Ceratostema zamorana M.M. Jiménez & Vélez-Abarca, 2021

Jiménez, Marco M., Vélez-Abarca, Leisberth, Horna, Luis Ocupa, Jaramillo, Nelson & Baquero, Luis E., 2021, A new species of Ceratostema (Ericaceae: Vaccinieae) from Ecuador, Phytotaxa 520 (3), pp. 265-272 : 266-270

Ceratostema zamorana M.M. Jiménez & Vélez-Abarca , sp. nov. ( Figs. 1–5 ).

This species is similar to Ceratostema reginaldii (Sleumer) A.C. Sm. , but differs in the subquadrangular pedicels with bracteoles located below the middle (vs. strongly flattened with bracteoles located above the middle), the obconic, purplish brown and ribbed (vs. cylindric and conspicuously winged) hypanthium with the open, spreading limb and the ovate lobes (vs. with the erect, irregularly split limb and the triangular lobes) and the cylindrical, shorter corolla (3.6–4.5 cm long vs. 4.4–5.5 cm long), pruinose and magenta colored (vs. glabrous, deep crimson to red), narrowing to the throat with the narrowly triangular lobes, brownish black inside (vs. cylindrical but obscurely pentagonal, expanding to the throat and the lanceolate lobes, red inside).

Type:— ECUADOR. Zamora-Chinchipe : Zamora River bank, outskirts of Zamora, 890 m, 12 December 2020, M. Jiménez 1094 (holotype: LOJA!)

Pendent epiphytic shrubs; axonomorphous roots with a well-developed lignotubers, lignotubers subspherical to broadly fusiform, 16.5–25.5 × 12.0–25.0 cm. Stems terete to subterete, glabrous, arching, to 59 cm long, arising from the lignotuber, the bark grayish, cracking longitudinally and exfoliating, twigs terete to subterete, sometimes bluntly angled, complanate or sharply ribbed, glabrous, striate after exfoliation, brownish red, to 95.5 cm long, sometimes producing stolons; axillary buds emerging up to 2 mm above the leaf node, compressed; axillar bud bracts 2, lanceolate to elliptic, 1.5–3.7 × 0.7–1.0 mm, apex acuminate to cuspidate. Leaves alternate; petioles pale green, sometimes suffused with pink, subterete, rugose, canaliculate dorsally, slightly winged to blade, 5.0–5.7 × 2.2 – 4.0 mm, glabrous; blades thickly-coriaceous, ovate-lanceolate to elliptic, 7.7–12.7× 3.7–6.5 cm, dark green adaxially, paler abaxially, polished adaxially, flat to revolute, sometimes sub-bullate, base shortly attenuate, decurrent into the petiole, apex cuspidate to acuminate-caudate, glabrous, weakly 3–5 plinerved from near the base, the midrib thickened and impressed in proximal 9 mm adaxially, raised and conspicuous abaxially, the lateral nerves plane to weakly impressed adaxially and plane to weakly impressed abaxially. Inflorescences axillary, racemose, congested, 3–8-flowered, long-pedunculate; peduncle subterete, complanate, bluntly angled to ribbed, striate, pale green, sometimes suffused with magenta, 4.0– 9.1 cm long; rachis subterete, striate, 2.6–3.3 cm long, 1.8–8.1 mm thick, glabrous; floral bracts very short, triangular, caducous, 1.3–1.9 × 1.4–1.6 mm; pedicel incurved, brownish purple, pruinose, terete at the base, subquadrangular, bluntly ribbed and striate from the bracteole to the apex, 2.2–4.1 cm long, 3.0– 3.8 mm thick, glabrous, articulate with the calyx; bracteoles 2, located below the middle and opposite, caducous, ovate, 1.3–1.7 × 0.6–0.7 mm, apex acuminate, margins faintly denticulate. Flowers 5-merous, pendent; calyx 12.4–14.6 × 16.2–19.0 mm, glabrous, slightly pruinose, brownish purple sometimes with a touch of green at the base; hypanthium obconic, truncate, 5-ribbed, 5.1–6.9 × 9.8–12.5 mm; limb open, spreading, 7.8–9.8 × 11.3–12.5 mm long; lobes 5, ovate, 5.0–6.8 × 7.2–9.3 mm, recurved, with margins thin and revolute, the sinuses acuminate. Corolla thick-carnose, bistratose, cylindrical but slightly narrowing distally, terete in cross-section, 3.6–4.5 cm long, 10 mm in diameter at base and 8 mm in diameter at throat, magenta to pale purple magenta, glabrous and slightly pruinose externally; lobes 5, spreading, narrowly triangular, acuminate, 15–16 × 3–4 mm, magenta externally, brownish black internally, polished and subverrucose internally. Stamens 10, nearly equaling the corolla in overall length, sometimes unequal with each other, 2.5–4.2 cm long; filaments connate, pilose at both sides, 4.5 mm long; anthers 3.0– 3.3 cm long overall, thecae 6–8 mm long, conspicuously papillose, tubules distinct, but seemingly connate in proximal 2/3, glabrous, 2.4–2.5 cm long, dehiscing by terminal pores 1.0 mm long; style exserted, 4.2–5.0 cm long, glabrous; stigma truncated. Fruits not seen.

