Miconia glandulipetala Ocampo & Almeda, 2014

Ocampo, Gilberto & Almeda, Frank, 2014, A new species of Miconia (Melastomataceae: Miconieae) from the eastern slope of the Peruvian Andes, Phytotaxa 163 (3), pp. 166-172 : 167-170

Miconia glandulipetala Ocampo & Almeda , sp. nov.

Miconia glandulipetala resembles Leandra caquetensis because of the presence of 4-merous flowers and 4-locular ovaries, but it is recognized by its axillary inflorescences and petals with subapical glandular hairs.

TYPE:— PERU. Junín: 3–5 km NW of Chequitavo , 1200 m, 10º45’S, 74º23’W, 3 April 1984, D.N. Smith 6710 (holotype: USM! ; isotypes: CAS! , MO! ). Figures 1–2 .

Shrub 0.5–0.8 m tall, the uppermost cauline internodes, inflorescence branches, and hypanthia moderately to densely covered with simple, appressed, strigillose hairs (0.3–) 0.7–1.6 mm long, and with an inconspicuous layer of glandular hairs <0.1 mm long. Leaves of a pair subequal to up to 30% unequal in size; petioles (0.5–) 0.8–2.1 cm long, the blades 2–7 cm long, (0.9–)1.3–3.4(–3.7) cm wide, 5-nerved or if 5-plinerved then the innermost pair of secondary veins diverging from the midvein up to 0.5 cm above the blade base, the blades elliptic to ovate-elliptic, the apex short acuminate, the base acute to widely acute, the margin crenulate to sometimes crenulate-dentate, ciliate, sparsely pubescent on both sides. Inflorescence an axillary pauciflorous panicle (up to 12 flowers) with cymose helicoid branches, 1.8–2.5 cm long, 1.5–2 cm wide; flowers 4-merous, secund, on pedicels 0.5–1.2 mm long; the bracteoles 1.0– 1.5 mm long, 0.3–0.5 mm wide, ovate to obtrullate, the apex long acuminate, persistent. Calyx tube up to 0.2 mm long, the calyx lobes 0.35–0.5 mm long, 0.7–0.9 mm wide, rounded, the calyx teeth 1.4– 1.7 mm long, ca. 0.5 mm wide at the base, lanceolate. Petals 2.4–2.6 mm long, 0.5–0.9 mm wide, lanceolate, the apex acute, with a subterminal glandular hair formed on the margin, 0.2–0.4 mm long, oriented toward the abaxial surface of the petal. Stamens 8, filaments glabrous, 1.3–1.7 mm long, anthers 1–1.1 mm long, 0.25–0.3 mm wide, isomorphic, oblong, 2-celled with a ventrally inclined pore, connective prolonged ca. 0.1 mm at the base, slightly bilobed. Ovary 4-locular, 9/10 inferior to fully inferior, covered by inconspicuous glandular hairs <0.08 mm long, collar ca. 0.2 mm long. Styles 3.0– 3.5 mm long, glabrous, stigma punctiform. Berries 3.5–4.2 mm long, 2.5–3.1 mm wide when dry, botuliform. Seeds ovoid, 0.25–0.3 mm long, 0.17–0.2 mm wide; lateral symmetrical plane ovate, the highest point toward the chalazal side or the central part of the seed, antiraphal symmetrical plane ovoid to elliptic; raphal zone elliptic to obovate,> 70% the length of the seed; appendage absent, but sometimes a small protuberance on the chalazal side may be present; cells arranged in an aligned pattern; individual cells elongated, anticlinal boundaries channeled, undulate, with U- and Ω-type patterns; periclinal walls par-convex, par-domed, microrelief verrucose.

Distribution — Miconia glandulipetala is only known from the type locality, described as a “perturbed primary forest” on the eastern slope of the central Peruvian Andes at 1200 m. According to Pennington et al. (2004) this corresponds to the lower montane wet forest that occurs between 500–1500 m on the lower Amazonian slopes of the Andes, which is similar to and shares many species and genera with lowland Amazonian forests.

Phenology —The few available flowers and abundant fruits suggest that April may correspond to the late flowering season.

