Eperua froesii, Fortes & Dos & Steege & Aymard & Secco & Martins-Da-Silva & Mansano, 2023

Fortes, Elenice A., Dos, Ilka P., Steege, Hans Ter, Aymard, Gerardo, Secco, Ricardo De S., Martins-Da-Silva, Regina Célia V. & Mansano, Vidal F., 2023, A taxonomic revision of the genus Eperua (Leguminosae, Detarioideae, Detarieae), Phytotaxa 617 (1), pp. 1-127 : 40-45

6. Eperua froesii E.A. Fortes, Aymard, H. ter Steege, & Mansano, sp. nov. (

Figures 8 , 23–25 )

Type:— BRAZIL. Pará: Rios Pacajá and Muirapiranga, Km 3,5–6,5, line SW of Ilha de Breu , 23 September 1965, Prance G. T. et al. 1458 (holotype IAN [117052]!, isotypes K [000807973] image!, MO [1780623] image!, NY [01171288]!, U [0083421] image!, US [00243011]!) .

Diagnosis: — Eperua froesii has short and erect inflorescences, non-tubular corollas, and exserted stamens. It differs from species with the same type of inflorescence, corolla, and stamen by the combination (see Table 3 ): stipules entirely joined, epunctate to inconspicuous pellucid punctate leaflets, flat to slightly revolute margins, depressed main vein on the adaxial surface, inconspicuous tertiary venation, brownish-yellow to reddish-brown inflorescence indumentum, white to light-red petals, stamens joined basally in a tube, glabrous stamens, ovary, and fruit.

Tree 20.0–25.0 m tall. Trunk and bark not seen. Stipules entirely joined, caducous, 5.6–44.5 × 10.1–44.0 mm, foliaceous, or 4.0–5.2 × 3.0– 4.7 mm, non-foliaceous, persistent to caducous. Leaves 4–5-jugate; petioles 1.0– 2.5 cm long; rachis 11.0–23.0 cm long; petiolules 4.2–7.6 mm long; blades 5.3–13.4 × 2.5–5.8 cm, coriaceous, glabrous, epunctate to inconspicuous pellucid-punctate, not discolorous to slightly discolorous, equilateral, lower pair elliptic to ovate, middle pairs elliptic, narrowly elliptic to ovate, upper pair elliptic, apex attenuate to acuminate, base symmetrical to asymmetrical, lower pair base obtuse to rounded, middle pair base obtuse to rounded, upper pair base obtuse to cuneate, margin flat to slightly revolute, secondary venation with one or two intramarginal veins (sometimes inconspicuous in developed leaves), vein closer to the margin continuous or not continuous, main vein straight, depressed on the adaxial surface, tertiary veins inconspicuous, areoles smaller concave. Inflorescences terminal or axillary, panicle, erect, puberulous, pubescent to tomentose (strigulose in infructescence), brownish-yellow to reddish-brown, 3.2–6.1(– 7.2 in infructescence) cm long, lateral racemes 1.0–2.7(–6.0 in infructescence) cm long, alternate and distichous; bracts 3.6–4.1 × 2.6–4.4 mm, ovate, concave, apex gland absent, strigose to tomentose, brownish-yellow to reddish-brown; bracteoles 4.5–9.0 × 2.9–6.1 mm, ovate to oblate, cucullate, apex gland absent, pubescent to tomentose, brownish-yellow to reddish-brown, persistent to caducous, attached to the lower middle portion of the pedicels; pedicel 4.0– 6.6 mm long, 1.6–3.4 mm in diameter, not twisted, tomentose, brownish-yellow to reddish-brown; buds 0.7–1.9 cm long, 0.5–1.0 cm in diameter, tomentose, brownish-yellow to reddish-brown. Flowers: hypanthium 4.3–4.9 mm long, 4.8– 6.4 mm in diameter, cup-shaped, equilateral, tomentose, brownish-yellow to reddish-brown; sepal 1.0–1.5 × 0.5–0.8 cm, elliptic to oblong, unequal, the dorsal one larger, cucullate, apex gland absent, green, tomentose, tomentulose to puberulous externally, brownish-yellow to reddish-brown, inner sepals scarious marginally; adaxial petal 0.9–1.4 × 1.2–1.8 cm, oblate, non-tubular, apex rounded, base truncate, white to light-red, glabrous; petalodia 0.6–0.8 × 0.4–0.5 mm; stamens exserted, joined basally in a tube, filaments 1.9–2.5 cm long, tube equilateral, 1.0– 1.6 mm long, glabrous, anthers 4.6–5.4 × 1.0– 1.3 mm, rectangular; ovary 5.0–8.6 × 2.6–3.1 mm, oblong to obovate, glabrous, stipe 5.9–9.5 mm long, glabrous, style 1.2(pre-anthesis)–2.0, stigma capitate, papillose. Legumes 13.2–23.5 × 3.8–9.8 cm, stipe 2.0– 2.5 cm long, oblanceolate, apex obtuse, apiculate, margin slightly thickened, dark-brown, veins absent, glabrous. Seeds not seen.

