Calvo, J. & Á.J. Pérez (2023). On the genus Dendrophorbium in Ecuador: a new species and identification key. Candollea 78: 91–97. In English, English and Spanish abstracts. DOI: http://dx.doi.org/10.15553/c2023v782a1
The new species, Dendrophorbium frezierifolium J. Calvo & Á.J. Pérez, is described from southern Ecuador, where it thrives at the edge of low montane forests near the limit with the paramo ecosystem. It differs from the most similar species D. dodsonii (H. Rob. & Cuatrec.) B. Nord. by its larger, chartaceous leaves with denser indumentum beneath, the stems with arachnoid indumentum, the shorter involucral bracts, and the lower number of disc florets. The species is preliminary assessed as “Endangered” [EN] using the IUCN Red List Categories and Criteria. Furthermore, images of living plants, a distribution map, and the first identification key to the species of Dendrophorbium (Cuatrec.) C. Jeffrey in Ecuador are provided.
Received on February 23, 2023. Accepted on August 16, 2023. First published online on September 13, 2023.
Calvo, J. & Á.J. Pérez (2023). Acerca del género Dendrophorbium (Compositae) en Ecuador: una nueva especie y clave dicotómica. Candollea 78: 91–97. En inglés, resúmenes en inglés y español. DOI: http://dx.doi.org/10.15553/c2023v782a1
La nueva especie, Dendrophorbium frezierifolium J. Calvo & Á.J. Pérez, se describe del sur del Ecuador, donde crece en los márgenes del bosque montano bajo cerca del límite con el ecosistema de páramo. Difiere de D. dodsonii (H. Rob. & Cuatrec.) B. Nord., la especie más similar, por sus hojas más grandes, cartáceas y con mayor indumento en el envés, los tallos con indumento aracnoideo, las brácteas involucrales más cortas y un menor número de flores del disco. De forma preliminar, se asigna la categoría IUCN “En peligro” [EN] a esta especie. Asimismo, se proporcionan imágenes, un mapa de distribución y la primera clave dicotómica para las especies del género Dendrophorbium (Cuatrec.) C. Jeffrey en Ecuador.
Introduction
The current circumscription of the genus Dendrophorbium (Cuatrec.) C. Jeffrey (Compositae, Senecioneae) has extensively been discussed in previous papers (Calvo & Buira, 2018; Calvo & Roque, 2018; Pruski, 2018). The genus comprises suffrutescent and tree-like species with usually moderately large, dentate leaves, and terminal synflorescences composed of radiate capitula (rarely discoid). Its distribution ranges from Venezuela to northwestern Argentina mainly through the Andean montane forests and a second disjunct area is located in the domain of the Atlantic Forest in southeastern Brazil. Lastly, D. lucidum (Sw.) C. Jeffrey occurs in the Caribbean islands of Dominica, Guadalupe, and Martinica.
In Ecuador, 17 species (14 of them endemic) were recorded in the “Catalogue” (Nordenstam, 1999). Some taxonomic adjustments were made later (Calvo, 2017; Pruski, 2018; Calvo et al., 2019), and Dendrophorbium azoguesense J. Calvo & Minga was described as a new species. However, no identification key was available until now, which probably hindered a better understanding of this plant group. Among the species listed by Nordenstam (1999), it should be noted that (1) D. kleinioides (Kunth) B. Nord. was recorded on the basis of a specimen here identified as Pentacalia floribunda Cuatrec. (i.e. Jaramillo & Proaño 1927; AAU, QCA); (2) Dendrophorbium moscopanum (Cuatrec.) C. Jeffrey was supported by a specimen here referred to D. tipocochense (Domke) B. Nord. (i.e. Boeke & Jaramillo 2651; NY, US); (3) D. reflexum (Kunth) C. Jeffrey was included as a dubious name, which is certainly a species restricted to Colombia and Venezuela. These species are therefore excluded from the flora of Ecuador. On the other hand, the species D. chingualense (Cuatrec.) S. Díaz & Cuatrec. and D. sibundoyense (Cuatrec.) C. Jeffrey (described from southern Colombia) are cited for the first time in the country. The record of D. chingualense is based on the collection Funk & Freire 11079 from NW Sucumbíos. The presence of D. sibundoyense is supported by Boeke & McElroy 403, Holm-Nielsen et al. 26422, 26605, and Jaramillo et al. 11991, 12037; these collections come from the surroundings of Baeza and Cosanga in Napo and most of them were previously identified in sched. as D. lloense (Hieron.) C. Jeffrey. Dendrophorbium sibundoyense differs from this latter species in having 8(–10) supplementary bracts (vs. 12–14), which mainly are ½ as long as the involucral bracts (vs. as long as the involucral bracts), and puberulous (vs. hirsute-pilose marginally). The involucral bracts are also shorter ((–5)6–8 mm vs. 9–10 mm).
