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

Jiménez, Marco M., Iturralde, Gabriel A., Kuethe, J. R., Vélez-Abarca, Leisberth & Garzón-Suárez, Henry X., 2024, New species of Ceratostema (Ericaceae: Vaccinieae) from the southeast Andes of Ecuador-I, Phytotaxa 663 (3), pp. 111-126 : 118-123

2. Ceratostema sieteiglesiana H.Garzón & M.M.Jiménez , sp. nov. Figs. 3 , 6–9 .

Type: — ECUADOR. Morona-Santiago: San Juan Bosco , 1757 m, 3 February 2023, H. Garzón & M. Jimenez 178 (holotype: HUTPL 14794 !) .

Diagnosis: The new species is similar to Ceratostema zamorana M.M.Jiménez & Vélez-Abarca , from which can be distinguished by the smaller leaves, 1.7–5.5 cm × 0.6–2.5 cm (vs. 7.7–12.7 cm × 3.7–6.5 cm), the sessile to very shortly-pedunculate inflorescences (vs. long-pedunculate), the puberulous floral parts (vs. pruinose), the shorter pedicels (1.9–2.7 cm vs. 2.2–4.1 cm long), subterete (vs. subquadrangular) in outline, subulate (vs. ovate) bracteoles, the longer calyx lobes (12.7–19.1 mm long vs. 11.3–12.5 mm long), with the sinuses and apices being acute (vs. acuminate), the longer corolla lobes (28–30 mm long vs. 15–16 mm long), externally black (vs. magenta), and the longer filaments (9.5–13.1 mm long vs. 4.5 mm long).

Pendant epiphytic shrub; axonomorphous roots with well-developed lignotubers, lignotubers subspherical to broadly fusiform, 10.5–25.6 × 10–22.5 cm in circumference. Stems terete to subterete, glabrous, slightly arching, up to 78 cm long, arising from the lignotuber, the bark dark brown, cracking longitudinally and exfoliating, twigs terete to subterete, sometimes bluntly angled, complanate or sharply ribbed, glabrous, striate after exfoliation, dark brown, up to 80 cm long, new twigs pale green sometimes suffused with magenta, minutely pubescent; axillary buds emerging up to 2 mm above the leaf node, compressed; bracts 2–3, long-triangular to subulate, 2.1–3.4 × 0.3–0.4 mm, acuminate at the apex, subtending the axillary bud. Leaves alternate, falcate to subfalcate; petioles pale greensuffused with pink, subterete, rugose, 2.1–5.2 × 1.0–2.0 mm, minutely pubescent; blades thickly-coriaceous, lanceolate to elliptic, 1.7–5.5 × 0.6–2.5 cm, dark green adaxially, paler abaxially, glabrous on both surfaces, slightly polished adaxially, centrally channeled, revolute, finely wrinkled, sometimes sub-bullate, base cuneate to shortly attenuate, extending down the petiole, apex obtuse or attenuate rarely acute, weakly plinerved with 2–3 pairs of secondary veins originating near the base, the midrib thickened and impressed in the proximal 5 mm adaxially, rised and conspicuous abaxially, the secondary veins anostomose, plane adaxially and plane to weakly impressed abaxially, veinlets slightly raised, anostomose, reticulate adaxially. Inflorescences axillary, racemose, congested, 2–7-flowered, sessile to very short-pedunculate; peduncle terete, obconical, puberulous, pale green suffused with magenta, to 4.8 mm long; rachis subterete, 1.5–4.4 mm long, 2.3–3.4 mm thick, puberulous; floral bracts very short, triangular, obtuse, puberulous, caducous, 1.5–1.9 × 1.2–1.4 mm; pedicel incurved, pale green suffused with magenta, brown to the tip, puberulous, subterete, subverrucose and faintly ribbed from the bracteole to the apex, 1.9–2.7 cm long, 2.1–3.6 mm thick, puberulous, recessed in the calyx; bracteoles 2, small, located below the middle and opposite, caducous, long-triangular to shortly-subulate, 1.8–2.6 × 0.4–0.7 mm, puberulous, apex acuminate, margins slightly undulate. Flowers 5-merous, pendant; calyx 22.7–29.7 × 20.5–21.1 mm, puberulous, pink to brownish red with darker margins on the ribs and lobes, sometimes green at the hypanthium; hypanthium widely obconic, truncate, 5-winged, 8.3–9.8 × 3.6–6.1 mm; limb open, spreading, 15.9–17.2 × 22.7–29.7 mm; lobes 5, ovate, 5.0–6.5 × 12.7–19.1 mm, surface faintly veined and rugose rarely provided with up to four circular black glands, margins microscopically repand and involute, the apices and sinuses acute. Corolla thick-carnose, bistratose, cylindrical but narrowing distally, terete in cross-section, 4.8–5.2 cm long, 11 mm in diameter at the base and 9 mm in diameter at the throat, pink or salmon colored, puberulous, polished; lobes 5, incurved at the base, slightly recurved to the apex, spreading, narrowly triangular, acuminate, 28–30 × 5–6 mm, black with the base salmon externally, black internally, polished, channeled and subverrucose internally. Stamens 10, nearly equaling the corolla in overall length, each pair unequal with each other, 4.2–4.6 cm long; filaments connate, sparsely pilose abaxially at thecae height, 9.5–13.1 mm long; anthers 3.6–4.0 cm long overall, thecae 6–7 mm long, conspicuously papillose, tubules distinct, but seemingly connate near the proximal 2/3, glabrous, 3.1–3.3 cm long, dehiscing by terminal pores 1.1 mm long; style exserted, 5.4–5.7 cm long, glabrous, green; stigma truncated. Fruits baccate, whitish-yellow, oblate, 1.5 × 1.1 cm in diameter, puberulous, with darkened ridges when ripe, apex with persistent calyx lobes.

