Miconia leonorae A.F. Augustin & Caddah

Augustin, Ana Flávia, Nery, Eduardo Koerich & Caddah, Mayara Krasinski, 2024, New discoveries for the genus Miconia (Melastomataceae): a new species for the brazilian Atlantic Forest, Phytotaxa 659 (2), pp. 205-212 : 206-210

Miconia leonorae A.F. Augustin & Caddah , sp. nov. Figures 1–4 .

Type:— BRAZIL. São Paulo: São José do Barreiro, Serra da Bocaína , March 6 th 2010 (fl), J. Cordeiro & J. M. Silva 3452 (Holotype: MBM!; isotypes: BCHB, CESJ, HCF!, HUEFS!, HUFU!, HVC, IPA, MG!, REAL!, SPSF) .

Diagnosis: — Miconia leonorae is similar to Miconia lepidota , but differs by its generally acute leaf blade apex and base (versus generally round to obtuse base and a predominantly acuminate apex in M. lepidota ), indument light brown to gray on leaf blade abaxial surface, glabrescent old leaves (versus ferrugineous indument, old leaves usually not glabrescent), cylindric, scorpioid inflorescences with basal branches only bifid or trifid (versus pyramidal inflorescence with basal branches racemose, with several bifid, scorpioid branches), and androecium with isomorphic stamens (versus slightly dimorphic stamens).

Description: Trees 2–19 m tall. Young branches, petioles, leaf blade abaxial surface, inflorescence branches, bracts, and hypanthium outer surface covered by a light brown to gray indument of appressed lepidote-stellate trichomes (arms better defined on young portions), nodal line absent. Young branches round to slightly compressed. Leaves opposite, flattened, clearly discolorous. Blades 6–18 × 2.5–7.5 cm, oblong to elliptic, the base generally acute, sometimes round, the apex acute, the margins entire. Adaxial leaf blade surface dark green, mostly glabrous, but with scattered stellate trichomes on young leaves, and dense indumentum on the main nerves. Abaxial leaf blade surface light brown to gray, covered by a thin layer of appressed lepidote-stellate trichomes that extends across the entire blade, including the main nerves, with older leaves becoming glabrescent. Venation acrodromous, 3-veined, the midvein and one pair of arching secondary veins, basal, plus an additional intramarginal pair, domatia absent; petioles 1–5 cm long. Inflorescences, terminal, thyrses of bifid (sometimes trifid), scorpioid branches, 24.5 × 1–4 cm (peduncle to the apex), basal branches sometimes racemose; accessory branches absent. Bracts and bracteoles subulate, to 1.7 mm, covered by lepidote-stellate trichomes on both surfaces, early caducous. Flowers 5-merous, sessile. Hypanthium campanulate, ca. 1.3 mm long, inner surface glabrous, free portion 1-1.1 mm. Calyx with triangular lobes with a dorsal tooth smaller than 0.1 mm, shorter than the lobes, inner surface completely glabrous, tube 0.2–0.4 mm long, lobes 0.2–0.5 mm long. Petals 5-merous, symmetrical, white, oblong, glabrous, the margin entire, 0.70-1 x 0.60-1 mm. Stamens 10, white, isomorphic, filaments white, glabrous, 4–5 mm long; anthers white, ca. 2 mm long, opening by a single pore, connective 0.2–0.5 mm prolonged below the thecae, with two ventral lobes and, sometimes, with a dorsal tooth. Ovary 3–5-locular, ca 0.8 mm long, 1/4 attached to the wall of the hypanthium, glabrous; style white, ca. 5 × 0.5 mm, glabrous, stigma capitate. Fruits globose, with persistent calyx, covered with sparse stellate trichomes, ca. 3 mm in diameter, green when immature, purple to black when ripe. Seeds 5–20, ca 0.8–1 mm, smooth, pyramidal.

