Myrcia bicolor Kiaerskou (1893: 65)

Santos, Matheus F., Lucas, Eve & Sano, Paulo T., 2018, A taxonomic monograph of Myrcia sect. Sympodiomyrcia (Myrteae, Myrtaceae), Phytotaxa 380 (1), pp. 448-450 : 448-450

4. Myrcia bicolor Kiaerskou (1893: 65) ( Figures 5A , 6E and 15 to 17)

Type:— BRAZIL. Rio de Janeiro : Floresta da Tijuca , 20 November 1878 (fl.), Glaziou 10797 (lectotype C [barcode C10015825]! designated by Santos et al. (2016b), isolectotypes BR [two sheets]!, C [barcode C10015826]!, F [two sheets]!, K!, LE!, NY!, P [three sheets]!, R!, US!)

Tree 3–22 m high. Epidermal peeling sometimes present in immature parts; trichomes brown to light brown (rarely ferruginous), 0.1–0.2 mm long. Twig when immature brownish or straw-like (when dry), flattened, sometimes sulcate, not keeled, puberulent or with scattered trichomes to glabrous; mature twig greyish (when dry), cylindrical, cortex slightly cracked, glabrescent to glabrous; branching sympodial (rarely monopodial), two branches per node (rarely more than two), epidermal protrusion present at the nodes, internode (1.2)2.0– 8.5 cm long; cataphyll scale-like to foliaceous, 1–7 × 1–5 mm, present in all internodes, early deciduous, free or adnate, widely depressed ovate or fusiform, externally puberulent to glabrous, internally glabrous; terminal node with central and lateral buds developed, with scattered trichomes to glabrous, or lateral ones undeveloped. Leaf discolorous (rarely concolorous), chartaceous (rarely coriaceous), blade 4.0–12.3 × 2.0– 5.3 cm, elliptic, widely elliptic, ovate or obovate, apex caudate or acuminate to obtuse, base attenuate, cuneate or obtuse, margin plane, secondary veins 2–8 (10) mm apart, held at an angle of 60– 80° relative to the midvein, one or two marginal veins, the first 1–3 mm and the second 0.5–1.0 mm from the margin, tertiary veins conspicuous (rarely inconspicuous); adaxial surface glabrous, midvein sulcate in the first half and flat in the second half, secondary veins inconspicuous (rarely raised), pellucid dots inconspicuous, less than 5 per mm 2; abaxial surface puberulent or with scattered trichomes to glabrous when immature, glabrescent to glabrous at maturity, midvein raised, secondary veins raised, pellucid dots conspicuous to inconspicuous, less than 5 to more than 15 per mm 2; petiole 4–12 × 1–2 mm, canaliculate (rarely semicylindrical), glabrous. Inflorescence 1.5–9.5 × 1.5–6.0 cm, pyramidal, axillar at the terminal node, terminal dichasia usually with three flowers, 22–100 flowers, rachis pubescent, puberulent or with scattered trichomes to glabrous, 2–5 branching at the base, first internode of central rachis 1–2 mm wide, cylindrical to flattened, distal internodes flattened, opposite branching, 2–5 branching per node, epidermal protrusion present at the nodes (usually absent in the apical branches); cataphylls at the base of the central rachis, oblong or ovate, externally puberulent, internally puberulent. Bract 1.0–2.4 × 0.8–1.6 mm, deciduous, ovate, concave, apex acute, base truncate, adaxial and abaxial surfaces puberulent or with scattered trichomes. Pedicel 0–2 mm long, cylindrical, pubescent, puberulent or with scattered trichomes to glabrous. Bracteole not seen. Floral bud 2–3 × 1–2 mm, clavate. Hypanthium 0.8–1.4 mm extending above the summit of the ovary, not tearing at anthesis, externally pubescent, puberulent or with scattered trichomes to glabrous, pellucid dots conspicuous, internally glabrous; calyx 3– 4–merous, lobes 0.4–2.0 × 0.4–1.6 mm, distinct from the hypanthium, deciduous, depressed ovate or widely depressed ovate, concave, apex rounded, base truncate, externally and internally puberulent to glabrous; corolla (2)4–5–merous, petals light brown to white, 1.0–1.6 × 0.8–1.6 mm, depressed ovate, widely ovate or very widely ovate, concave, apex rounded, base truncate, externally puberulent to glabrous, internally with scattered trichomes to glabrous; staminal ring 0.2 mm wide, glabrous, stamens 46–88, filament 2.0– 3.6 mm long, glabrous, anther 0.32–0.40 × 0.24–0.40 mm, square, oblong or transversely oblong; ovary 0.8 × 1.0– 1.8 mm, 2–locular, each locule with two ovules, style 4.4–5.0 mm long, glabrous, stigma punctiform, papillose. Fruit green when immature, 6–13 × 6–13 mm, depressed globose or globose, base rounded, glabrescent to glabrous, remnants of calyx lobes present or not; seeds 1–3.

