Disterigma micranthum A.C.Sm.
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Authority
Pedraza-Peñalosa, Paola. 2010.
(Ericaceae, Vaccinieae). Fl. Neotrop. Monogr. 108: 1-126. (Published by NYBG Press) -
Family
Ericaceae
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Scientific Name
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Type
Type. Ecuador. El Oro: Moro-moro region, ca. 21 miles W of Portovelo, 1035 1280 m, 7 Oct 1944 (fl), W. H. Camp E-616 (holotype, NY; isotype, fragment US ex NY). Photo NY neg. 9892 of NY, photo US neg. 3434 of NY.
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Etymology
The epithet micranthum refers to the very small flowers.
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Description
Species Description - Epiphytic or terrestrial shrubs, scandent or erect, ca. 1 m tall. Young branchlets ridged, ±, smooth, villosulous, the hairs eglandular and brown, the indumentum of the mature branches similar but glabrate. Leaves 4–5 per cm, apparently distichous, diffuse; petiole 1 mm long, glabrate, the hairs eglandular; lamina ovate or elliptic, 0.4–1 × 0.3–0.4 cm, basally cuneate, marginally entire, apically ciliolate with eglandular hairs, apically subacute or blunt-acute, adaxially glabrous, abaxially glabrate with glandular hairs, the venation adaxially and abaxially obscure. Axillary solitary flowers; bracts 4–5, chartaceous, ovate or elliptic, 0.6–1.5 × 0.6–1.1 mm, marginally eciliate, apically obtuse, abaxially glabrous; pedicel 1–2 mm long, reduced and hidden by overlapping bracts, glabrous; differentiated apical bracteoles 2, distinct, chartaceous, enveloping to upper half of calyx lobes or entire calyx, covering 54–93% of calyx, elliptic or transverse-elliptic, 2–3 × 2–3 mm, marginally eciliate, apically obtuse, the surface smooth, abaxially and adaxially glabrous. Flowers 4-merous. Calyx aestivation valvate, campanulate, 2.3–3 mm long; tube terete, 0.9–1.2 mm long, abaxially glabrate with glandular hairs; limb 1.3–2.1 mm long, abaxially and adaxially glabrous; lobes triangular, 0.9–1.5 × 0.8–1.1 mm, marginally eciliate; sinuses acute (V-shaped). Corolla white, thin-fleshy, bistratose, urceolate, 3–4.5 mm long, 3 mm diam., 2 mm wide at throat, abaxially glabrate with minute and very few glandular hairs, adaxially glabrous; lobes 0.9 × 0.6 mm, apically acute, adaxially rugose. Stamens 8, 3–3.5 mm long, included; filaments distinct, straight, broader at base, 1.8–2.3 mm long, abaxially and adaxially pilulose; anthers distinct, papillae on both thecae and tubules; thecae 0.7–0.8 mm long, with or without basal appendages; tubules 2, distinct, 0.6–0.8 mm long, dehiscing introrsely by longitudinal slits, 0.4–0.5 mm long. Ovary 4-locular; style 3.4–3.5 mm long, exserted. Berry white, ± spherical, 4.5–5.6 mm diam., the persistent calyx lobes erect or spreading, becoming succulent (at least at base), same color as mature berry; embryo white.
Distribution and Ecology - Disterigma micranthum is known from only two populations in the Ecuadorian Andes (Fig. 31). The type specimen is from the Moro- Moro region in southwestern Ecuador, where it was recollected in 2004. The second known population was recorded in 1980 on the old road to Santo Domingo de Los Colorados, Prov. Pichincha. This species grows in secondary vegetation in low-altitude premontane cloud forest, at 900–1600 m. Flowering in Aug and Oct; fruiting in Aug.
Conservation Status - Disterigma micranthum is known from only three collections representing two disjunct populations—one from Pichincha (old road to Santo Domingo de Los Colorados) and the other from El Oro (around Moro-Moro). This plant was first collected in 1980 and not recollected until 2004. In the Moro-Moro region there is now a protected area called Reserva Forestal Buenaventura (Fundación Jocotoco). When I visited the place I found the species growing along a major road in a dense patch of secondary vegetation that bordered the reserve; no additional populations were found inside the protected area. Colonization, agriculture, and mining are the main threats in this region. In the IUCN red list of plants endemic to Ecuador it is categorized as EN B1 ab(iii) (Pedraza- Peñalosa et al., in press).
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Discussion
Disterigma micranthum (Figs. 2E, 30B) is distinguished by having very small flowers (3–4.5 mm long), very small stamens (3–3.5 mm long), and tubules under 1 mm long; its terete calyx tube is also characteristic. Disterigma micranthum belongs to a group of taxa that are closely related and that exhibit great vegetative and reproductive variation; they are D. dendrophilum and D. noyesiae, with D. cryptocalyx and D. humboldtii probably more distantly related. Although it is possible to find morphological features that characterize each of these species (see Table IX), the differences between them are not that many, except when the species with extreme morphologies are compared, such as D. cryptocalyx and D. micranthum.
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Objects
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Distribution
Ecuador South America| El Oro Ecuador South America| Pichincha Ecuador South America|