Ceratostema jorgebritoi M.M.Jiménez & H.Garzón, 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 : 112-113

1. Ceratostema jorgebritoi M.M.Jiménez & H.Garzón , sp. nov. Figs. 1–4 .

Type: — ECUADOR. Morona-Santiago: Gualaquiza, Jempe Lodge , 1789 m, 28 January 2023, H. Garzón & M. Jiménez 172 (holotype: HUTPL!) .

Diagnosis: The new species is most similar to Ceratostema flexuosum (A.C. Sm.) J.F. Macbr. , in having tetramerous flowers, from which it is distinguished by the ovate (vs. lanceolate) calyx lobes, 5–9 plinerved (vs. 3–5 plinerved) leaves that are spirally arranged (vs. distichous), terminal inflorescence (vs. axillary), much larger floral bracts (26.0 × 9.5 mm vs. 4.0–5.0 × 2.0 mm), longer hypanthium (3.4–10.1 mm vs. 3.0–4.0 mm long), lanceolate-deltate (vs. ovate) calyx lobes with an acuminate apex (vs. acute), and narrowly triangular (vs. lanceolate) corolla lobes.

Erect epiphytic shrub; axonomorphous roots with well-developed lignotubers, lignotubers subspherical 10.0–21.5 × 10.2–23.8 cm in circumference. Stems terete to subterete, glabrous, slightly arching, up to 61 cm long arising from the lignotuber, covered by leaves from near the base, the bark dark brown, cracking longitudinally and exfoliating, twigs terete to complanate, glabrous or minutely pubescent in new twigs, striate after exfoliation, dark brown, up to 36 cm long, new twigs pale green suffused with pink; axillary buds emerging up to 1 mm above the leaf node, compressed; axillary bud bracts 2–3, long-triangular to subulate, 1.8–1.9 × 1.0 mm, apex acuminate. Leaves alternate, spirally, rarely subsecundly or distichously arranged, suberect, caducous; petioles suffused with pink, subterete, rugose, 3.7–4.9 × 1.8–2.4 mm, minutely pubescent; blades thickly-coriaceous, ovate, 3.8–6.6 × 1.9–3.8 cm, dark green adaxially, paler abaxially, slightly polished adaxially, centrally channeled, revolute, finely wrinkled, base cordate to subcordate, apex subobtuse, glabrous, weakly 5–9 plinerved from near the base, the midrib thickened and impressed in the proximal 8 mm adaxially, raised and conspicuous abaxially, the secondary veins anostomose, plane adaxially and plane to weakly impressed abaxially, veinlets slightly rised, anostomose, reticulate adaxially. Inflorescence terminal, racemose, congested, 2–8-flowered, sessile to very short-pedunculate; peduncle subterete, pubescent, pale green, up to 9.4 mm long; rachis subterete, ribbed, 0.7–2.9 cm long, 2.4–3.2 mm thick, pubescent; floral bracts large, pink to green-salmon in color, elliptic, acuminate, puberulent at both sides with caducous hairs, concave, 14–26.0 × 7–9.5 mm, ciliate up to the margin; pedicel slightly recurved to arcuate, pale green suffused with magenta or salmon, turning darker to the hypanthium, pubescent, subterete, 1.4–2.4 cm long, 2.8–3.3 mm thick, articulate with the calyx; bracteoles 2, located near the base and opposite, pink to greenish salmon colored, sparsely pilose with caducous hairs, concave to slightly concave to the base, lanceolate to elliptic, 11.8–12.5 × 3.8–4.5 mm, apex triangular, obtuse to acute. Flowers 4-merous, descending; calyx 19.8–33.1 × 20.1–24.6 mm, pubescent, pink to salmon with the hypanthium darker especially the ribs; hypanthium widely obconic, truncate, 5-ribbed, 5.1–6.7 × 3.4–10.1 mm; limb open, spreading, 18.0–19.9 × 20.8– 33.1 mm; lobes 4, ovate, 5.7–7.5 × 15.4–16.9 mm, surface puberulous at both sides, with caducous hairs, faintly veined and rugose, margins thin and involute, the apices and sinuses acute. Corolla thick-carnose, bistratose, cylindrical but slightly narrowing distally, terete in cross-section, 4.3–4.9 cm long, 9 mm in diameter at the base and 6 mm in diameter at mouth, pink or salmon colored with white pubescence; lobes 4, spreading, narrowly triangular, acuminate, 18–23 × 3–5 mm, black with the tip glabrous, internally black, polished, channeled, subverrucose and puberulous. Stamens 8, nearly equaling the corolla in overall length, each pair unequal with each other, 4.0– 4.1 cm long; filaments 8.2–8.5 mm long, connate, white to the base and apex, pinkish around the middle, with very few hairs to densely pilose towards the junction with thecae; anthers 3.5–3.8 cm long overall, thecae much shorter than the tubules, 4–5 mm long, conspicuously papillose; tubules distinct, but seemingly connate near the proximal 5/6, glabrous, 3.3–3.4 cm long, dehiscing by terminal pores 0.7 mm long; style as long as the corolla, 4.8–5.0 cm long, glabrous, pale green with the tip pink-black; stigma truncated. Fruits baccate, puberulent, 3.0 × 4.3 cm in diameter, greenish-yellow when ripe, a tetragonal pyramid with the base pinacoid and the persistent calyx lobes to the apex.