Herein, as part of ongoing studies of the Ecuadorian Senecioneae, a new species of Dendrophorbium is described based on morphological evidence and the first key to the Ecuadorian species is presented. Pictures of living plants accompany the description, as well as a distribution map.
Materials and methods
This contribution is the result of field work carried out in Ecuador and the revision of herbarium specimens kept at AAU, G, HA, HUTPL, LOJA, Q, QAP, QCA, QCNE, and QPLS. The qualitative characters of the herbarium specimens examined were studied with the aid of a binocular dissecting microscope (Leica M60) when needed, whereas the quantitative characters were recorded using a Mitutoyo digital calliper, CD-15DC. The preliminary conservation status of the new species was assessed following IUCN Red List Categories and Criteria (IUCN, 2012, 2022). We calculated the extent of occurrence (EOO) and the area of occupancy (AOO, with a 2 × 2 km grid) using the online “GeoCAT” software ( http://geocat.kew.org; Bachman et al., 2011).
Taxonomy
Dendrophorbium frezierifolium J. Calvo & Á.J. Pérez, sp. nov.
(Fig. 1, 2).
Holotypus: Ecuador. Morona-Santiago: Gualaceo–Sigsig–Gualaquiza road, 28 km SSE of Sigsig, 3°10′S 78°42′W, 3250 m, 2.XII.1990, Luteyn, Jørgensen & Ulloa 14276 (QCA [QCA237372]!; iso-: AAU, K, NY [NY04348943] image!, US [US03066642] image!).
Among the species with c. 8 involucral bracts, this species differs in having leaves lanceolate with indumentum on both surfaces. It can be differentiated from D. dodsonii (H. Rob. & Cuatrec.) B. Nord., the most similar species, by its larger, chartaceous leaves with denser indumentum beneath, the stems with arachnoid indumentum, the shorter involucral bracts, and the lower number of disc florets.
Shrubs 2–2.5 m tall, erect, not branched or with branches only at upper half. Stems terete, with scattered arachnoid indumentum, finally glabrescent, distal parts with arachnoid indumentum. Leaves alternate, simple, petiolate; laminas lanceolate, 9.5–15 × 3.5–6.2 cm, base obtuse to rounded (basal cauline leaves subcordate), apex acute to attenuate, margins dentate, pilose on adaxial surface, pilose-tomentose on abaxial surface, with secondary and tertiary venation noticeable on abaxial surface (on dried specimens and living plants), chartaceous; petioles 1–2.8 cm, with scattered arachnoid indumentum. Synflorescences corymbose-paniculiform; lower synflorescence bracts foliose, similar in shape to cauline leaves, upper synflorescence bracts linear-subulate. Capitula 25–65, heterogamous, radiate, pedunculate; peduncles 7–15 mm long, with arachnoid indumentum and 2–4 bracteoles. Involucres cylindrical, 3.2–4.6 × 2.9–4.1 mm, with remnants of arachnoid trichomes; receptacle flat, foveolate; involucral bracts 8, linear-oblong, 3.1–3.9 × 0.9–1.3 mm, covered with scattered trichomes to glabrescent; supplementary bracts (calyculus) 2–5, linear, 1.2–2.0 × 0.3–0.5 mm, with scattered trichomes to glabrescent. Ray florets 8 – 10(– 13), pistillate; corollas 7.1–9 mm long, limbs c. 4.3–6 × 1.5–1.8 mm, patent to erect-patent, apex subentire to 2–3-toothed, glabrous, yellow. Disc florets c. 10, hermaphrodite; corollas 5.1–6.1 mm long, tubular, 5-lobed, yellow, limbs 3.9–4.1 mm long; filament collar balusterform; anthers c. 4 mm long, yellowish, bases acute, appendages c. 2.2 × 0.9 mm; style branches truncate with a crown of sweeping trichomes, yellowish. Achenes cylindrical, c. 2.1–2.6 × 0.5–0.9 mm, 5–8-ribbed, glabrous; pappus 4–5 mm long, barbellate, white.
