Macrolobium longistipitatum 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 : 162-166

Macrolobium longistipitatum A.M.Trujillo & Londoño-Ech. , sp. nov. ( Figs. 4 & 5 )

Type:— COLOMBIA. Antioquia. Mun. San Luis: Quebrada “La Cristalina”, Sector NE, 760–770 m, 6°00ʹ00ʹʹN, 74°45ʹ00ʹʹW, 22 March 1987 (fl), J. G. Ramírez & D. Cárdenas 708 (holotype: JAUM-19258!, isotypes: HUA-75151!, COL-323419 [digital image!]) .

Diagnosis:— Macrolobium longistipitatum differs from all congeners by the following morphological combination: stipules caducous, leaves with numerous leaflets (17–39 pairs) and shorter distance between leaflets (2–5.8 mm long), leaflet blades slightly rounded and occasionally retuse apically, with veins prominent up the fourth-order on both surfaces, secondary veins closely parallel; longer and (sub-) terminal inflorescences (7.5–16.7 cm long including peduncle), shorter peduncle (1.2–3.3 mm long), shorter flowering pedicel (0.7–1.3 mm long), bracteoles glabrous, single petal long-unguiculate, hypanthium cupular with longer stipe (1.7–3.9 mm long stipitate), sepals 4, elliptic to oblong, petalodia 2, staminodes 2, filaments of fertile stamens sparsely villose at base and ovary glabrous.

Trees 12–40 m tall, cataphylls 0.4–3.8 × 0.9–3.8 mm, broadly ovate, rounded and obtuse apically, occasionally ripped and apparently emarginate, abaxially puberulous at base, sparsely puberulous towards apex, adaxially glabrous and papillose, papillae conspicuously orange, caducous, margin entire; branchlets striate, villose, glabrescent, indumentum shiny brownish red, whitish with age, branchlet surface dark red, smooth waxy with age, bearing 9–12 leaves; stipules (3.8–) 8.9–14.8 × 1.2–3.5 mm, lanceolate, obtuse and rounded at the apex, sparsely puberulous abaxially, otherwise glabrous, papillose and sparsely smooth waxy adaxially, caducous, veins parallel basally becoming reticulate apically, raised abaxially, flat adaxially, margin entire, papillose. Leaves pinnate, with 17–39 pairs of leaflets, distichous, indumentum shiny brownish red but whitish with age throughout leaves; petiole 1.7–5.2 mm long, slightly canaliculate adaxially, villose; rachis 6.0– 20.2 cm long, winged adaxially, villose, wings ca. 0.5 mm high, revolute when mature (flat when young), villose, distance between leaflets 2–5.8 mm long; leaflet blades 5.4–23.5 × 2.2–6.6 mm, oblong, lanceolate or ovate, basally obtuse and rounded at basiscopic half, truncate to cuneate and auriculate at acroscopic half, apically obtuse and slightly rounded, occasionally retuse, villose at very base and pilosulose on midvein in both surfaces, surfaces otherwise glabrous, concolorous; veins up to fourth-order raised on both surfaces, secondary veins numerous, not clearly differentiable from intersecondary veins, closely parallel, mainly brochidodromous, some veins cladodromous, intersecondary veins present, tertiary veins ramified, margin entire, ciliate. Inflorescences as racemes 7.5–16.7 cm long (axis including peduncle), (sub-) terminal, glabrous, surface smooth waxy basally, 1.2–3.3 mm long pedunculate, 36–75-flowered; bracts 6.9–8.6 × 2.5–3.6 mm, elliptic, acute and straight apically, glabrous and sparsely smooth waxy on both surfaces, early caducous, margin entire; pedicel 0.7–1.3 × 0.8–1.1 mm (fruiting pedicels 5.1–8.2 mm long), glabrous, bracteoles 5.6–8 × 1.7–2.9 mm, oblong, obtuse and rounded apically, glabrous and sparsely smooth waxy on both surfaces, longitudinally ridged at medial abaxial surface, opening completely in both sides of the flower but belatedly on the adaxial side, caducous, margin entire; hypanthium 4.5–5.9 × 1.1–2.1 mm, (including stipe), 1.7–3.9 mm long stipitate, cupular, zygomorphic, glabrous, calyx 4-merous, sepals 6.5–9.8 × 2.2–3.9 mm, elliptic to oblong, obtuse and rounded to straight apically, glabrous and papillose in both surfaces, slightly unequal in shape and size, margin entire; single petal 15.2–15.8 × 6–6.1 mm (including claw), obovate, obtuse and rounded apically, 6.3–6.8 mm long unguiculate, villose on midvein adaxially, otherwise glabrous and papillose, occasionally smooth waxy at abaxial surface, margin entire, undulate; petalodia 2, 2.3–6.6 × 0.6–1.9 mm, lanceolate, obovate to oblong, acute and straight apically, glabrous and papillose in both surfaces, borne at each lateral side of single petal; filaments 21.1–27.2 mm long, flattened adaxially, sparsely villose, anthers 1.7–1.8 × 0.7–0.9 mm, ellipsoid, very sparsely villose, papillose; staminodes 2, 0.7–1.1 × 0.2–0.4 mm, ovate to lanceolate, acute and straight to rounded apically, glabrous in both surfaces, alternate with stamens (i.e., at each lateral side of central stamen); gynophore 2.6–4 mm long, glabrous, inserted near the apex of the adaxial wall of the hypanthium, ovary 4.1–4.9 × 1.3–1.8 mm, oblong, glabrous, 3-ovulate, style 20.9–26.6 mm long (including stigma), glabrous, stigma papillose. Fruits 14.6–18 × 5.3–6.7 cm (including stipe), 0.6–0.7 cm long stipitate, oblanceolate to obovate, obtuse and rounded basally, obtuse and obliquely truncate apically, glabrous, sparsely dark-punctate, dehiscent, 2–3 seeds per fruit. Seeds 2.8–3.4 × 2.2–2.9 cm, (nearly) orbiculate, glabrous, dark brown, surface venulose.

