Myrcia rupestris M.F.Santos, 2015

Santos, Matheus F., Lucas, Eve & Sano, Paulo T., 2015, Five new South American species of Myrcia s. l. (Myrtaceae), Phytotaxa 234 (2), pp. 159-171 : 166-167

4. Myrcia rupestris M.F.Santos , sp. nov. ( Figs. 2 , 4A–E )

Myrcia rupestris is related to Myrcia lenheirensis Kiaerskou (1893: 98) , but differs in the dense indument covering several structures (vs. structures essentially glabrous), immature branches that are not keeled (vs. keeled immature branches) and the branched inflorescence bearing complete terminal dichasia (vs. not or little branched with only a central flower in the terminal dichasia).

Type:— BRAZIL. Minas Gerais: Mun. Botumirim, Estrada Botumirim–Rio do Peixe, afloramento rochoso no lado esquerdo da estrada (sentido Botumirim), 16 o 55’00’’S, 43 o 00’00’’W, 10 February 2011 (fl.), M.F. Santos 642 (holotype SPF!, isotypes BHCB!, K!, NY!, RB!).

Shrub to tree, 0.5–3.0 m. Immature parts with epidermal peeling; trichome brown or light brown, 0.1–0.5 mm long, dibrachiate. Twig when immature reddish, flattened, not keeled, tomentose or pubescent; greyish at maturity, cylindrical, cortex slightly cracked, glabrescent to glabrous; branching monopodial, 2–3 branches per node (rarely more than three), epidermal protrusion absent at the internodes, internode 0.5–1.5 cm long; cataphyll scale-like to foliaceous, 1–4 × 1 mm, usually only present at the basal internodes, early deciduous, free, lanceolate or ovate, externally and internally puberulent; branch with a single apical bud, puberulent. Leaf discolorous, coriaceous, blade 0.8–2.6 × 0.1–0.9 cm, narrowly elliptic or elliptic, apex acuminate, acute, obtuse or rounded, base narrowly cuneate or cuneate, margin slightly revolute at the base, secondary, marginal and tertiary veins inconspicuous; immature adaxial surface pubescent or puberulent, glabrescent to glabrous at maturity, midvein sulcate to plane in the first half and flat in the second half, pellucid dots slightly conspicuous to inconspicuous, less than 5 to more than 15 per mm 2; immature abaxial surface tomentose or pubescent, puberulent or glabrescent at maturity, midvein prominent, pellucid dots slightly conspicuous to inconspicuous, less than 5 per mm 2; petiole 1–3 × 1 mm, canaliculate to semicylindrical, tomentose or pubescent when immature, glabrescent to glabrous at maturity. Panicle 0.3–4.5 × 0.5–3.0 cm, corymbiform, terminal axillary or subterminal, 13–37 flowers, rachis tomentose, pubescent or puberulent, 1–2 branching at the base (sometimes with a central vegetative branch), first internode of central rachis 1 mm wide, semicylindrical to flattened, distal internodes flattened, opposite branching, 2–3 (rarely four) times per node, epidermal protrusion present at the internodes, usually absent in apical branches. Bract 1.2–3.2 × 0.4–0.8 mm, deciduous, lanceolate or ovate, concave or plane, apex acuminate, base truncate, adaxial surface puberulent to glabrous, abaxial surface puberulent. Pedicel 0–2.4 mm long, cylindrical, pubescent or puberulent. Bracteole 0.8–1.2 × 0.2–0.4 mm, deciduous, lanceolate or ovate, concave, apex acuminate, base truncate, adaxial surface puberulent to glabrous, abaxial surface puberulent. Floral bud 2–3 × 2–3 mm, turbinate. Hypanthium extending 0.8–1.0 mm above the summit of the ovary, not tearing at anthesis, externally pubescent or puberulent, glabrescent towards the apex, pellucid dots conspicuous, covering the whole surface, internally glabrous; calyx 3–5-merous, lobes 0.2–1.2 × 0.8–1.8 mm, distinct from the hypanthium, the external ones smaller than the internal ones, deciduous, depressed ovate, concave, apex rounded, base truncate, externally puberulent or with scattered trichomes, internally puberulent; corolla 3–4-merous, petal light brown to white, 1–2 × 1.2–2.2 mm, depressed, ovate to very widely ovate, concave, apex rounded, base truncate, externally and internally puberulent or with scattered trichomes to glabrous; staminal ring 0.2–0.4 mm wide, glabrous (rarely with scattered trichomes), stamens 28–64, filament 1.6–4.0 mm long, light brown to white, glabrous, anther 0.24–0.32 × 0.24–0.40 mm, square, oblong or transversely oblong; ovary 0.6–0.8 × 0.8–1.0 mm, 2-locular, each locule with two ovules, style 3.6–4.6 mm long, glabrous (rarely with scattered trichomes), stigma punctiform, papillose. Fruit green to yellowish when immature, mature fruit not seen, 5 × 5 mm, globose, glabrescent to glabrous, pellucid dots covering the whole surface, remnants of calyx lobes present or not; seeds 1–2.

