Lonchocarpus verticillatus Ariza-Cortés, C. Rivera & Zapata-Corr., 2023

Ariza-Cortés, William, Jiménez, Cristiam Camilo Rivera & Correa, Diego Alejandro Zapata-, 2023, Lonchocarpus verticillatus (Leguminosae-Papilionoideae): A new species from Seasonally Dry Tropical Forest in Colombia, Phytotaxa 622 (2), pp. 146-154 : 147-151

Lonchocarpus verticillatus Ariza-Cortés, C. Rivera & Zapata-Corr. , sp. nov. ( Figs. 1–3 )

Type:— COLOMBIA. Antioquia: Mun. Venecia, corregimiento de Bolombolo, predio MarValle , dos km al sur del corregimiento, 667 m, 5°57’32.26′′N, 75°50’29.91′′W, 31 July 2021 (bud, fl), C. Rivera, W. Ariza, D. Zapata-C. & M. Cepeda 1370 (holotype UDBC!; isotypes: COL!, HUA!, TOLI!) .

Diagnosis: — Lonchocarpus verticillatus is similar to Lonchocarpus berriozabalensis Miranda ex M. Sousa (2009: 244) from Central America but can be distinguished by its whorled leaves (vs. distichous to occasionally congested leaves at the end of branches in L. berriozabalensis ), laxiflorous inflorescences up to 31.5 cm long (vs. densiflorous inflorescences up to 18 cm long), flower stalks 5–12 mm long (vs. 1.5–3 mm long) and pedicels 4–11 mm long (vs. 2.5–4 mm long).

Tree, evergreen, 7–18 (–25) m tall, trunk base slightly ribbed, up to 45 cm in diameter; outer bark lenticellate and slightly fissured, grayish to light brown, living bark cream, no exudate; terminal branches cylindrical or angular, 0.4–0.9 cm diam., fistulose, glabrous, slightly fissured, with abundant lenticels, 0.5–1 mm long, elliptical to lanceolate, cream, irregularly arranged. Stipules free, deciduous, on either side of the buds, orbicular, 2–2.8 × 2 –2.5 mm, glabrous or sparsely puberulent toward the center abaxially. Leaves imparipinnate, verticillate, with 3–8 leaves per nude, subopposite, rarely alternate spiral, (15)19–39(47) cm long, (11–)13–15(–17) leaflets opposite or rarely alternate, subopposites in the basal leaflets; pulvinus 0.7–1 cm long., rough longitudinally; pulvinulated petiole, 5.5–10.5 cm long., rachis 10.5–18.5 cm long, both cylindrical or slightly cylindrical adaxially; petiolules 0.4–0.9 cm, ribbed adaxially, rough transversely, glabrous; leaflets punctate, 3.7–8.8 × 1.2–3.4 cm, opposite, subopposite, occasionally alternate, basal leaflets elliptical and ovate-elliptic, distal leaflets elliptic and oblong-elliptic, terminal leaflet elliptical and rarely broadly elliptic, base generally symmetrical, occasionally acute in the basal leaflets, sometimes obtuse, straight or convex, insertion of the lamina occasionally asymmetrical, apex acute or acuminate-attenuated, margin slightly revolute, carthaceous, olive-green dry leaflets, concolorous, glabrous, distance between each pair of leaflets regular, (0.8) 2–3.5 cm; secondary veins eucamptodromous(6)7–10(12) pairs, marginal secondary vein present, slightly thickened; 0–1 intersecundary veins per intercostal space, parallel to adjacent secondary veins; tertiary vein fabric irregular reticulate, occasionally alternate percurrent, epimedial tertiaries reticulate, exterior tertiaries course looped and tertiary veins occasionally margin ending; quaternary vein fabric irregular reticulate; well-developed, polygonal areoles; middle vein adaxially immersed, abaxially prominent, other orders of venation adaxially prominulos, abaxially flat, to slightly prominulous. Pseudoracemes 5.5–31.5 cm long, axillary, solitary, erect, lax; peduncle (1.3–) 2–13 cm long; rachis 4.2–20.5 cm, cylindrical in green, angled, 1–2.5 mm diam., glabrous, dark brown in dry material; ovate bracts, 0.8–1 mm long, rounded apex, hyaline margin, ciliate, whitish trichomes; peduncle 0.5–1.2 cm long, terete, glabrous; Two secondary bracts on the outer part of the apex of the secondary axis, ovate, 0.4–0.6 mm long, apex rounded, hyaline, ciliate, abaxially glabrous; pedicels 4–11 mm long, bracteoles located in the upper half of the pedicel length, ovate, 0.5 × 0.3 mm, ovate, ciliate margin, adaxially strigulose, particularly towards the center, abaxially glabrous. Flower bud ellipsoid. Flowers 1.5–1.7 cm long; calyx 3.5–4.5 × 4.7–5.1 mm, violet or lilac, subtruncated, cupuliform, carthaceous, brown, abaxially glabrous, adaxially puberulent in the subapical region, ciliolate margin; corolla lilac or light pink, standard 1.3–1.5 × 1.3–1.5 cm, reflex, with a white spot at the base, suborbicular, broadly ovate, apex emarginate, sinuous margin, basal callous auricles, 1–1.25 mm wide, adaxially glabrescent, abaxially puberulent, with abundant adpressed trichomes on the basal third, claw 1–1.5 × 1 mm; wings 1.4–1.5 × 0.4–0.5 cm, falcate or oblong-falcate, auriculate base, rounded apex, abaxially puberulent through the central groove, claw ca. 4 mm, keel 1.3–1.4 × 0.4–0.5 cm, elliptical-falcate, acute apex, acute base, umbonds, junction segment between keels 1.5–2.5 mm, abaxially puberulent, mainly towards the apex, claw 4–4.5 mm; androecium 1.4–1.6 cm long, staminal tube 0.8–1.2 cm long, pseudomonadelphous, glabrous, free portion of filament 2–3.5 mm long, curved, anthers ca. 0.9 mm long; pistil 1 × 0.4–0.5 cm long, ovary 0.7–0.8 cm long, densely covered by adpressed trichomes, grayish, style 0.7–0.9 cm long, curved, strigose, spherical stigma ca. 0.2 mm, puberulent, ovules 5–7. Legume, 6.5–16.8 × 2.7–4.2 cm, oblong or oblong-elliptic, occasionally falcate, vexillary margin ribbed, acute base, cuneate, acuminate apex, slightly constricted between seeds, coriaceous, glabrous, 1–3 seeds, persistent calyx. Seeds, 0.9–1.7 × 0.6–0.9 cm, reniform.