Etymology. – The epithet frezierifolium refers to the resemblance of the leaves with those of some species of Freziera Willd. (Pentaphylacaceae).
Distribution, ecology and phenology. – Putative endemic species known only from southern Ecuador (Azuay, Morona-Santiago), at elevations of 2900–3300 m (Fig. 3). It thrives at the edge of low montane forests near the limit with the paramo ecosystem. Specimens in bloom have been collected from September to December.
Conservation status. – Dendrophorbium frezierifolium is known from three locations with an estimated EOO of c. 123 km2 and an AOO of 12 km2. None of the known locations currently receive any formal protection, and the habitat is in constant decline due to agricultural activities. On this basis, the new species is assigned to a preliminary risk of extinction status of “Endangered” [EN B1ab(i,ii,iii)+2ab(i,ii,iii)] using the IUCN Red List Categories and Criteria (IUCN, 2012, 2022).
Dendrophorbium frezierifolium has an ornamental potential and should be propagated in ex situ collections.
Notes. – The new species keys out in the species group with capitula with c. 8 involucral bracts, which comprises Dendrophorbium azoguesense, D. dodsonii (H. Rob. & Cuatrec.) B. Nord., and D. sotarense (Hieron.) C. Jeffrey. The new species clearly differs from the former in having pubescent leaves (vs. glabrous; see Calvo et al., 2019: fig. 1). Dendrophorbium dodsonii is a species quite variable regarding the indumentum, which varies from irregularly pilose to nearly glabrous. Dendrophorbium frezierifolium might be confused with the pilose forms, but it has larger, chartaceous leaves (9.5–15 cm long vs. subcoriaceous, 6–7 cm long) with denser pubescent indumentum on the abaxial surface (vs. sparsely hirsute-pilose), stems with arachnoid indumentum (vs. with scattered stout trichomes), shorter involucral bracts (3.1–3.9 mm long vs. 4–5 mm long; Fig. 4A), and a lower number of disc florets (c. 10 vs. c. 17). The new species can be readily separated from D. sotarense by the shape of the ray florets because this latter species has reduced limbs curved downward (Fig. 4B).
The leaves of Dendrophorbium frezierifolium slightly resemble those of D. dielsii C. Jeffrey and D. gesnerifolium (Cuatrec.) B. Nord. because of the indumentum; the latter two species, however, have involucres composed of 13–14 involucral bracts and whitish-lanate abaxial leaf surfaces.
Additional specimens examined. – Ecuador. Azuay: Oña, subiendo al páramo de Yacuambi por Urdaneta, 3°35′31″S 79°08′00″W, 2970 m, 30.X.2018, Calvo 7826 (HA). Morona-Santiago: along road between Gualaceo and Gualaquiza, 27.4 km SE of plaza in Sigsig, 21.9 km NW of Chiquinda, 3°11′40″S 78°46′30″W, 2933 m, 13.IX.2007, Croat & Ferry 98550 (MO n.v., QCNE).
Fig. 1.
