Helietta magna Londoño-Ech., A.M.Trujillo, Pirani & Pérez-Zab, 2023

Londoño-Echeverri, Yeison, Trujillo-López, Ana María, Pirani, José Rubens & Pérez-Zabala, Jorge Andrés, 2023, A new species of Helietta (Pilocarpinae, Zanthoxyloideae, Rutaceae) from Colombia and notes on the morphology and circumscription of H. glaziovii, Phytotaxa 625 (1), pp. 98-107 : 99-101

Helietta magna Londoño-Ech., A.M.Trujillo, Pirani & Pérez-Zab ., sp. nov. ( Figs. 1 , 2 , 3 )

Type:— COLOMBIA. Caldas. Mun. La Dorada: Margen del río La Miel , Vereda La Atarraya , Finca Los Achiles , relictos de bosque al margen trasero de la Finca , 214 m, 5°40ʹ44.6ʹʹN, 74°44ʹ16.2ʹʹW, 3 August 2021 (fl & fr), D. Sanín & D. Jaramillo 7973 (holotype: FAUC!; isotypes: COL!, FMB!, HUA!, MEDEL!).

Diagnosis:— Helietta magna shares the character of leaflets with involute margin at apex only with H. apiculata Bentham in Hooker (1882: 67) and H. glaziovii . From both, H. magna can be differentiated by its leaflets mainly acuminate without a drip tip and with the involute margin only over the acumen of apex (versus leaflets apiculate with drip tip, margin involute along entire length of apiculum and adjacent margins in H. apiculata , or leaflets rounded to blunt at apex and occasionally with involute margin only laterally at very apex in H. glaziovii ), by its larger leaflets blade (4–)5–12(–17.3) × (1.1–)2.1–5.6(–7) cm [vs. (3–)5–8.5(–9.5) × 0.5–1.7(–2.5) cm in H. apiculata or 3–8(–9) × 1.4–3.4(–4.2) cm in H. glaziovii ] and its ovary puberulous apically (vs. glabrous in H. apiculata and H. glaziovii ).

Shrub or tree 2–25 m tall, the branches striate, velvety, glabrescent. Leaves 3-foliolate, (sub-) opposite, commonly 1–2 leaflets aborting, the petiole (0.4–) 1–4 cm long, canaliculate, shortly winged distally, striate, puberulous, glabrescent; petiolules ca. 0.5 mm long, puberulous, glabrescent; leaflet blade (4–)5–12(–17.3) × (1.1–)2.1–5.6(–7) cm, obovate to elliptic, occasionally oblong (very rarely orbicular in stunted leaflets); basally acute (slightly obtuse) and decurrent, symmetrical or asymmetrical (in lateral leaflets), apically acute to obtuse and acuminate without drip tip (very rarely retuse to emarginate in stunted leaflets), glabrous to sparsely puberulous toward the midvein on both surfaces, the glandular reddish trichomes sparsely in both surfaces; pellucid-punctate, glands visible as dark dots on both surfaces, the margin entire, slightly revolute for almost all length, but noticeably involute only over the acumen of apex; the midvein raised abaxially, slightly raised to flattened adaxially, striate on both surfaces; secondary veins slightly raised on both surfaces, (8–)12–20 pairs, brochidodromous, intersecondaries present, tertiary veins irregularly reticulate. Inflorescence a terminal diplothyrse, 5.4–12.8 cm long including peduncle, shorter or longer than the subjacent leaves, puberulous to velvety, peduncle 0.4–1 cm long; bracts ca. 0.5 × 0.7 mm, ovate, present in all nodes of inflorescence, puberulous abaxially, glabrous adaxially, ciliolate; pedicels ca. 0.5 mm long, puberulous to velvety; bractlets 2 per pedicel, ca. 0.5 × 0.5 mm, opposite, in the middle of the pedicel, ovate, puberulous abaxially, glabrous adaxially, ciliolate. Flowers 5-merous; calyx quincuncial; sepals 0.6–0.9 × 0.7–0.9 mm, semiorbicular to ovate, apically obtuse and rounded to cuneate, puberulous in both surfaces, the margin erose, ciliolate; petals 2.5–2.9 × 1–1.3 mm, obovate, basally acute and cuneate to unguiculate, apically obtuse and rounded, white in vivo, glabrous, recurved in anthesis, the margin erose; the filaments 1.5–1.6 × 0.1–0.3 mm, glabrous, the anthers 0.4–0.5 × 0.3–0.4 mm, dorsifixed, bilobate at apex by extension of the thecae over the connective, thecae ovoid to ellipsoid; disk 0.4–0.6 mm high, plicate, equal to or slightly enclosing the ovary, glabrous, the margin sinuate; ovary 0.4–0.5 mm high, 5-carpellate, puberulous apically, the style 0.4–0.6 mm long, glabrous, the stigma ca. 0.1 × 0.3 mm, glabrous. Fruit a samarium of 5 samaroid mericarps, each free at maturity, glandular reddish trichomes scattered on the entire surface, occasionally with very few and isolated simple trichomes; each mericarp with seed locule 0.8–1.3 cm long, ellipsoid, the wing (1.7–)2.1–3 × (0.8–) 1–1.3 cm, obovate to elliptic. Seed 1 per mericarp, ca. 9.1 mm long, ellipsoid, the testa slightly rugose without, dark brown to black in rehydrated material, glabrous, the radicle ca. 1 mm long, fleshy, smooth, the cotyledons ca. 6 × 1.3 mm, fleshy, smooth.

