Miconia amplipedunculata Almeda & O. Ortíz, 2022

Almeda, Frank & Ortíz, Orlando O., 2022, Miconia amplipedunculata (Melastomataceae: Miconieae), a new species from the Caribbean lowlands of Panama, Phytotaxa 575 (3), pp. 294-300 : 295-298

Miconia amplipedunculata Almeda & O. Ortíz , sp. nov. ( Figs. 1 & 2 )

Diagnosis:— Miconia amplipedunculata can be recognized by its shortly petiolate lanceolate to oblanceolate leaf blades that are alternately 3-plinerved, brown amorphous stellulate-lepidote indumentum on the primary and secondary veins of abaxial foliar surfaces and inflorescence, long-pedunculate (to 12.5 cm) inflorescence, persistent bracts and bracteoles, unlobed calyx that is truncate and flangelike, prominent subulate calyx teeth that exceed the calyx in length, 5-merous flowers, distally constricted anther filaments, and isometric stamens that lack appendages.

Type:— PANAMA. Colón: Distrito Donoso, Valle Grande , antiguas oficinas MPSA, Quebrada arriaba nacia Patio Limosa , 08º4934.1’ N, 80º40’15.9’ W, 279 m, 4 November 2015, fl., I. Vergara-Pérez 1050 & Rojas (holotype PMA [127052]!; isotype MO [6718180]!) .

Shrub to 2 m tall, cauline nodes of uppermost branchlets somewhat swollen, the internodes rounded, glabrous and vaguely ridged when dry. Leaves of a pair equal to slightly unequal in size, concolored when dry, petioles 0.4–1 cm long, canaliculated adaxially; blades 16–25 × 4–6 cm, subcoriaceous when dry, lanceolate to oblanceolate, apex acuminate, base rounded to obtuse, margin entire, 3-plinerved with an elevated midvein and one pair of secondaries mostly alternately diverging from the midvein 2.5–8 cm above the blade base, the tertiary veins conspicuous, elevated and spaced 5–8 mm apart at the wider portions of the abaxial surface of the blade, adaxially glabrous at maturity, abaxially essentially glabrous or glabrate on the actual surface but moderately to copiously beset with a brown stellulate-lepidote indumentum on primary and secondary veins. Inflorescence terminal, thyrsoid, 15 cm long with distal branching, the elongate typically widely spreading peduncle 12.5 cm long, copiously stelluate-lepidote; bracts of the rachis nodes 1.5–3 × 0.5 mm, sessile, persistent, lanceolate to elliptic, glabrous adaxially, abaxially moderately and inconspicuously brown amorphous lepidote; bracteoles 0.75–1 × 0.5 mm, sessile, persistent, ovate-lanceolate, adaxially glabrous and abaxially with an indumentum like the bracts. Flowers 5-merous, perfect, pedicels 1–1.5 mm long, hypanthia campanulate, 1.5 × 1.5 mm (excluding tube and flangelike calyx), copiously to moderately brown stelluate-lepidote, the calyx unlobed, reduced to a truncate flangelike rim ca. 0.25 mm long; exterior calyx teeth 5, erect, bluntly subulate, 0.5 mm long and exceeding the truncate calyx; torus minutely glandular-puberulent adaxially. Petals 3.5–4 × 0.75–1 mm, pink to pink-magenta, glabrous, elliptic-oblong, apically obtuse with a minute apical mucro. Stamens 10, isometric and isomorphic, forming a ring around the style at anthesis, filaments 1.5 mm long, white, glabrous, complanate, constricted distally just below the anther thecae; anthers 1 mm long and ca. 0.25 mm wide, pale yellow, linear oblong, the apex with a ± truncate or somewhat dorsally inclined terminal pore; connective slightly thickened but unappendaged. Ovary (at anthesis) ca. 3/5 inferior, 5-locular, ± globose, apex conspicuously fluted, densely white-papillate. Style straight or somewhat declinate, glabrous, 3.5–4 mm long, white; stigma capitellate. Mature berries and seeds not seen.

Distribution, habitat, and phenology:— Miconia amplipedunculata is presently known only from low elevations (below 300 m) in the Donoso district of coastal Colón province on the Caribbean slope of Panama ( Fig. 3 ). At its only known locality, where it is evidently uncommon, M. amplipedunculata grows in or at the margins of mature secondary rainforest. The type and only known collection was flowering in early November.

