Myrcia lucasae R. B. Almeida, Antar & B. S. Amorim 2020, sp. nov.
Creators: name: Almeida, Roberto Baptista Pereira
name: Antar, Guilherme Medeiros
name: Vasconcelos, Thais
name: Santos, Leidiana L.
name: Amorim, Bruno S.
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Myrtales
Myrtaceae
Myrcia
Myrcia lucasae

description: Myrcia lucasae R.B. Almeida, Antar & B.S. Amorim, sp. nov. (Figure 1 and 2)
Type:— Brazil. Bahia: Mucugê, Estrada entre Mucugê e Andaraí, 12º57’57”S, 41º18’47”W, Alt: 1109m, 07 January 2019, T.N.C. Vasconcelos, M.C. Antonicelli, R.C. Pizzardo & A. Cabral 1029 (holotype: SPF, isotypes: HUEFS, K, RB).
Myrcia lucasae is morphologically related to Myrcia lughadhae B.S. Amorim (2014: 3) but differs in the stems, leaves, inflorescences and fruits with strigose indumentum of ferruginous trichomes, absence of ribs on fruits and elliptic or subulate bracteoles, while M. lughadhae have stems, leaves and inflorescences puberulent to glabrous, never strigose, 8-ribbed fruits and lanceolate bracteoles. It also resembles Myrcia virgata by the narrowly elliptic leaves and the elliptic fruits, but can be distinguished by the thecae displacement and the slightly extended hypanthium that are typical of Myrcia sect. Gomidesia.
Shrub to tree 1−2,5 m tall; younger stems strigose, covered by ferruginous simple trichomes, older stems with longitudinal ribs, glabrous to glabrescent with scattered white, simple trichomes. Leaves opposite in angulate 60º, leaf blade narrow elliptic, 4.5−12.4 x 0.8−3.0 cm, chartaceous, apex acute, base cuneate or truncated, abaxial surface densely strigose with simple tricomes, ferruginous, becoming white when older, adaxial surface strigose with simple ferruginous trichomes; midvein strigose, impressed in the adaxial surface, prominent in the abaxial surface, secondary veins 14−18 pairs, diverging 60º−70º from midvein, marginal vein ca. 0.1 cm from the margin; petiole 0.5–1.0 cm long, strigose with ferruginous trichomes, getting white when older, adaxially sulcate, abaxially flat or cylindrical, rugose. Inflorescence paniculate, rachis strigose, denser near the apex, with simple trichomes, ferruginous, with white trichomes, main floral axis 5–11 cm long, secondary axes 1–2.5 cm long, tertiary axes 0.8–0.9 cm long, multi-flowered, evenly distributed along the axes; bracteoles 2.1–2.6(–3) mm long, elliptic or subulate, strigose. Flowers pentamerous, sessile or with pedicel 0.2–0.5(–3.5) mm long; flower bud obovoid, 4.2–4.8 × 4.5–5 mm, hypanthium not ribbed, prolonged 0.6–0.8 mm beyond the ovary, strigose; 5 calyx lobes 1.8–2 mm long, triangular with acute to obtuse apex, persistent, strigose, with ferruginous trichomes on both surfaces; 5 petals oblong with truncated base, 3–3.5 × 3–3.3 mm, concave, soon deciduous, glabrous with ciliated margins on the adaxial surface and strigose abaxial surface, with ferruginous simple trichomes; stamens ca. 250, 3.6–4.3 mm long, white to reddish when older, anthers 3–5 mm long, oblong-ellipsoid, thecae with irregular dorsal openings with septum visible; staminal ring 3.8 mm diam., ca. 0.8 width, canescent; style 4.7–5.3 mm long, strigose-canescent, glabrous at apex, stigma cylindrical-botuliform; ovary 2–locular with 2 ovules per locule. Fruit 0.5 × 0.9 cm, green and strigose when immature, red and glabrous with strigose apex when ripe, smooth, elliptic, calyx lobes persistent. Seed one, 4.9 × 3.8 mm, glabrous, shiny.