Distribution and Habitat:—The species occurs in Campo Rupestre vegetation between 700–1300 m elevation, in the northern part of the Espinhaço range in Minas Gerais state. Myrcia rupestris inhabits fissures in rocks or patches of sandy soil in rocky outcrops.

Phenology:— Myrcia rupestris was collected with flowers from February to April and from September to November, with the strongest flowering in February. Fruits were seen from May to July and in February, September and November.

Etymology:—The specific epithet refers to the habitat of this species. Myrcia rupestris is found exclusively on rocky outcrops in the northern portion of the Espinhaço Range in the Minas Gerais state.

Conservation status:— Myrcia rupestris is endemic to the northern part of the Espinhaço range in Minas Gerais state, occupying an area smaller than 500 km 2. Unlike the southern part, the northern Espinhaço range does not contain an extensive area of Campo Rupestre habitat, but disjunct areas within it ( Saadi 1995). Campo Rupestre is commonly used for grazing or affected by anthropogenic fire ( Drummond et al. 2005) leading us to classify Myrcia rupestris as Endangered (EN, criteria B2a, biii; IUCN 2001).

Discussion:—Specimens of Myrcia rupestris have commonly been identified as Myrcia lenheirensis [e.g., Kawasaki 2004, under the homotypic synonym Marlierea angustifolia ( Berg 1857: 143) Mattos (1967: 333) ]. However, beyond the characters described in the diagnosis, the species have distinctive distribution, as M. lenheirensis is just found in eastern São Paulo, southeastern Minas Gerais and southern Espírito Santo states ( Santos 2014). Myrcia rupestris also resembles Myrcia subavenia ( Berg 1857: 69) Silveira (1985: 66) , but differs in not possessing keeled immature branches and having smaller leaves.

Paratypes:— BRAZIL. Minas Gerais: Mun. Botumirim, ca. 800 m, 16 o 55’0’’S, 43 o 0’0’’W, 10 February 2011 (fl.), M.F. Santos 640 ( SPF!). Mun. Cristália , 700 m, 28 September 1997 (fl.), M.L. Kawasaki 1020 ( MBM!) ; 17 November 2007 (fr.), A.M. Teles 516 ( BHCB!) ; 700 m, 28 September 1997 (fr.), M.L. Kawasaki 1021 ( SP!) ; 1200 m, 16 o 43’28’’S, 42 o 55’42’’W, 12 July 2001 (fr.), V.C. Souza 25789 ( ESA!). Mun. Grão-Mogol , 13 April 1981 (fl.), I. Cordeiro CFCR 791 ( NY!) ; 1210 m, 27 September 1997 (fl.), M.L. Kawasaki 1019 (K!); 5 September 1985 (fr.), R. Mello-Silva CFCR 8544 ( NY!) ; 1200 m, 22 July 1985 (fr.), G. Martinelli 11255 ( RB!) ; 1100–1150 m, 16 o 32’30’’S, 42 o 55’W, 3 October 1987 (fl.), R. Mello-Silva CFCR 11463 ( SPF!) ; 1000 m, 15 June 1990 (fr.), R. Simão-Bianchini CFCR 13087 (K!); 28 October 1978 (fl.), G. Hatschbach 41595 (C!); 1150 m, 16 o 32’871’’S, 42 o 54’447’’W, 28 March 2002 (fl.), K. Matsumoto 793 (K!); Parque Estadual de Grão-Mogol , 2006 (fl.), C.V. Vidal 207 ( BHCB!) ; Serra do Espinhaço , 950 m, 19 February 1969 (fr.), H.S. Irwin 23532 ( US!) ; 1200 m, 11 February 1991 (fl.), G. Hatschbach 55080 (C!). Mun. Itacambira , 1220 m, 17 o 4’S, 43 o 18’W, 14 February 1988 (fl.), J.R. Pirani 2268 ( SPF!) ; 1250 m, 17 o 4’48’’S, 43 o 18’42’’W, 8 November 2002 (fl.), F.F. Mazine 559 ( ESA!) ; 1292 m, 17 o 4’45.3’’S, 43 o 19’47.5’’W, 12 February 2011 (fl.), M.F. Santos 654 ( SPF!) ; Serra de Itacambira , 20 May 1991 (fr.), M. Brandão 19050 ( PAMG!) .

Figures

FIGURE 2. Species distributions. Myrcia ascendens=star; Myrcia attenuata=triangle; Myrcia costeira=circle; Myrcia rupestris=square; Myrcia subterminalis=diamond.

FIGURE 4. Myrcia rupestris. A. habit. B. detail of inflorescence with one basal ramification only. C. floral bud. D. longitudinal section of the flower at anthesis. E. fruit with calyx lobes remnants. Myrcia subterminalis. F. habit. G. floral bud. H. longitudinal section of flower at anthesis. I. fruit with calyx lobes remnants. Vouchers: A–D. Santos 642 (SPF); E. Kawasaki 1021 (SPF); F and G. Rossini 482 (SPF); H. Kollmann 4776 (SPF); I. Kollmann 5156 (SPF).