Distribution and habitat:— Helietta magna is endemic to Colombia, where it has been recorded so far only for the eastern slopes of the Cordillera Central (Central Mountain Range) in the municipalities of Puerto Berrío and La Dorada, in the departments of Antioquia and Caldas respectively ( Fig. 4 ). It is found at an elevation of near 220 m, which corresponds to the biogeographic region of the Magdalena Valley (sensu Bernal 2016), under equatorial rainforest climate (Af climate type). Mature individuals, i.e. flowering or fruiting, have been observed as emergent trees over the forest canopy, where individuals reach to 18–25 m tall; less frequently as shrubs on disturbed areas in early ecological succession up to 5 m canopy, where individuals were recorded from 2 m tall.

Phenology:— Helietta magna has been recorded blooming in August and fruiting in August, November and December.

Etymology:— The epithet from the Latin “Magna”, referencing the great height that individuals reach and also to the size of leaflets, which are the largest within the genus.

Preliminary conservation status:— Helietta magna is only known by two isolated subpopulations with an AOO= 8 km 2 and EOO= 16 km 2, none of these occur inside official protected areas. Its range of distribution comprises small and very fragmented forest patches (<50 km 2) due to the expansion of the agricultural and livestock frontier; in fact, the Magdalena River Valley is currently considered one of the hotspots of deforestation in Colombia by Sánchez-Cuervo & Aide (2013). Both subpopulations are located less than 10 km from populated centers and are immersed in mining and oils licenses areas. The subpopulation on the department of Caldas is inside the Jardín Botánico del Magdalena (Magdalena Botanical Garden), a recent private initiative for the support and encouragement of the biological research and conservation. Here the proposed category for Helietta magna is “Endangered” EN according to the criteria B: B1ab(iii)+2ab(iii) of IUCN (2012), based on its small and restricted geographical distribution, the poor conditions of its habitat, proximity to population centers, as well as the null ecological connectivity of its subpopulations with other forest matrix.

Additional specimens examined:— COLOMBIA. Antioquia. Mun. Puerto Berrío: Hacienda La Suiza, cerca a la escuela La Espiga , 240 m, 6°17ʹ28.8ʹʹN, 74°34ʹ52.4ʹʹW, 23 January 2001 (st), A. Idárraga et al. 1944 ( HUA!, JAUM!); vereda La Cristalina, predios de la hacienda bufalera La Suiza , escuela La Espiga (parcela), 250 m, 6°17ʹ27.8ʹʹN, 74°34ʹ52.4ʹʹW, 15 November 1999 (st), E. Riascos & A. Duque 1 ( JAUM!) ; hacienda La Suiza , cerca de la exescuela La Espiga , 216 m, 6°17ʹ30.97ʹʹN, 74°34ʹ36.88ʹʹW, 30 November 2018 (im fr & fr), Y. Londoño et al. 287 ( COL!, CUVC!, FAUC!, HUA!, ICESI!, JAUM!, MEDEL!, SPFR!); ibid., 30 November 2018 (im fr & fr), A.M. Trujillo et al. 68 ( FAUC!, HUA!, JAUM!, MEDEL!, SPF!) . Caldas. Mun. La Dorada : vereda La Atarraya , finca Los Achiles , predios del Jardín Botánico del Magdalena , entrando por un caño al margen de la via, 224 m, 5°40ʹ0.5ʹʹN, 74°44ʹ12.9ʹʹW, 5 December 2021 (fr), D. Sanín et al. 8005 ( COL!, FMB!, FAUC!, HUA!, JAUM!, MEDEL!, UDBC!, UIS!).

Notes:— Helietta magna is a unique species within the genus, because of its larger leaflets and as it inhabits very humid forest, i.e. under equatorial rainforest climate (vs. mesic to dry habitats where all other species are found, Pirani 1998), which expands the ecological spectrum of the genus. Table 1 presents the main features that are useful for the recognition between the species of Helietta that exhibit leaflets with margin involute at apex, besides some morphological data not previously reported for Helietta glaziovii (see the comments for H. glaviovii below).

Figures

FIGURE 1. Isotype of Helietta magna at HUA (Sanín & Jaramillo 7973).

FIGURE 2. Illustration of Helietta magna: A. Distal portion of flowering branch, B. Apex of leaflet with involute margin over the acumen, C. Flower, upper view, showing the ovary puberulous apically D. Flower without two petals and one sepal, lateral view, showing the ovary puberulous apically E. Distal portion of stamen, adaxial and abaxial view, F. Mericarp. (A from the isotype at FMB, B–E from the holotype, F from Y. Londoño et al. 287. Illustration by Diego Armando Zapata, HUA illustrator).

FIGURE 3. Photographs of Helietta magna: A. Tree top view from drone, B. Fruiting branchlet in vivo, C. Samarium in vivo, D. Leaflets apex in dried specimen, E. Distal portion of inflorescence in dried specimen, F. Samarium in dried specimen. (A from D. Sanín et al. 8005, B–D, F from Y. Londoño et al. 287, E from the holotype. Composed by Ana Cristina Pareja, HUA illustrator.A by Miguel Uribe, B–F by Y. Londoño).

FIGURE 4. Geographical distribution of Helietta magna.