Distribution and habitat: —The species is found in both dry and humid forests of the Cauca River Canyon in the department of Antioquia Colombia, at elevations between 250 and 670 m ( Fig. 4 ). It occurs in relicts of riparian vegetation and isolated trees within pastures dedicated to livestock. In the type locality, it is associated with species such as Luetzelburgia jacana D.B.O.S. Cardoso (2018: 937-940) , Zanthoxylum caribaeum Lamarck (1786: 39) , Z. schreberi (J.F. Gmelin 1791: 498) Reynel (2015: 22) , Z. martinicense ( Lamarck 1792: 334) Candolle (1824: 276) ( Rutaceae ), Ficus insipida Willdenow (1806: 1143) ( Moraceae ), Machaerium kegelii Meisner (1848: 257) ( Fabaceae ), Aiouea montana ( Swartz 1788: 65) R. Rohde (2017: 1102) , Brosimum alicastrum Swartz (1788: 12) , Styphnolobium sporadicum M. Sousa & Rudd (1993: 279) , among others.

Phenology: —Collected with flowers in March, July, and August and with fruit in July and August.

Etymology: —The specific epithet refers to the unique verticillate leaf arrangement within the genus.

Local name: —In its type locality, this species is commonly known as “matarratón” due to its morphological resemblance to the species Gliricidia sepium ( Jacquin 1760: 28) Kunth ex Walpers (1842: 679) . In the municipality of Briceño, it is known as “Aceituno,” as recorded in the specimen (C. Velásquez-Rúa & G. Holguín 5775, HUA-168637).

Conservation status: —The tropical dry forest in the Cauca River Canyon has undergone a drastic transformation because of livestock farming, agricultural activities, and the implementation of hydroelectric and road infrastructure projects. Recently, urban expansion, driven by tourism growth and mining concessions, represents another threat to the area’s vegetation cover. Under this scenario, Lonchocarpus verticillatus has only been recorded in four localities, in small forest fragments (<500 km 2) highly intervened and generally associated with streams. Considering the reduced area of occupation (AOO = 16 km 2) and extent of occurrence (EOO = 263 km 2); the absence of protected areas in the occurrence sites, the progressive deterioration of its habitat quality, and the record of only two subpopulations, is proposed to include this species in the EN (Endangered) category according to the IUCN criteria B1a+B2ab(iii) ( IUCN, 2012).