Distribution and Habitat:— Myrcia bicolor occurs in lowland to high montane rainforest in the Atlantic Forest domain of southern Bahia and southeastern Brazil (Espírito Santo, Rio de Janeiro and São Paulo sates) ( Figure 17 ). It usually inhabits forest understory.

Phenology:— It flowers in January, June and September to November. Fruits are found from January to September and in December (mature fruits in July and September).

Conservation Status:— The species presents an extensive Extent of Occurrence (about 307,000 km 2), but its Area of Occupancy is small (60 km 2). It has been recorded from more than five locations, some of them in protected areas. However, it is endemic to the Atlantic Forest, which accounts only for 7.5 % of is original area ( Myers et al. 2000), most of it severely fragmented. Due to the conflicting information, Myrcia bicolor is considered as Data Deficient (DD; IUCN 2001).

Discussion:— The species is distinguished by the combination of: sympodial vegetative branching ( Figure 5A ); cataphyll scar present in all internodes; immature twig usually straw-like when dry, cylindrical and not keeled; obovate leaf blade (rarely elliptic), usually discolorous; and clavate floral bud ( Figure 6E ).

There are specimens with intermediate morphology between Myrcia bicolor and Myrcia subcordata (e.g. Kummrow 2005 [SP]) in eastern Paraná state and in the municipality of Campos do Jordão (São Paulo state). These specimens are similar to M. bicolor in the leaf shape and the inconspicuous venation on the adaxial surface of leaf blade, but they differ in the non–straw-like immature twig and the turbinate floral bud. They were placed in M. subcordata because floral features in Myrcia sect. Sympodiomyrcia are more conservative than vegetative ones and some specimens show a clear transition to typical form of M. subcordata . This intermediate morphology may be an evidence of hybridization between the two species, but further studies are required to confirm it.

Available illustrations and images:— Kiaerskou (1893).

Additional specimens examined:— BRAZIL. Bahia: Mun. Amargosa, 13 ° 1’0”S, 39 ° 36’0”W, 28 January 2006 (fr), M.A.A.Costa 141 ( ALCB!); 13 ° 1’0”S, 39 ° 36’0”W, 29 October 2005 (fl), M.A.A.Costa 145 ( ALCB!). Mun. Arataca, RPPN “Caminho das Pedras”, 1000 m, 15 ° 10’2,5”S, 39 ° 20’3”W, 15 June 2006 (fr), A.M.A.Amorim 6066

