Alibertia mahechae Cortés-Ballén, Zapata-Corr. & Delprete, 2024

Cortés-B, Rocio, Zapata-Correa, Diego A., Persson, Claes & Delprete, Piero G., 2024, Alibertia mahechae (Gardenieae, Rubiaceae), a new species from the Eastern Colombian Andes, Phytotaxa 675 (2), pp. 158-166 : 160-164

Alibertia mahechae Cortés-Ballén, Zapata-Corr. & Delprete , sp. nov. ( Figs. 1 & 2 )

Type:— COLOMBIA. Santander: Mun. Charalá, vereda El Palmar, cuchilla El Fara, 06°04ʹ10.08ʹʹN, 73°13ʹ38.71ʹʹW, 2477 m, 17 March 2008 (female fl), S. Cómbita, R. Medina & O. Chaparro 101 (holotype: UDBC-021869!; isotype: COL-544343!) .

Diagnosis:— Alibertia mahechae shows morphological similarities with A. occidentalis , from which it differs by the coriaceous leaf blades (vs. papyraceous in A. occidentalis ), (5–)7–9 pairs of secondary veins [vs. 9–14(–16)], male flowers with truncate calyx (vs. denticulate to slightly undulate), corolla tubes (15–) 20–27 mm long (vs. 11–18 mm long), anthers 16–17.5 mm long (vs. 6.5–10 mm long), female flowers 7–8-lobed (vs. 6-lobed), and fruits (5.5–)8.1–8.6 × 8.8 cm (vs. 5.5–6 × 6–7 cm).

Description:— Trees or treelets, dioecious, (5.5–) 8–15 m tall, (3–) 11–30 cm DBH; basal portion of trunk canaliculate, conical treetop. Distal branchlets laterally flattened to subterete, with decussate internodes, solid, striate, 4–6 mm diam., glabrous, rhytidome with plates, brown-reddish to grayish. Stipules sheathing at basal 8 mm, free portion ovate to oblong-elliptic, 12–15(–18) × 5–7.5 mm, acute or occasionally obtuse at apex, coriaceous, glabrous abaxially, with an often prominent central costa and parallel veins, adaxially glabrous, with colleters at base up to 1 mm long, persistent, brown-reddish. Leaves opposite, isophyllous; petioles (2.3–)3–4.5(–6) cm long, 2–3.5(–4) mm thick, canaliculate, glabrous, transversally striate at the proximal portion, slightly geniculate; blades broadly elliptic, elliptic or occasionally obovate (7–)10.5–23.5(–31) × (3.5–)6–14(–17) cm,, acute at base, decurrent, acute at apex, obtuse to shortly acuminate (acumen up to 1.5 cm long), coriaceous, margin entire, plane; venation pattern pinnate, secondary veins eucamptodromous, (5–)7–9 on each side of midrib, irregularly spaced, decurrent toward the base, excurrent toward the apex, course straight to exmedially curved, intersecondary veins occasionally present, parallel to the secondary veins; intercostal and epimedial tertiary veins mixed percurrent, exterior tertiary veins looped; quaternary veins irregularly reticulate or alternate percurrent, areoles occasionally present between quaternary veins; adaxially primary vein flat in the proximal one third and slightly prominent in the distal two thirds while secondary, tertiary and quaternary veins prominulous, glabrous, shiny, clear or dark brown; abaxially primary vein prominent, secondary veins prominent, puberulous, tertiary and quaternary veins usually flat to slightly prominulous, glabrous; domatia tufts of long hairs, intercostal area glabrous. Staminate inflorescences terminal, capitate, 5–10 flowered, flowers fragrant, peduncle 6–10 mm long, glabrous, subtended by two pairs of bracts 5–7 × 4–6 mm, ovate-elliptic, glabrous, acute at apex; pedicels 1–2.5 mm long, 1–2 mm thick, glabrous, dark brown, calyx tubular to occasionally cup-shaped, coriaceous, 8–12 (–14) × (4.5–) 6–9 mm, truncate, less often undulate, glabrous, colleters inside up to 1 mm long, dark brown dried, green fresh; corollas 5–6-lobed, 2.7–3.5 cm long, white, with contorted aestivation; tubes cylindrical to narrowly obconical, (15–) 20–27 mm long, 3.5–6 mm wide at base, 6–8 mm at medial and distal portion, densely retrorsely sericeous outside, with golden-cream hairs, glabrous at the basal portion up to 1 mm, internally glabrous at the basal third (about 7–8 mm from the base), the distal two thirds (about 18–20 mm) with sericeous indument to densely puberulent toward the throat; lobes narrowly oblong to oblanceolate, 14–16 × (2.5–) 3–5.5 mm, acute or sometimes obtuse at apex, puberulent, indument gradually less dense toward the apex; stamens five, included, inserted in the middle portion of the corolla tube, subsessile, filaments ca. 1 mm long, flat, adaxially with sericeous indument, abaxially glabrous; anthers subulate to linear, 16–17.5 × 0.5–1 mm, dorsifixed, apiculate, thecae with longitudinal dehiscence, introrse; style ca. 20 mm long, glabrous, style branches 3–4, erect, 8–9 mm long. Pistillate flowers terminal, solitary, fragrant, peduncle up to 10 mm long, glabrous, subterete; sessile; hypanthium ellipsoid, 10–12 × 10–12 mm, glabrous; calyx tubular, coriaceous, 13 × 9 mm, truncate, occasionally irregular, glabrous, colleters inside up to 1 mm, dark brown dried, green fresh; corollas 7–8-lobed, white, with contorted aestivation; tubes cylindrical to narrowly obconical, 9–11 × 6–8.5 mm, densely retrorsely sericeous outside, with golden-cream hairs, glabrous at basal portion up to 1.5 mm from the base; lobes obovate to spathulate, 20–23 × 7–9 mm (14–18 mm long in bud), obtuse at apex. Fruit solitary, globose, (5.5–)8.1–8.6 × 8.8 cm, peduncle up to 3 cm long, 4–5 mm thick, glabrous, smooth, shiny, green when immature, brown at maturity, calyx tube persistent, mesocarp woody, (10–) 16–18 mm thick; seeds numerous, lenticular, ca. 5.5 × 6.5 mm, with irregular margin, and rough surface.