Conservation:— The Caribbean slope rainforest habitat where Miconia amplipedunculata grows is not part of a protected area. Because the type was the only collection available for this study we were unable to calculate area of occupancy and extent of occurrence for a recommended conservation assessment using IUCN guidelines and criteria ( IUCN 2019). The type locality appears to be within the Concesión del Proyecto Mina de Cobre , a large-scale open-pit copper mine development in Panama. The concession consists of four zones amounting to 13,600 hectares (https://www.first-quantum.com). We have no information on the exact occurrence of M. amplipedunculata within this concession. Until the distribution of this species is better known we regard its conservation status as Data Deficient ( DD) .

Etymology:— The epithet for this species, amplipedunculata , is derived from the Latin word “amplus” (ample, large, abundant, or great). It highlights the unusually long inflorescence peduncle of this species which readily distinguishes it from all allied species.

Affinities:— Miconia amplipedunculata is morphologically most similar to a group of species that includes M. iteophylla Almeda (1989: 214) , M. jefensis Almeda (2000: 43) , M. ligulata Almeda 1989: 216 ), and M. peltata Almeda (1989: 217) . Like M. amplipedunculata , most of these species are restricted to Panama; only M. ligulata has a range that extends from Nicaragua to Colombia and Venezuela ( Almeda 1989, 2009; Almeda et al. 2016). All of these species share a brown amorphous stellulate-lepidote indumentum, oblong petals, unappendaged anther connectives, filaments that are constricted distally, a torus that is puberulent adaxially, persistent bracts and bracteoles, and 5-locular ovaries. Miconia peltata can be distinguished from all other species in this complex by its peltate, 5–7-plinerved leaves that are broadly rounded to subcordate at the base, an inflorescence that is divaricately branched at the initiating node, five welldefined triangular calyx lobes, and higher elevation (850–1000 m). Our new species is probably closest to M. jefensis which has wider (7–14 cm) leaf blades that are 5–7-nerved (vs. blades 4–6 cm and 3-plinerved) and well-defined rounded-triangular calyx lobes (vs. an unlobed truncate calyx), and grows at higher elevations (700–1000 m vs. 279 m). Miconia iteophylla also has 3-plinerved leaves with the inner pair of secondary veins diverging from the median nerve in opposite or subalternate fashion like M. amplipedunculata but its leaves are narrowly elliptic and smaller (4.5–9 × 0.6–1.7 cm), its inflorescence is a terminal panicle that branches 0.6–3 cm above the node initiating the inflorescence, its calyx consists of five depressed triangular undulations, its petals are white, and it grows at somewhat higher elevations (200–600 m). Miconia amplipedunculata is only superficially similar to M. ligulata , the most widespread species among this group of congeners; the latter grows in habitats spanning the elevational range of all closely related species in this group (0–1100 m). Miconia ligulata has leaf blades of comparable size to M. amplipedunculata but they are 5-plinerved, attenuate to long-acuminate apically with a base that is gradually tapering and decurrent on the petiole, its inflorescence branches at the initiating node, its calyx consists of five depressed triangular lobes, and its petals are white. All of the close relatives of M. amplipedunculata were included by Kriebel (2016) in his enlarged concept of the genus Conostegia D. Don (1823: 284 , 316). A cladogram of a molecular phylogenetic hypothesis in Kriebel’s monograph ( Fig. 1 ) shows three of the four sampled species ( M. jefensis , M. ligulata , and M. peltata ) grouping with Clidemia trichosantha Almeda (1984: 274) and Miconia brenesii Standley (1938: 816) in his sect. Geniculatae . We here interpret all of these species to be part of a greatly expanded Miconia ( Michelangeli et al. 2022) .

Figures

FIGURE 1. Miconia amplipedunculata. A. Habit. B. Inflorescence rachis (enlarged to show indumentum). C. Cauline internode. D. Representative leaf (abaxial surface). E. Flower in profile view. F. Petal (adaxial surface) G. Stamen (profile view showing distal filament constriction). H. Stamen (dorsal view). I. Hypanthium, truncate calyx, and exterior teeth (profile view). J. Style and stigma. K. Ovary in cross section. L. Bracteoles. M. Inflorescence bracts. Drawn from MO isotype.

FIGURE 2. Miconia amplipedunculata. A. Field photograph showing habit and spreading long-pedunculate inflorescence. B. Field photograph showing close-up of inflorescence with open flowers and buds). Photographs of type collection by Irving Vergara-Pérez.

FIGURE 3. Distribution of Miconia amplipedunculata.