A new species of Miconia (Melastomataceae, Miconieae) from the Ecuador-Peru border

Abstract Miconia machinazana C.Ulloa & D.A. Neill, sp. nov.,a new species of Melastomataceae from the Ecuador-Peru border is described and illustrated. It is characterized by the narrow, decussate leaves, dense reddish brown indument, small flowers in short panicles, pale yellow petals, and anthers opening by two large terminal pores.


Introduction
Miconia Ruiz & Pav., is a megadiverse genus, the largest in the family Melastomataceae, and comprises some 1050 Neotropical species (Goldenberg et al. 2008). Some 250 species have been recorded for Ecuador (Wurdack 1980, Renner 1999, Cotton 2000, Ulloa Ulloa and Homeier 2008, occurring from sea level to ca. 4000 m. Within the Melastomataceae, Miconia belongs to the Neotropical tribe Miconieae DC. Miconia is paraphyletic, and its current circumscription is rather arbitrary. Miconia is distinguished only by plesiomorphic characters found elsewhere in the tribe, and by eliminating other genera (Goldenberg et al. 2008, Michelangeli et al. 2004. As currently understood, the genus is characterized by its woody habit, terminal infl orescences, hypanthium not apically constricted, calyx of small lobes not forming a circumscissile cap, anthers without a bifurcation at the base, and a fl eshy fruit (Cogniaux1891, Skean 1991, Goldenberg et al. 2008).
Explorations in the remote Cordillera del Cóndor in southern Ecuador yielded a shrub erroneously identifi ed in the fi eld as the genus Myrteola O. Berg (Myrtaceae) due to the decussate, coriaceous, small, linear leaves reminiscent of Myrteola phylicoides (Benth.) Landrum. Th e leaf arrangement and the non-apparent classic checkerboard venation, of many species in the Melastomataceae led to that mistake. However, the habit of this plant is characteristic of a few high Andean species of Miconia, including the widespread M. salicifolia (Naudin) Naudin, to which this plant shows a similar habit. Further study has revealed unique features that lead us to propose it as a new species of Miconia.

Methods
Herbarium and laboratory work involved taking measurements of the vegetative parts from the dry herbarium specimens; the fl owers were rehydrated before taking measurements under a dissecting scope. Seeds were sputter coated with gold/palladium and photographed with a scanning electron microscope (JEOL JCM-5000). Herbarium specimens were consulted and compared at HA, K, LOJA, MA, MO, QCA, and QCNE; necessary herbarium specimens were requested on loan, and additional material was consulted over the internet in various virtual herbaria (COL, NY, US, JStor Plant Science types).  Description. Small, profusely branched shrub 0.5-1.2 m tall; internodes 1.5-7.0 × 1.2-2.4 mm. A thick indument of pinoid trichomes densely covering and totally concealing the surface of branches, petioles, both surfaces of young leaves, bracts, pedicels, hypanthium, calyx lobes outside surface, and fruits, the indument reddish-brown (cinnamon) colored on young parts and becoming darker, maroon-brown, and caducous on older organs, leaving the base of older branches and the adaxial surface of leaves with scattered trichomes. Leaves decussate, the petiole erect and nearly parallel to the stem, and the blade ascending at an angle of 90-120º with the petiole, 11.8-35.1 × 2.2-10.5 mm, narrowly elliptic to nar- rowly lanceolate, coriaceous, with 15-22 pairs of faintly visible nerves adaxially, the base acute, the margins revolute and remotely crenate, the minute teeth dark, the adaxial surface dark green with scattered pinoid whitish trichomes on the surface and covering the midrib, the abaxial surface concealed by the indument, the apex bluntly acute and mucronate; petiole 1.6-4.5 mm. Infl orescences 10-20 mm, panicles, terminal at the tip of the branches or on short lateral branches, 1-3 fl owers open at a time; bracts 3-9 mm, spatulate, persistent. Hypanthium 1.0-2.4 mm, campanulate, maroon red, glabrous inside. Flowers 5-merous; calyx lobes ca. 1.2 × 1.2 mm, maroon red and glabrous adaxially, the external teeth thick, ca. 0.35 mm, projecting, concealed by the indument. Corolla pale yellow, the petals 1.3-2 × 1.5-1.7 mm, concave, the apex oblique, the margin minutely erose, the outer surface granulose. Stamens 10, slightly dimorphic in size, the fi laments 2.0-2.3 mm, geniculate above the middle, twice as wide below the folding point towards the base, cream colored, tinged with pink in older fl owers, the anthers 0.9-1.2 mm, 2-celled, obovate, retuse at apex, initially uniformly cream colored and later tinged with pink, opening by two broad, apical, ventrally inclined pores, the connective at the base ventrally with a blunt, bilobed appendage and dorsally with a blunt, minutely notched tooth, slightly longer than the ventral lobes; ovary 3-celled, 3/4 inferior, ridged, with a ring of pinoid trichomes at the apex, the style ca. 3.5 mm, straight, pale yellow, glabrous, the stigma clavate but not conspicuously so, pale yellow. Infructescences with up to 22 mature fruits. Berries 5-7 × 5.5-7.5 mm, nearly globose, fl eshy, the surface concealed by the indument, maroon red apically, ridged and with a few trichomes at the base of the attachment of the style; seeds 15-25, globose, ca. 0.99 × 0.93 mm.

