Meliosma quercifolia Idrobo ex D. Ruiz-Mol. & F. Ávila, 2024

Molina, Daniel Ruiz, Ávila, Fabio A. & Cortés-B, Rocío, 2024, Two new species of Meliosma (Sabiaceae) from the Eastern Cordillera in Colombia, Phytotaxa 666 (2), pp. 107-120 : 114-119

Meliosma quercifolia Idrobo ex D. Ruiz-Mol. & F. Ávila sp. nov. ( Figs. 5–8 )

urn:lsid:ipni.org:names:77348348-1

Type:— Colombia. Cundinamarca: Mun. La Vega, Vda. San Antonio, Finca Buenos Aires , 4°56’52.7”N, 74°21’41.4”W, 1700 m, 30 October 2021 (fl), D. Ruiz M., D. Suárez, R. Cortés B. 436 (holotype: UDBC 47443!; isotypes: COL!, FMB!, UIS!) .

Diagnosis:— Meliosma quercifolia is very similar to M. cundinamarcensis Cuatrecasas & Idrobo (1988: 12) but differs by having chartaceous leaves (vs. coriaceous), the abaxial surface of the blades and venation with simple, curved, and appressed trichomes (vs. abaxial surface and venation glabrous), a higher number of secondary veins per side (10–18 vs. 9–13) and young branches and petioles pilose (vs. glabrous). The inflorescences of M. quercifolia are pilose with short erect and long curved trichomes (vs. inflorescences puberulous and with glandular trichomes).

Trees up to 10 m tall. Terminal branchlets terete or slightly angled, 1–5 mm diameter, pilose with simple, curved or appressed trichomes, 0.5 mm long, mature branches glabrescent.Terminal buds are densely pilose with long (0.5–1 mm), simple curved trichomes. Leaves alternate; petioles terete or slightly canaliculate, (0.3–) 0.4–0.7 (–0.9) cm × 1–2 mm, pilose with curved and appressed trichomes, pulvinus inconspicuous after drying; blade (4–) 6–12 (–16) × 1.5–3 (–4) cm, narrowly elliptic to oblong elliptic, occasionally slightly falcate, chartaceous, base acute decurrent to the petiole, margin entire, apex acute or acuminate, acumen up to 2 cm ending in a mucro; venation pinnate, eucamptodromous to brochidodromous towards the apex, with 10–18 secondary veins per side with a regular spacing of 0.5–1 cm, tertiary veins with a poorly defined alternate percurrent pattern, resulting in an irregular reticulum in most cases, secondary marginal vein present; adaxial surface with scattered appressed trichomes, eventually glabrescent, midvein immersed pilose to glabrescent and secondary veins flat, abaxial surface with simple, short and curved trichomes, midvein prominent, pilose with simple curved or appressed trichomes, secondary veins prominulous, with simple and curved trichomes. Inflorescence axillary up to 10 cm long, secondary axes up to 1.5 cm long, two times branched, axes citrine (when fresh), densely pilose-puberulous with short erect and long curved trichomes; bracts 1–3 mm long, cymbiform, linear with acute apex, pilose on the dorsal surface, bracteoles 0.7–0.9 × 0.5 mm, suborbicular to ovoid, obtuse to rounded apex and ciliate margin. Flowers subsessile or pedicellate 0.2–0.4 mm; sepals 5, suborbicular to ovate, 0.8–1 × 0.8–1 mm margin, glabrous; outer petals 3, 1.4–1.8 × 1.4–2 mm, same sized or the two lateral narrower than the central, suborbicular, rounded to convex apex, ascending in anthesis, white (when fresh), glabrous; inner petals 2, 0.6– 1.2 × 0.2–0.4 mm, equal or shorter than the stamens, oblong or lanceolate, obtuse, rounded or truncate apex, ascending in anthesis, white (when fresh); stamens 2, 1.2–1.8 mm, connective tissue triangular, obtuse apex; staminodes 3, 0.6–0.8 × 0.6–0.8 mm; ovary 0.7–0.9 × 0.7–0.9 mm, bilocular, subglobose and glabrous, style 0.4–0.6 mm, stigma truncate and slightly divided. Infructescence axes glabrescent, grayish with scarce simple trichomes. Fruits oblique to the axis, suborbicular to obovoid, 1.6–2 × 1.4–1.5 cm; endocarp suborbicular to oblate 0.6–1.2 × 0.8–1.2 × 0.6–1.2 cm, pyrene surface slightly rough and rugose.

Distribution and habitat: — Meliosma quercifolia is an endemic species of the Colombian Andes inhabiting

Andean forests at 1700–2500 m elevation. It has only been collected in the department of Cundinamarca, located in the Eastern Cordillera ( Fig. 4 ). Additionally, the José Celestino Mutis Botanical Garden in Bogotá has a specimen in its living collections.

Phenology: —It flowers between October and January and fruits between April and July.

Etymology: —The specific epithet refers to the similarity between the leaves of the only oak species present in Colombia — Quercus humboldtii ( Fagaceae ), a species with adult non-lobed leaf margins. This species was initially spotted by the Colombian botanist Jesús M. Idrobo Muñóz, who described several species of the genus Meliosma along with the botanist José Cuatrecasas. However, this name was never published, even though Idrobo identified several specimens under this name.

