Marcetia santosiae Almeda & R. B. Pacifico 2022, sp. nov.
Creators: name: Pacifico, Ricardo
name: Almeda, Frank
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Myrtales
Melastomataceae
Marcetia
Marcetia santosiae

description: Marcetia santosiae Almeda & R.B.Pacifico, sp. nov. (Figs. 6–7).
Type:— BRAZIL. Bahia: Abaíra, Distrito of Catolés, Chapada Diamantina, Trail to Pico do Barbado, 13°17’20.5”S, 41°53’30.5”W, 24 May 2019, fl., fr., F. Almeda 10790, R.B. Pacifico, L. Daneu & L.C. Gomes (holotype: HUEM!, isotypes: ALCB!, CAS!, CEPEC!, HUEFS!).
Diagnosis:— Differs from Marcetia auricularia by the longer cauline internodes 2–22 mm long (vs. 3–8 mm long), the shorter calyx lobes 3–4 mm long (vs. 5–6 mm long) that are not auriculate (vs. auriculate), shorter petals 5–7 mm long (11–14 mm long), stamen filaments 2.5–3.5 mm long (vs. 8–9 mm long), anthers 1.8–2.2 mm long (vs. 3.5–4.5 mm long), styles 4–5 mm long (vs. 13–15 mm long), and raphal zone covering nearly 40% the length of the seed (vs. ca. 80–90% the length of the seed).
Erect shrubs 0.4–1 m tall, dichotomously branched. Upper cauline internodes 2–22 mm long, light green (when fresh) or reddish becoming pale brown (when dry) and defoliated with age, quadrangular and sulcate on two of the four opposing faces, densely covered with stout glandular trichomes 0.3–1.1 mm long. Leaves decussate, moderately ascending, not concealing uppermost internodes, chartaceous to coriaceous, slightly discolored (when fresh), adaxial surface vivid green, abaxial surface pale green, both leaf surfaces becoming pale brown or reddish (when dry); petioles up to 0.8 mm long; blades 7–14 × 4–11 mm, ovate, apex rounded or slightly acute, base truncate to cordate, margin entire to inconspicuously crenulate-ciliate with hyaline trichomes up to 0.5 mm long, often flushed with red, narrowly revolute, adaxial surface densely covered with glandular trichomes 0.3–0.9, abaxial surface densely covered with glandular trichomes 0.3–1.1 mm long, the stouter trichomes concentrated on the veins, 9–11-nerved from the base (basal acrodromous), venation prominent on the abaxial surface and impressed on the adaxial surface, secondary venation not evident. Flowers 4-merous on short pedicels up to 0.5 mm long, concentrated at the apex of the branches, bracteolate. Bracteoles 2, inconspicuous, 1.5–2 × 0.4–0.8 mm, narrowly triangular, apex acute, base attenuate, densely covered with glandular trichomes 0.3–1.1 mm long on both surfaces, margin ciliate with similar glandular trichomes, 1-nerved. Hypanthia (at anthesis) 3–4 mm long, 3–4 mm wide at the torus, light green or reddish, campanulate, equaling the capsule in length at maturity, densely covered with stout glandular trichomes 0.3–1.1 mm long. Calyx tube inconspicuous, ca. 0.1 mm long. Calyx lobes 3–4 mm long, 1.5–2.6 mm wide, light green or reddish (when fresh) becoming pale brown (when dry), erect at anthesis, ovate to foliaceous, not auriculate, apex acute, margins entire and ciliate with glandular trichomes 0.3–0.9 mm long, both surfaces covered with glandular trichomes 0.3–0.9 mm long, the indumentum evenly distributed. Petals 5–7 × 6–8 mm, obovate, magenta, the base attenuate, apex obtuse, both surfaces glabrous, margins entire and ciliate with minute gland-tipped trichomes up to 0.4 mm long. Stamens 8, isomorphic, erect and clustered around the base of the style (at anthesis); filaments 2.5–3.5 mm long, white becoming red with age or following pollination, glabrous; anthers 1.8–2.2 × 0.6–0.8 mm, yellow, oblong but somewhat tapering distally, erostrate, pedoconnectives up to 0.2 mm, unappendaged. Ovary (at anthesis) ca. 1.5–1.8 × 1.2–1.4 mm, superior, subglobose, glabrous, 3-locular, 1/5 basally adnate to the hypanthium; style 4–5 mm long, magenta, glabrous, somewhat curved, stigma punctiform. Fruit at maturity a globose loculicidal capsule ca. 4–5 × 4–5 mm, pale brown, glabrous, 3-valvate, enveloping hypanthia, rupturing and flaking away with age. Seeds ca. 0.7 × 0.5 mm, brown, rounded-cochleate, testa tuberculate, raphal zone elliptic, ca. 40% the length of the seed.
