Myrcia rupestris M.F. Santos (2015a: 166)

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

15. Myrcia rupestris M.F. Santos (2015a: 166) ( Figures 2D , 3B , 4E , 5C , 30 and 42 )

Type:— BRAZIL. Minas Gerais: mun. Botumirim, Estrada Botumirim–Rio do Peixe , afloramento rochoso no lado esquerdo da estrada (sentido Botumirim), 16º55’00’’S, 43º00’00’’W, 10 February 2011 (fl.), Santos 642 (holotype SPF!, isotypes BHCB!, K!, NY!, RB!)

Shrub to tree, 0.5–3.0 m high. Epidermal peeling present in immature parts; trichomes brown or light brown, 0.1– 0.5 mm long. Twig when immature brownish (when dry), flattened, not keeled, tomentose or pubescent; greyish at maturity (when dry), cylindrical, cortex slightly cracked, glabrescent to glabrous; branching monopodial, 2–3 branches per node (rarely more than three), epidermal protrusion absent at the nodes, internode 0.5–1.5 cm long; cataphyll scale-like to foliaceous, 1–4 × 1 mm, usually only present at the basal internode of a new branch, early deciduous, free, lanceolate or ovate, externally and internally puberulent; terminal node with central bud developed, puberulent, lateral ones undeveloped. Leaf discolorous, coriaceous, blade 0.8–2.6 × 0.1–0.9 cm, narrowly elliptic or elliptic, apex acuminate to rounded, base narrowly cuneate or cuneate, margin slightly revolute at the base, secondary, marginal and tertiary veins inconspicuous; adaxial surface pubescent or puberulent when immature, glabrescent to glabrous at maturity, midvein sulcate to flat 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; abaxial surface tomentose or pubescent when immature, puberulent or glabrescent at maturity, midvein raised, 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. Inflorescence 0.3–4.5 × 0.5–3.0 cm, corymbiform, axillar at the terminal or subterminal nodes, terminal dichasia usually with three flowers, 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 nodes (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, internally glabrous; calyx 3–5-merous, lobes 0.2–1.2 × 0.8–1.8 mm, distinct from the hypanthium, deciduous, depressed ovate, concave, apex rounded, base truncate, externally puberulent or with scattered trichomes, internally puberulent; corolla 3–4-merous, petals 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, base rounded, glabrescent to glabrous, remnants of calyx lobes present or not; seeds 1–2.

Distribution and Habitat:— Myrcia rupestris is found in campo rupestre vegetation in the northern part of the Espinhaço Range in Minas Gerais state, between 700–1300 m of elevation. It inhabits fissures in rocks or patches of sandy soil in rocky outcrops ( Santos et al. 2015a; Figure 30 ).

Phenology:—The species flowers from February to April and from September to November, with flowering peak in February. Specimens with fruits were collected from May to July and in February, September and November (mature fruits were not seen).

Conservation Status:— The analysis on Geocat showed that Myrcia rupestris has small Extent of Occurrence (ca. 1,300 km 2) and Area of Occupancy (36 km 2). We then agree with the classification of M. rupestris as Endangered by Santos et al. (2015a), adding the Extent of Occurrence criterion (EN, criteria B1a, biii and B2a, biii; IUCN 2001).

Discussion:—The species is characterized by the monopodial vegetative branching ( Figure 3B , 4E ), cataphyll scar present only at the basal internode of a new branch, short internodes, small leaves revolute at the base, secondary and marginal veins inconspicuous and inflorescence with only 1–2 branches at the base ( Santos et al. 2015a; Figure 5C ). Specimens of Myrcia rupestris have been identified as Myrcia lenheirensis (e.g. Kawasaki 2004, as Marlierea angustifolia ), but the former differs by the dense indumentum, immature branches that are not keeled and branched inflorescence with complete terminal dichasia ( Santos et al. 2015a). Myrcia rupestris is also similar to Myrcia subavenia , but differs by the habitat, the immature branches not keeled, the smaller leaves and the multi-flowered inflorescence.

Available illustrations and images:— Kawasaki (2004; misidentified as Marlierea angustifolia ); Santos et al. (2015a).