Conservation status: —Considering the diminution and disappearance of the Andean Forest in the country due to anthropic activity primarily driven by ongoing agricultural expansion and livestock farming (see additional comments on Meliosma primogenita ), the natural habitat of this species, with an Area of Occupancy (AOO) of only 16 km 2, restricted to a small region in the department of Cundinamarca in the Eastern Cordillera of Colombia, the existence of only three subpopulations (r = 5 km) corresponding to three localities for this species, and the continued decrease in its area and habitat, it is proposed to include Meliosma quercifolia in the “Endangered” (EN) category of the IUCN according to criteria B2b(ii,iii) related to its reduced AOO. Furthermore, it is essential to note that this species has not been collected or found in any protected area, significantly increasing its vulnerability. The absence of known populations within conservation zones means there are currently no safeguarded populations, further emphasizing the urgent need for protection measures to ensure the species’ long-term survival.

Discussion: — Meliosma quercifolia is a narrowly-distributed species of medium or small-sized leaves (less than 15 cm long) and short petioles (less than 2 cm long), whose combination of characters can be confused with M. meridensis Lasser (1943: 233) from Colombia and Venezuela, M. gracilis Cornejo & Bonifaz (2008: 96) from Ecuador (probably southern Colombia) and M. tachirensis Steyermark & A.H. Gentry (1992: 215) from Colombian eastern Cordillera and Venezuela.

Meliosma gracilis is distinguished by having a paniculate and lax inflorescence up to 30 cm, three times branched, with pedicels 1–2 mm long (vs. racemiform inflorescence up to 10 cm, two times branched and pedicels up to 0.4 mm long). The leaves are longer, 14–30 cm (vs. 6–12 cm) and have a higher number of secondary veins per side, 16–25 (vs. 10–18). Additionally, this species has only been found in the western Andean Forest in Ecuador.

Meliosma meridensis is distinguished by its coriaceous and glabrous leaves (vs. chartaceous leaves with sparse pilose indumentum), rounded apex (vs. acute or acuminate apex), fewer secondary veins (8–12 vs. 10–18) and inconspicuous tertiary venation on the lower surface (vs. prominent tertiary venation on the lower surface). The inflorescences present a puberulous indumentum (vs. pilose), the inner petals are longer (1.4–1.6 vs. 0.6–1.2 mm), and the style is shorter (0.2–0.3 vs. 0.4–0.6 mm).

Meliosma tachirensis has longer petioles (1–4vs. 0.4–0.7 cm)and serrate leaf margins(vs. entire).The inflorescences of M. tachirensis are pyramidal panicles with longer pedicels 0.5–1.5 mm (vs. racemiform inflorescences with shorter pedicels).

Additional specimens examined (Paratypes): — COLOMBIA. Bogotá: Jardín Botánico de Bogotá José Celestino Mutis, Robledal, Colecciones vivas, 4°40’10.8”N, 74°06’01.5”W, 2600 m, 28 January 2002 (fl), G. Morales 1698 (JBB 3733!, UDBC 32071!) ; Cundinamarca: Mun. La Vega, Vda. San Antonio, Finca Buenos Aires. 4°56’52.7”N, 74°21’41.4”W, 1700 m, 31 December 2011 (fl), F. Ávila 1990 (UDBC 28114!, COL 567954!, COL 567999!), ibid. 17 October 2021 (fl), F. Ávila, R. Cortés & D. Ruiz 4552 (HUA!, JAUM!, JBB 32340!, UDBC 49852!) ; Mun. Pacho, Vda. El Hatillo , 03 November 1988 (fr), G. Mahecha 5323 (UDBC 08277!), Vda. La Esmeralda , Finca del señor Arévalo , Quebrada de Los Cristales , 2050 m, 01 September 1974 (fr), G. Mahecha 1610 (UDBC! 4453!, COL 150692!, COL 151929!) ; Mun. Supatá , 2100 m, 01 June 2014 (fr), G. Morales 3677 (JBB 32060!) .

Figures

FIGURE 4. Distribution map of Meliosma primogenita and Meliosma quercifolia.

FIGURE 5. Meliosma quercifolia Idrobo ex D. Ruiz-Mol. & F. Ávila. A. Fertile terminal branch. B. Mature flower showing the relative position of inner petals. C. Central outer petal showing the position of staminode and stamens. D. Left outer petal with adnate staminode. E. Central outer petal with adnate staminode. F. Right outer petal with adnate staminode. G. Lateral view of stamen with adjacent inner petal. H. Ventral view of stamen. I. Dorsal view of stamen. J. Dorsal view of inner petal. K. Ventral view of the inner petal. Scale bar = 1 mm. (A–K from the holotype; Illustration by Omar Bernal).

FIGURE 6. Meliosma quercifolia Idrobo ex D. Ruiz-Mol. & F. Ávila. A. Floral branch bearing lateral inflorescences and detail of flowers on a terminal axis. B.Abaxial surface detail. C. Three outer petals with adnate staminodes. D. Mature flower without outer petals. E. Ovary with disc. F. Dorsal and ventral view of stamens. G. Inner petal. H. Sepal. I. Fruit. (A–H from the holotype, I from Mahecha 5323).

FIGURE 7. Meliosma quercifolia Idrobo ex D. Ruiz-Mol. & F. Ávila. A. General view of fertile terminal branches. B. Detail of inflorescence axis and flowers: yellow arrows pointing to stamens, green arrows pointing to outer petals, orange arrow pointing to barely visible inner petal. (A–B from the holotype; Photos by Rocío Cortés).

FIGURE 8. Meliosma cundinamarcensis Cuatrec. & Idrobo (A–C): A. Inflorescence axis with puberulous indumentum and glandular trichomes. B. Glabrous young branch. C. Glabrous abaxial leaf surface. Meliosma quercifolia Idrobo ex D. Ruiz-Mol. & F. Ávila. (D–F): D. Inflorescence axis with pilose indumentum. E. Young branch with pilose indumentum. F. Abaxial leaf surface and pilose indument on venation. Scale bar = 1 mm. (A–C from R. Cortés et al. 2628 (COL!, UDBC!); D–F from the holotype).