 3E ); absence of leaf glands on the petiole ..................................................................................................... Bronwenia acapulcensis

- Concave-convex petiole contour ( Fig.2D ); presence of accessory bundles on the petiole ( Fig. 2D, E ); conformation of the vascular system in an open arch with convoluted ends on the petiole ( Fig. 2D, E ); conformation of the vascular system in an open arch in the midrib ( Fig. 3D ); presence of leaf glands on the petiole ( Fig.1A ) ............................................................. Bronwenia megaptera

4. Plane-convex contour of petiole ( Fig.2E ); absence of leaf glands on the petiole ............................................ Bronwenia mathiasiae

- Concave-convex petiole contour ( Fig.2D ); presence of leaf glands on the petiole ( Fig.1A ).............................................................5

5. Flat surface glands ( Fig.1 C-1D); presence of idioblasts ( Fig.3B, C )............................................................... Bronwenia cineracens

- Concave surface glands ( Fig. 1F ); absence of idioblasts ................................................................................. Bronwenia ferruginea

6. Convex surface glands ( Fig. 1B, E ); presence of bundle sheath extension in the mesophyll ( Fig. 3F, G ); absence of dairy products; absence of secretory cavities ............................................................................................................................. Bronwenia cornifolia

- Flat surface glands ( Fig.1C, D ); absence of bundle sheath extension in the mesophyll; presence of laticifers ( Fig.3H, I ); presence of secretory cavities ( Fig. 2C ) ........................................................................................................................... Bronwenia wurdackii

Multivariate analysis: —From the analysis of similarity with UPGMA ( Fig.5 ) the species of Bronwenia were grouped according to the degree of similarity of the anatomical characters analyzed. The highest degree of similarity pointed out in the analysis occurred between the species Bronwenia cineracens and B. ferruginea as they share 15 similar characteristics, such as: presence of external leaf glands on the leaf, concave-convex contour, glands with convex surface, presence of prismatic crystals on the leaf and irregular quinternary veins. Another group was formed by B. cineracens , B. ferruginea , B. megaptera and B. mathiasiae that present the same type of conformation of the vascular system of the petiole/ midrib and the presence of accessory bundles in the petiole. The species B. acapulcensis and B. wurdackii share the presence of external leaf glands among the other species, however, B. acapulcensis presents a low degree of similarity, and this fact is explained by the exclusivity in the type of conformation of the petiole/ midrib vascular system main beam and absence of accessory beams. Bronwenia wurdackii was the species with the lowest degree of similarity with the other taxa, due to the presence of exclusive characteristics such as the presence of laticifers and secretory structures that visually resemble secretory cavities, but further studies are needed to determine the type of structure.

Figures

FIGURE 1. Morphology of the outer leaf glands of Bronwenia ferruginea (F), B. megaptera (A, B and E) and B. wurdackii (C and D): A. External gland on the petiole, B. Gland at the base of the leaf blade, C. Glands scattered in the leaf blade, D. Gland at the margin on the leaf blade, E. Gland with a convex surface, F. Gland with a concave surface. Abbreviation: arrow = Glands.

FIGURE 2. Details of leaf glands and leaf anatomy of Bronwenia acapulcensis (F and G), B. cineracens (A), B. ferruginea (D), B. mathisiae (E), B. megaptera (B) and B. wurdackii (C): A, B and C. Gland anatomy, D. Concave-convex contour, E. Plane-convex petiole contour, F. T-shaped trichome, G. Conformation of the vascular system in an open arch. Abbreviations: arrow = accessory bundle; P = phloem; PE = palisade epidermis; Sc = sclerenchymatic fibers; SC= Secretory cavity, VS = vascular system; X = xylem.

FIGURE 3. Leaf anatomy of Bronwenia acapulcensis (A, E, F and G), B. cineracens (B), B. mathiasiae (D), B. megaptera (C) and B. wurdackii (H and I): A. Drusae, B. Idioblast and prismatic crystals, C. Idioblasts, D. Biconvex contour, E. Open arch conformation with convoluted ends, F. Cross section, G. Parenchymatous sheath extension, H. Laticifers (longitudinal section), I. Laticifers (cross section).Abbreviations: BE = non-continuous bistratified epidermis of the adaxial surface; C = prismatic crystal; D = Druse; Id = Internal secretory structures; La = Laticifer; P = Phloem; PP = palisade parenchyma; Sc = sclerenchymatic fibers; SP = spongy parenchyma; UE = unistratified epidermis; X = xylem; * = stomata.

FIGURE 5. Similarity Analysis (UPGMA) of Bronwenia species. Baca—B. acapulcensis; Bcin—B. cineracens; Bcor- B. cornifolia; Bfer—B. ferruginea; Bmat—B. mathiasiae; Bmeg—B. megaptera; Bwur—B. wurdackii.