Distribution and habitat:— Ceratostema jorgebritoi was found in the canton of Gualaquiza, province of Morona-Santiago, southeastern Ecuador. Additional specimens were observed 1.6 km south and 4 km southeast of the type specimen and were vouchered with photographs. The new species is known from the eastern Andean foothills at altitudes of 1600–1800 m, where it grows both in primary forests and disturbed secondary areas ( Figs. 3 , 4 ). Within its natural habitat, it has been found on tree branches near the canopy, while in pastures the species is restricted to relict trees. C. jorgebritoi is mainly founded growing on Alzatea verticillata Ruiz & Pavón (1792: 72) , Beilschmiedia costaricensis (Mez & Pittier in Mez 1903: 228) Allen (1945: 415), Cedrela nebulosa Pennington & Daza (in Pennington & Muellner 2010: 91) ( Fig. 4B ), Miconia sp. , Micropholis venulosa ( Martius & Eichler 1863: 52) Pierre (1891: 40) , Sapium sp. , and Vismia baccifera (Linneaus 1771: 277) Triana & Planchon (in Milne-Edwards et al. 1862: 300).

Conservation status:—EN (Endangered). The three localities of Ceratostema jorgebritoi are located near the buffer zone of the Runahurco Municipal Conservation Ecological Area (AECMR) ( Fig. 3 ). The new species is restricted to the forests of the eastern foothills of the southeastern Andes which are threatened by deforestation carried out for cattle pastures ( Fig. 4 ). Despite this, we assume C. jorgebritoi is protected due to its near presence to the AECMR, a protected buffer zone of consistent and stable habitats. Applying conservation analysis using the georeferenced collections, the calculated extent of occurrence (EOO) for C. jorgebritoi is 6.39 km 2, with an area of occupancy (AOO) of 24 km 2. We recommend a conservation status of EN (Endangered) according to the criteria B2ab(i,ii) and C due to the species having a very restricted distribution with very few individuals found (IUCN 2022).

Eponymy:— This species is dedicated to Jorge Brito-Molina from Gualaquiza, Morona-Santiago Province in Ecuador. Jorge is a biologist who has significantly contributed to the scientific knowledge of amphibians and terrestrial micromammals found in the southeastern regions of Ecuador.

Taxonomic discussion:— Ceratostema jorgebritoi is distinguished from its nearest related species by a unique combination of morphological traits. First of all, the petiolate and plinerved leaves are spiral to subsecundly arranged, making a distinct diagnostic characteristic even when plants are sterile, considering all other members of Ceratostema with distichous leaves. In flower, the large floral bracts and bracteoles, subtending its tetramerous pubescent flowers, make for another distinct difference from its most similar species, which often have smaller, glabrous flowers. Tetramerous flowers are also known in Ceratostema flexuosum (Luteyn 1996) , which differs in its distichous leaf arrangement and glabrous flowers ( Fig. 5 ). Reporting on the character of inflorescence in the Ecuadorian Ericaceae is useful for species identification, and the authors would like to encourage future research to include this diagnostic trait (Luteyn 1996, Pedraza-Peñalosa 2010, Luteyn & Pedraza-Peñalosa 2013).

Other differences between Ceratostema jorgebritoi and C. flexuosum are the cordate to subcordate (vs. cuneate to attenuate) base of the flower, the narrowly triangular to acuminate (vs. lanceolate, long-acuminate) corolla lobes with subobtuse (vs. obtusely short-acuminate) apices and the shorter stamens (4.0– 4.1 cm vs. 4.8–5.0 cm long) and thecae (4–5 mm vs. 7–8 mm long). The bracteoles are much longer (12.5 mm vs. 6 mm long), long-acuminate to lanceolate (vs. obtuse to acute), with pilose margins (vs. glandular-fimbriate), which are located near the base of the pedicel (vs. just below the middle) (Luteyn 1996).

Additional specimens examined (paratype):— ECUADOR. Morona-Santiago: Gualaquiza , 1765 m, 28 January 2023, H. Garzón, M. Jiménez & C. Villalta 173 ( HUTPL 14789 !) .

Figures

FIGURE 1. Lankester Composite Dissection Plate (LCDP) of Ceratostema jorgebritoi. A. Habit. B. Terminal branch and inflorescence. C. Leaves in adaxial and abaxial views. D. Flower with floral bract and bracteoles and a close-up of the corolla indumentum. E. Floral bract in adaxial and abaxial views. F. Bracteole in adaxial and abaxial views. G. Longitudinal section of the calyx and ovary showing pedicel and style. H. Longitudinal section of the corolla with a close-up of the junction of the filaments and thecae. I. Stamens, ventral (uppermost), lateral (middle) and dorsal (lowermost) views. J. Nearly mature fruit. Elaborated by Henry X. Garzón-Suárez based on photographs of the type.

FIGURE 2. Line drawing of Ceratostema jorgebritoi. A. Habit. B. Flower. C. Longitudinal section of the calyx showing ovary and pistil. D. Longitudinal section of the corolla showing stamens. E. Stamens, ventral (leftmost), dorsal (middle) and lateral (rightmost) views. F. Floral bract, abaxial view. G. Bracteoles, adaxial and abaxial views. Drawing by Leisberth Vélez-Abarca based on the type.

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 4. Cerarostema jorgebritoi in situ. A. Habitat. B. Habit. C., D. Inflorescences. Photographs by H. Garzón-Suárez.

FIGURE 5. Holotypes of Ceratostema jorgebritoi (left) and C. flexuosum (right). Holotype of C. flexuosum collected in Colombia, “Wood Rosario” by W. Lobb. Reproduced with the kind permission of the Royal Botanic Gardens, Kew.