Macropsychanthus ruschii Fonseca-Cortés & L.P. Queiroz, 2023

Fonseca-Cortés, Andrés, Cardoso, Domingos Benício Oliveira Silva, Snak, Cristiane & Queiroz, Luciano Paganucci De, 2023, A new endemic species of Macropsychanthus (Leguminosae: Papilionoideae) from the Brazilian Atlantic Forest, Phytotaxa 620 (3), pp. 225-234 : 227-231

Macropsychanthus ruschii Fonseca-Cortés & L.P. Queiroz , sp. nov.

Within the Atlantic Forest clade, M. ruschii can be easily recognized by a combination of unique morphological features: stipules measuring 1.7–2.0 × 0.2–0.3 cm, leaflets glabrescent with 7–10 pairs of secondary veins, inflorescences to 15 cm long, flowers with predominantly pink petals, measuring 1.0– 1.2 cm long, and keel 0.8–1.0 × 0.7–0.9 cm.

Type:— Brazil, Espírito Santo, Santa Teresa, Reserva Biológica Santa Lúcia ; trilha do Sagui , floresta ombrófila densa, no topo da serra, 734 m. elev., 19°56ʹ2ʹʹS, 40°35ʹ22ʹʹW, 3 April 2009, D. Cardoso et al. 2471 (holotype: HUEFS-151379! ). Fig 2 .

Lianas scanding up to the forest canopy; stems rounded, brown, hollow, glabrous; indumentum of fulvous and strigose trichomes on the young branches, stipules, petiole, petiolules and rachis, leaflet undersurface on primary and secondary veins and inflorescence peduncle and rachis. Stipules 1.7–2.0 × 0.2–0.3 cm long, medifixed, both lobes lanceolate-falcate, the upper lobe longer and wider. Leaves alternate, spirally arranged; petiole 4–6 cm long, terete to angular, canaliculate; rachis 0.5–0.7 cm long, terete or angular; stipels 0.3–0.5 cm long, linear; pulvinules 0.4–0.6 cm long, cylindrical; leaflets three, chartaceous, elliptical, glabrescent, base rounded, truncate or cordate, apex extended into a 0.5–1.0 cm long acumen, mucronate, pinnately veined with 7–10 pairs of secondary veins; terminal leaflet 8–9 × 4.0– 4.5 cm; lateral leaflets 7–9 × 4.0– 4.5 cm, base slightly asymmetric. Inflorescence 9–15 cm long, ramiflorous, emerging below the coeval leaves, pseudoracemose, straight; peduncle of inflorescence 4–6 cm long; brachyblasts 2–4 mm long, incurved, pedicellate, 0.3–0.5 cm apart; first order bract (at the brachyblast attachment) 3–5 × 1–2 mm, erect, lanceolate, sericeous, fulvous; second order bract (at the pedicel attachment) 2–3 × 1–2 mm, ovate, sericeous, fulvous; bracteoles (at calyx base) 2, opposite, 2–3 × 2–3 mm, rounded, sericeous, fulvous or dark brown; pedicel 0.4–0.5 cm long, sericeous, fulvous. Flowers 10–12 mm long; calyx 8–12 × 7–9 mm, campanulate, slightly gibbous behind the upper lobe, glabrous or strigose, fulvous, upper lobe 3–5 × 6–8 mm, rounded, emarginated; lateral lobes 3–5 × 2–3 mm, triangular, straight; lower lobe 3–5 × 2–3 mm, triangular; petals glabrous, pink; standard petal 12–15 × 8–12 mm, rounded, with two callosities and two auricles at the base, apex emarginate, claw 2–4 × to 1 mm; wing petals 10–13 × 4–6 mm, lower lobe and apex rounded, claw 4–6 × to 1 mm, with a dorsal spur near the base of the claw; keel petals 8–10 × 7–9 mm, with one straight lobule, apex rounded, claw 5–6 × to 1 mm, with a spur; stamens 10–13 mm long, pseudomonadelphous, 5 fertile stamens on longer filaments, anthers ovate, 5 staminodes on shorter filaments, anthers ovate with the apex caudate; intrastaminal nectariferous disk shortly cylindrical; ovary sessile, ovoid, 2–3-ovulate, covered with dark brown sericeous indumentum, style 7–9 mm, linear, with the basal portion covered by dark brown sericeous indumentum; stigma truncate. Fruits and seeds unknown.

Etymology:—The specific epithet commemorates Augusto Ruschi (1915–1986), an important Brazilian conservationist, who fought against the deforestation of the Atlantic Forest, mainly in the state of Espírito Santo and actively promoted the conservation of some areas of the Atlantic forest in Brazil including the creation of the reserve where this new species was found.

Distribution and habitat:—The new species is only known from the Santa Lúcia Biological Station, at the Santa Teresa municipality in the state of Espírito Santo ( Figure 4 ). Vegetation of the area is mostly composed by evergreen rain forests on a steepy landscape. Macropsychanthus ruschii was collected in a mountain slope at about 750 m elev. This area is an important richness center of the eastern Brazilian Atlantic Forests and several new species had been described from there in different plant groups including Begonia ruschii L.Kollmann ( Begoniaceae ; Kollmann, 2003), Bertolonia ruschiana Bacci & R.Goldenb. ( Melastomataceae ; Bacci et al., 2016), Didymopanax ruschianus (Fiaschi & Pirani) Fiaschi & G.M.Plunkett ( Araliaceae ; Fiaschi & Pirani, 2005), Myrcia santalucia (Sobral) A.R.Lourenço & E.Lucas ( Myrtaceae ; Sobral, 2013), Unonopsis sanctae-teresae Maas & Westra ( Annonaceae ; Maas et al., 2007) amongst several other species, highlighting the importance of that preserved area.