Phenology:— Flowering in September and October; fruiting in October and November.

Distribution:— Occurring in Pará ( Brazil) along the Acaraí River, a tributary of the Xingu River, and Pacajá, Anapu, and Muirapiranga (connected with Alto Anapu River) rivers, which are tributaries of the Tocantins River.

Habitat:— Floodplain forests, likely occurring in both igapó and várzea forests. The floodplain forests of the Xingu and Tocantins rivers are considered Igapó due to their clear-water rivers ( Junk 2011), while the floodplains near Portel in the Anapu river region are classified as várzea forests ( Junk 2011) due to Amazon River influence.

Conservation status:— Categorized as Near Threatened (NT) according to the IUCN criteria ( IUCN 2012, IUCN Standards and Petitions Committee 2022). The estimated extent of occurrence for the species is 21,015.730 km 2 and the estimated area of occupancy is 16.000 km 2.

Occurrence in protected areas: —Unknown.

Etymology:— The specific epithet is a tribute to Ricardo de Lemos Fróes, a Brazilian botanist (1891–1960) who collected the first two specimens of E. froesii in 1955–56, along with many other species of Eperua .

Vernacular names:— Ipê do Bento (Prance G.T. et al. 1458).

Uses:— Unknown.

Taxonomic notes:— Eperua froesii , E. cerradoensis , E. duckeana , E. reddeniae , and E. schomburgkiana are part of the group with short and erect inflorescences, non-tubular corolla, exserted stamens, falcate fruit with a length/width ration of 3:1 (vs. tubular corolla, included stamens, non-falcate fruit with a length/width ratio of 1:1 to 2: 1 in other species with short and erect inflorescence). They also share multijugate leaves with straight leaflets and inflorescence with dense indumentum. E. froesii shares characteristics such as stamens joined in a glabrous tube with E. cerradoensis , and glabrous ovary with E. schomburgkiana . Please refer to Table 3 for a summary of the similarities and differences among these species. Eperua froesii is this group`s only species with entirely glabrous stamens, ovary, and fruits. It was previously identified as E. schomburgkiana mainly by the glabrous ovary and fruit. However, besides the allopatric distribution ( E. froesii is restricted to the Eastern Amazonia, and E. schomburgkiana occurs in the Guyana Shield, see Figure 8 ), E. froesii is a different species by the entirely joined stipules (vs. free in E. schomburgkiana ), stamens joined in a tube (vs. in a diadelphous sheath 9+ 1 in E. schomburgkiana ), and glabrous stamens (vs. irregularly tomentose sheath in E. schomburgkiana ). The separation of the species is also supported by phylogenetic studies using nuclear and ribosomal data ( ter Steege et al. 2023 in press, Fortes et al. in prep).

We chose the collection Prance G.T. et al. 1458 as the holotype over Fróes R. de L. 32452 because the former collection has more preserved flowers. Both collections could potentially be the type of E. froesii because they have glabrous stamens joined basally in a tube and glabrous ovary, which are the key characteristics to differentiate E. froesii from E. schomburgkiana and other species of the group.