Additional specimens examined:— BRAZIL. Bahia: Abaíra. Distrito of Catolés, Chapada Diamantina, Trail to Pico do Barbado, 13°17’28.2”S, 41°53’48.9”W, [ca. 1543 m], 24 May 2019, fl., F. Almeda et al. 10782 (CAS!, CEPEC!, HUEM!); Catolés, caminho para a Serra do Barbado, 13°17’S, 41°50’W, 30 April 2006, fl., fr., M.L. Guedes et al. 12389 (ALCB!); Campo de Ouro Fino (baixo), 13°15’S, 41°54’W, 1600–1700 m, 10 January 1992, fl., fr., R.M. Harley et al. H50727 (HUEFS!, K-online image!, NY-online image!, SPF!); Serra do Barbado, 13°18’S, 41°54’W, 1950–2000 m, 12 January 2007, fl., fr., A.K.A. Santos et al. 970 (HUEFS!). Rio de Contas. Trilha para o Campo do Queiroz, 13°30’55.4”S, 41°56’51.7”W, 1410–1470 m, 20 May 1999, fl., fr., F. Almeda et al. 8326 (CAS!, HUFU-online image!, NY!, UEC!); estrada para Pico das Almas, ca. 24.1 km da cidade, 19 November 2000, fl., fr., J.F.A. Baumgratz et al. 742 (CEPEC!, RB!); trilha para o Pico das Almas, próximo ao Campo do Queiroz, 14 February 2012, fl., fr., J.G. Freitas et al. 763 (HUEFS!); caminho para o Pico das Almas, na subida para o Campo do Queiroz, 13°30’52”S, 41°56’54”W, 1502 m, 11 February 2002, fl., fr., R.M. Harley & A.M. Giulietti 54443 (HUEFS!); trilha para o Pico das Almas, 13°30’52.9”S, 41°56’54.6”W, 1382 m, 14 June 2022, fl., fr., R. Pacifico et al. 575 (CAS!, HUEFS!, HUEM!, RB!); trilha para o Pico do Itobira, 13°22’38.9”S, 41°53’10.6”W, 1542 m, 16 June 2022, fl., fr., R. Pacifico et al. 618 (CAS!, HUEM!, HUEFS!, RB!); Pico das Almas, trilha para o Pico das Almas, 13°30’53”S, 41°56’55”W, 1504 m, 14 February 2012, fl., fr., M.J.R. Rocha et al. 335 (BHCB, RB!); trilha na subida para o Pico das Almas, antes do Campo do Queiroz, 13°31’01”S, 41°55’35”W, 1507 m, 18 January 2003, fl., fr., A.K.A. Santos et al. 27 (HUEFS!, UEC-online image!); trilha para o Pico das Almas, 18 February 2006, fl. fr., A.K.A. Santos et al. 809 (HUEFS!); trilha para o Pico das Almas, 14 February 2012, fl., fr., A.K.A. Santos et al. 1204 (HUEFS!).
Distribution, habitat and phenology:— Apparently endemic to the Chapada Diamantina, Bahia, Brazil (Appendix 2; Fig. 3). It grows in campo rupestre (Fig. 4) with rocky outcrops exposed to full sun at elevations between 1382–2000 m. Collected flowering from January to June, and fruiting in November, and from January to June (except March).
Etymology:— The epithet honors professor Andrea Karla Almeida dos Santos (b. 1979–). Besides leading important field expeditions to the Chapada Diamantina, focused on Melastomataceae, Andrea Karla has described new species of Marcetia (Santos et al. 2008, 2013), authored a checklist for the family in Rio de Contas (Santos & Silva 2005) and the treatment of Marcetia for the Flora of Brazil (Santos 2022).
Notes:— Marcetia santosiae is also morphologically similar to M. nummularia (Fig. 5 A–B). Both species share a dense indumentum of glandular trichomes on the internodes, abaxial leaf surfaces and hypanthia, as well as triangular calyx lobes and magenta petals. Marcetia santosiae differs by the modally longer leaf blades 7–14 mm long (vs. 6–8 mm long) that are ovate (vs. orbicular to suborbicular) and less markedly revolute, the shorter anthers 1.8–2.2 mm long (vs. 3–4 mm long) and 3-locular ovaries (vs. 4-locular). These species may occur sympatrically in Abaíra and Rio de Contas (Appendices 1–2). There appears to be no overlap in the distributions of M. santosiae and M. auricularia (Appendix 2) (for their distinctions see the diagnosis).
Suggested conservation status:— Critically Endangered (CR): B1ac(iv) (Appendix 2).
description: Published as part of Pacifico, Ricardo & Almeda, Frank, 2022, New species of Marcetia and Microlicia (Melastomataceae) endemic to the campo rupestre of Chapada Diamantina, Bahia, Brazil, pp. 39-69 in Phytotaxa 573 (1) on pages 44-47, DOI: 10.11646/phytotaxa.573.1.3, http://zenodo.org/record/7329459