Paratypes:— BRAZIL. Bahia: Andaraí, south of Andaraí, along road to Mucugê near small town of Xique-Xique. 41º19’S, 12º54’W, 14 February 1977, R.M. Harley et al. 18675 (ESA!, K); caminho para a antiga estrada para Xique-Xique do Igatú 12º25’15’’S, 41º18’25’’W Alt: 560 m, 14 February 1997, T.R. Santos et al. PCD 5646 (ALCB!); ca. 1 km S do Distrito de Igatú, 12º53’S, 41º19’W, 15 December 1999, J.G. Jardim et al. 2311 (CEPEC, NY, RB); ca. 2 km S de Andaraí na estrada para Mucugê, 12º49’48’’S, 41º19’30’’W, 10 March 2003, L.P. Queiroz et al. 13592 (HUEFS [scan seen]); estrada Andaraí para Mucugê, 12º51’05’’S, 41º18’36’’W, Alt: 414 m, 17 December 2009, M.L. Guedes et. al. 16867 (ALCB!); margem da rodovia entre Mucugê e Andaraí, próximo ao segundo córrego, 12º56’56”S, 41º17’04’’W, Alt: 850, 26 Sep 2011, J.E.Q. Faria 1927 (HUEFS, HUEG, UB). Mucugê, estrada Mucugê/ Andaraí, ca. 8 km de Mucugê, torre da telebahia, 12 November 1998, R.P. Oliveira et al. 45 (HUEFS [scan seen]); margem da estrada de terra Palmeiras para Mucugê & Andarai, 12º57’41”S, 41º18’58’’W, Alt: 1129, 27 October 2014, T.N.C. Vasconcelos 439 (HURB, K!, UB, SPF!); Parque Municipal de Mucugê, 13º0’S, 41º23’W, 27 March 2003, T.C. Faustino 28 (HUEFS [scan seen]); ibid., 30 Jan 2003, T.C. Faustino 47 (HUEFS [scan seen]); Capa Bode, 12º58’27’’S, 41º19’23’’W, 30 March 2004, R. Funch 253 (HUEFS [scan seen]); Chapada Diamantina, Estrada entre Mucugê e Andaraí, 12º57’50.1”S, 41º18’47.1”W, Alt: 1116 m, 14 September 2018, T.N.C. Vasconcelos & J.E.Q. Faria 998 (SPF!, UB).
Phenology: —Specimens of Myrcia lucasae were found flowering between September and January and producing fruits between December and March (Figure 3).
Etymology:—The epithet of this species honors Dr. Eve Lucas, botanist and prolific Myrcia specialist. Dr. Lucas is the first author of the first comprehensive phylogenetic study for Myrcia (Lucas et al. 2011) and of the current infrageneric classification for the genus (Lucas et al. 2018). She also contributed immensely to Myrtaceae studies in Brazil by supervising innumerous Brazilian graduate students.
Habitat and distribution:— Myrcia lucasae is endemic to the Chapada Diamantina, in the municipalities of Andaraí and Mucugê, Bahia state. It is recorded from areas of high altitude (1100 m elev.) in rocky outcrops of the campo rupestre vegetation. Most collections appear to have been made within the protected areas of the Parque Municipal de Mucugê and Parque Nacional da Chapada Diamantina, but remarkably following the road between Mucugê and Andaraí (a well-known bias in botanical collecting, Oliveira et al. 2016). In this sense, it is likely that other populations of Myrcia lucasae occur in and out the conservation units close to the area where the species was frequently collected (Figure 4).
Similar species and remarks:— Myrcia lucasae is morphologically placed in Myrcia sect. Gomidesia due to the presence of erect, distinct and imbricate calyx lobes in flowers and fruits, thecae with irregular dorsal openings with visible septum. The phylogenetically placement of this species in sect. Gomidesia was also confirmed by molecular data evidence (T. Vasconcelos unpublished). M. lucasae is morphologically similar and sympatric to Myrcia lughadhae but differs by the narrow elliptic and chartaceous leaves, elliptic or subulate bracteoles, absence of ribs and strigose trichomes on fruits; while M. lughadhae presents lanceolate and coriaceous leaves, lanceolate bracteoles, fruits 8- ribbed and puberulent (never strigose).
Further examination demonstrated that several collections from the Chapada Diamantina previously identified as Myrcia virgata were actually Myrcia lucasae. These species share some morphological features, such as narrow elliptic leaves and elliptic fruits (uncommon in sect. Gomidesia), as well as characters that are common to both sections, such as trichomes in the staminal ring, number of locules and number of ovules per locule. However, they differ in the morphology of the anthers, the slightly extended hypanthium in M. lucasae (vs. up to 0.2 mm beyond the ovary summit in M. virgata) and the narrow staminal ring, comprising less than 30% of the total disc width in M. lucasae (vs. more than 60% of the total disc width in M. virgata). Collections of Myrcia virgata that actually correspond to its type collection and protologue both in terms of morphology and geographical distribution appear endemic to the region of Serra Dourada in the state of Goiás, which interestingly is also a campo rupestre vegetation.
Conservation status:—The AOO and EOO are both small, of just 32 km ² and 106.150 km ², respectively. The restricted geographical range is also a common feature of species endemic to the campo rupestre ecosystems. Although some specimens were collected within the protected areas of the Parque Municipal de Mucugê and the Parque Nacional da Chapada Diamantina, the area has intense tourism, with high probability of anthropic fires and presence of invasive species (Silveira et al. 2016). In this sense, Myrcia lucasae should be considered endangered according to the IUCN criteria B1ab(iii)+2ab(iii) (IUCN 2012).
description: Published as part of Almeida, Roberto Baptista Pereira, Antar, Guilherme Medeiros, Vasconcelos, Thais, Santos, Leidiana L. & Amorim, Bruno S., 2020, Myrcia lucasae (Myrtaceae), a new species from the campo rupestre of Chapada Diamantina, Brazil, pp. 227-234 in Phytotaxa 435 (3) on pages 228-233, DOI: 10.11646/phytotaxa.435.3.2, http://zenodo.org/record/13875610