Conservation status:—As the species is only known for one locality, it is not possible to assess the conservation status using the criterion B (AOO and EOO) ( IUCN, 2022). Despite being collected in a reserve, the new species could probably occur in other AF forests of Espírito Santo or in other states. In this sense, the DD (data deficient) category is proposed for this species.

Additional specimens examined:— Brazil, Espírito Santo, Santa Teresa, Reserva Biológica de Santa Lúcia , Trilha do Sagui , Floresta Ombrófila , densa e áreas de capoeira em afloramento de arenito, 656 m. elev., 19° 58ʹ4ʹʹS 40° 32ʹ4ʹʹW, 25 May 2011, L.P. Queiroz et al. 15254 ( HUEFS) .

Notes:— The predominantly pink petals observed in M. ruschii is unknown in any species of the genus. Macropsychanthus ruschii is morphologically similar to M. grandistipula , but differing by presenting stipules 1.7–2.0 × 0.2–0.3 cm (vs. 1.5–3.0 × 0.7–1.5 cm in M. grandistipula ) flowers 1.0– 1.2 cm long (vs. 1.7–2.0 cm long), pink petals with white stripes (vs. white petals with pink stripes) and keel 0.8–1.0 cm long (vs. 1.4–1.7 cm long). Further differences between the new species and its morphologically and phylogenetically closely related species are presented in Table 1 and illustrated in Figure 3 .

The newly described species of Macropsychanthus is also confirmed here as phylogenetically placed in the Atlantic Forest clade ( Figure 1 ). Although the phylogenetic topology did not resolve interspecies relationships within the AF clade, species in this clade can be readily divided into two main morphological groups: (1) it includes only M. grandistipula , which possesess glabrescent leaflets, ramiflorous or caulinar inflorescences, flowers as in Figure 2b , and laterally compressed fruits; (2) it is comprised of M. edulis , M. rufescens and M. schottii , all of which bearing pubescent leaflets, axillary inflorescences, flowers as in figure 2c–2d, and turgid fruits.Although its fruits are not known, the new Macropsychanthus species fits in the first morphological pattern since its leaflets, inflorescences and flowers are more similar to M. grandistipula . However, the phylogenetic analysis does not resolve those morphogically-defined groups within the AF clade, yet it shows a poor relationship of the new species and possibly sister to M. aff. edulis . Future studies employing more sequence data in a phylogenomic approach could shed more light on the Macropsychanthus species relationships, enabling more conclusive insights into the morphological evolution within the AF clade.

Figures

FIGURE 1. Phylogenetic position of Macropsychanthus ruschii based on the Bayesian majority-rule consensus phylogram derived from the combined nuclear ribosomal (ITS, ETS) and plastid (matK) DNA sequence data.

FIGURE 2. Macropsychanthus ruschii. A. Branch. B. Stipule. C. Ramiflorous inflorescence. D. Flower bud. E. Flowers. F. Petals. G. Androecium. Scales: A: 1 cm, B: 5 mm, C: 15 cm, D: 3 mm, E: 3 mm, F: 6 mm, G: 2 mm. Drawn from Cardoso et al. 2471 (HUEFS). Elaborated by Andrés Fonseca-Cortés. E. from a field photograph by Domingos Cardoso.

FIGURE 3. Representative Macropsychanthus species of the Atlantic Forest clade.A. M. grandistipula. B. M. ruschii. C. M. schottii. D. M. edulis. Photographs:A. Robson Ribeiro. B. Domingos Cardoso. C.Andrés Fonseca-Cortés D. Helton Josue. Scales A: 5 mm, B: 3 mm. C–D: 4 mm. Elaboration: Andrés Fonseca-Cortés.

FIGURE 4. Distribution map of M. ruschii (pink) and its closest morphological related species, M. grandistipula (black), in gray the Atlantic Forest Domain, down the habitat in which M. ruschii grows. Elaboration: Andrés Fonseca-Cortés.

Tables

TABLE 1. Morphological characteristics for distinguishing M. ruschii of other morphological similar species of the AF, in bold the diagnostic characters of each species.

Characters	M. edulis	M. grandistipula	M. rufescens	M. ruschii	M. schottii
Stipule length (mm)	10–20	15–30	10–20	17–20	10–20
Stipule width (mm)	3–6	7–15	3–6	2–3	3–5
Rachis length	1–2	2–2.5 cm long	To 0.5 cm	0.5–0.7 cm	0.2–1.5 cm
leaflet undersurface indumentum	Strigose to sericeous and fulvous	Glabrescent	Strigose to sericeous and fulvous	Glabrescent	Sericeous and argenteus
bracteoles size (mm)	3–4 × 3–4	1–3 × 1–3	3–4 × 3–4	2–3 × 1–3	2–4 × 2–3
flower length (mm)	13–16	17–20	13–16	10–12	13–16
petal color	White to bright pink	White with the center with lilac stripes	White to bright pink	Lilac with white stripes	White to bright pink
keel petal apex	Concave	Rounded	Concave	Rounded	Concave
keel petal length (mm)	8–12	14–17	8–12	8–12	9–13