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

Jiménez, Marco M., Minda, Alisson Fierro, Vélez-Abarca, Leisberth, Iturralde, Gabriel A. & Garzón-Suárez, Henry X., 2024, A new species of Ceratostema (Ericaceae: Vaccinieae) from the province of Morona-Santiago, Ecuador, Phytotaxa 650 (1), pp. 73-82 : 74-80

Ceratostema agettiorum M.M.Jiménez & H.Garzón , sp. nov. Figs. 1 –2,4.

Type: — ECUADOR. Morona-Santiago: Limón Indanza , (coordinates omitted for conservation reasons; detailed data on the type specimen), 30 January 2023, H. Garzón 176 (holotype: HUTPL!) .

Diagnosis:— This species is most similar to Ceratostema megabracteatum Luteyn but differs in the leaves not embracing the stem at the base, strongly plinerved (vs. amplexicaul, pinnately nerved, or weakly plinerved), with the midrib and lateral nerves thickened and impressed adaxially (vs. all veins impressed, including the reticulate veinlets), the inflorescence predominantly terminal (vs. axillary), the floral parts pink with the base green excluding the corolla (vs. pale yellowish-green, sometimes with a red base), the obconic hypanthium (vs. cylindrical) with long-triangular lobes (vs. lanceolate), the corolla dark scarlet and black towards the apex (vs. pinkish-red) with the lobes long-triangular (vs. lanceolate), the pink filaments (vs. golden-yellow), and the much shorter thecae (5–6 vs. 15–16 mm long).

Plant erect pendent shrubs; axonomorphous (provided with a main pivotal root) roots with well-developed lignotubers, lignotubers subspherical 14.0–19.5 × 14.9–21.6 cm. Stems terete to subterete, glabrous, slightly arching, to 82.5 cm long arising from the lignotuber, covered by leaves from the basal third, the bark dark brown, cracking longitudinally and exfoliating, twigs terete to complanate, minutely pubescent, striate after exfoliation, dark brown, to 44.7 cm long, new twigs pale green; axillary buds emerging above the leaf node, compressed; axillary bud bracts 2–3, long-triangular to subulate, 8.1–2.8 × 1.3 mm, apex acuminate. Leaves alternate, descending in natural position; petioles pale green with long-pubescent white hairs, terete, 6.3–8.4 × 2.8–3.6 mm; blades thickly-coriaceous, broadly ovate to ovate, 7.1–15.3 × 4.0– 8.4 cm, dark green adaxially, paler abaxially, slightly polished adaxially, centrally channeled, revolute, finely wrinkled, base cordate to subcordate, apex attenuate to acuminate, covered with white puberulent and caducous indumentum abaxially, strongly 7–11 plinerved from near the base, midrib and lateral nerves thickened and impressed adaxially, conspicuous raised abaxially, lateral nerves reticulate, plane adaxially and plane to weakly impressed abaxially, veinlets slightly raised, anastomosed adaxially. Inflorescence terminal or rarely axillary, racemose, up to 15 flowers per raceme, usually branching from the base, short-pedunculate; peduncle subterete, pubescent, pale green, to 3.1–3.5 cm long, covered by persistent bracts; bracts 5.8–34.0 × 3.7–18.4 mm; rachis ribbed, 6.5–13.2 cm long, 4.8–7.3 mm thick, pubescent; floral bracts large, elliptic, caudate, lanate adaxially, glabrous abaxially, reticulate veined, pink and green to the base, 46.9–49.4 × 20.3–21.5 mm; pedicel pink, pubescent, obconic, lanate, 1.0 cm long, 3.7–4.3 mm thick, articulate with the calyx; bracteoles 2, large, opposite, narrowly ovate, lanate abaxially, glabrous adaxially, 41.3–41.6 × 7.6–7.8 mm, apex acuminate. Flowers 5-merous, pendent; calyx 23.6–28.0 × 8.1–9.1 mm; hypanthium obconic, truncate, 10-ribbed, 5.3–6.1 × 3.6–5.2 mm, green; limb open, erect, 20.2–22.6 × 8.1 mm, magenta with white lanate hairs; lobes 5, narrowly-lanceolate 17.8–19.2 × 3.7–3.9 mm, erect, the sinuses acute. Corolla thick-carnose, bistratose, tubular but slightly narrowing distally, terete in cross-section, 4.7–5.0 cm long, 8 mm in diameter at base and 6 mm in diameter at throat, dark scarlet with white, tomentose hairs, glabrous on the covered part; lobes 5, half-spreading, linear-lanceolate, acute, 18.4–25.0 × 3.0 mm, with white pubescence, dark scarlet and black at both extremes externally, blackish internally, polished, channeled and subverrucose internally. Stamens 10, nearly equaling the corolla in overall length, each pair unequal with each other, 4.1–4.5 cm long; filaments connate forming a staminal tube, pink with the base white, glabrous and polished on both sides, 9.9 mm long; anthers 3.7–4.0 cm long overall, thecae 5–6 mm long, conspicuously papillose, tubules distinct, but seemingly connate in proximal 1/3, glabrous, 3.2–3.4 cm long, dehiscing by terminal pores 1.7 × 0.3 mm; style not exserted, shorter than the stamens and hidden by them, 4.7–4.9 cm long, glabrous, turning dark scarlet with the black tip above the upper half; stigma truncated. Fruits a pearl white berry when ripe, globose, sparsely pubescent, 2.7 × 1.5 cm, seeds greenish yellow.

