Monographs Details – Flora of Las Orquideas National Park

Monographs Details:

Authority:

Pedraza-Peñalosa, Paola. 2010. (Ericaceae, Vaccinieae). Fl. Neotrop. Monogr. 108: 1-126. (Published by NYBG Press)

Family:

Ericaceae

Scientific Name:

Disterigma acuminatum (Kunth) Nied.

Synonyms:

Gaylussacia microphylla Don, Disterigma elassanthum Blake, Vaccinium acuminatum (Kunth) Kunth, Metagonia acuminata (Kunth) Nutt.

Description:

Species Description - Epiphytic or terrestrial shrubs, scandent or erect, 0.3-3 m tall. Young branchlets ridged, ± smooth, villosulous, the hairs eglandular and brown, the indumentum of the mature branches similar but glabrate or villosulous. Leaves 4-9 per cm, apparently distichous or spirally arranged, patent; petiole 0.4-1.2 mm long, puberulous, the hairs eglandular; lamina ovate or rarely elliptic, 0.3-1.1 × 0.2-0.6 cm, basally obtuse or less often cuneate, marginally entire or very rarely inconspicuously crenulate, the teeth apically setaceous and glandular, often revolute towards base, sometimes apically ciliolate with eglandular hairs (especially in young leaves), apically acute, acuminate, or long-acuminate, adaxially glabrous or glabrate with eglandular hairs, abaxially glabrous or glabrate with eglandular and glandular hairs, the venation obscure on both sides or sometimes 5-nerved abaxially. Axillary solitary flowers and rarely 2-flowered fascicles; bracts 3-6, chartaceous, ovate, 0.5-1.8 × 0.6-2.3 mm, marginally ciliolate with eglandular hairs (especially at apex), apically obtuse, abaxially glabrous; pedicel (0.8-)1-2 mm long, much reduced and hidden by overlapping bracts, glabrous or glabrate with eglandular hairs; differentiated apical bracteoles 2, distinct, chartaceous, enveloping entire calyx tube, covering 40-60% of calyx, transverse-elliptic or reniform, 1.2-2.5 × 2-3.6 mm, marginally ciliolate with eglandular hairs, apically obtuse, the surface longitudinally striate, abaxially and adaxially glabrous. Flowers 4-merous. Calyx aestivation valvate, campanulate, 2-3.6 mm long; tube angled, 0.9-2 mm long, abaxially glabrous; limb 1-2 mm long, abaxially and adaxially glabrous; lobes triangular, 1-2 × 1-2 mm, rarely marginally ciliolate with eglandular hairs, apically acute; sinuses acute (V-shaped). Corolla light green and sometimes with marked pink hue under intense sunlight conditions (only few unusually large corollas in Peru and southern Colombia are white), thick-fleshy, bistratose, mostly campanulate or sometimes urceolate (inflated at the middle), (2.8-)3-5.5 mm long (up to 6 mm in large corollas from Peru and southern Colombia), 3.8-4.5 mm diam. (up to 6 mm in large campanulate corollas from Peru and southern Colombia), 2-4.5 mm wide at throat, abaxially glabrate with eglandular or glandular hairs, adaxially glabrous; lobes 1-2.5 × 1.2-3.5 mm, apically acute, or acute and apiculate, adaxially slightly rugose. Stamens 8, 1.8-2.8 mm long (in large corollas from Peru 2.8-3.9 mm, from southern Colombia Venezuela, south through Colombia 4–4.5 mm), included; filaments distinct, straight, broader at base, (0.4–)0.6–1(–1.2) mm long (in large corollas from Peru 1.2–1.8 mm, in southern Colombia 1.6–2 mm), glabrous or rarely glabrate with a couple of abaxial hairs (glabrate to puberulous on both sides in large corollas from Peru and southern Colombia); anthers distinct, papillae on both thecae and tubules; thecae 0.8–1.5 mm long, without basal appendages; tubules 2, distinct, 0.7–1(–2) mm long, dehiscing introrsely by longitudinal slits, 0.4–0.6 mm long. Ovary 4-locular; style (2–)3–3.7 mm long (4.2–5.5 mm in large corollas from Peru and southern Colombia), included. Berry white (reported to turn purple/dark blue in plants with larger corollas from southern Colombia; white in the plants with larger corollas from Peru), ± spherical or hemispherical, 6–7 mm diam., the persistent calyx lobes erect or spreading, becoming succulent (at least at base), same color as mature berry; embryo white (unknown in plants with large corollas from southern Colombia).