Additional specimens examined:— BRAZIL. Minas Gerais: Mun. Botumirim , ca. 800 m, 16 ° 55’0”S, 43 ° 0’0”W, 10 February 2011 (fl), M.F.Santos 640 (BHCB!, K!, NY!, SPF!) . Mun. Cristália , 17 November 2007 (fr), A.M.Teles 516 (BHCB!, RB!) ; ibidem, 700 m, 28 September 1997 (fl), M.L. Kawasaki 1020 (MBM!, SP!, SPF!) ; ibidem, 700 m, 28 September 1997 (fr), M.L. Kawasaki 1021 (SP!, SPF!) ; ibidem, 1200 m, 16 ° 43’28”S, 42 ° 55’42”W, 12 July 2001 (fr), V.C. Souza 25789 (ESA!, SPF!) . Mun. Grão-Mogol , 28 October 1978 (fl), G.Hatschbach 41595 (C!, MBM!, SPF!) ; ibidem, 1200 m, 22 July 1985 (fr), G. Martinelli 11255 ( RB!) ; ibidem, 13 April 1981 (fl), I. Cordeiro CFCR791 (NY!, SP!, SPF!) ; ibidem, 1150 m, 16 ° 32’871”S, 42 ° 54’447”W, 28 March 2002 (fl), K. Matsumoto 793 (K!, SPF!, UEC!) ; ibidem, 1210 m, 27 September 1997 (fl), M.L. Kawasaki 1019 (K!, MBM!, NY!, SPF!) ; ibidem, 5 September 1985 (fr), R. Mello-Silva CFCR8544 (NY!, SP!, SPF!, UEC!) ; ibidem, 1100–1150 m, 16 ° 32’30”S, 42 ° 55’0”W, 3 October 1987 (fl), R. Mello-Silva CFCR11463 (NY!, SP!, SPF!) ; ibidem, 1000 m, 15 June 1990 (fr), R. Simão-Bianchini CFCR13087 (K!, NY!, SPF!) ; ibidem, 1200 m, 11 February 1991 (fl), G. Hatschbach 55080 (C!, G!, MBM!) ; 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 (MBM!, MICH!, MO!, NY!, R!, UB!, US!) . Mun. Itacambira , 1250 m, 17 ° 4’48”S, 43 ° 18’42”W, 8 November 2002 (fl), F.F.Mazine 559 (ESA!, SPF!) ; ibidem, 1220 m, 17 ° 4’0”S, 43 ° 18’0”W, 14 February 1988 (fl), J.R. Pirani 2268 (NY!, SP!, SPF!, UEC!) ; ibidem, 1292 m, 17 ° 4’45,3”S, 43 ° 19’47,5”W, 12 February 2011 (fl), M.F. Santos 654 (BHCB!, K!, SPF!) ; Serra de Itacambira , 20 May 1991 (fr), M. Brandão 19050 ( PAMG!) . Total: 20 specimens .

Figures

FIGURE 2. Habits of Myrcia sect. Sympodiomyrcia. A. Shrub, Myrcia mutabilis (Santos 591 [SPF]). B. Shrub, Myrcia densa (Santos 820 [SPF]). C. Tree, Myrcia subcordata (Faria 3105 [UB]). D. Shrub, Myrcia rupestris (Santos 654 [SPF]). E. Shrub, Myrcia mucugensis (Santos 823 [SPF]). F. Treelet, Myrcia densa (Santos 813 [SPF]). G. Subshrub, Myrcia nitida (Santos 831 [SPF]). H. Shrub, Myrcia ascendens (Santos 829 [SPF]). Image credit: C. Jair E.Q.Faria.

FIGURE 3. A. Detail of the leaf of Myrcia summa showing foveolate dots (Prance 29040 [RB]). B. Wax peeling (white) on the leaf of Myrcia rupestris (Santos 641 [SPF]). C. Wax peeling (white) on the leaf of Myrcia costeira (Santos 851 [SPF]). D. Keeled twig of Myrcia costeira (Santos 851 [SPF]). E. Keeled twig of Myrcia densa (Santos 643 [SPF]). F. Leafy cataphyll of Myrcia subcordata covering immature leaves (Rochelle 55 [SPF]). G. Leafy cataphyll (indicated) of Myrcia costeira (Santos 851 [SPF]). H. Scale-like cataphyll (indicated) of Myrcia subavenia (Santos 715 [SPF]). Scales:A=4 mm; B–H=1 cm.

FIGURE 4. A. Myrcia plusiantha, with cataphylls (arrow indicating the scar) present at all internodes; note sympodial branching (Santos 705 [SPF]). B. Myrcia nitida, with cataphylls (arrow indicating the scar) present only at the basal internode of a new branch; note monopodial branching (Harley CFCR 4530 [SPF]) C. Myrcia ascendens, without cataphyll—they are rarely formed in this species; note monopodial branching (Santos 829 [SPF]). D. Sympodial branching of Myrcia mutabilis (Santos 716 [SPF]). E. Monopodial branching of Myrcia rupestris (Santos 640 [SPF]). F. Monopodial branching of Myrcia ascendens (Santos 829 [SPF]). G. Bifid vegetative bud in Myrcia insigniflora (Santos 682 [SPF]). H. Leaf of Myrcia subcordata against light showing the venation (Santos 681 [SPF]). Scales: A, D and F=2 cm; C and H=1 cm.

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 30. Distribution of Myrcia lenheirensis (circles), Myrcia mucugensis (triangles) and Myrcia rupestris (squares). Continuous lines represent South American country and Brazilian state boundaries. The grey gradient represents elevation.

FIGURE 42. Images of representative specimens of Myrcia sect. Sympodiomyrcia species: Myrcia rupestris (holotype: Santos 642 [SPF]).