Myrcia elevata M.F.Santos, 2015

Santos, Matheus F., Lucas, Eve, Sobral, Marcos & Sano, Paulo T., 2015, New species of Myrcia s. l. (Myrtaceae) from Campo Rupestre, Atlantic Forest and Amazon Forest, Phytotaxa 222 (2), pp. 100-110 : 103-104

2. Myrcia elevata M.F.Santos , sp. nov. ( Figs. 1F–J , 2 )

Myrcia elevata is related to Marlierea velutina McVaugh (1956: 178) , but differs by the smooth mature branches (vs. with longitudinal grooves), discolorous leaves (vs. concolorous), leaves with inconspicuous or flat secondary venation on the adaxial surface and inconspicuous on the abaxial surface (vs. conspicuous on both surface), abaxial surface of leaves pubescent or puberulent with epidermal exfoliation (vs. puberulent and without epidermal exfoliation).

Type:— BRAZIL. Rondônia: Basin of Rio Madeira, 8 km, NE of Porto Velho, 7 November 1968 (fl.), G.T.Prance 8260 (holotype INPA!, isotypes K!, M!, NY!, S!).

Shrub to tree 3–8 m high. Immature parts with epidermal exfoliation; trichome brown to light brown, 0.1–0.4 mm long, simple or dibrachiate. Twig light brown, cylindrical, cortex smooth, immature puberulent, mature glabrescent to glabrous; branching monopodial, two branches per node, internode 2.1–8.2 cm long; cataphyll absent; branch with a single apical bud, pubescent and exfoliating. Leaf discolorous, chartaceous, blade (5.9)8.3–22.0 × (2.2) 2.9–6.6 cm, lanceolate, narrowly elliptic (obovate), apex caudate, base attenuate or obtuse, margin plane, secondary veins 3–4 mm apart, held at an angle of 70–80° relative to the midvein, marginal vein 0.5 mm from the margin, tertiary veins inconspicuous (slightly conspicuous on the adaxial surface); adaxial surface green, glabrous (except the midvein), midvein sulcate along the entire length, secondary veins inconspicuous (rarely flat), pellucid gland dots inconspicuous; abaxial surface greyish, pubescent to puberulent with intense exfoliation, midvein prominent, secondary veins inconspicuous, pellucid gland dots inconspicuous; petiole 5.0–13.0 × 1.0–2.0 mm, canaliculate, puberulent with peeling to glabrescent. Panicle 7.0–9.0 × 4.5–8.0 cm, pyramidal, terminal axillary or subterminal, 16–60 flowers, rachis pubescent to pubescent-sericeous, 2–3 branching at the base (rarely 4), first internode of central rachis 2.0–3.0 mm wide, flattened, distal internodes flattened with longitudinal grooves, opposite branching (sometimes alternate), three branches per node (rarely 1–5). Bract 3.0–5.0 × 1.5–3.0 mm, deciduous, widely to very widely ovate, concave, apex acute or obtuse, base atenuate-truncate, adaxial and abaxial surfaces pubescent. Pedicel 0–3.0 mm long, flattened, pubescent. Bracteole 2.5–3.5 × 1.0– 2.5 mm, deciduous, widely ovate, concave, apex acute or obtuse, base obtusetruncate, adaxial and abaxial surfaces pubescent. Floral bud 3.0–6.0 × 2.5–5.0 mm, obovate, constriction in the central part. Hypanthium 1.5–2.5 mm extending above the summit of the ovary, tearing vertically after the anthesis, externally sericeous, pellucid gland dots inconspicuous (covered by the indument), internally pubescent; calyx 4–5- merous, lobes 1.5–3.0 × 1.5–2.5 mm, distinct from the hypanthium, free, unequally sized, persistent, depressed to widely depressed ovate or widely to very widely ovate, concave or plane, apex acute, obtuse or rounded, base truncate, externally pubescent or pubescent-sericeous, internally pubescent; corolla 4–5-merous, petal 1.5–4.0 × 1.5–3.5 mm, widely depressed ovate or widely to very widely ovate, concave, apex rounded (rarely emarginate), base truncate, externally pubescent in the central part, internally glabrous; staminal ring 0.2–0.4 mm wide, puberulent, stamens 111– 148, filament 2.5–7.0 mm long, glabrous, anther 0.3–0.5 × 0.2–0.6 mm, rimose, square, oblong or transversely oblong, single gland at the apex of the connective; ovary 1.0–3.0 × 1.5–2.0 mm, costate, receptacle pubescent, 2-locular, each locule with two ovules, style glabrous. Fruit not seen.