(CEPEC!, NY!); ibidem, 700–900 m, 15 ° 12’1”S, 39 ° 24’2,9”W, 29 March 2008 (fr), A.M.A. Amorim 7215 ( CEPEC!) ; RPPN Palmeira /IESB, 450 m, 15 ° 10’2,7”S, 39 ° 20’2,2”W, 18 December 2005 (fr), J.G.Jardim 4855 ( CEPEC!) . Mun. Jussari , RPPN Serra do Teimoso, 25 September 1999 (fl), A.M.V.Carvalho 6829 (BHCB!, CEPEC!, RB!, SPF!) ; ibidem, 15 ° 9’37”S, 39 ° 32’10”W, 14 January 2000 (fr), J.G. Jardim 2409 (BHCB!, CEPEC!, RB!) ; ibidem, 15 ° 9’29”S, 39 ° 31’43”W, 19 September 2002 (fl), P. Fiaschi 1073 (BHCB!, CEPEC!, SPF!) . Mun. Una , Reserva Biológica do Mico-Leão (IBAMA), 15 ° 9’0”S, 39 ° 5’0”W, 17 September 1993 (fl), A.M.A.Amorim 1388 (CEPEC!, MO!, NY!, RB!, SP!, UB!, US!) . Mun. Uruçuca , 380 m, 14 ° 29’59”S, 39 ° 6’54”W, 2 April 2004 (fr), P. Fiaschi 2203 (BHCB!, CEPEC!, SPF!) . Espírito Santo : Mun. Santa Teresa, 750 m, 28 October 1998 (fl), L.Kollmann 828 (BHCB!, MBML!) ; ibidem, 750 m, 30 September 1998 (fl), L. Kollmann 644 (MBML!, UEC!) ; ibidem, 700 m, 12 July 2001 (fr), L. Kollmann 4177 (MBML!, SPF!) ; Reserva Biológica Augusto Ruschi , 30 July 2002 (fr), R.R.Vervloet 580 (MBML!, SPF!) ; Reserva Biologica Santa Lucia, 27 May 1999 (fr), W.P. Lopes 766 (MBML!, SPF!) . Mun. Venda Nova do Imigrante , 900 m, 17 May 1999 (fr), G. Hatschbach 69113 (MBM!, SP!) ; ibidem, 1100 m, 17 January 1995 (fl), G. Hatschbach 61597 (C!, MBM!) . Rio de Janeiro : Mun. Macaé, 950 m, 5 June 2000 (fr), M.G.Bovini 1867 (RB!, RUSU, SPF!) ; ibidem, 1000 m, 8 August 1985 (fr), S.V.A. Pessoa 71 ( RB!) . Mun. Nova Friburgo , 721 m, 22 ° 24’24,7”S, 42 ° 25’7,2”W, 1 March 2004 (fr), E.J.Lucas 219 (K!, RB!) ; ibidem, 1100 m, 25 May 1987 (fr), G. Martinelli 12074 (RB!, SPF!) ; Reserva Ecológica Municipal de Macaé de Cima , 22 ° 33’22,28”S, 42 ° 30’42,34”W, 11 September 1990 (fr), C.M.B.Correia 121 ( RB!) . Mun. Nova Iguaçu , 15 January 2002 (fr), S.J. Silva Neto 1614 (BHCB!, RB!) . Mun. Paraty , 300–500 m, 31 March 2009 (fr), M.G.Bovini 2738 ( RB!) . Mun. Rio de Janeiro , 29 September 1932 (fr), Victorio s.n. (RB 204729!, SPF!) . São Paulo : Mun. Caraguatatuba, 23 ° 38’31”S, 45 ° 40’32”W, 6 November 2003 (fl), J.Paula-Souza 3626 (ESA!, SPF!) . Mun. São Paulo , 23 ° 49’7,5”S, 46 ° 43’1”W, 14 September 1994 (fl), N.S. Ávila 388 (HRCB!, SP!, SPF!, UEC!) . Mun. Ubatuba , Ilha Vitória, 30 March 1965 (fr), J.G.Gomes 2658 (SP!, SPF!) . Total : 28 specimens .

Figures

FIGURE 5. Inflorescence of Myrcia sect. Sympodiomyrcia. A. Myrcia bicolor, sympodial branching at the base of the inflorescence, with terminal dichasia (Ávila 388 [SPF]). B. Myrcia tenuifolia, multiple branches at the base, including also vegetative branches (Santos 1223 [ICN]). C. Myrcia rupestris, inflorescence with one branch per axillary node, terminal dichasia present (Santos 640 [SPF]). D. Pyramidal inflorescence of Myrcia plusiantha (Barbosa 931 [SPF]). E. Corymbiform inflorescence of Myrcia densa (Santos 813 [SPF]). F. Umbelliform inflorescence of Myrcia mucugensis (Kral 75641 [SP]). Scales: C=1 cm; F=5 mm.

FIGURE 6. A. Myrcia lenheirensis, three terminal dichasia with only the central flower (Forzza 3692 [SPF]). B. Myrcia bicarinata, terminal dichasia with aborted lateral flowers (indicated) (Heringer 623 [IBGE]). C. Flowers of Myrcia nitida, one flower (right) with bracteole in the regular position (indicated), and the other (left) with one “migrant” bracteole at the hypanthium (indicated) (Lombardi 4532 [SPF]). D. Turbinate flower bud of Myrcia subcordata (Messias 5 [RB]). E. Clavate flower bud of Myrcia bicolor (Carvalho 6829 [SPF]). F. Obovate flower bud of Myrcia insigniflora (Assis 83 [BHCB]). G. Cross section of flower of Myrcia subcordata after anthesis, showing the hypanthium (indicated) not torn and internally glabrous, and the narrow staminal ring above (Santos 842 [SPF]). H. Flower of Myrcia insigniflora after anthesis, with the hypanthium tearing vertically, adnate petals (indicated) and persistent (but dry) stamens (Santos 682 [SPF]). Scales: A, C, D, G and H=2 mm; B and E=1mm; F=3 mm.

FIGURE 15. Images of representative specimens of Myrcia sect. Sympodiomyrcia species: Myrcia bicolor (Ávila 388 [SPF]).

FIGURE 17. Distribution of Myrcia bicolor (circles) and Myrcia densa (squares). Continuous lines represent South American country and Brazilian state boundaries. The grey gradient represents elevation.