Etymology —The specific epithet refers to the subterminal glandular hair that is present on the margin of the petals, a distinctive feature among the species of the “ Leandra + Ossaea (scorpioid)” clade (see below).

Discussion —The morphological features of M. glandulipetala agree with those of Ossaea sect. Diclemia , which have 4-locular ovaries and 4-merous flowers arranged on one side of the branches of the panicle. Analyses of DNA sequence data have shown that species of this section and taxa that belong to Leandra Raddi sect. Secundiflorae (Candolle) Cogniaux (1886: 192) form a strongly supported clade, which has been informally named as the “ Leandra + Ossaea (scorpioid)” clade ( Goldenberg et al. 2008, Martin et al. 2008). The clade consists of ca. 30 shrubby species distributed from southern Mexico to northern South America. A number of them have wide distribution ranges [e.g., L. dichotoma (Pavón ex. D.Don) Cogniaux (1886: 200), L. granatensis Gleason (1937: 319) , L. longicoma Cogniaux (1886: 202) , Ossaea quadrisulca (Naudin) Wurdack (1973: 408) ], while some others are narrow endemics [e.g., L. neblinensis Wurdack (1964: 163) , L. rotundifolia J.F. Macbride (1941: 339) , Ossaea secundiflora Cogniaux (1907: 361) ]. The members of this clade can be distinguished by the presence of a combination of characters such as the presence of ovoid seeds with cells arranged in an aligned pattern, with parconvex periclinal walls [except O. capillaris (D.Don) Cogniaux (1888: 550) ], and flowers arranged in a cymose helicoid pattern. This arrangement has been termed as “scorpioid” for the members of this clade ( Goldenberg et al. 2008, Martin et al. 2008, Martin & Michelangeli 2009), which describes an inflorescence with flowers that develop, alternately, on both sides of the rachis. As the flowers of these species are born on one side of the branches, the term “helicoid cyme” should be used for describing the branch architecture of the inflorescences in this clade ( Radford et al. 1976, Sousa & Zárate 1988).

Miconia glandulipetala is morphologically similar to L. caquetensis Gleason (1930: 64) , a taxon ranging from southern Colombia to Peru that is traditionally considered a member of Leandra sect. Secundiflorae . Similarities between both species include the presence of 4-merous flowers, 4-locular ovaries, and petals with a subapical hair. However, the petal subapical hairs of M. glandulipetala are glandular, a character that is not present in other known members of the “ Leandra + Ossaea (scorpioid)” clade. In addition, those two species differ in the position of the inflorescence, as well as in the size and shape of other foliar and floral characters ( Table 1 ). Species of this clade like L. dichotoma , L. retropila Cogniaux (1886: 198) , L. secunda (D.Don) Cogniaux (1886: 199) , and Ossaea quadrisulca (Naudin) Wurdack (1973: 408) may co-occur with M. glandulipetala , but they can be discriminated from the new taxon by a number of morphological characters ( Table 1 ). Because the new species can be diagnosed by a unique combination of morphological traits, it can fit the morphological-phenetic ( Judd 2007) and phylogenetic ( Wheeler & Platnick 2000) species concepts.

The flowers are only known from the isotype deposited at CAS. It is noteworthy that one flower had an anther with a basal-dorsally inserted glandular hair on the connective, ca. 0.6 mm long. However, the rest of the anthers, like the anthers from a second flower, lacked the glandular hair, so it is likely that its presence in only one anther is due to a developmental anomaly. Further collections may clarify if the glandular hairs found on the flowers are a consistent trait present in all individuals of M. glandulipetala .

Figures

FIGURE 1. Miconia glandulipetala Ocampo & Almeda. A. Branches with infructescences. B. Flower at anthesis. C. Longitudinal section of a flower (petals and stamens removed). D. Petal showing a subapical glandular hair. E. Stamens in lateral (left) and dorsal (right) views. F. Transversal section of an ovary. G. Mature berry.

FIGURE 2. Scanning electron microscopy images of the seeds of Miconia glandulipetala Ocampo & Almeda. A. Antiraphal view. B. Lateral view. C. Raphal view. D. Close-up of the testa cells. Scale bars = 0.03 mm.