Miconia paucartambensis Jan.M.Burke & Michelang., 2018

Burke, Janelle M. & Michelangeli, Fabian A., 2018, Six new species of Miconia (Miconieae, Melastomataceae) from the Andes, Phytotaxa 361 (2), pp. 131-150 : 148

Miconia paucartambensis Jan.M.Burke & Michelang. , sp. nov. ( Fig. 10 , 11 , 12 )

Diagnosis: Shrub distinct among Andean Miconia in having combination of indumentum with simple, barbed hairs, unisexual flowers and sessile leaves.

Type:— PERU: Cusco. Paucartambo, Challabamba , Parque Nacional Manu , Trocha Union , 2053 m, 13.0741S, 71.5549W, 17 June 2011 (male fl), F. A. Michelangeli 1677 & C. Arenas (holotype: CUZ!; isotypes: NY!, WFU!) .

Small tree, up to 7 m. Young stems terete, the indumentum dense, with simple, barbed hairs, 0.2–0.3 mm long, longitudinal ridges absent, nodal line absent. Leaves isophyllous; the petiole 0.2–0.3 cm long, the indumentum adaxially with dense, simple hairs up to 1.5 mm, abaxially as on the stem; the blade 12.5–18.6 × 4.9–7.5 cm, ovate to elliptical, subcoriaceous, the apex acuminate, apex ca. 0.7 mm, the base round to cordate, the margin finely serrulate, teeth 0.25 mm; secondary veins 4 (2 pairs) pairs, basally nerved, marginals only slightly fainter than first pair of secondary veins, tertiary veins percurrent, arising at 80–90° angle from primary vein, 3–4 mm apart, mostly running perpendicular to tertiary veins, areoles approximately 1–1.5 mm wide mm wide, veins slightly impressed on the adaxial surface and raised on the abaxial surface; adaxial surface slightly nitid, the indumentum on the surface with very sparse hairs, and lined with minute, sessile, white glands on the primary and secondary veins; abaxial surface light green, the indumentum on the surface moderately to sparsely pubescent with simple hairs, reddish tinged, indument on veins denser, individual hairs wider and barbed, 0.3 mm long, reddish tinged. Inflorescences terminal well-branched panicles of clustered dichasia, 8.6–10.8 cm long; peduncles terete, reddish brown, the indumentum as on the stem; bracts 0.8–1.5 × 0.4–0.6 cm, oblong, persistent at anthesis, serrulate with rimose apex; bracteoles 0.5–0.7 x 0.3 cm, oblong, persistent at anthesis, serrulate. Flowers 5-merous, unisexual, sessile. Hypanthium 0.75 mm long, urceolate, 1.2 mm wide at the torus, external indumentum sparse, simple hairs and sessile glands, internal surface glabrous, androecial fringe absent. Calyx open in bud, the tube 0.2 mm long at anthesis, the lobes 0.3 × 0.5 mm, round, red (in vivo); calyx teeth shape and length as lobes, serrulate tooth at apex, red. Petals 1.2 × 0.4 mm, obovate, oblong at base, flared distally, spreading, white at anthesis (drying pale yellow), the apex flared with erose margins, the base not attenuate, the margin entire except at apex. Male flowers diplostemenous, slightly dimorphic in size, actinomorphic, spreading at anthesis; the filaments 1.6–2 mm long, geniculate 2/3 of length, glabrous, white; anthers with 2 locules, thecae 0.4–0.5 × 0.5 mm, broad, opening by 1 apical to ventrally inclined 0.2–0.3 mm broad pore, white at anthesis, later turning pale yellow, connective not prolonged below thecae. Gynoecium absent. Female flowers diplostemenous, slightly dimorphic in size, actinomorphic, spreading at anthesis; the filaments 1.4–1.5 long, geniculate 2/3 of length, glabrous, white; anthers with 2 locules, thecae 0.4–0.5 × 0.4 mm, ovate, with 1, 0.2 mm, collapsed apical to ventrally inclined pores, white at anthesis, later turning pale yellow, connective not prolonged below the thecae. Ovary 3-locular, 1/3 free, free portion 0.25 mm × 0.6–0.75 mm, hemi-spherical, with a collar of short, ciliate hairs; style 1.3 mm, straight, white, glabrous; stigma broadly capitate, 0.65 mm wide. Berries not seen. Chromosome number not known.

Distribution.— Humid montane forest, 1650–2433 m, in Prov. Paucartambo, Cusco, Peru ( Fig. 9 ).

Phenology.— Flowering in June and July.

Etymology.— The epithet refers to the distribution of this species, only found within the Province of Paucartambo in Cusco, Peru.

Conservation Assessment.— Miconia paucartambensis is known from five collections of the same population in the upper slopes of Parque Nacional Manu, despite recent increase in collection activity in this protected area. The species has only been collected on top of ridges, which may indicate that it has a restricted habitat preference, with an estimated EOO of <2 km 2 (5 data points). We recommend that this species is categorized as critically endangered, CR B1ab(i,iii) ( IUCN 2001).

Additional specimens examined: PERU: Cusco. Paucartambo, Challabamba, Parque Nacional Manu, Trocha Union, 2433 m, 13.0823˚ S, 71.5688˚ W, 17 June 2011, Michelangeli 1676 & Arenas CUZ, NY, WFU), 1917 m, 13.07120˚ S, 71.55708˚ W, 19 July 2016 (m. fl), Griffiths & Chambi s.n. ( E, MOL, NY), 1874 m, 13.0705˚ S, 71.55613˚ W, 21 July 2016 (fr), Griffiths 53 & Chambi ( E, MOL), S 13.04708˚ S, 71.54015˚ W, 1651 m (f. fl), 3 July 2017, Griffiths 295 et al. ( E, MOL).

Miconia paucartambensis is distinctive among species of Miconia in having conspicuously unisexual flowers and sessile leaves. No other South American species with sessile leaves are similar to this species. The dioecious habit is also remarkable among dioecious Miconia , in that the gynoecium is completely lacking in the staminate flowers ( Fig. 10F ). Other functionally dioecious Miconia often retain vestigial organs of the other sex (Burke, unpublished; Almeda & Dorr, 2006). This species has a distribution that is similar to M. farfanii , though not as common locally.

Figures

FIGURE 9. Distribution map of Miconia farfanii □ and Miconia paucartambensis▲, in Manu National Park, Cusco, Peru.

FIGURE 10. Miconia paucartambensis staminate plant A. Habit. B. Vegetative node with sessile leaves. C. Inflorescence axis D. Inflorescence cyme at anthesis. E. Bracts subtending bracteoles. F. Flower at anthesis (R) and longitudinal section (L). G. Inner surface of hypanthium with calyx teeth and lobes. H. Petal. I. Stamens from left to right: dorsal, ventral and side view. Drawn from Michelangeli 1676, 1677, NY.

FIGURE 11. Miconia paucartambensis pistillate flowers A. Bracts and bracteole morphology (L) and flower at anthesis (R). B. Longitudinal section of flower, with detail of petals. Note collar of hairs at ovary apex. C. Longitudinal section of flower showing ovules, and detail of calyx teeth and lobes. D. Stamens from left to right: dorsal, ventral and side view. Drawn from Griffiths 295, E.

FIGURE 12. Miconia paucartambensis. A. Branch with young inflorescence. B. Node and leaf bases, adaxial surface. C. Leaf, abaxial surface. D. Staminate inflorescence, detail. E. Staminate inflorescence.F.Staminate flowers. (all photos by F.A. Michelangeli;A–C, from Michelangeli 1676, E–F from Michelangeli 1677).