Paratypes: — BRAZIL: ESPÍRITO SANTO: Águia Branca , 07 June 2006 (fr), V. Demuner 2495 ( FLOR, MBML) ; Alegre : 10 June 2008 (bd, fl), D. A. Folli 6084 ( UPCB) ; Cariacica: 06 May 2008 (bd), R. Goldenberg 1113 ( MBM, MBML, UPCB) ; Governador Lindenberg , 12 May 2015 (bd), R. Goldenberg 2166 ( MBML, UPCB) ; Marilândia , 27 September 2006 (bd) L. F. S. Magnago 1414 ( MBML) ; Santa Maria de Jetibá : 18 March 2003 (bd), L. Kollmann 6061 ( MBML, UPCB) ; 17 June 2003 (fr), L. Kollmann 6222 ( FLOR, MBM, UPCB), 21 August 2003 (fr), L. Kollmann 6280 ( FLOR, MBML) ; Santa Teresa : 09 July 1998 (fr), L. Kollmann 195 ( FLOR, MBML, UPCB), 16 July 1998 (fr), L. Kollmann 262 ( MBML, UPCB), 16 June 1999 (fr), L. Kollmann 2571 ( FLOR, MBML, UPCB), 12 July 2001 (fr), L. Kollmann 4190 ( FLOR, MBML, UPCB), 09 July 2003 (fr), J. Rossini 343 ( MBML, UPCB), 22 June 1993 (st), L. D. Thomaz 841 ( MBML) . MINAS GERAIS: Belo Horizonte : 09 April 2008 (fl), J. Ordones 1326 ( UPCB) . RIO DE JANEIRO: Quatis : 07 May 2013 (fr), J. F. A. Baumgratz 1288 ( MBML) ; Silva Jardim : 19 January 1994 (st), H. C. de Lima 4876 ( FLOR) ; 15 April 2013 (bd) P. Rosa 478 ( FLOR), 22 May 2013 (fr), P. Rosa 496 ( FLOR, MG), 25 June 2013 (fr), P. Rosa 508 ( FLOR), 25 June 2013 (fr), P. Rosa 500 ( FLOR), 25 July 2013 (fr), P. Rosa 549 ( FLOR) . SÃO PAULO: São José do Barreiro , 01 July 2007 (bd, fl, fr), H. Serafim 34 ( UPCB) .

Habitat and distribution: Confirmed records are from southeastern Brazil, in the states of Espírito Santo, Minas Gerais, Rio de Janeiro, and São Paulo. This species may extend to the state of Bahia, although these records remain unconfirmed. Plants are common in understory evergreen forests and forest edges in the Atlantic Forest, but there are also documented records in semideciduous and Cerrado forests.

Phenology: The new species was collected with flowers from April to July, and with fruits from May to August.

Etymology: The species name honors the botanist Maria Leonor D’El Rei Souza, who served as a professor at the Federal University of Santa Catarina until 2013. She was a specialist in plant systematics, making significant contributions to the taxonomy of Melastomataceae .

Conservation status: Currently, Miconia leonorae has confirmed occurrences in four Brazilian states, all in the Southeast region. Based only on the materials used for the species description, we conducted a preliminary assessment on its conservation status using the Geospatial Conservation Assessment Tool (GEOCAT) ( Bachman et al. 2011). Its Extent of Occurrence (EOO) and Area of Occupancy (AOO) are, respectively, 120,414 km 2 and 48 km 2. Despite the AOO indicating a possible state of threat, and the decline in the quality of M. leonorae ’s habitat, the Atlantic Forest, we believe that the data available at the moment do not allow us to infer that M. leonorae is (a) limited to severely fragmented populations or a small number of threatened locations, or (c) conditioned to extreme fluctuations, as instructed by ( IUCN, 2012). Thus, we preliminarily estimate that the species cannot be categorized as threatened. However, a more careful approach to the subject is necessary for a definitive categorization of its conservation status.

Notes: Miconia leonorae is proposed to be classified within Miconia supersect. Discolores sect. Multispicatae Caddah & R.Goldenb. in Caddah et al. (2022: 11) because of its morphological similarity to Miconia lepidota . In its current circumscription, the section occurs from the Greater Antilles and Costa Rica to Southeastern Brazil and is distinguished from other sections of Miconia supersect. Discolores Caddah & R.Goldenb. in Caddah et al. (2022: 11) by the abaxial leaf surface usually moderately covered by stellate trichomes, scorpioid inflorescences, and the capitate stigma ( Caddah et al. 2022). Until now, Miconia lepidota was the only species of this section featured with blade completely covered abaxial leaf surface, a character shared with M. leonorae (see Figure 3 ). Moreover, these two species share several characters such as a similar leaf size, thyrses with scorpioid bifid or trifid branches, lepidote-stellate trichomes with only partially fused radii (indument type #38, following Wurdack 1986), white anthers, and the capitate stigma. The main differences between M. leonarae and M. lepidota are leaf blade shape (lanceolate to oblong-lanceolate in M. leonorae vs. ovate-elliptic to oblong-elliptic in M. lepidota ), leaf blade apex (acute vs. acuminate), leaf blade base (usually acute vs. usually round to obtuse), indument color (gray vs. brown), inflorescence shape (cylindrical, with short basal branches vs. pyramidal, with long, multi-branched basal branches) and stamens’ (isomorphic vs. slightly dimorphic). Although we were not able to examine all herbarium sheets from eastern Brazil identified as M. lepidota , we strongly posit that this species does not inhabit this region, being endemic to the northern portions of South America, and, therefore, at least a large portion of these herbarium sheets would correspond to M. leonorae . Besides M. lepidota , some M. leonorae sheets were previously identified as M. argyrophylla Candolle (1828: 181) and M. stenostachya Candolle (1828: 181) , species from M. supersect. Discolores sect. Albicantes Caddah & R.Goldenb. in Caddah et al. (2022: 11), which also have scorpioid thyrses, but the leaves, branches, and flowers are covered with amorphous, vermiform trichomes (indument type #34, following Wurdack 1986), typical of sect. Albicantes. Additional distinctions include glandular-ciliate margins on the petals (absent in M. leonorae ) and a truncate to clavate stigma (capitate in M. leonorae ). In addition, M. stenostachya is a shrub ( M. leonorae is a tree) with yellow anthers that turn red with age (contrary to the -white anthers in M. leonorae ). While Miconia argyrophylla occurs from the northern portions of South America to Central Brazil, M. stenostachya reaches the eastern parts of the Brazilian Cerrado, but neither is found in the evergreen Atlantic Forest.

