Macrolobium ceriferum A.M.Trujillo & Londoño-Ech., 2023

Trujillo-López, Ana María & Londoño-Echeverri, Yeison, 2023, Novelties in Macrolobium (Detarioideae, Fabaceae) for Northern South America: Two new species and new chorological records from Colombia and Ecuador, Phytotaxa 599 (3), pp. 155-170 : 156-162

Macrolobium ceriferum A.M.Trujillo & Londoño-Ech. , sp. nov. ( Figs. 1 & 2 )

Type: — COLOMBIA. Chocó. Mun. Alto Baudó: Cerca del campamento dos bocas, por la quebrada Munduquera en dirección Oeste por el camino que conduce a Jurubidá, PNN Ensenada de Utría , [181 m], 5°55ʹ35ʹʹN, 77°09ʹ30ʹʹW, 21 May 1990 (fl & fr), C. Barbosa 6697 (holotype: HUA-134863!, isotypes: HUA-134787!, FMB-56077!) .

Diagnosis:— Macrolobium ceriferum differs from morphologically similar Macrolobium pittieri (Rose in Britton & Rose 1930: 226) Schery in Woodson & Schery (1951: 33) by its leaflets surface bullate, discolorous, whitish and sparsely dark-punctate abaxially (vs. not bullate, concolorous, not whitish and epunctate abaxially), its secondary veins raised abaxially, impressed adaxially (vs. slightly raised in both surfaces), its shorter inflorescence axis 11.1–18.1 mm long, surface scaly waxy (vs. ca. 35 mm long, not scaly waxy), its shorter bracts 1.3–1.8 mm long (vs. ca. 2.5 mm long), its pedicels surface scaly waxy (vs. not scaly waxy), its bracteoles very sparsely puberulous adaxially, otherwise glabrous, surface scaly waxy abaxially (vs. glabrous, not scaly waxy abaxially), its hypanthium very sparsely puberulous, surface smooth waxy (vs. glabrous, not smooth waxy), its smaller sepals 9–12.9 × 1.7–3.2 mm, sparsely puberulous in both surfaces, sparsely scaly waxy abaxially, margin ciliate (vs. 17–18.5 × 4 mm, margin sparsely and irregularly ciliolate, otherwise glabrous, not scaly waxy), its smaller petal 11.7–17.8 × 4.5–7.1 mm, 0.7–1.1 mm long unguiculate (vs. ca. 43 × 15 mm, 5 mm long unguiculate), its shorter filaments 18.5–22.9 mm long, glabrous (vs. ca. 25 mm long, villose basally), its shorter anthers 3.1–3.4 mm long (vs. ca. 5 mm long), its ovary puberulous marginally, smooth waxy (vs. pilosulose marginally, not smooth waxy), its style puberulous basally (vs. pilosulose basally), fruits sparsely puberulous marginally (vs. glabrous throughout).

