Ceratostema gualaquizensis M.M.Jiménez & H.Garzón, 2024

Jiménez, Marco M., Iturralde, Gabriel A., Kuethe, J. R., Lapo-González, Nadia, Baquero, Luis E., Vélez-Abarca, Leisberth & Garzón-Suárez, Henry X., 2024, Ceratostema gualaquizensis (Ericaceae: Vaccinieae), a new species from Ecuador known from previously misidentified specimens and new insights on Ceratostema loucianae, Phytotaxa 671 (2), pp. 113-127 : 114-118

Ceratostema gualaquizensis M.M.Jiménez & H.Garzón , sp. nov. ( Figs. 1 , 3–4 ).

Type: — ECUADOR. Morona-Santiago: Gualaquiza, Nueva Tarqui, sector de Campo Paraíso, 1350 m, 17 May 2023, H. Garzón 198 (holotype: HUTPL 14828!).

Ceratostema gualaquizensis is distinguished from other members of the genus by the elliptic leaves which are convex with involute margins at the base, the axillary, solitary flowers with the turbinate hypanthium, and the magenta corolla with the apices of the lobes being black, spreading, narrowly linear-triangular, and acuminate.

Description. 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, lignotubers subspherical. 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, cylindric 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 seemingly connate near the proximal half, glabrous, 3.4–3.5 cm long, dehiscing by terminal pores ca. 0.7 mm long; style slightly exserted, 4.8–5.1 cm long, glabrous, pale green, brownish red to the apex; stigma truncated. Fruits not seen.

Distribution and habitat:— Ceratostema gualaquizensis is known only from two localities near Gualaquiza in southern Morona-Santiago Province, Ecuador. The type locality of the new species is located near Nueva Tarqui and another individual was observed 15 km northwest of the mentioned locality ( Figure 2 ). The new species is found growing epiphytically on trees of Celtis iguanaea ( Jacquin 1760: 16) Sargent (1895: 64) ( Cannabaceae ), Protium sp. ( Burseraceae ), Piptocoma discolor ( Kunth 1818: 35–36) Pruski (1996: 97) ( Asteraceae ) and Tachigali sp. ( Fabaceae ). It grows in the branches near the tree canopy in primary forests and relict trees near pastures ( Figure 3 ).

Conservation status and illegal export from Ecuador:— At the moment, the new species has not been found in any protected area, but rather it has been registered only in the buffer zone of the Runahurco Municipal Conservation Ecological Area (AECMR) ( Figure 2 ). The habitat of Ceratostema gualaquizensis is threatened by deforestation for livestock activities.

This species is presently known only from two localities near the town of Gualaquiza in south-eastern Ecuador. The Extent of Occurrence (EOO) calculated for the new species resulted in an area of 15 km 2 with an area of occupancy (AOO) of 20 km 2. This scales Ceratostema gualaquizensis as CR (Critically Endangered) following IUCN (2022) criteria B2ab(i,ii) and C, evidenced by its very restricted distribution and very few specimens known to represent this species. In addition, the close vicinity to the town of Gualaquiza and its urban expansion means great uncertainty to the longevity of the habitats, especially given the stress imposed by the discovery of mining in the area.

This species is sold by nurseries in Ecuador and is known in private collections and commercial nurseries in the United States, Europe and Asia under the erroneous name “ Ceratostema pendens ”. What appears to be an “honest mistake” due to the complicated taxonomy of this group of plants is addressed by several authors as a conscious and predetermined practice (Parra-Sánchez et al. 2004, Yeager et al. 2020). These practices are not limited to just one plant family and have been most commonly reported in plants of the Orchidaceae family illegally exported during the last decades using permits, including CITES, of other species. Such is the case of Dracula trigonopetala Meyer & Baquero ex Doucette in Doucette (2012: 59), Scaphosepalum luanneae Baquero (2019: 272) , Scaphosepalum tarantula Baquero & Hirtz in Baquero et al. (2018: 231) and Trisetella pachycaudata Mogrovejo-Herrera & Baquero in Baquero & Mogrovejo (2021: 272) where the authors already mention the illegal export of new species from Ecuador as a common practice. By having these ornamental plants at a certain price on the market for ornamental purposes, illegal collections put the natural populations of these species at risk.

Etymology:— This new species is named after Gualaquiza, the name of the township and municipality where the new species was found.

Taxonomic discussion:— Ceratostema gualaquizensis is most similar to C. pendens by sharing its long-pendent branches; the spirally arranged leaves with very short petioles; the convex blades, of which the sides are involute at the base; the sessile inflorescences and the axillary flowers with corollas expanding slightly distally. The new species can be distinguished from the latter by the smaller, non-amplexicaul leaves, measuring 3.9–6.0 × 2.2–2.5 cm (vs. amplexicaul, 7.0–10.0 × 4.0–7.0 cm); the leaf base obtuse (vs. deeply cordate and auriculate); the inflorescence exclusively 1-flowered (vs. 1–4-flowered); the ovate-triangular and acuminate bracteoles (vs. ovate and acute); the calyx with a longer turbinate hypanthium, 3.9–4.2 mm long (vs. obconic, 2.7–3.5 mm long), the magenta and tubular corolla that is sparsely puberulous in the apical half (vs. dark maroon, cylindric and short-pilose throughout) with narrowly linear-triangular and acuminate, recurved lobes (vs. narrowly-triangular, long-acuminate and straight lobes) having black (vs. dark maroon) apices and the shorter thecae (up to 5.1 mm long vs. ca. 7.0 mm long) ( Luteyn 2005). Another relevant feature observed in C. gualaquizensis is the leaves abaxially green (vs. suffused with purple) and the glabrous style (vs. pilose) in C. pendens ( Figure 4 ).

Figures

FIGURE 1. Lankester Composite Dissection Plate (LCDP) of Ceratostema gualaquizensis. A. Fertile branch with lateral view of a leaf (A1) and a close-up of the trichomes (A2). B. Adaxial (left) and abaxial (right) views of the leaves with a close-up of the basal leaf venation (B1) and trichomes (B2). C. Complete flower (left) with a ventral view of the corolla lobes (C1) and longitudinal section of the corolla without stamens (right). D. Calyx, pedicel and style with a close-up of the bracteole (D 1) and its longitudinal section with a close-up of the ovary and ovules (D2). E. Stamens with a close-up of the thecae (E1). Elaborated by Nadia Lapo-González based on photographs of the type.

FIGURE 2. Distribution of Ceratostema gualaquizensis and C. loucianae in the southeastern region of Ecuador. C. gualaquizensis (pink), C. loucianae (red), collected specimens (stars), and observed specimens (circles). Map prepared using ArcGIS by Henry X. Garzón- Suárez.

FIGURE 3. Ceratostema gualaquizensis in situ. Photos by Henry X. Garzón-Suárez.

FIGURE 4. Terminal branches with inflorescences. A. Ceratostema gualaquizensis. B. C. pendens. C1–C3. The entire flower, without corolla and stamens of C. gualaquizensis. C4–C6. The entire flower, without corolla and stamens of C. pendens. D1. Pedicel with a closeup of the base showing the bracteole of C. gualaquizensis. D2. Pedicel with a close-up of the base showing the bracteoles of C. pendens. Photos by Henry X. Garzón-Suárez based on the type and M. Jiménez 2282.