Distribution and habitat:— Alibertia mahechae was collected on the west slope of the Eastern Andes of Colombia, in the Boyacá, Cundinamarca, and Santander departments ( Fig. 3 ). It grows along creeks and rivers or in secondary forests associated with many species of Miconia Ruiz & Pavón (1794: 60) , Palicourea Aublet (1775a: 172) , Ocotea Aublet (1775b: 780) , Anthurium Schott (1829: 828) , and Clusia Linnaeus (1753: 509) , or in “Robledales” (oak woodlands) dominated by Quercus humboldtii Bonpland in Humboldt (1809: 155), at 1700–2480 m elevation. According to Holdridge’s (1987) life zone system, collection localities correspond to the wet and moist premontane and lower montane forests.

Phenology:—Specimens with staminate flowers were collected in January, March, and July, with pistillate flowers in March, and with fruits in January and March.

Eponymy:—The specific epithet honors the memory of Gilberto Emilio Mahecha Vega (1942–2021), a dendrology Professor at the Universidad Distrital Francisco José de Caldas, Bogotá, Colombia, who founded the UDBC Herbarium. He also made the first collections of the new species described here and knew the taxonomic novelty when he asked the first author, “When are you planning to describe the new Andean borojó that I collected in my hometown?”

Common names:—The species is known in Cundinamarca as Calabacillo (Mahecha s.n., UDBC-19919) or Calabazo (Mahecha s.n., UDBC-05351), while in Santander as Clavo or Azuceno ( Reina et al. 2010).