Distribution and habitat:— Macrolobium longistipitatum is endemic to central Colombia, where occurs in the limits between Andes and Magdalena Valley biogeographical regions at the eastern slopes of the Central Cordillera. It has been collected in the department of Antioquia, on the municipalities of Maceo and San Luis. Macrolobium longistipitatum inhabits lowlands rainforest, at elevations between 570 and 970 m, under equatorial rainforest climate (Af) according the Köppen-Geiger climate classification ( Kottek et al. 2006) ( Fig. 3 ).

Phenology:— Flowering in March and August and fruiting in February, March, November and December.

Etymology:— The epithet longistipitatum is derived of the Latin “longus” (long) and “stipitatum” (that has stipe), indicating that this species has a hypanthium long-stipitate, an unique feature for species with pinnate leaves within M. sect. Macrolobium .

Conservation status:— Macrolobium longistipitatum has an area of occupancy (AOO) of 12 km 2, an extent of occurrence (EOO) of 336 km 2, and has three known subpopulations. All subpopulations occur outside of protected areas and are located less than 10 km from an urban center. The species is found in very small and fragmented forest patches (<50 km 2), which are in continuous decline due to agricultural expansion frontier and the deforestation, which is considered one of the main environmental disturbs at the Magdalena Valley Region, giving a category of “deforestation hotspot” in Colombia ( Sánchez-Cuervo & Aide 2013). In addition, innumerable limestone mining projects surround the potential habitat of M. longistipitatum , which subpopulations are located less than 9 km from the mentioned projects. For these reasons, M. longistipitatum is here propose under “Endangered” EN category.

Additional specimen examined (paratypes): — COLOMBIA. Antioquia. Mun. Maceo: Vereda San Pedro, Finca San Pedro, 970 m, 6°24ʹ13ʹʹN, 74°45ʹ38ʹʹW [6°27ʹ43.89ʹʹN, 74°47ʹ16.51ʹʹW], June 2009 (st), P. A. Morales et al. 308 (HUA-188544!); Vereda San Pedro, Reserva Natural Hacienda San Pedro, 925 m, 6°27ʹ43.89ʹʹN, 74°47ʹ16.51ʹʹW, 27 March 2023 (st), A. M. Trujillo 1060 ( HUA!); ibid., A. M. Trujillo 1061 ( HUA!). Mun. San Luis: Vereda Altavista-Río Claro, 690–710 m, 5°57ʹ23.12ʹʹN, 74°51ʹ53.87ʹʹW, 5 June 2018 (st), J. D. Acosta et al. 726 (MEDEL-67805!); Autopista Medellín-Bogotá, sector Río Samaná-Río Claro , camino hacia la vereda La Primavera, 790 m, 13 November 1982 (fr), A. Cogollo & C. C. Estrada 223 (JAUM-12798!, JAUM-12799!, MO-3094192 [n.v.]); Autopista Medellín-Bogotá, sector Río Samaná-Río Claro , Puente sobre la quebrada La Cristalina, 790 m, 19 December 1982 (fr), A. Cogollo & C. C. Estrada 320 (JAUM-13135!, MO-3094193 [n.v.]); Autopista Medellín-Bogotá, Sector Río Samaná-Río Claro , Carretera Autopista-Altavista, 700 m, 5°57ʹ19.40ʹʹN, 74°51ʹ54.82ʹʹW, 24 August 1982 (fl), J. J. Hernández & S. E. Hoyos 487 (COL-281685 [digital image!], COL-281686 [digital image!], HUA-16333!); Quebrada “La Cristalina”, Sector SE, 570–770 m, 6°00ʹ00ʹʹN, 74°45ʹ00ʹʹW, 23 February 1987 (fr), J. G. Ramírez & D. Cárdenas 631 (COL-323164 [digital image!], HUA-75276!, JAUM-20980!, MO-4000714 [n.v.]).