Etymology: — This new species is named after the town of Zamora, the capital of Zamora-Chinchipe Province in Ecuador, where the new species was found.

Discussions:— This new species is distinguished among other species of Ceratostema by a unique combination of characters, i.e., the purplish brown ribbed hypanthium with ovate lobes and acuminate sinuses and, specially, the magenta corolla narrowing to the throat with the lobes brownish black inside. In Luteyn’s (1996) revision of the Ecuadorian species of Ceratostema , the species were firstly grouped by the leaf shape of the base, and, latterly by the characteristics of calyx limb and lobes and the hypanthium shape. Within the group of species with the calyx limb very conspicuous and the lobes from 10 mm upwards, there are four taxa, namely C. lanceolatum Bentham (1844: 142) , C. megalobum Luteyn (1996: 221) , C. oellgaardii Luteyn (1996: 224) and C. reginaldii , similar to Ceratostema zamorana by sharing the clearly 5-winged hypanthium ( Fig. 3 ). However, the most similar species to the new species is C. reginaldii ( Fig. 3D ), because the two species both own plinerved leaves and stamens with connate filaments, while other species own pinnately nerved leaves and stamens with distinct filaments.

Furthermore, the two species are reported in southeastern Ecuador have not been found growing sympatrically. Ceratostema zamorana grows at lower elevations from 890 to 930 m, restricted to the warmer premontane forests of the township of Zamora in Zamora Chinchipe Province ( Fig. 5 ), while according to Luteyn (1996), C. reginaldii which inhabits nearby areas, grows at higher altitudes from 1738 to 3400 m in wet montane and subparamo forests of the Azuay, Morona Santiago and Zamora Chinchipe provinces. By the different ecological preferences there is no gene flow between the locations where both species grow in southeast Ecuador, suggesting they can be recognized as separate species-level taxa.

Distribution and habitat:— Ceratostema zamorana is only known in the area surrounding the town of Zamora, in southeastern Ecuador. The species is found growing as an epiphyte ( Fig. 4 ) generally on branches and trunks of Zygia longifolia ( Willdenow 1806: 1010) Britton & Rose (1928: 40) (Fabaceae) in premontane forests along the banks of the Zamora River at elevations of 890– 930 m. The holotype specimen was found on a single remnant tree with a population of a dozen individuals, sympatric with other ericads such as Sphyrospermum cordifolium Bentham (1846: 222) , Macleania floribunda Hooker (1837: 109) , ferns, orchids and bromeliads. One more specimen was found in the same township, but 10 km northeast of the holotype, near Cumbaratza and was vouchered with a photograph by Günter Gerlach ( Fig. 4 ).

Conservation status: — The area where Ceratostema zamorana grows is not within the National System of Protected Wildlands in Ecuador; nevertheless, does not rule it out its presence in the Podocarpus National Park, which is near where the species grows. A total number of thirteen individuals of two populations were found in areas where alluvial mining, slash and burn agriculture and infrastructure works are common; so, the new species is under threat. Based in the IUCN categorization by applying the B1a criteria (limited geographical range), also by the conditions of continuing decline, observed, inferred or projected in the area of occupancy and according to the reduced number of locations and subpopulations, the limited geographical range (B2a, less than 10 km 2), given the uncertain future in the preservation of the habitat in most part of the distribution of this species, C. zamorana is recommended as an endangered species following the IUCN criteria ( IUCN 2019).

Figures

FIGURE 1. Ceratostema zamorana. A. Habit. B. Branch with leaves and an inflorescence. C. Base of the leaf, abaxial view. D. Bracteole on the pedicel. E. Flower and longitudinal section of the corolla showing stamens. F. Longitudinal section of calyx showing ovary and pistil. G. Stamens, dorsal (leftmost), lateral (middle) and ventral (rightmost) views. H. Anther dehiscence pores. Prepared by L. Ocupa Horna from photos by M. Jiménez.

FIGURE 2. Ceratostema zamorana. A. Lignotuber with roots. B. Habit. C. Branch with leaves and an inflorescence D. Base of the leaf, abaxial view. E. Bracteole in the pedicel. F. Flower and longitudinal section of the corolla showing stamens. G. Longitudinal section of calyx showing ovary and pistil. H. Stamens, dorsal (leftmost), lateral (middle) and ventral (rightmost) views. Drawing by L. Vélez and M. Jiménez.

FIGURE 3. Species of Ceratostema with 5-winged hypanthium. A. Ceratostema lanceolatum. B. C. megalobum. C. C. oellgaardii. D. C. reginaldii. E. C. zamorana. Photos A–C taken by G. Lewis, D, E by M. Jiménez.

FIGURE 4. Ceratostema zamorana in situ. A. Habit, showing lignotuber, taken by G. Gerlach; B. Flowering branch, taken by M. Jiménez.

FIGURE 5. Distribution map of Ceratostema zamorana prepared with collection locality data using ArcGIS. Prepared by N. Jaramillo and L. Vélez.