Suggested conservation status:—Endangered (EN). According to the criteria B 1a+ B 2a of the IUCN, taking into account that: i) the Extent of occurrence (EOO) is lower than 5,000 km 2 (824 km 2), ii) the Area of occupancy (AOO) is lower than 500 km 2 (24 km 2), and iii) it has been recorded in less than ten localities (5 localities), and three subpopulations (criteria 2Ba), we suggest that Alibertia mahechae is in the Endangered (EN) category.

The new species was collected in localities within two protected areas: the Cachalú Biological Reserve, located in the buffer zone of the Sanctuary of Fauna and Flora “Guanentá Alto Río Fonce,” in Santander Department ( Solano 2006), and the Regional Natural Park “Serranía El Peligro” in Boyacá. The population located in Pacho, Cundinamarca, is not protected.Although two of the three subpopulations are found in protected areas, we consider this species highly threatened, considering the extent of forest fragmentation in this area of the Colombian Andes. Etter & Villa (2000) showed the impact of human activities on forest fragmentation in the Colombian Andes, particularly in the eastern Cordillera in the Boyacá and Santander Departments, where A. mahechae grows. They found that just 16.7 % and 9.9% of the original area remains of the Oak and mixed forests, respectively.

Paratypes:— COLOMBIA. Boyacá: Mun. Arcabuco, Reserva “El Peligro”, 5°49ʹ48ʹʹN, 73°30ʹ42.9ʹʹ, 1900–2200 m, 2006 (imm fr), M. Cárdenas s.n. (UDBC-022222!). Cundinamarca: Mun. Pacho, 1965 (st), G. Mahecha s.n. (UDBC-005351!); Mun. Pacho, vereda La Esmeralda 5°07ʹ15ʹʹN, 74°10′14″, 2200 m, January 2007 (male fl), G. Mahecha s.n. (UDBC-19919!). Santander: Mun. Encino , Reserva Biológica Cachalú , 6°04′31.9″N, 72°08′26.8″W, 17 March 2008 (male fl), A. Ávila, S. Ángel, M. Reina & R. Cortés 529 (UDBC-027170!, UDBC-021797!, COL-544254!, FMB-97507!) ; Mun. Encino, Reserva Biológica Cachalú, vereda Río Negro , 6°05′N, 73°08′W, 2100 m, 16 March 2008 (fr), R. Cortés, G. Téllez, S. Ángel, A. Ávila, A. González & M. Reina 2395 (UDBC-022617!) ; Mun. Encino, Reserva Natural Cachalú, Fundación Natura , 6°06′25.8″N, 73°13′33.9″W, 1730 m, 4 July 2008 (male fl), R. López , K. Benavides , N. Sícua, L. Cárdenas, A. Avella & Pepe 12992 (UDBC-50000!) ; Mun. Encino, Las Lajas, Reserva Cachalú , 6°05′N, 73°08′W, 2060 m, 15 March 2008 (female fl), S. Ángel , R. Cortés , M. Reina, A. Ávila & J. Martínez 245 (UDBC-22100!, COL-544160!) ; Mun. Suaita, cerca a la quebrada que hace límite entre Suaita y Gámbita , 06°03′11.2″N, 73°15′23.5″W, 2030 m, 23 March 2010 (st), A. Jara , R. Medina & M. Alfonso 777 (COL-547787!) ; Mun. Suaita, Corregimiento Olivar , vereda Corbaraque , cuenca de la quebrada Oibito , 6°06′25.8″N, 73°13′33.9″W, 1730 m, 9 January 2008 (fr), R. López , O. Chaparro, M. Medina, E. Herrera, C. Bello & P. Zambrano 12738 (UDBC-021786!, UDBC-021993!, COL-544532!) .