Notes:— Macrolobium longistipitatum belongs to M. sect. Macrolobium due to its bracteoles opening completely in both side of the flower, hypanthium cupular and petal long-unguiculate. Although the bracteoles remain attached at early anthesis (as shown in Fig. 5-E ), these opening completely with age and even are easily detach when handled.

The specimens of Macrolobium longistipitatum were previously identified under the names Macrolobium gracile Spruce ex Bentham (1870: 223) and Macrolobium machaerioides . Due fact, M. longistipitatum can be confused with these two species by its leaves with numerous leaflets, the base of leaflets auriculate on the acroscopic half (shared with M. machaerioides ), its shorter pedicel, and filaments indumented at the base ( M. machaerioides villose, M. gracile villosulose), however, the new species can be differentiated from M. gracile by both vegetative and reproductive features: its leaflet veins up to fourth-order raised on both surfaces (vs. secondary to high-order veins strongly obscure in both surfaces, not discernable, immersed in a thick smooth waxy cover abaxially), its inflorescence (sub-) terminal, 7.5–16.7 cm long, axis glabrous (vs. axillary, 1–6.5 cm long, axis puberulous), its bracteoles glabrous (vs. at least pilose, pilosulose, puberulous or villosulose), its sepals 4 (vs. sepals 5), its ovary glabrous (vs. villose or pilose marginally, glabrous laterally). From Macrolobium machaerioides the new species can be recognized by its leaves with 17–39 pairs of leaflets (vs. 13–21), its leaflets slightly rounded, occasionally retuse apically, concolorous (vs. strongly emarginate apically, discolorous), its leaflet veins raised up to fourth-order on both surfaces (vs. secondary to high-order veins strongly obscure in both surfaces, not discernable, immersed in a thick smooth waxy cover abaxially), its leaflet margin ciliate (vs. glabrous), its longer and (sub-) terminal inflorescence, 7.5–16.7 cm long, axis glabrous (vs. axillary, 1.5–3 cm long, axis puberulous), its bracts 6.9–8.6 × 2.5–3.6 mm (vs. 1.5–2 × 1 mm), its bracteoles glabrous (vs. shortpilosulose and puberulous abaxially, villose adaxially), its hypanthium 4.5–5.9 mm long, long-stipitate (vs. 1 mm long, sessile), its sepals 4 (vs. sepals 5), its ovary glabrous (vs. villose marginally, glabrous laterally). Macrolobium longeracemosum Amshoff (1948: 389) , is also similar to the new species, see Table 2 for the differences between these species.

The new species represents the first and unique record of the M. sect. Macrolobium for the Inter-Andean Valleys of the northern Andes (all other species belonging it occurs at east of the Andes, mainly at Amazon, Guianas and Atlantic Forest regions), which may have important implications for future biogeographical and evolutionary studies in the genus. All records of M. sect. Macrolobium from west of Andes in Ecuador and Colombia provided in the distribution map by Murphy et al. (2018) are wrongly georeferenced or misidentified; due fact, their specimen labels indicate that were collected at east of Andes in Amazon Region and others no correspond to the identification provided.Additionally, the records for the section at Inter-Andean Valleys of central Colombia correspond to M. longistipitatum . The specimen R. Espinoza 92 (MO) identified as Macrolobium microcalyx Ducke (1932: 729) and cited by Murphy et al. (2018) from Costa Rica was well georeferenced but was not available to examine in this study, however, its identification seems doubtful. This specimen and some duplicates were previously identified under genus Clusia Linnaeus (1753: 509) and its field observations (Epiphyte to 15 m. Fruit immature green) matched with this genus; furthermore, M. microcalyx was described based on Amazonian specimens. While this specimen and its duplicates are not observed, it is not possible to clarify its identity, or ensure that it is a mixed collection, or that it is an error in databases.

The description of M. longistipitatum increases the number of species for M. sect. Macrolobium to 57.

Figures

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

FIGURE 4. Holotype of Macrolobium longistipitatum.

FIGURE 5. Macrolobium longistipitatum: A. Flowering branch, B. Leaflets (arrow indicates the abaxial surface), C. Flower, D. Bract abaxially, E. Bracteoles abaxially, F. Pedicel, hypanthium, base of filament and ovary (arrow indicates the indument of filament), G. Sepals adaxially, H. Petal adaxially, I. Petalodia adaxially, J. Filament, K. Anthers (left abaxial, right adaxial) L. Staminodes, M. Stigma, N. Fruit, O. Seed. [A, C, H, M from J. J. Hernandez et al. 487, B from P.A. Morales 308, D–G, I–L from J. G. Ramírez et al. 708, N from leaf A. Cogollo et al. 223 & right A. Cogollo et al. 320, O from J. G. Ramírez et al. 631. Digital plate by Y. Londoño.]