Myrcia amanana Sobral & M.A.D.Souza, 2017

Sobral, Marcos & Souza, Maria Anália Duarte De, 2017, Four new Myrtaceae from Amazonian Brazil, Phytotaxa 307 (1), pp. 55-64 : 61

3. Myrcia amanana Sobral & M.A.D.Souza , sp. nov.

Type:— BRAZIL. Amazonas: Maraã, Reserva de Desenvolvimento Sustentável Amanã, igapó do igarapé do Juá Grande, próximo à comunidade Boa Esperança, June 2004, L. L. Souza & J. C. Reis 207 (holotype MG!). Figure 3 .

Diagnosis: —This species is related to Myrcia splendens (Swartz) De Candolle (1828: 244) , from which it is distinguished by the greyish, floccose indumentum on the abaxial surface of blades, inflorescences and flowers. It may also resemble M. tomentosa (Aublet) De Candolle (1828: 245) , but differs by its acuminate blades (vs. obtuse in M. tomentosa ) and flowers with elliptic to rounded calyx lobes (vs. triangular) and staminal ring with more than 60% of the width of the flower (vs. staminal ring less than 40% the width of the flower).

Description: —Tree to 20 m. Twigs brown or grey, slightly applanate, densely covered with simple ascending and sometimes appressed white or grey trichomes to 0.4 mm, these falling with age; internodes 28–40 × 2–3 mm. Leaves with petioles 3–4 × 1–1.5 mm, semiterete, deeply sulcate adaxially, pilose as the twigs; blades elliptic, obovate or lanceolate, 95–145 × 44–65 mm, 1.8–3 times longer than wide, markedly discolorous when dry, the adaxial side dark brown, shining, glabrous except for scattered simple white trichomes to 0.3 mm along the midvein, the abaxial side light grey to dark grey, dull, sometimes floccose, more or less densely covered by simple appressed trichomes 0.4–0.6 mm, these grey or white but with the very basal portion (mostly to 0.05 mm) consistently brown or reddish, in younger leaves sometimes forming denser and darker tufts, in adult leaves sometimes falling except along the veins; glandular dots 6–10 /mm², to 0.05 mm in diameter, sometimes visible and darker than the surface adaxially, but usually visible only when backlit; lateral veins 13–20 at each side, leaving the midvein at angles 50–60°, plane or slightly impressed adaxially, markedly raised abaxially; marginal vein 1–2.7 mm from the margin, the margin itself plane or slightly undulate. Inflorescences pilose as the twigs, axillary, paniculiform, the main axis 65–120 × 1.8–3 mm, the peduncle 25–30 mm, with up to five secondary branches, the proximal ones about 45 mm and the distal ones to 4 mm, the tertiary branches reduced to tufts of up to three flowers along the secondary ones; bracts not seen; flowers sessile; bracteoles not seen; flower buds globose or obovate, 3–4 × 3–4 mm, usually grey or white due to the dense indumentum as that of the twigs, the apex of the calyx lobes occasionally less densely pilose; calyx lobes five, elliptic to rounded, slightly to markedly unequal between them, 1–1.8 × 1–1.5 mm, glabrous adaxially; petals five, rounded, 2–2.5 mm in diameter, glabrous adaxially and with scattered simple white trichomes at its central portion abaxially; stamens not counted, to 6 mm, the anthers globose or oblate, 0.4–0.5 × 0.5 mm, eglandular, the thecae opening through longitudinal slits and sometimes unequal between them; staminal ring to 2 mm in diameter and to 0.7 mm wide, encompassing about 70% of the width of the flowers (the calyx lobes not considered), densely covered with grey to brown simple trichomes to 0.3 mm; calyx tube to 0.3 mm deep; style 6–7 mm, glabrous or with trichomes to 0.3 mm proximally, the stigma punctiform and papillose; ovary with two locules and two ovules per locule. Fruits not seen.

Distribution, habitat and phenology: —This species is presently known from flooded forests (“igapós”) from the municipality of Maraã, in the central-eastern portion of the state of Amazonas; flowers were collected in June and November.

Conservation: —The municipality of Maraã has an area of 16830 km ² ( IBGE 2017b) from where 600 collections are recorded ( INCT 2017, JBRJ 2017), resulting in an amount of 0.03 collection/km², a very low sampling effort. Considering this lack of knowledge, it seems adequate to score this species as DD (Data Deficient) according to IUCN criteria ( IUCN 2001).

Affinities: —This species is apparently related to the widespread Myrcia splendens (Swartz) De Candolle (basionym: Myrtus splendens Swartz (1788: 79) ; type image: G barcode 00227975!); for description see McVaugh 1958: 659), it may also resemble M. tomentosa (basionym: Eugenia tomentosa Aublet (1775: 504 ; type image: BM barcode 000953642)). They are distinguished from M. amanana in the diagnosis. Considering the resemblance with M. splendens , we can also assign this species to the informal group 5 of the phylogenetic scheme proposed by Lucas et al. (2011).

Etymology: —The epithet is allusive to the Amanã Reserve, where the species was collected.

Vernacular names: —araçapeu (collection Souza & Reis 96); remela-de-cachorro (collection Souza & Reis 207).

Paratypes: — BRAZIL. Amazonas : mun. Maraã , Reserva de Desenvolvimento Sustentável Amanã , igapó Jaquirana , margem esquerda do igarapé do Juá Grande, próximo à comunidade Boa Esperança, 7 November 2002, L. L. Souza & J. C. Reis 95 ( MG!) ; idem, Reserva de Desenvolvimento Sustentável Amanã , igapó Jaquirana , margem esquerda do igarapé do Juá Grande, próximo à comunidade Boa Esperança, 7 November 2002, L. L. Souza & J. C. Reis 96 ( MG!) ; idem, Reserva de Desenvolvimento Sustentável Amanã , igapó do igarapé do Juá Grande, próximo à comunidade Boa Esperança, June 2004, L. L. Souza & J. C. Reis 208 ( MG!) .

Figures

FIGURE 3. Myrcia amanana. Holotype (scale: 50 mm).