Trees 6–8 m tall, indumentum whitish to pale yellowish throughout, cataphylls not seen, branchlets glabrous, dark greyish brown, slightly lustrous, bearing ca. 3 leaves; stipules 3.8–4.1 × 1.2–1.5 mm, lanceolate, acute and straight apically, glabrous on both surfaces, caducous, margin entire, ciliate. Leaves 2-foliolate, petiole 2–6.6 mm long, adaxially flattened and slightly canaliculate at apex, sparsely puberulous, rachis mucro ca. 6.1 mm long; petiolules ca. 0.5 mm long, glabrous; leaflet blades (20.1–) 23.5–35.6 × (6.3–) 9–11.8 cm, elliptic to oblanceolate, asymmetrical, basally obtuse and truncate to slightly cordate at basiscopic half, cuneate at acroscopic half, apically acute and straight; puberulous toward the midvein and secondary veins abaxially, glabrous adaxially; obliquely attached to petiolule, bullate, discolorous; abaxial surface whitish, sparsely dark-punctate, smooth waxy, the wax red-punctate; midvein and secondary veins raised abaxially, impressed adaxially, secondary veins 20–27 pairs, brochidodromous, intersecondary veins present, tertiary veins percurrent, margin entire. Inflorescences as racemes 11.1–18.1 mm long (axis including peduncle), axillary to fallen leaves, i.e. ramiflorous to cauliflorous, 1.1–4.9 mm long pedunculate, 15–32-flowered, glabrous, surface scaly waxy on the axis, the wax red-punctate; bracts 1.3–1.8 × 1–1.5 mm, ovate, acute and straight apically, caducous, margin entire, ciliate; pedicels (3.8–) 5.1–13.2 mm long (fruiting pedicel not seen), glabrous, surface scaly waxy, the wax red-punctate; bracteoles 7.9–13.3 × 3.8–4.8 mm, obovate, obtuse and rounded apically, very sparsely puberulous adaxially, otherwise glabrous, opening completely abaxially and incompletely on the adaxial side of the flower, abaxial surface scaly waxy, the wax red-punctate, adaxial surface smooth waxy; hypanthium (6.1–) 7.7– 11.9 × 1.7–2 mm (including stipe), cylindric, curved, gibbose basally, 0.7–1.3 mm long stipitate, sparsely puberulous, surface smooth waxy, the wax red-punctate; calyx 4-merous, sepals 9–12.9 × 1.7–3.2 mm, oblanceolate, obtuse and rounded apically, sparsely puberulous in both surfaces, abaxial surface sparsely scaly waxy, the wax red-punctate, adaxial surface smooth waxy, all sepals equal in shape and size, margin entire, ciliate; single petal 11.7–17.8 × 4.5–7.1 mm (including claw), elliptic, obtuse and rounded apically, 0.7–1.1 mm long unguiculate, sparsely puberulous on midvein adaxially, otherwise glabrous and papillose, margin entire, undulate; androecium 3-merous, filaments 18.5– 22.9 mm long, flattened with a groove adaxially, glabrous, papillose, anthers 3.1–3.4 × 1.9–2.2 mm, broadly ellipsoid, glabrous, papillose; gynophore 1.4–1.6 mm long, puberulous, surface smooth waxy, the wax red-punctate, inserted at top of the adaxial wall of the hypanthium, ovary 4.2–4.6 × 1.2–1.5 mm, oblong, puberulous marginally, otherwise glabrous, surface smooth waxy, the wax red-punctate, 3–5-ovulate, style 19.9–24.2 mm long, puberulous basally to sparsely puberulous apically, surface smooth waxy, the wax red-punctate, stigma papillose. Fruits 13.6–16.6 × 5.1–5.6 cm (without stipe, this not seen), narrowly obovate, obtuse and rounded basally (over stipe), obtuse and obliquely truncate apically, sparsely puberulous on the margin, otherwise glabrous, surface smooth waxy, the wax red-punctate, dehiscent, 2–3 seeds per fruit. Seeds ca. 2.7 × 1.6 cm, oblong to elliptic, surface smooth waxy, the wax red-punctate.

Distribution and habitat:— Macrolobium ceriferum is endemic to western Colombia, where occurs in the Pacific biogeographical region. It has been collected in the departments of Chocó and Valle del Cauca, on the municipalities of Alto Baudó and Buenaventura respectively. Macrolobium ceriferum inhabits on the lowland rainforest near to banks of the Baudó and Calima rivers, at elevations between 50 and 182 m, under equatorial rainforest climate (Af) according the Köppen-Geiger climate classification ( Kottek et al. 2006) ( Fig. 3 ).

Phenology:— Flowering in May and December and fruiting in May.

Conservation status:— Macrolobium ceriferum is only known by two subpopulations, both outside of any official protected areas, and with an small area of occupancy (AOO) of 8 km 2. The subpopulations are isolated between them by ca. 200 km, and one of these is located to less than 13 km from Buenaventura city. Its habitat is inside to areas of high mining and selective logging impact, which, although not evident in satellite images, are reported as the main economic activities of the Pacific biogeographical region and produce the mains environmental problematics for the region, such deforestation, soils degradation, disturb to water courses, among others ( Moreno & Ledezma-Rentería 2007). According to Rangel-Ch. (2014), the deforestation in this area is estimated at 25–36 %, causing deterioration and loss of habitat quality for plant communities. For these reasons, Macrolobium ceriferum is here proposed under “Endangered” EN category.

Etymology:— The epithet ceriferum is derived from the Latin “cera” (wax) and the suffix “-fer” (bearing), indicating that this species bears wax at its surfaces, referring to both, the scaly wax at the inflorescence and flower axes, and the smooth wax at the abaxial surface of leaflet blades, features that help to recognize the new species.

Additional specimen examined (paratype):— COLOMBIA. Valle del Cauca. Mun. [Buenaventura]: Bajo Calima, near San Isidro, N of Buenaventura , Cartón de Colombia concession, tropical wet/ pluvial forest transition above mouth of Río Calima , 50 m, 4°0ʹ0ʹʹN, 77°0ʹ0ʹʹW, 8 December 1981 (fl), Al Gentry 35466 (COL-258969 [digital image!], MO-3011247 [n.v.], MO-3011248 [n.v.], US-2981970 [digital image!]) .

