Ceratostema loucianae Cornejo, G. Tello & Luteyn, 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 : 119-124

Ceratostema loucianae Cornejo, G. Tello & Luteyn ( Figs. 5–7 ).

Type: — ECUADOR. Morona-Santiago: Macas, 0.2 km N of San Isidro, lower Sangay National Park , eastern Andean slopes, 2°12′33.51″S, 78°10′1.94″W, ca. 1165 m, montane wet forest, 29 Dec 2023 (fl), X. Cornejo & G. Tello 10152 [holotype: GUAY (mounted and spirit); isotype: QCA] .

Description. Pendant epiphytic shrubs; axonomorphous roots with well-developed lignotubers, lignotubers broadly fusiform to globose, 10.0–23.0 × 10.0–24.0 cm in circumference. Stems terete to subterete, up to 44.5–50 cm long arising from the lignotuber, glabrous, slightly arching, the older stems maroon, cracking longitudinally and exfoliating; branches pendant, terete to complanate, filiform, up to 200 cm long (and keeps growing continuously), green, striate after exfoliation, villose, trichomes eglandular, 1.8–2.8 mm long, light brown, deciduous; axillary buds compressed, emerging up to 1 mm above the leaf node; bracts 2–3, villose. Leaves alternate, spirally arranged, subpendulous, minutely glandular, new leaves salmon in color; petioles subterete, 1.2–1.5 × 2.0– 2.5 mm, pale green sometimes suffused with pink, rugose, villose, trichomes to 0.4 mm long; blades ovate to lanceolate, 2.5–6.0 × 1.5–3.3 cm, dark green adaxially, paler abaxially, somewhat lustrous adaxially, pilose and glabrescent adaxially, villose and scabrid abaxially, canaliculate, thinly-coriaceous, base subcordate to truncate, apex attenuate to long-attenuate, margins slightly revolute, trichomes 0.4–1.8 mm long; weakly 5–7 plinerved near the base, the midrib impressed in the proximal 15 mm adaxially, raised and conspicuous abaxially, the lateral nerves branching, weakly impressed adaxially and plane abaxially, veinlets slightly raised, finely anastomose adaxially. Inflorescence axillary or supraxillary, congested, 1–2- flowered, very short-pedunculate; peduncle subterete, 1 mm long, pale green, covered by up to 4 persistent bracts, bracts broadly ovate, small, 0.6–1.1 × 0.7–0.9 mm, sparsely villose, apiculate; rachis obconic, very short, 0.1 cm long, 2 mm thick, glabrous; floral bracts ovate-triangular, small, 1.0–1.2 × 1.0 mm, pale green, caducous, subacute, long-ciliate to the margin; pedicel subterete, 0.6–1.1 cm long, 2.6–3.0 mm thick, pale green suffused with magenta to the apex, mostly straight to slightly incurved, striate, articulate with the calyx, sparsely villose, trichomes to 1.9 mm long; bracteoles 2, ovate-triangular, 0.9–1.0 × 0.5–0.6 mm, pale green, flat, minute, located near the base and opposite, apex acuminate, long-ciliate to the margin. Flowers pentamerous, divergent to pendulous; calyx 4–5.3 × 5.4–6.1 mm, green or green suffused with red with white hairs, densely villose, trichomes to 1.9 mm long; hypanthium obconic, 2.9–3.5 × ca. 3.9 mm, truncate, subterete to bluntly 10-costate; limb campanulate, 1.6–3.0 × 4.8–5.4 mm, open, spreading; lobes 5, broadly deltoid to hemiorbicular, 0.7–2.0 × 1.6–2.9 mm, minute, short acuminate to apiculate, villose, the sinuses rounded. Corolla thick-carnose, bistratose, cylindric-urceolate to tubular, 1.8–2.8 cm long, 6.0–9.0 mm in diameter at the base and 6–8 mm in diameter at the throat, crimson red or rarely pink cream, somewhat ventricose to the base, slightly narrowing distally, bluntly 5-angled, villose with white hairs, trichomes 0.9–2.4 mm long; lobes 5, narrowly linear-triangular, 11.5–17.8 × 2.6–3.3 mm, spreading, black, acuminate, recurved; internally black, sparsely villose and verruculose, lustrous, papillose. Stamens 10, 2.6–3.1 cm long, nearly equaling the corolla in overall length, each pair slightly unequal with each other; filaments equal, 4.7–6.9 mm long, connate in the basal ca. 4.3 mm, white, glabrous; anthers 1.9–2.4 cm long overall, thecae 6–10 mm long, conspicuously papillose; tubules 1.2–1.5 cm long, glabrous, distinct, but seemingly connate near the proximal 1/2, dehiscing by terminal pores 0.5–1.2 mm long; style exserted, 3.0– 3.5 cm long, dark green to greenish, glabrous, stigma truncated. Fruits a subovoid to subglobose berry, ca. 1.5 × 1.4 cm, white or pearl-white berry when ripe, villose; mesocarp white; seeds cream-colored with embryos deep green.