Eperua froesii shows some contrasting morphological characteristics within the species with short and erect inflorescence and non-tubular corollas. While most species have clearly white petals ( E. cerradoensis , E. duckeana , and E. schomburgkiana ) and E. reddeniae has non-white petals (pink to purple), E. froesii shows a range of petal colors from white (Prance G.T. et al. 1458) to light-red (Fróes R. de L. 32418). Another variation is the stipule type, which is entirely joined in E. froesii , ranging from foliaceous ( Figure 23d–f , 25b, c ) to non-foliaceous ( Figure 25d ). Foliaceous stipules are found in flowering branches (Fróes R. de L. 32418, Prance G.T. et al. 1458), and the non-foliaceous stipules are found in flowering, fruiting and sterile branches (Fróes R. de L. 32418, 32452, Prance G.T. et al. 1458, 1652). Further collections are needed to fully understand the petal color and the stipule patterns in E. froesii .

Specimens examined (Paratypes):— BRAZIL. Pará , Portel , regi„o do Anapú, rio Pracajaí, à beira do rio, 10 October 1956, Fróes R. de L. 33051 ( IAN [097476]!, K [000807978]image!). Rio Acaraí, afl. do Xingú, regi„o onde foi feito um levantamento estatístico florestal pelo IAN, SPVEA e FAO, 29 November 1955, Fróes R. de L. 32418 ( INPA [0005049]!, NY [1171155] image!, R [collection number 106671]!); Fróes R. de L. 32452 ( IAN [090190]!); rios Pacajá and Muirapiranga , west bank of rio Pacajá., 15 October 1965, Prance G. T. et al. 1652 ( F [ V0111469 F]!, IAN [117165]!, K [000807974, 000807976] image!, NY [01171289]!, U [0181543] image!, US [00243010]!).

Figures

FIGURE 8. Geographic distribution of Eperua species with short and erect inflorescence and non-tubular corolla: Eperua cerradoensis, E. duckeana, E. froesii, E. reddeniae, and E. schomburgkiana.

FIGURE 23. Eperua froesii: A. leaves; B. fruiting branchlet; C. adaxial surface of a leaflet showing the depressed main vein; D–E. foliaceous joined stipules, showing the variation in size; G. intramarginal vein, abaxial surface; H. inconspicuous pellucid-punctate leaflet; I, J. inflorescences; K. detail of the inflorescence indumentum; L. part of a flower showing one bract at the base of the pedicel, a pair of bracteoles, and the hypanthium. Specimens, A, D–L: Prance G.T. et al. 1458; B–C: Prance G.T. et al. 1652. Photos, E.A. Fortes.

FIGURE 24. Eperua froesii:A. inflorescence; B. flower with bracteoles attached to the lower portion of the pedicels; C.flower showing the bracteoles, sepals, and exserted stamens. D. flower showing the scar of the bracteoles in the middle portion of the pedicel, hypanthium, and sepals; E. flower showing the hypanthium, adaxial petal and stamens (bracteoles and sepals removed); F. flower showing the hypanthium, stamens joined at the base, and ovary (bracteoles, sepals, and adaxial petal removed); G. detail of the hypanthium indumentum; H. sepals; I. detail the sepal indumentum; J. adaxial petal (partially broken on the left); K. detail of a flower showing the bracteoles scars, hypanthium, stamens, and ovary; L. detail of the base of the stamens joined in a tube; M. stamens in a bud (sepals and adaxial petal removed); N. anther and part of the filament; O. glabrous carpel. Specimens, A, B: Fróes R. de L. 33051; C–O: Prance G.T. et al. 1458. Photos, E.A. Fortes.

FIGURE 25. Eperua froesii: A. fruiting branchlet; B. big joined foliaceous stipules; C. medium joined foliaceous stipules; D. nonfoliaceous joined stipules; E. detail of leaflet margin, abaxial side, showing the intramarginal vein; F. inflorescence; G. inflorescence indumentum; H. flower showing the bracteoles, sepal, and exserted stamens; I: flower showing the hypanthium, adaxial petal, and stamens (bracteoles and sepals removed); J. adaxial petal; K. part of a flower showing the bracteole scars at the middle portion of the pedicels, hypanthium, and glabrous stamens joined at the base in tube; L. anther and part of the filament; M. glabrous carpel. Specimens, A, D: Prance G.T. et al. 1652; B, C, E–L: Prance G.T. et al. 1458. Illustrated by Marcus Falc„o.