Gualaquiza hanging flower (Ceratostema gualaquizensis) from Ecuador is new to science, similar to Ceratostema pendens

NEWS - Gualaquiza hanging flower (Ceratostema gualaquizensis M.M.Jiménez & H.Garzón, sp. nov.) from southern Ecuador is reported as a species new to science as part of an ongoing study of the biodiversity of the Cordillera Real de Los Andes.

Ceratostema Jussieu (1789) includes 35 known species of which 2 are native to Colombia, 3 from Peru, 1 from Venezuela-Guayana and 32 in Ecuador of which 26 are endemic. The species are mostly restricted to the eastern montane forests of the Ecuadorian Andes.

Ceratostema are terrestrial or epiphytic, but sometimes grow as dwarf shrubs and often exhibit lignotubers. The genus is characterized by flower stalks that are mostly articulated to the calyx; flowers with large, thick corollas and elongated lobes; long stamens; coarse anthers and elongated tubules.

C. gualaquizensis are pendant epiphytic shrubs; indumentum consisting of short, white, almost persistent, eglandular trichomes of 0.2–0.9 mm long, trichomes arranged unevenly, sparsely to densely on younger branches, petioles, leaf blades, inflorescences and flowers excluding stamens and style; axonomorphous roots with well-developed lignotubers, subspherical lignotubers.

Stems terete to subterete, glabrous, slightly arching, arising from the lignotuber, the older stems dark brown, cracking longitudinally and exfoliating, younger branches pendant, terete to complanate, filiform, tomentose to puberulous, striate after exfoliation, dark brown, ca. 120 cm long (keeps growing continuously); axillary buds emerging up to 1 mm above the leaf node.

Leaves spirally arranged, descending, petioles very short, puberulous, pale pink, 0.7–1.8 × 0.8–1.7 mm; blades coriaceous, elliptic, 3.9–6.0 × 2.2–2.5 cm, dark or pale green and somewhat lustrous adaxially, paler abaxially, slightly convex with margins partially revolute in older or throughout the younger branches, convex with margins involute at the base so to conceal flowers and fruits, base obtuse, apex acuminate, puberulent adaxially and abaxially, glabrate in the adaxial side, weakly 5–7 plinerved from near the base, the midrib impressed in the proximal 4 mm adaxially, raised and conspicuous abaxially, the lateral veins branching, weakly impressed adaxially and slightly raised abaxially, veinlets raised slightly, anostomose adaxially.

Inflorescence axillary, solitary, sessile, bracts persistent; rachis very short, obconic, 1 mm long, 1.4 mm thick; floral bracts minute, pale green, puberulous, ovate-triangular to broadly ovate, subacute, 1.0–1.5 × 1.1–1.2 mm, long-ciliate along the margin.

Pedicel slightly recurved, pale green, puberulous, striate, subterete, 0.5–0.6 cm long, ca. 2.4 mm thick, articulate with the calyx; bracteoles 2, minute, located near the base and opposite in orientation, pale green, slightly convex, ovate-triangular, 1.7–1.8 × ca. 0.6 mm, apex acuminate, long-ciliate along the margin.

Flowers pentamerous, descending; calyx 7.8–8.7 × 5.4–8.4 mm, tomentose, pale green with white hairs; hypanthium turbinate, truncate, obscurely 5-winged, 3.9–4.2 × ca.4.4 mm; limb open, campanulate, spreading, 4.0–5.0 × 5.4–8.4 mm; lobes 5, small, deltate, acuminate at the apex, tomentose, 3.4–4.7 × 2.4–3.0 mm, the sinuses acute.

Corolla thick-carnose, bistratose, tubular, sparsely puberulous in the apical half, with white hairs, obscurely to bluntly 5-angled, cylindrical to the base, expanding slightly distally, 4.5–4.7 cm long, ca. 7 mm in diameter at the base and ca. 7 mm in diameter at the throat, magenta or rarely garnet, lustrous.

Lobes 5, 12.1–17.0 × 3.7–4.0 mm, spreading, magenta or garnet with black apices, puberulous, narrowly linear-triangular, acuminate, recurved; internally black, puberulous, lustrous, papillose.

Stamens 10, as long as the corolla in overall length, each pair unequal with each other, longer stamens 4.6–4.7 cm long, shorter stamens 4.4–4.5 cm long; filaments equal, connate, glabrous externally, white to the base and apex, magenta around the middle, 7.6–8.2 mm long.

Anthers 3.8–4.0 cm long overall, thecae ca. 5.1 mm long, conspicuously papillose, tubules distinct, flattened, but apparently connate near the proximal half, glabrous, 3.4–3.5 cm long, dehiscing by terminal pores ca. 0.7mm long; style slightly exserted, 4.8–5.1 cm long, glabrous, pale green, brownish red to the apex; truncated stigma. Fruits not seen.

The new species differs from other members of the genus by its convex elliptical leaves with volute margins at the base, axillary single flowers with a turbinate hypanthium and magenta corollas with black, spreading, narrow-linear-triangular and pointed lobes.

C. gualaquizensis is known only from two sites near Gualaquiza in southern Morona-Santiago Province, Ecuador. The type site is near Nueva Tarqui and another individual was observed 15 km northwest of the site. The epithet Gualaquiza is the name of the municipality where it was found.

It grows epiphytically on Celtis iguanaea trees (Jacquin 1760) Sargent (1895), Protium sp. (Burseraceae), Piptocoma discolor (Kunth 1818) Pruski (1996) and Tachigali sp. Grows on branches near the tree canopy in primary forests and relict trees near Meadow.

The new species has not been found in any protected area and only in the buffer zone of the Runahurco Municipal Conservation Ecological Area (AECMR). The habitat is threatened by deforestation for livestock activities. Area of Occurrence (EOO) is 15 km2 and area of occupancy (AOO) is 20 km2. Researchers propose it as CR (Critically Endangered).

C. gualaquizensis is most similar to C. pendens in that it has long, hanging branches; spirally arranged leaves with very short petioles; convex blades, whose sides are curved at the base; sessile inflorescence and axillary flowers with corollas slightly widened distally.

Both differ in smaller, less amplexicaul leaves, measuring 3.9–6.0 × 2.2–2.5 cm (vs. amplexicaul, 7.0–10.0 × 4.0–7.0 cm in C. pendens); leaf base obtuse (vs. cordate and densely leafy); inflorescence 1-flowered (vs. 1–4-flowered); bracteoles triangular-ovate and acute (vs. oval and acute).

Calyx with turbinate hypanthium, 3.9– 4.2 mm (vs. obconic, 2.7–3.5 mm), magenta and tubular corolla sparsely pubescent apically (vs. dark maroon, cylindrical, hairy throughout) with narrow linear triangular lobes and pointed, curved (vs. narrow triangular, long pointed and straight) with black apices (vs. dark maroon) and 5.1 mm (vs. 7.0 mm) thecae. Another relevant feature is the abaxial green leaves ( vs. filled with purple) and the style is glabrous (vs. hairy).

Original research

Marco M. Jiménez, Gabriel A. Iturralde, J.R. Kuethe, Nadia Lapo-González, Luis E. Baquero, Leisberth Vélez-Abarca & Henry X. Garzón-Suárez (2024). Ceratostema gualaquizensis (Ericaceae: Vaccinieae), a new species from Ecuador known from previously misidentified specimens and new insights on Ceratostema loucianae. Phytotaxa 671 (2): 113–127, DOI:10.11646/phytotaxa.671.2.1

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