Among Eastern Brazilian species, Miconia goldenbergiana Caddah in Caddah & Meirelles (2018: 168) is a tree from the Atlantic Forest that also has elliptic leaf blades with the abaxial surface densely covered by appressed lepidote-stellate trichomes. However, it has plinerved leaves, glomerulate inflorescences, and flowers with punctiform stigmas ( Caddah & Meirelles 2018). Other species like Miconia buddlejoides Triana (1872: 118) , M. cinerascens Miquel (1849: 543) var. cinerascens , M. dodecandra Cogniaux (1887: 243) , M. flammea Casaretto (1845: 85) , and M. willdenowii Klotzsch ex Naudin (1850: 199) may also exhibit lanceolate or oblong-lanceolate leaf blades of a similar size, with the abaxial surface completely covered by stellate trichomes (but not appressed nor with partially fused arms, as observed in M. leonorae ). However, distinctions arise in the inflorescence structure (dichasial in M. dodecandra and glomerulate in the others, while scorpioid in M. leonorae ) and the stigma shape (all punctiform, while capitate in M. leonorae ). In addition, M. dodecandra and M. flammea also differ because of their tawny leaf indument, and M. willdenowii stands out with strongly flattened young branches with longitudinal ridges. Notably, scorpioid inflorescences are less common among Atlantic Forest species compared to those in the Cerrado and Amazon domains. Among the few species with scorpoioid inflorescences in the Atlantic Forest is M. caiuia , recently described based on specimens previously assigned to M. lepidota . This species could be distinguished from M. leonorae by the larger, suprabasal leaves with the abaxial blade surface only sparsely to moderately covered by lepidote-stellate trichomes ( Chagas et al. 2013).

Cryptic species, identified under a single name often due to challenges in differentiation by taxonomists ( Bickford et al. 2007), may not necessarily be sister species, and their similarities extend beyond morphology. The overall morphological similarity between Miconia leonorae and M. lepidota might suggest shared biochemical features and similar ecological roles in their respective ecosystems. However, this should not be taken for granted, and therefore, careful consideration should be taken when dealing with the name Miconia lepidota in previous publications, since they could be referring to Miconia leonorae or M. caiuia .

Figures

FIGURE 1. Miconia leonorae, specimen from Espírito Santo.A. Branch, inflorescence and leaves. B. Detail of the inflorescence buds. C. Detail of the leaf base and gray abaxial surface. Pictures from Renato Goldenberg (R. Goldenberg 1113).

FIGURE 2. Line drawing of Miconia leonorae. A. Branch with leaves and inflorescences. B. Mature flower with petals, stamens and capitate stigma. C. Longitudinal section of the flower showing the ovary and locules. D. Hypanthium showing the triangular calyx lobes. E. Stamen showing the dorsal side with a tooth. F. Stamen showing the ventral side with 2 lobes. A from Goldenberg 1113 (paratype, MBML), B–F from J. Ordones 1326 (paratype, UPCB).

FIGURE 3. Scanning electron microscopy images of the abaxial surface of the leaf blade. A and B from Macedo 5774, specimen of Miconia leonorae from Minas Gerais state (NY). C and D from N.T. da Silva 1858, specimen of Miconia lepidota from Pará state (NY).

FIGURE 4. Distribution of Miconia leonorae. Confirmed occurrences in four states from Southeastern Brazil: Minas Gerais, Espírito Santo, São Paulo, and Rio de Janeiro. Black dots indicate the coordinates where the occurrences were confirmed.