Notes:— Macrolobium ceriferum belongs to Macrolobium sect. Stenosolen due to its bracteoles opening completely abaxially and incompletely on the adaxial side of the flower, hypanthium cylindric, sepals four, equal in shape and size and petal with a short claw.

This new species is sympatric with Macrolobium archeri Cowan (1953: 334) , both restricted to the Pacific biogeographical region in Colombia, however, M. ceriferum differs from it by its leaflet blades bullate, discolorous, whitish abaxially (vs. not bullate, concolorous, not whitish in M. archeri ), its secondary veins raised abaxially, impressed adaxially (vs. flat to slightly raised in both surfaces), its shorter inflorescence ramiflorous to cauliflorous 11.1–18.1 mm long (vs. inflorescence terminal ca. 35 mm long), its inflorescence axis glabrous, scaly waxy (vs. minute puberulous, not scaly waxy), its smaller bracts 1.3–1.8 × 1–1.5 mm (vs. bracts ca. 3 × 1.5–2 mm), its smaller bracteoles 7.9–13.3 × 3.8–4.8 mm (vs. ca. 17 × 6.5 mm), its shorter hypanthium (6.1–) 7.7–11.9 mm long, 0.7–1.3 mm long stipitate (vs. ca. 14 mm long, ca. 4.5 mm long stipitate), its smaller sepals 9–12.9 × 1.7–3.2 mm (vs. 20–22 × 4.5–7 mm), its smaller petals 11.7–17.8 × 4.5–7.1 mm, 0.7–1.1 mm long unguiculate (vs. ca. 28 × 12 mm, sessile), sparsely puberulous on the midvein adaxially (vs. glabrous), its shorter filaments 18.5–22.9 mm long (vs. ca. 27 mm long), glabrous (vs. pilose basally), its shorter anthers 3.1–3.4 mm long (vs. 9–10 mm long), its style puberulous basally to sparsely puberulous apically (vs. glabrous), and its smaller ovary 4.2–4.6 × 1.2–1.5 mm (vs. 5–7 × 2 mm). Furthermore, Macrolobium ceriferum shares with Macrolobium dressleri Cowan (1973: 451) and Macrolobium floridum Karsten (1858: 151) their leaves 2-foliolate, their leaflet blades basally obtuse and truncate to slightly cordate at basiscopic half, their bracteoles and hypanthium with puberulous indumentum, but other characters distinguish M. ceriferum from these two species and are provided in Table 1 together to differences from M. pittieri and M. archeri .

Macrolobium archeri is a widely used name for specimens from both Amazon and Pacific regions in Ecuador and Colombia, however, the specimens review carried out in this study allows conclude that there are different taxonomic entities under this name. Macrolobium archeri remains endemic to the Pacific biogeographical region in Colombia, in the departments of Choco and Valle del Cauca. All additional records from the Ecuadorian Amazon and even some from Colombian Pacific, correspond to undescribed species that will be published in ongoing studies focused on give clarity about this species group.

The description of M. ceriferum increases the number of species for the M. sect. Stenosolen to 20.

Figures

FIGURE 1. Holotype of Macrolobium ceriferum.

FIGURE 2. Macrolobium ceriferum: A. Vegetative branchlet and part of floriferous branch, B. Detail of leaflet abaxially, C. Inflorescence (arrow indicates the insertion of the inflorescence), D. Flower, E. Pedicel and hypanthium, F. Pedicel, G. Bracteole (left abaxial, right adaxial), H. Detail of bracteole adaxially, I. Sepal (left abaxial, right adaxial), J. Petal adaxially, K. Filament, L. Detail of filament, M. Anthers (left adaxial, right abaxial), N. Gynoecium, O. Hypanthium and detail of ovary, P. Fruit. [A from Al Gentry 35466, Source: National Museum of Natural History Smithsonian Institute, US2981970, Available: http://n2t.net/ark:/65665/36927828c-0644-4363- bfb3-0f09e8304f55, B–P from the holotype. Digital plate by Y. Londoño.]

FIGURE 3. Geographical distribution of Macrolobium ceriferum and M. longistipitatum, and of M. machaerioides from Colombia and Ecuador (type locality georeferenced, indicated with *).