Distribution and habitat:— Ceratostema sieteiglesiana is endemic to the forests surrounding the town of San Juan Bosco in Morona-Santiago Province, Ecuador.According to Baéz et al. (2013) and Guevara & Josse (2013), the type of forest of this area is classified as evergreen lower montane and premontane forest at the southeastern Cordillera of the Andes (BSBN02 & BsPn04). The new species was found at elevations between 1500–1700 m, where the type locality shows a stratified forest containing trees and treelets covered in mosses and lichens ( Figs. 3 , 8 ). The local species componentry is composed of other ericads such as Anthopterus gentryi Luteyn (1996: 390) , Ceratostema pendens Luteyn (2005: 1272) , Disterigma utleyorum Wilbur & Luteyn (in Luteyn & Wilbur 1977: 259) and Sphyrospermum spp. , with local flora dominated by Blakea subvaginata Wurdack (1979: 347) , Cabralea canjerana ( Vellozo 1825: 176) Martius (1843: 38) , Ceratostema charianthum Smith (1950: 360) and Meriania neillii Mendoza (2021: 85) . Another specimen was observed in flowers approximately 10 km north and 500 m east from the type locality, and were vouchered with photographs shown in Fig. 8 .

Conservation status:— Ceratostema sieteiglesiana is known only from three locations which are near the Siete Iglesias Municipal Conservation Area (ACMSI), bordering the Runahurco Municipal Conservation Ecological Area (AECMR). Deforestation carried out for cattle pastures is acutely threatening the current habitat of the new species. Despite this, the authors believe C. sieteiglesiana is protected because of its vicinity to the aforementioned municipal reserves, which are important nature preservation areas protected under local government treaties. Using the georeferenced material, the calculated extent of occurrence (EOO) for C. sieteiglesiana is 8.03 km 2, with an area of occupancy (AOO) of 12 km 2. We recommend a conservation status of EN (Endangered) according to the criteria B2ab(i,ii) and C due to the very restricted area of occupancy of the species (IUCN 2022).

Etymology:— The new species is named after the Municipal Conservation Ecological Area Siete Iglesias (AECMSI), which marks the type locality of this rare species. This local reserve in southeastern Ecuador protects fragile and threatened ecosystems and is additionally important as a major resource for watercourses and springs. Dedicating the species after this reserve will aid in its scientific impact, environmental education, recovery of degraded areas, and ecotourism.