Notes:—Fruiting specimens of Alibertia mahechae look like the fruits of Agouticarpa isernii ( Standley 1940: 212) C.H. Persson (2003: 191) or Agouticarpa williamsii ( Standley 1918: 642) C.H. Persson (2003: 197) . These three species have globose fruits that are similar in size [(5.5–)8.1–8.6 × 8.8 cm vs. 4–10 × 4–10 cm or 4.5–8 × 4.5–9 cm, respectively] and mesocarp of about the same thickness [(10–) 16–18 mm vs. up to 20 or 18 mm, respectively]. However, Alibertia mahechae differs in having persistent stipules (vs. caducous), leaf blades acute to decurrent at base (vs. truncate, obtuse, or acute in A. isernii or cuneate, obtuse or truncate in A. williamsii ), and a distinct persistent tubular calyx (vs. absent or poorly developed). Additionally, sterile specimens of A. mahechae are similar to those of Tocoyena costanensis ( Steyermark 1963: 73) . However, there are notable differences. T. costanensis has subcoriaceous leaves (vs. coriaceous in A. mahechae ), with 9–11 secondary veins on each side [vs. (5–)7–9], tertiary venation not evident at the naked eye (vs. prominent all over the leaf blades, percurrent), and a lack of domatia (vs. with domatia).

Alibertia mahechae is the species recorded at the highest elevation of the genus (1700–2480 m). This contrasts with most Alibertia species found in the lowlands of Mesoamerica and the Amazon basin ( Persson & Delprete 2017).

Key to the Alibertia species occurring in Colombia

1. Stipules 5–10 mm long.......................................................................................................................................................................2

- Stipules> 13 mm long.........................................................................................................................................................................4

2. Bark not flaking; male flowers with narrowly triangular calyx lobes; fruit fleshy...................................................... A. bertierifolia

- Bark flaking or with vertical fissures; male flowers with truncate or uneven calyx; fruit woody .....................................................3

3. Bark flaking ......................................................................................................................................................................... A. latifolia

- Bark with vertical fissures .................................................................................................................................... A. edulis var. edulis

4. Male inflorescence 1-flowered....................................................................................................................................... A. tessmannii

- Male inflorescence> 1-flowered........................................................................................................................................................5

5. Fruit fleshy..........................................................................................................................................................................................6

- Fruit woody ........................................................................................................................................................................................7

6. Stipules 13–27 mm long; leaf blades with 10–14 secondary veins on each side............................................................. A. duckeana

- Stipules (19–)25–35(–45) mm long; leaf blades with (9–)12–17 secondary veins on each side......................................... A. patinoi

7. Stipules> 40 mm long, saccate ................................................................................................................ A. verticillata var. stipularis

- Stipules up to 20 mm long, flat ..........................................................................................................................................................8

8. Male inflorescence 5–10–flowered; male flower calyx 8–12 (–14) × (4.5–) 6–9 mm; male flower corolla tube 20–27 mm long; fruit (5.5–) 8.1–8.6 × 8.8 cm; fruit mesocarp (10–) 16–18 mm wide ...................................................................................... A. mahechae

- Male inflorescence 3–25-flowered; male flower calyx 3–7 × 3–6 mm; male flower corolla tube 10–27 mm long; fruit 1–6 × 1–6 cm; fruit mesocarp up to 10 mm wide.................................................................................................................. A. edulis var. edulis

Figures

FIGURE 1. Alibertia mahechae. A. Staminate flowering branch. B. Leaf venation detail. C. Detail of domatia. D. Staminate corolla, lateral view. E. Branch tip with pistillate flower. F. Fruit, cross-section. G. Seed.A, B, C from Ávila et al. 529 (UDBC); D from Mahecha s.n. (UDBC-19919); E from Cómbita et al. 101 (UDBC). Illustration by Marcela Morales Sánchez.

FIGURE 2. Alibertia mahechae. A. Staminate flowering branch. B. Leaf, abaxial surface. C. Staminate inflorescence with one flower in anthesis. D. Pistillate flower bud. E. Immature fruit. F. Mature fruit, cross-section. Photographs A–C, F by John Rojas; D, E by Rocio Cortés-B.

FIGURE 3. Distribution map of Alibertia mahechae.