Ceratostema revoluta M. M. Jiménez, H. Garzón & Iturralde, 2025

Jiménez, Marco M., Garzón-Suárez, Henry X. & Iturralde, Gabriel A., 2025, A new species of Ceratostema (Ericaceae) with nearly tubular leaves from the Cordillera del Cóndor, Ecuador, PhytoKeys 261, pp. 77-86 : 77-86

publication ID	https://doi.org/10.3897/phytokeys.261.156555
DOI	https://doi.org/10.5281/zenodo.16762629
persistent identifier	https://treatment.plazi.org/id/92698485-F256-50E9-A897-66DFE6A0CA62
treatment provided by	PhytoKeys by Pensoft
scientific name	Ceratostema revoluta M. M. Jiménez, H. Garzón & Iturralde
status	sp. nov.

Treatment

Ceratostema revoluta M. M. Jiménez, H. Garzón & Iturralde sp. nov.

Figs 1 View Figure 1 , 3 View Figure 3

Diagnosis.

Ceratostema revoluta is distinguished from other members of the genus by its nearly tubular, linear-lanceolate leaves with revolute margins, pulvinate petioles, sessile inflorescences with reddish flowers with white base and brownish to black lobes, short complanate pedicels with basal carinate appressed bracteoles and appressed calyx lobes that overlap each other below the middle (Fig. 1 View Figure 1 ).

Type.

Ecuador • Morona-Santiago: Cerca de San Juan Bosco , 1298 m elev., 8 Mar 2024, H. Garzón 265 (holotype: HUTPL!) .

Description.

Erect, epiphytic shrubs; indumentum of subpersistent trichomes, arranged unevenly, white, eglandular, 0.3–0.9 mm long, sparse to dense on younger branches, petioles, leaf blades, inflorescences and flowers, excluding stamens and style; roots axonomorphous, with well-developed lignotubers, lignotubers subspherical to fusiform, 5.6–8.5 × 4.3–7.4 cm, 13.4–17.3 cm in diameter. Stems terete to subterete, slightly arching, up to 1 m long, glabrous, arising from the lignotuber; older stems dark brown, cracking longitudinally and exfoliating; younger branches pendent, slightly arcuate, pale green, terete, ca. 25.7 cm long, 2.8 mm wide, puberulous, becoming striate and dark brown when old or after exfoliation; axillary buds 2–3, emerging 1 mm below leaf node, foliar bracts pale pink, narrowly triangular, 0.9–1.2 × 0.7 mm, puberulous. Leaves spirally arranged, suberect to nearly horizontal; petioles pale pink, pulvinate, 2.1–3.0 × 1.3–1.7 mm, puberulous; blades dark green and somewhat lustrous adaxially, paler abaxially, linear-lanceolate, nearly tubular, 2.0–5.7 × 0.4 cm, thinly coriaceous, puberulent adaxially and tomentulose abaxially, glabrescent, mid-vein impressed adaxially, conspicuous and raised abaxially, venation obscure, 3 - plinerved from near base and reticulate against a backlight, base cuneate, margins strongly revolute and longitudinally curled, apex acute. Inflorescence supraxillary, sessile, congested, 4–8 mm × 4.1–5.9 mm, 3–9 - flowered; rachis obconic, rugose, covered by bracts, tomentose; bracts persistent, up to 10, dark brownish-red, paler towards base, ovate to transversely ovate, 3.0–14.2 × 3.6–9.5 mm, apex obtuse; bracts persistent, similar in colour and texture to bracts, ovate, 16.5–21.0 × 6.3–10.5 mm, acute to attenuate; pedicel dark red, complanate, 4.0–4.4 × 3.1–3.6 mm, tomentose; articulation present between pedicel and hypanthium; bracteoles persistent, 2, located near middle, oppositely arranged, dark brownish-red, long ovate-triangular, 15.2–17.6 × 3.9–4.3 mm, channelled abaxially, centrally carinate adaxially, margins long-ciliate, apex attenuate. Flowers pentamerous, pendulous; hypanthium green, except margins pale purple, reddish towards apex, obconic, obscurely pentagonal, 3.0–4.2 × 4.0– 5.7 mm, tomentose; calyx erect, open, 12.7–21.5 × 4.0–7.0 mm, tomentose, hairs white, limb 0.4–1.3 × 4.0– 5.7 mm; lobes 5, nearly reaching throat of corolla, overlapping in basal half, black, except reddish towards base, lanceolate, slightly convex, 12.3–20.2 × 4.0– 5.4 mm, tomentose, base attenuate, margin long-ciliate, apex acuminate, sinuses acute. Corolla white-tomentose on apical half, whitish at base, reddish-brown in middle, tubular, except slightly dilated proximally and expanded distally, 4.0– 5.1 cm long (including lobes), 4.5 mm in diameter at base and throat, thick-carnose, bistratose; lobes 5, spreading, black, narrowly linear-triangular, 15.9–22.5 × 2.3–2.8 mm, lustrous, tomentose externally, glabrous internally, channelled and subverrucose internally, slightly recurved to base, apex acute. Stamens 10, nearly equalling corolla, in two series somewhat unequal in length, 3.7–4.7 cm long; filaments connate, each separated by a longitudinal line dorsally, white, 10.4–12.7 mm long, glabrous and lustrous on both sides; anthers 3.2–4.3 cm long, thecae conspicuously papillose, 6.6–7.7 mm long, prognathous with a basal appendage ca. 0.4 mm long; tubules distinct, but apparently connate in proximal 5 / 6, 2.5–3.2 cm long, glabrous, dehiscing by terminal pores, ca. 1.1 × 0.2 mm. Style exserted, longer than stamens, dark reddish-brown, 4.1–4.7 cm long, glabrous, base white; stigma truncate. Fruit a berry, purplish when ripe, globose, ca. 12.8 × 12.9 mm in diameter, pubescent, calyx lobes persistent.