Taxonomic discussion:— Luteyn (1996) grouped the Ecuadorian species of Ceratostema that share a combination of unique features including the not amplexicaul leaves, the five-winged hypanthium with a very conspicuous calyx limb, and the lobes with lengths of 10 mm upwards. These traits apply to the following five species: C. lanceolatum , C. megalobum , C. oellgaardii , C. reginaldii and the recently described C. zamorana ( Jiménez et al. 2021) . The new species shares these defined traits, marking the sixth species belonging to this informal group. It is also worth considering that the axillary inflorescences and the small floral bracts and bracteoles are additionally common characters present in this morphological similar group, furthering a botanical relationship between the species in question.

Ceratostema sieteiglesiana seems to be most similar to C. zamorana ( Fig. 9 ), a species restricted to the premontane forests of Zamora, a town in the southeast of Ecuador. These two species are related by the glabrous, weakly plinerved leaves, with 3–5 pairs of secondary veins; the few-flowered inflorescences; the bracteoles located below the middle of the pedicel; the calyx limb remaining open with spreading ovate and acute lobes; and the cylindrical corolla. The corolla lobes of both species are narrowly triangular, acuminate at the apex, and internally black; with the staminal filaments being connate and the style exserted. The new species can be distinguished from Ceratostema zamorana by the lanceolate leaves (vs. ovate-lanceolate), the pink or salmon floral parts (vs. purplish brown and magenta), the subverrucose pedicels (vs. striate), the longer calyx (20.5–21.1 mm long vs. 12.4–14.6 mm long), the broadly obconic hypanthium (vs. obconic), and the longer corolla (4.8–5.2 cm long vs. 3.6–4.5 cm long). Additionally, the corolla lobes of the new species are markedly incurved (vs. spreading) ( Jiménez et al. 2021).

Ceratostema sieteiglesiana is also similar to C. megalobum ( Fig. 9 ), a species endemic to the outskirts of Loja, in southern-central Ecuador. The two species share the glabrous, lanceolate leaves, the very shortly-pedunculate inflorescences, and the large calyx lobes; C. sieteiglesiana differs by the plinerved leaves (vs. pinnately veined), the puberulous floral parts which are mostly pink or salmon colored (vs. glabrous and red colored), the broadly obconic hypanthium (vs. somewhat campanulate), the spreading, ovate calyx lobes (vs. erect-spreading, long-triangular), and the acute apex (vs. acuminate to incurved). The corolla of the new species is slightly longer (4.8–5.2 cm long vs. 4.0– 4.5 cm long) with much longer lobes (28–30 mm long vs. 8–9 mm long), narrowly triangular-acuminate apices (vs. triangular), brownish-black in color, both externally and internally (vs. paler red outside and whitish inside), and the staminal filaments being connate (vs. distinct) (Luteyn 1996). A summary comparing the principal morphological differences between C. sieteiglesiana and the other mentioned species is provided in Table 1 .

Figures

FIGURE 3. Distribution of Ceratostema jorgebritoi (pink star) and C. sieteiglesiana (red star) in the southern region of Morona-Santiago, southeast of Ecuador. Prepared using ArcGIS.

FIGURE 6. Lankester Composite Dissection Plate (LCDP) of Ceratostema sieteiglesiana. A. Habit. B. Flowering branch. C. Flower with a close-up of the indumentum of the corolla. D. Lobes of the calyx, abaxial and adaxial views. E. Flower without corolla and a close-up of the longitudinal section of the calyx and bracteole. F. Corolla (right) and its longitudinal section (left). G. Stamens with a close-up of the thecae and pores of the tubules. H. Mature fruit and transversal section showing the seeds. Elaborated by Henry X. Garzón-Suárez based on photographs of the type.

FIGURE 7. Line drawing of Ceratostema sieteiglesiana. A. Habit with a close-up of the axillary bud. B. Flower. C. Longitudinal section of the corolla showing the stamens. D. Longitudinal section of the calyx showing the calyx and pistil. E. Stamens, dorsal (leftmost), ventral (middle) and lateral (rightmost) views. Drawing by Leisberth Vélez-Abarca based on the type.

FIGURE 8. Ceratostema sieteiglesiana in situ. A. Habitat. B. Flowering branch. C., D. Inflorescences. A, B, D. Photographs by H. Garzón-Suárez. C. Photograph by Daysy Vera.

FIGURE 9. Species of Ceratostema with similar flowers.A. Ceratostema sieteiglesiana. B. C. zamorana. C. C. megalobum. A. by Henry Garzón-Suárez. B. by Marco M. Jiménez. C. by G. Lewis.