Eponymy: — Named after Nancy Agett and twin brothers Jack and James (Jaime) Agett. The latter being a Peace Corps volunteer contributed to the establishment in 1966 of the first concrete school in San Juan Bosco, Morona Santiago.

Distribution and habitat:— Ceratostema agettiorum has been reported in the canton of Limon Indanza, province of Morona Santiago, which is here allocated as the type locality. In addition, the species has also been observed in the canton of San Juan Bosco, 9 km south of its type locality. This is a pendant epiphytic species known from the eastern Andean foothills, where it grows at elevations between 1600 and 1900 m above sea level in both primary forests and disturbed primary and secondary areas. Within primary forests, it has been seen growing on tree branches near the canopy, while in pastures it grows on relict trees, mainly on high branches of Piptocoma discolor (Kunth 1818: 35) Pruski (1996: 97) ( Asteraceae ).

Conservation status: — The two localities of Ceratostema agettiorum are located within the buffer zones of the municipal and conservation areas of Tinajillas–Río Gualaceño (Limón Indanza) and Siete Iglesias (San Juan Bosco). These municipal reserves provide a legal framework to establish areas dedicated to conservation, as well as the responsibility of the municipalities to protect nature in these areas. Unfortunately, the sad reality is local farmers continue to destroy primary forests for wood harvesting and pasture planting for cattle production. Moreover, another important threat is the construction of new roads which facilitates easy access and intervention of people to previously inaccessible sites. As current farming methods are non-sustainable, habitat loss and land degradation remain a serious threat to the preservation of these areas. The extent of occurrence (EOO) calculated for C. agettiorum resulted in an area of 4.41 km 2 and an area of occupancy (AOO) of 16 km 2; therefore, we recommend classifying C. agettiorum as Endangered (EN) according to the criteria B2ab (i, ii) ( IUCN 2022).

Notes:— Ceratostema agettiorum belongs to a group of species where the leaves are basally cordate or amplexicaul; the inflorescence is pubescent with eglandular hairs: having a very conspicuous calyx limb; the calyx lobes 9 mm long or more; a calyx hypanthium with 10-costate and bracteoles of 15–35 mm long or more located at or below the middle of the pedicel ( Luteyn 1996). From this group, the new species is most similar to C. megabracteatum by the large floral bracts covering much of the flowers during anthesis, and the bracteoles reaching the throat of the corolla ( Fig. 3 ). However, the species is noticeably different by the strongly 7–11 plinerved leaves (vs. with 3–5 lateral nerves); the shorter, 46.9–49.4 mm long, elliptic-caudate floral bracts (vs. 60–70 mm long, lanceolate); the shorter calyx (up to 28 vs. 35 mm long); the corolla being slightly narrowing towards the apex; glabrous in the covered part (vs. slightly swollen basally, mostly pubescent overall); the longer filaments (10 vs. 7–8 mm long); and the longer tubules (32–34 mm vs. 22 mm long). C. agettiorum is also similar to C. nodosum Luteyn (1986: 489) having large, persistent bracts that cover much of the flowers, the latter is differentiated by the extremely reduced lobes around the calyx.

The geographic distribution of the species also provides additional evidence to segregate the new taxon. Ceratostema agettiorum grows at lower elevations from 1600 to 1900 m and is restricted to the evergreen lower montane at the southeastern Cordillera of the Andes (BSBN02) in the southeast region of Morona-Santiago province in Ecuador. Unlike the lower montane forests of the eastern slopes of northern Ecuador, this ecosystem has minimum influence from the Amazonian flora and most of the trees belong to taxa of Andean origin ( Baéz et al. 2013).According to Luteyn (1996), C. megabracteatum is distributed around Cosanga at higher altitudes from 1850 to 2240 m in cloud forests of the province of Napo, northeastern Ecuador ( Fig. 5 ). Santiana et al. (2013a: 112, 2013b: 114), mentioned that the type of forest of this area is classified as evergreen montane and lower montane forest in the northern part of the Eastern Cordillera (BsMN01 & BsBN01).

The new taxon has been found sympatrically with Ceratostema glans Luteyn (1996: 228) and C. pendens Luteyn (2005: 1272). C. glans can be distinguished by the presence of glands in most of its vegetative and floral anatomy, the turbinate hypanthium with abruptly short-acuminate lobes of the calyx, and the slightly ventricose corolla. C. pendens is characterized by having pinnately veined leaves with cordate blades that are involute at the base thus concealing the 1–2 flowers, and the relatively inconspicuous floral bracts, bracteoles and calyx lobes ( Luteyn 1996, 2005).

Figures

FIGURE 1. Lankester composite digital plate (LCDP) of Ceratostema agettiorum. A. Habit. B. Terminal branch and inflorescence with close-up of the basal nerves of the adaxial side and trichomes of the abaxial side of the leaf. C. Flower with floral bracts and bracteoles in adaxial and abaxial views. D. Flower without floral bracts and a close-up of the longitudinal section of the calyx and ovary. E. The entire corolla and its longitudinal section. F. Stamens with a close-up of the thecae and pores of the tubule. G. Immature (left) and mature (right) fruit. Elaborated by Henry X. Garzón-Suárez based on photographs of the type.

FIGURE 3. Ceratostema megabracteatum in situ with the detail of the inflorescences. Elaborated by Henry X. Garzón-Suárez from photos by Paul Maas (uppermost) and James L. Luteyn.

FIGURE 5. Distribution map of Ceratostema agettiorum (star) and Ceratostema megabracteatum (triangle) prepared using collection locality data in ArcGIS. Elaborated by Henry X. Garzón-Suárez.