Marcetia auricularia R. B. Pacifico & Almeda 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 auricularia

description: Marcetia auricularia R.B.Pacifico & Almeda, sp. nov. (Figs 1–2).
Type:— BRAZIL. Bahia: Mucugê, Arredores do Pico da Batávia, Parque Nacional da Chapada Diamantina, 13°18’30.3”S, 41°17’31.3”W, 1603 m, 24 June 2022, fl., fr., R. Pacifico 689, V.E. Bressan & L. Daneu (holotype: HUEM!, isotypes: CAS!, HUEFS!, RB!).
Diagnosis:— Differs from Marcetia nummularia Markgraf (1927: 51) by the modally larger leaves 7–15 mm long (vs. 6–8 mm long), equaling or up to twice the length of the internodes (vs. usually shorter than the internodes), the adaxial leaf surfaces becoming glabrous and vaguely granulose-tuberculate (vs. covered with glandular trichomes 0.7–1.2 mm long), longer hypanthia 5–8 mm long (vs. ca. 3 mm long), and by its foliaceous calyx lobes 5–6 mm long (vs. lanceolate, ca. 3 mm long) that are auriculate (vs. not auriculate).
Erect shrubs 0.4–1 m tall, dichotomously branched. Upper cauline internodes 3–8 mm long, reddish (when fresh) 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, mostly concealing uppermost internodes, chartaceous to coriaceous, slightly discolored (when fresh), adaxial surface shiny green, abaxial surface pale green, both leaf surfaces becoming pale brown or reddish (when dry); petioles up to 0.7 mm long; blades 7–15 × 5–10 mm, elliptic to slightly 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 glabrous and vaguely granulose-tuberculate, abaxial surface densely covered with glandular trichomes 0.3–1.1 mm long 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, concentrated at the apex of the branches, essentially sessile, bracteolate. Bracteoles 2, inconspicuous, 1.2–1.8 × 1.8–2.2 mm, widely ovate, apex acute, base cordate, sparsely covered with hyaline trichomes ca. 0.4 mm long on both surfaces, margin ciliate with similar hyaline trichomes, 1-nerved. Hypanthia (at anthesis) 5–8 mm long, 6–8 mm wide at the torus, 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 5–6 mm long, 5–6 mm wide, reddish, erect at anthesis, foliaceous, auriculate, apex acute, margins entire and ciliate with glandular trichomes ca. 0.5 mm long, both surfaces covered with glandular trichomes 0.3–1.1 mm long, the indumentum concentrated on the central portion of the basal half of both surfaces. Petals 11–14 × 8–10 mm, obovate, magenta, the base not unguiculate, apex obtuse, both surfaces glabrous, margins entire and ciliate with minute gland-tipped trichomes up to 0.5 mm long. Stamens 8, isomorphic, erect and ± clustered around the base of the style at anthesis; filaments 8–9 mm long, white, becoming red like the anthers with age or following pollination, glabrous; anthers 3.5–4.5 × 1–1.5 mm, yellow, oblong but somewhat tapering distally, erostrate, pedoconnectives up to 0.3 mm, unappendaged. Ovary (at anthesis) 1.7–2 × 1.3–1.5 mm, superior, subglobose, glabrous, 3-locular, 1/5 basally adnate to the hypanthium; style 13–15 mm long, magenta, glabrous, sigmoid, stigma punctiform. Fruit at maturity a globose loculicidal capsule ca. 5 × 4 mm, pale brown, glabrous, 3-valvate, enveloping hypanthia, rupturing and flaking away with age. Seeds ca. 0.9 × 0.7 mm, brown, rounded-cochleate, testa tuberculate, raphal zone elliptic, ca. 80–90% the length of the seed.
Additional specimens examined:— BRAZIL. Bahia: Mucugê. Serra do Gobira, ca. 8.4 km ao sul de Mucugê na linha reta, na última subida próxima ao cume, 13°04’26”S, 41°22’44”W, 1555 m, 19 January 2005, fl., R.M. Harley et al. 55394 (HUEFS!); trilha para o Pico da Batávia, Parque Nacional da Chapada Diamantina, 13°18’34.3”S, 41°17’35.3”W, 1576 m, 24 June 2022, fl., fr., R. Pacifico et al. 686 (CAS!, HUEM!, HUEFS!, RB!); Pico do Gobira e arredores, 13°04’29.0”S, 41°22’44.6”W, 1549 m, 27 June 2022, fr., R. Pacifico et al. 719 (CAS!, HUEM!, HUEFS!, RB!); Pico do Gobira e arredores, 13°04’30.7”S, 41°22’43.4”W, 1532 m, 27 June 2022, 1532 m, fr., R. Pacifico et al. 720 (CAS!, HUEM!, HUEFS!, RB!); Pico do Gobira, 13 March 2008, fr., A.K.A. Santos et al. 1107 (HUEFS!, UEC-online image!); Chapada Diamantina, Pico do Gobira, área encharcada no sopé do morro, 13°04’36”S, 41°22’40”W, 1471 m, 20 January 2015, fl., fr., E.B. Souza et al. 1000 (HUEFS!).
Distribution, habitat and phenology:— Apparently endemic to the Chapada Diamantina, Bahia, Brazil (Appendix 2; Figure 3). It grows in campo rupestre (Fig. 4) with rocky outcrops exposed to full sun at elevations between 1471–1603 m. Collected flowering in January and June, and fruiting in January, March and June.
Etymology:— The epithet refers to the auriculate calyx lobes that are typical of this species.
Notes:— Marcetia santosiae is another probable relative that shares with M. auricularia the internodes, leaf abaxial surfaces and hypanthia densely covered with glandular trichomes, as well as leaf blades that are similar in size (7–14 mm long vs. 7–15 mm long, respectively), flowers subtended by a pair of inconspicuous bracteoles, magenta petals and isomorphic stamens. For their differences, see the diagnosis of Marcetia santosiae. Marcetia auricularia also has a distinct distribution restricted to Serra do Gobira and Serra da Batávia. The compared species have never been collected in these localities and sympatric distribution is unlikely (see Appendix 2). For photos of Marcetia nummularia and Marcetia santosiae, see Figures 5A–B, 6, and 7.
Suggested conservation status:— Critically Endangered (CR): B1ac(iii)+B2ac(iii) (see 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 40-42, DOI: 10.11646/phytotaxa.573.1.3, http://zenodo.org/record/7329459