Distribution and habitat:— Ceratostema loucianae has been reported in the southeastern Ecuadorian provinces of Morona Santiago and Zamora Chinchipe ( Figure 2 ). The species is known only from the eastern Andean foothills surrounding the towns of Macas ( Cornejo et al. 2024), Limón, Santiago de Méndez, Sucúa and Zamora at elevations between 1100–1400 m, where it grows both in primary forests and in disturbed secondary areas ( Figure 6 ).

Additional specimens were observed 8.5 km northwest of Macas, 8 km south of Sucúa and 3.6 km northwest of Limón and were vouchered with photographs ( Figure 6 ). In the area of Santiago de Méndez, the species was found in pastures growing epiphytically on relict trees of Pouteria caimito ( Ruiz & Pavón 1802: 18) Radlkofer (1882: 333) ( Sapotaceae ) and Protium sp. ( Burseraceae ). Near Zamora it was seen growing on phorophytes of Alchornea sp. , Centronia laurifolia Don (1823: 314) , Graffenrieda sp. and Protium sp. within its natural habitat, it has been seen on tree branches from near the canopy to the understory (up to 2 m aboveground).

Conservation status:— This species is currently known only from 11 localities across south-eastern Ecuador. The Extent of Occurrence (EOO) calculated for the species resulted in an area of 1,650 km 2 with an area of occupancy (AOO) of 32 km 2. This scales C. loucianae as EN (Endangered) according to IUCN (2022) criteria B2ab(i,ii), focusing on restricted distribution and stability of habitat.

Ceratostema loucianae has been registered only in the lower part of the Sangay National Park ( Cornejo et al. 2024), the buffer zone of the Podocarpus National Park and the surrounding area of the Río Negro-Sopladora National Park. Nevertheless, the populations outside these areas are highly threatened by deforestation in favor of cattle pastures, slash-and-burn agriculture and infrastructure activities.

Ex situ, the species is being sold by nurseries in Ecuador and is known in private collections and commercial nurseries in the United States, Europe and Asia under incorrect names such as “ Ceratostema villosa ” and “ Ceratostema rauhii var. villosa ”.

Notes:— Ceratostema loucianae is similar to C. rauhii (1992: 314), C. glans Luteyn (1996: 54) and C. lanigera ( Sleumer 1941: 398) Luteyn (1984: 367) by the epiphytic habit, the vegetative and floral parts variously covered with indumentum, the plinerved leaves that are arranged in a spiral manner, the axillary to supraxillary inflorescences that are sessile to short-pedunculate and the red colored corollas with triangular, spreading to slightly recurved, acuminate lobes (being black in C. loucianae and the two latter species). A summary of the morphological differences between the aforementioned species is presented in Table 1.

Additional specimens examined:— ECUADOR. Morona-Santiago: Santiago de Méndez, Chupianza, vía a la reserva municipal, 1367 m, 6 May 2023, H. Garzón 197 ( HUTPL 14828 !). Zamora Chinchipe: Zamora, vía Zamora-Parque Nacional Podocarpus, 1070 m, 14 May 2023, M. M. Jiménez & M. Jiménez Villalta 1770 ( HUTPL 15001 !) ; Zamora, vía Zamora-Parque Nacional Podocarpus , 1117 m, 9 Jun 2023, M. M. Jiménez León 1927 ( HUTPL 15032 !) .

Figures

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 5. Lankester Composite Dissection Plate (LCDP) of Ceratostema loucianae. A. Fertile branch with a close-up of the trichomes (A1) and base of the inflorescence (A2). B. Adaxial (left) and abaxial (right) views of the leaves with a close-up of the trichomes (B1) and basal leaf venation (B2). C. Flower with part of the pedicel (left) and longitudinal section of the corolla (right). D. Calyx, pedicel, and style with a dorsal view of the limb (D1) and a close-up of the bracteole (D2) and the apex of the calyx lobe (D3). E. Stamens with a close-up of the thecae and pores of the tubule. Elaborated by Nadia Lapo-González based on photographs by Henry X. Garzón-Suárez based on H. Garzón 197.

FIGURE 6. Different populations of Ceratostema loucianae in southeastern Ecuador. A–C. Zamora D. Limón. E. Sucúa. F. Santiago de Méndez. Photos by Marco M. Jiménez and Henry X. Garzón-Suárez.

FIGURE 7. Species with similar flowers. A. Ceratostema loucianae. B. C. rauhii. C. C. lanigerum. D. C. glans. Photos A, D. by Henry Garzón-Suárez, B. by Werner Rauh, C. by Marco M. Jiménez.