Holotype of Dendrophorbium frezierifolium J. Calvo & Á.J. Pérez at QCA. [Luteyn et al. 14276, QCA237372; © Pontificia Universidad Católica del Ecuador, Quito]
Key to the species of Dendrophorbium in Ecuador
1. Involucral bracts c. 8 2
1a. Involucral bracts c. 13 6
2. Leaves glabrous to glabrescent 3
2a. Leaves with indumentum, at least on abaxial surface 4
3. Leaves lanceolate to narrowly elliptic, laminas 12.5–17 (–27) cm long, glabrous to glabrescent; involucral bracts 2.6–3 mm long D. azoguesense
3a. Leaves broadly lanceolate to broadly elliptic, laminas 6–7 cm long, irregularly pilose to nearly glabrous; involucral bracts 4–5 mm long D. dodsonii
4. Ray florets with reduced limbs, curved downward D. sotarense
4a. Ray florets with well-developed limbs, patent to erect-patent 5
5. Leaf laminas 9.5–15 cm long, densely pilose-tomentose on abaxial surface; stems arachnoid; involucral bracts 3.1–3.9 mm long D. frezierifolium
5a. Leaf laminas 6–7 cm long, sparsely hirsute-pilose on abaxial surface; stems with stout trichomes; involucral bracts 4–5 mm long D. dodsonii
6. Cauline leaves sessile 7
6a. Cauline leaves petiolate 8
7. Leaves semiamplexicaul; synflorescences congested; uppermost bracteoles and supplementary bracts somewhat foliose, usually as long as involucral bracts or almost so D. amplexicaule
7a. Leaves amplexicaul; synflorescences lax; supplementary bracts linear-subulate, remarkably shorter than involucral bracts D. pericaule
8. Cauline leaves > 25 cm long; petioles ≥ 5 cm long; plants that can reach several meters 9
8a. Cauline leaves < 20 cm long; petioles < 3 cm long; plants usually < 3 m tall 12
9. Involucral bracts 2.5–3.5 mm long D. gr. tipocochense1
9a. Involucral bracts 5–10 mm long 10
10. Supplementary bracts 12–14, as long as involucral bracts, hirsute-pilose marginally; involucral bracts 9–10 mm long D. lloense
10a. Supplementary bracts 8(–10), ½ as long as involucral bracts, puberulous; involucral bracts 5–8 mm long 11
11. Uppermost cauline leaves attenuate into petiole; involucral bracts c. 5 mm long; involucres wider than long in dried specimens (NW Sucumbíos) D. chingualense
11a. Uppermost cauline leaves usually auriculate at base; involucral bracts (–5)6–8 mm long; involucres rather as long as wide in dried specimens (Napo) D. sibundoyense
12. Involucral bracts < 4.5 mm long; leaves usually narrowly lanceolate to narrowly elliptic D. scytophyllum
12a. Involucral bracts > 6 mm long; leaves usually broadly elliptic to ovate 13
13. Leaves glabrous, cuneate to rounded at base D. elatum
13a. Leaves whitish-lanate on abaxial surface, subcordate to cordate at base 14
14. Involucral bracts arachnoid; peduncles 5–20 mm long; supplementary bracts ½–¾ as long as involucral bracts D. dielsii
14a. Involucral bracts pilose; peduncles 20–30 mm long; supplementary bracts ¼ as long as involucral bracts D. gesnerifolium
Acknowledgments
We are very grateful to the curators and staff of the herbaria mentioned in the text. Special thanks to Thomas Couvreur (IRD) for helping in several ways and to Amy Weiss (NY Collection Manager) for locating the isotype at NY. The comments and corrections of the reviewers highly improved the first draft of the manuscript. Their time and help are much appreciated.
© CONSERVATOIRE ET JARDIN BOTANIQUES DE GENÈVE 2023
Literature Cited
Notes
[1] 1 Preliminary studies suggest that Dendrophorbium balsapampae (Cuatrec.) B. Nord. and D. ingens (Benoist) B. Nord. fall within the variability of D. tipocochense. Dendrophorbium pururu (Cuatrec.) was placed in the synonymy of the latter species in CALVO (2017).