Additional specimens examined (paratypes): — COLOMBIA. Antioquia: Mun. Briceño, predio Capitán , 323 m, 07°08’17.34”N, 75°38’36.65”W, 14 May 2015 (fr), A. Caro et al. 285 ( MEDEL-64403 !); ibid., (fl), A. Caro et al. 286 ( MEDEL-64404 !); Mun. Briceño, cuenca baja del río San Andrés, margen derecha, cerca al corregimiento El Valle de Toledo , 450 m, 07°03’37”N, 75°40’40”W, March 2007 (fl), C. Velásquez-Rúa & G. Holguín 5775 ( HUA-168637 !); Mun. Ituango, La Tesalia , 283 m, 07°08’27.93”N, 75°39’0.4”W, 20 March 2015 (fl), A. Caro et al. 251 ( MEDEL-64369 !); Mun. Ituango, corregimiento de El Aro, vereda Filadelfia , 250 m, 3–17 February 2010 (st), D. Molina et al. 1024 ( HUA-190251 !); Mun. Tarso, vereda San Francisco , margen izquierda del río Mulatos , 586 m, 5°55’08”N, 75°50’01”W, 22 July 2020 (fr), J.P. Tobón et al. 3430 ( JAUM-85691 !); ibid., 595 m, 5°55’09”N, 75°50’03”W, 9 July 2020 (bud, fl), J.P. Tobón et al. 3395 ( JAUM-85685 !); Mun. Venecia, corregimiento de Bolombolo, predio MarValle , 662 m, 5°57’33.87”N, 75°50’28.61”W, 8 July 2019 (fr), C. Rivera & Y. Guzmán 1348 ( UBDC!); ibid., 667 m, 5°57’32.26”N, 75°50’29.91”W, 31 July 2021 (fr), W. Ariza-C. et al. 9523 ( UBDC, COL) .

Notes: —According to Sousa (2009a), the species is circumscribed within the section Punctati ( Pittier 1917) ; however, phylogenetic analyses show that the group is not monophyletic (Silva et al. 2012). It is necessary to conduct phylogenetic studies in order to establish the systematic position of this species into the Millettieae tribe. Lonchocarpus verticillatus can be easily distinguished from other species of the genus for being the only one with whorled leaves. Their congeners species exhibit an alternate pattern of leaf arrangement, with a distichous or occasionally spiraled arrangement on the branches, We decided to compare the new species with L. berriozabalensis , because after reviewing all the species described and currently circumscribed within the genus Lonchocarpus , this species was considered to have morphological similarity with L. verticillatus , this is mainly due to the presence of alternate spiral leaves clustered at the ends of the branches with congested appearance ( Sousa et al. 2014), however, a comparison of some morphological characteristics between Lonchocarpus verticillatus and L. berriozabalensis is presented in Table 1 , in order to distinguish them.

The continuous discovery of taxonomic novelties in the Cauca River Canyon highlights the need to continue to characterize and monitor natural vegetation remnants in the area. Lonchocarpus verticillatus shares the same distribution area with Luetzelburgia jacana D.B.O.S. Cardoso (2018: 937-940) , a tree legume so far geographically confined to the remnants of seasonally dry forests in the Cauca River canyon, Antioquia ( Fig. 3A , 4 ).

The forest fragments where Lonchocarpus verticillatus occurs are highly threatened by the expansion of the livestock frontier and infrastructure projects. Therefore, further research is needed to deepen our knowledge of the species, including its phylogenetic position, population dynamics, propagation studies, autecology, wood properties, and potential uses.

Figures

FIGURE 1. Illustration of Lonchocarpus verticillatus A. Terminal branch with the arrangement of leaves and inflorescence. B. Branch showing the whorled arrangement of the leaves. C. Lenticels on branches. D. Detail of the venation in the intercostal space in abaxial view. E. Detail of pseudoracemose inflorescence with a pair of pedicellate flowers at the end of a short peduncle or brachyblast which form a “Y”. F. Ventral view of flower at anthesis. G. Dorsal view of flower. H. Lateral view of flower with standard petal reflexed. I. Detail of bracteoles in the subapical segment of the pedicel. J. Calyx open adaxial surface. K. Standard. L. keel petals partially attached. M. wings. N. Staminal tube with callosities at the base (left) and tube open view inner surface (right). O. Anthers dorsal (left) and ventral (right) views. P. Gynoecium with stigma detail, Q. Infructescence. R. Fruits.A–P based on C. Rivera et al 1370; Q–R based on W. Ariza-C. et al. 9523. Illustration by Omar Bernal.

FIGURE 2. Lankester Composite Digital Plate (LCDP) Lonchocarpus verticillatus. A. Terminal branch with the arrangement of leaves and infructescence. B. Shapes and sizes of leaflets. C. Pre-anthesis flowers. D. Flower at anthesis (lateral view). E. Standard petal in frontal view; wing petal and keel petal in lateral view. F. Calyx, staminal tube, and gynoecium. G. Fruits. A, G based on C. Rivera et al 1370; B–F based on W. Ariza-C. et al. 9523. Photographs by Cristiam Rivera.

FIGURE 3. Habitat and vegetative morphology of Lonchocarpus verticillatus A. Habitat in the Cauca River Canyon. B. Isolated tree in a pasture. C. Branch with whorled leaves and discolorous leaflets. D. Node of the branch and stipules (red arrows). E. Lenticellate trunk and yellowish inner bark. Photographs A–E: William Ariza.

FIGURE 4. Distribution map of Lonchocarpus verticillatus.