Miconia machinazana
Distribution. Miconia machinazana has only been found on the Machinaza plateau, one of the highest-elevation Hollín Sandstone plateaus in the Cóndor region between 2315 and 2420 m (Fig. 5). Th e area is precisely on the Ecuador-Peru international border, near the end of the trail from the Paquisha Alto military post. Since the population actually straddles the border it is recorded as occurring in the province of Zamora-Chinchipe in Ecuador and in the department of Amazonas, Peru.
Ecology. Th e specimens collected in June have just a few open fl owers and several fruits, while the specimens collected in March have abundant fruits. Th e Cóndor is an eastern outlier of the main Andes chain and has revealed a fascinating and unexpected biogeographical connection between the sub-Andean cordilleras and the Guayana Shield in northeastern South America (Ulloa Ulloa and Neill 2006). Th e soils are very nutrient-poor, and consist of a bare sandstone substrate or coarse-to medium-grained quartzite sand derived there from. Th e vegetation is mostly dwarf scrub, dominated by shrubs to about 0.5 m tall, with occasional small trees to four meters tall (Fig. 5). Th e vegetation seems to be recovering slowly from an extensive fi re that occurred between 1990 and 1995, with charred woody stems in abundance on the ground.
Etymology. Th e species name machinazana commemorates the name of the Machinaza plateau and river in the Cordillera del Cóndor area where this species was collected.
Conservation status. Miconia machinazana has a restricted distribution, only known from scattered populations within a single mountain range. Th e Area of Occupancy (AOO) of the species is 3 km 2 and it falls completely outside any protected area under Ecuador's System of Protected Areas. In terms of our current knowledge, the species is assigned a provisional IUCN (2001)

Discussion
Miconia machinazana diff ers from other species of Miconia by the combination of the strictly decussate arrangement of very narrow, coriaceous leaves, thick reddish brown (cinnamon) indument of pinoid trichomes, pale yellow petals, the anthers opening by two large pores, and the berries with large seeds. Following Wurdack's (1980) Flora of Ecuador key to Artifi cial Species Groups, this species will key out within group D, the group of species with the lower leaf surface completely concealed by the dense pubescence, and next to Miconia ledifolia (DC.) Naudin. In Cogniaux's (1891) classifi cation and following Goldenberg et al. (2008) this species belongs in Miconia sect. Cremanium (D.Don) Hook.f., that is characterized by the very short anthers with two or four, wide apical pores.
Miconia machinazana has pale yellow petals, yellow being a color uncommon in the tribe Miconieae (Almeda 2000, Morales-Puentes et al. 2008. Th is new species resembles in its habit the widespread M. salicifolia, however, a closer examination immediately diff erentiates the species belonging not only to diff erent sections (the latter belongs to sect. Chaenopleura (DC.) Hook.f.), but showing diff erences in fl ower merosity, stigma shape, fruit size, and number of seeds per fruit (see Table 1). Miconia rigens Naudin, M. ledifolia, M. stenophylla Wurdack, and M. tephrodes Wurdack are all high-Andean shrubs with short infl orescences, crowded leaves with the lower surface totally concealed by a dense indument, and the stamens opening by two apical pores, as in M. machinazana, but the combination of characters separates each of these taxa and with the new species (see Table 1). Th e species here compared from sect. Chaenopleura have 4-merous fl owers, but the fl owers are 5-merous in the ones from sect. Cremanium. Miconia rigens, from Colombia's Cordillera Oriental, is distinct by its much wider 3-nerved leaves (up to 3 cm) and longer internodes.
Th e species compared in Table 1, apart from for Miconia salicifolia, are all narrow endemics. Miconia rigens is a seemingly rare species, restricted to the páramo of a small area of Colombia's Boyacá Department (Fernández Alonso pers. comm.), and the rest occur in southern Ecuador, where M. tephrodes is only known from four collections from the Eastern Andean Cordillera, and M. machinazana farther east from the remote Cóndor sandstone plateau (Fig. 6). Table 1.

Comparison of
Miconia machinazana and other Andean species of Miconia with leaf lower surface completely concealed by indument.