Distribution and Ecology - Disterigma acuminatum is widespread throughout the Andes, from Trujillo, Venezuela, south through Colombia and Ecuador where it is abundant, and reaching its southernmost distribution in Puno, Peru, where it has been collected only once (Fig. 8). It generally grows in montane cloud forests, subpáramos, and less often in páramos, at (1800–)2000–3700 m. It has been recorded growing in sandy soils, clay soils, or Sphagnum bogs in both primary and secondary vegetation, as well as on roadsides and pasturelands with remnant vegetation. Flowering and fruiting year-round.

Local Names and Uses - This species is known as "mortiño" and "pipisiki" in Tungurahua and Sucumbíos, Ecuador, and as "buze-ievcheshaj" in Putumayo, Colombia. In Peru and Ecuador, both humans and birds eat its fruits.

Discussion:

Disterigma acuminatum is among the most common and frequently collected species of the genus in South America. Because of the small nature of its flowers, it was confused for a long time with D. dendrophilum (e.g., Luteyn, 1996; Smith, 1933), which has nearly identical leaves. In the description of D. acuminatum Kunth (1818) noted that the flowers were by no means evident on the specimens and that the floral characters used in the description were taken from the field notes chosen by Bonpland; consequently, the accompanying illustration showed only calyces and very immature fruits. However, from the best reproductions of the holotype photos it is possible to discern the presence of one corolla; when I examined the type material only a single mature corolla was found. The calyx, 3.6 mm long, the corolla, 3.2 mm long and campanulate, and the stamens, 2.8 mm long, of the holotype are identical to those of D. elassanthum and Gaylussacia microphylla (= D. microphyllum), which are synonymized here. Disterigma acuminatum (Figs. 2A, 7A) is characterized by its small and usually acuminate leaves; its differentiated apical bracteoles longitudinally striate; its small flowers with the corollas around 3.5–5 long, light green, campanulate or sometimes urceolate, and adaxially glabrous; its small stamens usually up to 3 mm long, with filaments usually shorter than the anthers and ca. 1 mm long; and by its white berries with white embryos. Among the few collections known from Peru, two populations represented by H. Qquellón 51 (CUZ) and Salinas-R. 7636-7 (COL, CUZ, NY, USM), differed by having corollas white and 6 mm long, which is slightly longer than the average 4 mm and green corollas of D. acuminatum. Plants with larger corollas have also been found in southern Colombia (D. acuminatum/Galeras in the phylogenetic analyses), but in this case the collections are more numerous and the plants occur in the Mun. Pasto, Nariño, and the nearby Mun. Sibundoy, Putumayo, where they are reported to be abundant. Besides the differences in the corolla color and corolla, stamen, and filament lengths (which are the same differences observed in Peru; see description for details), the berries of these populations are reported to be purple/dark blue at maturity (Luteyn et al. 4997) and not white, which is the fruit color of D. acuminatum observed in the field through its entire distribution. Unfortunately, fieldwork was not possible in places where plants with white fruits/small and green corollas, and plants with purple-blue fruits/large and white corollas grow one next to the other. The molecular and total evidence analyses resolved these OTUs into the same general clade, but the resolution at the species level was too poor to find further evidence regarding the species status (D. acuminatum and the large corolla/purple-blue fruit OTU, D. acuminatum/Galeras, differed only in three single indels and one substitution) (Pedraza-Peñalosa, 2009, 2010; see Phylogenetic Relationships). A possible hybrid between Disterigma acuminatum and D. balslevii, another species that inhabits the same area, is discussed under D. balslevii (Table V). Species vegetatively similar to Disterigma acuminatum are discussed under D. staphelioides. Moreover, D. acuminatum can be differentiated from D. dendrophilum by differences in the corolla shape (campanulate or urceolate vs. tubular, respectively), pedicel conspicuousness (hidden by bracts vs. at least partially evident), and the surface of the differentiated apical bracteoles (striate vs. smooth).

Common Names:

mortiño, pipisiki, buze-ievcheshaj

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