Distribution and Habitat:— Myrcia elevata is known from few records making it impossible to estimate its real distribution. Available data show records in the Rio Madeira basin (Rondônia) and in the Adolpho Ducke Reserve (Manaus, Amazonas). In the flora of the Adolpho Ducke Reserve ( Souza et al. 1999), Myrcia elevata was identified as Myrcia subsericea Gray (1854: 533) , which is endemic to the Atlantic Forest (Sobral et al. 2015). Myrcia elevata inhabits the understory of Terra Firme (not flooded) Amazon Forest.

As stated above, the Amazon Forest is not one of the most species rich areas for Myrtaceae , however endemic species of Myrcia s.l. do occur, such as Myrcia elevata , Calyptranthes cuspidata Martius ex De Candolle (1828: 258) , Marlierea spruceana Berg (1857: 34) and Myrcia huallagae McVaugh (1956: 192) ( McVaugh 1958a, Govaerts et al. 2015).

Phenology:— Myrcia elevata is recorded flowering in November. Fruiting material has not been seen.

Etymology:—The specific epithet refers to the hypanthium of this species that is elevated above the summit of the ovary. This characteristic is not rare in Myrcia s.l., but this is the first record of this feature in the clade with which this species is associated (see discussion below).

Conservation Status:—Based on the area of occurrence and habitat availability, a wide distribution might be expected. However, the few available records of Myrcia elevata make it impossible to have a precise idea of its range. Myrcia elevata is therefore treated as Data Deficient (DD; IUCN 2001).

Discussion:—In a phylogenetic study of Myrcia s.l. ( Santos 2014), Myrcia elevata was placed in clade 5 ( sensu Lucas et al. 2011 ) that corresponds to the genus Myrcia sensu Berg (1855–1856, 1857–1859). Clade 5 is characterized, among other things, by a hypanthium that does not extend above the summit of the ovary and does not tear at anthesis, and a calyx with five lobes that remain erect in the fruit ( Lucas et al. 2011). None of these characteristics correspond to Myrcia elevata as in this species the hypanthium extends above the summit of the ovary and tears at anthesis; the number of calyx lobes can vary from five to four and the lobes are reflexed after anthesis (all characters of clade 9 sensu Lucas et al. 2011 ). However, significant characteristics of clade 5 are present in Myrcia elevata , such as monopodial branching, inflorescence with opposite branching, free calyx lobes and particularly, a pubescent floral disc, a unique and diagnostic feature of this group ( Lucas et al. 2011, Santos 2014). This unusual combination of distinctive characteristics highlights the morphological complexity of Myrcia s.l. and the enormous plasticity of the calyx ( McVaugh 1958b, 1968, Lucas et al. 2011).

Marlierea velutina shares with Myrcia elevata all the characteristics cited above and may be another atypical species of clade 5 ( sensu Lucas et al. 2011 ). Myrcia subsericea shares with M. elevata the lanceolate or narrowly elliptic leaf blade with a greyish abaxial surface, which has a dense indument and inconspicuous secondary veins. However, the floral characteristics of M. subsericea are very distinct. This species has a hypanthium that does not extend above the summit of the ovary and does not tear at anthesis, and possesses the typical anther of the former genus Gomidesia Berg (1855: 6; now a synonym of Myrcia ).

Paratypes:— BRAZIL. Amazonas: mun. Humaitá, Rio Madeira , road Humaitá to Labrea , km 50, between Rios Ipixuna and Itaparana, beside road, 7°29’51”S, 63°29’1”W, 23 November 1966 (fl.), G.T.Prance 3228 (K!, NY!, R!, S!) ; mun. Manaus, Reserva Florestal Adolpho Ducke, trilha à direita, no início da estrada para o igarapé Acari, 134 m elev., 2°55’45.6”S, 59°58’23.5”W, 10 December 2011 (st.), M.F.Santos 763 (K!, SPF!). Mato Grosso (probably Rondônia): Source of the Jatuaraba River, Machado River region, 8°52’S, 62°13’W, December 1931 (fl.), B.A.Krukoff 1677 (G!, K!, MICH!, NY!). Rondônia: Basin of Rio Madeira , track from Mutumparaná to Rio Madeira , 9°0’S, 65°0’W, 30 November 1968 (fl.), G.T.Prance 9001 (INPA!, K!, NY!, S!) .

Figures

FIGURE 1. Myrcia cataphyllata. A. habit. B. twig with persistent cataphyll. C. abaxial surface of leaf blade. D. detail of persistent bracts in the inflorescence rachis. E. fruit with remnants of calyx lobes. Myrcia elevata. F. habit. G. detail of the inflorescence. H. floral bud. I. flower after anthesis (top view). J. cross section of the costate ovary. Vouchers: A–E. Sant’Ana 782 (CEPEC); F–H and J. Prance 8260 (INPA); I. Prance 9001 (INPA).

FIGURE 2. Distribution map of the new species. Myrcia cataphyllata=triangle; Myrcia elevata=circle; Myrcia megaphylla=square; Myrcia sessilissima=diamond.