Distribution and habitat.

Ceratostema revoluta has been reported in the south-eastern Province of Morona Santiago (Fig. 2 View Figure 2 ). The species is only known from the steep western foothills of the northern part of the Cordillera del Condor, where it was found in the region east of San Juan Bosco at elevations between 1300 and 1700 m.

Etymology.

The new species is named by the strongly revolute margins of the leaves.

Taxonomic discussion.

Ceratostema revoluta is similar to C. agettiorum M. M. Jiménez & H. Garzón , C. bracteolatum and C. doucettei H. Medina & J. Portilla in being variously covered with indumentum, the mostly sessile inflorescence, the conspicuous calyx lobes with acute sinuses, the darkly coloured corollas (Fig. 3 View Figure 3 ) and the stamens with the filaments connate, but can be distinguished by various characters (Table 1 View Table 1 ). From this group, the new species is most similar to C. agettiorum in the conspicuous floral bracts covering the rachis of the inflorescence, the pentamerous flowers with the calyx erect, the acuminate calyx lobes and the nearly tubular corollas with the lobes black, straight half-spreading. The new species is distinguished from C. agettiorum by the erect stems (vs. pendent), the smaller, 2.0–5.7 × 0.4 cm, linear-lanceolate, nearly tubular leaf blades (vs. 7.1–15.3 × 4.0– 8.4 cm, broadly ovate, flat), leaf blades cuneate at the base (vs. cordate) and acute at the apex (vs. attenuate), leaf blades obscurely 3 - plinerved at the base (vs. strongly 7–11 - plinerved), the sessile inflorescence with up to 9 flowers per raceme (vs. short-pedunculate, up to 15 flowers), the floral bracts 16.5–21.0 × 6.3–10.5 mm, ovate, acute, dark brownish-red (vs. 46.9–49.4 × 20.3–21.5 mm, elliptic, caudate, pink), the pedicel 4.0– 4.4 mm long, torulose, red (vs. 10 mm long, obconic, pink), the bracteoles 15.2–17.6 × 3.9–4.3 mm (vs. 41.3–41.6 × 7.6–7.8 mm), carinate adaxially, attenuate (vs. convex, long acuminate), the hypanthium obscurely pentagonal (vs. 10 - ribbed), the calyx black (vs. magenta), the corolla expanding distally (vs. narrowing distally), pubescent in the apical half including the lobes (vs. tomentose), the corolla white towards the base (vs. reddish-brown) and the filaments white, forming a tube (vs. pink, dilated towards the base) ( Jiménez et al. 2024 a).

Conservation status.

Ceratostema revoluta is only known from several individuals in the southeast of Morona Santiago near San Juan Bosco. This region is strongly threatened by deforestation for cattle pastures, slash and burn agriculture, mining, and infrastructure works. We recommend Ceratostema revoluta to be characterised provisionally as Data Deficient (DD) according to the IUCN Red List ( IUCN 2024).