Sigmoidotropis snakiae F.S. Santos, C.L. Ribeiro & K. Soares, 2024

Santos, Felipe Da Silva, Ribeiro, Carolina Lima, Oliveira, José Florencio Cerqueira, Soares, Kleber De Araújo & Queiroz, Luciano Paganucci De, 2024, A New Species Of Sigmoidotropis (Papilionoideae, Leguminosae) From Atlantic Forest, Eastern Brazil, Phytotaxa 666 (2), pp. 146-154 : 148-151

Sigmoidotropis snakiae F.S. Santos, C.L. Ribeiro & K. Soares , sp. nov. ( Figs. 1 , 2 )

Type:— BRAZIL, Espírito Santo, Muniz Freire, ES –379, estrada de terra sentido Iúna, ca. 1,5 a 2 km saindo de Muniz Freire, em um inselberg ao lado da estrada, 550 m elev., 20°27ʹ35.2ʹʹS, 41°26ʹ16.4ʹʹW, 30 January 2024, F. S. Santos, et al. 146 (Holotype: HUEFS, barcode HUEFS000100277445 ; Isotype: HUEFS, RB) .

Diagnosis:— Sigmoidotropis snakiae is more similar to S. speciosa in presenting a twining vine habit, pubescent branches, leaves, and inflorescences, leaflets measuring 4–10.2 cm long, and lilac petals. Sigmoidotropis snakiae differs by presenting lanceolate leaflets typically yellowish-green (vs. oval and green leaflets in S. speciosa ); larger flowers with standard approximately 29 × 33 mm, wings approximately 34 × 29 mm, and keel approximately 35 × 12 mm (vs. flowers with standard 23 × 26 mm, wings approximately 26 × 20 mm, and keel approximately 32 × 12 mm); wings diverging at an angle of ca. 45°, the right one with a descending apex and the left one with an ascending apex ( Fig. 2 D ; vs. wings parallel and more or less horizontal, only with the apex slightly recurved downwards, Fig. 2 F ); obtuse wing spurs (vs. short acute); keel rostrum 27 mm long (vs. 20 mm long), seeds 6.5–7 mm long, oblong (vs. 1.9–2.2 mm long, widely oblong).

Description:— Twining vine, with green branches, pubescent to tomentose. Stipules (3–3.5)6.1–9 × 1–2 mm, narrowly triangular, rarely triangular, apex acute, base truncate, glabrescent with ciliate margins to pubescents. Leaves trifoliolate; petiole 2.2–8.3 cm long, rachis 0.7–2.3 cm long, canaliculate, glabrescent to pilose; stipels 1.2–2.7 mm long, subulate; leaflets membranaceous, papyraceous to cartaceous, apex acute, mucronate, pinnately veined, secondary veins 5–8 pairs, brochidodromous, upper surface sparsely pubescent to pubescent and lower surface tomentose; lateral leaflets 4–8.5 × 1.6–4 cm, ovate, ovate-lanceolate to lanceolate, asymmetrical, base rounded to obtuse; terminal leaflets 5.4–10.2 × 1.7–4.1 cm, lanceolate, lanceolate-elliptic, elliptic to ovate, base cuneate, obtuse to rounded. Inflorescence an axillary nodose pseudoraceme, peduncle (0.9–2.3) 6.7–20.5 cm long, pubescent to tomentose; rachis (1.2) 1.8–7.5 cm long, pubescent to tomentose, nodosities globose; pedicels 2.8–7.5 mm long; bracteoles 2.2–4.1 mm long, obovate to oblong, tomentose, caducous. Flowers 26–26.5 × 26.1–26.2 mm, with the length almost equal to the width when the flower is open; calyx green, the tube 4.2–5.3 × 7.5–8.5 mm, campanulate, pubescent on the outer surface, 4-toothed, the teeth with ciliate margins, vexillary teeth joined, 2.8–3.3 mm long, depressed ovate, apex rounded, lateral teeth 2.9–4.3 mm long, carinal teeth 3.9–5.2 mm long, both triangular, apex acute; corolla lilac with standard slightly rosy, standard petal c. 29 × 33 mm, widely depressed ovate, apex retuse, callosity absent, papillae in the centre of the lamina until the base of the claw, auricles hook-shaped, with membranacenous extensions perpendicular to the centre of the blade, claw c. 3.3 mm long; wing petals c. 34 × 29 mm, diverging at approximately 45°, the right petal with a descending apex and the left one with an ascending apex ( Fig. 2 D ), expanded at rounded apex, pocket in the inner face absent, base with a obtuse spur, claw c. 7.6 mm long; keel petals perimeter c. 35 mm long, 27 × 12 mm, sigmoid, extending in a long curved hook-shaped beak above 180°, the two petals connected by inconspicuous interlocking marginal trichomes along the adaxial (inner) margin, trichomes 0.15–0.2 mm, claw c. 8 mm long; androecium c. 53 mm long, diadelphous, 9 stamens joined in a sheath and the vexillary stamen free, the base of the filament of the free stamen with a short irregular and fleshy protuberance, stamens at different heights, anthers dorsifixed; nectary ring; ovary c. 20 × 1 mm, sessile pubescent; style 44 mm long, the apex arching outwards and slightly flattened, stigma terminal, capitate, brush of hairs encircling the entire stigma. Fruit a legume, 100–165 × 4–5.4 mm, linear, laterally flattened, apex acuminate, pendulous on the inflorescence rachis, elastically dehiscent; valves rigidly coriaceous, brown, sparsely pubescent to pubescent. Seeds 8–14 per fruit, 6.5–7 × 3–3.2 × 1–1.2 mm, reniform with oblong margins, laterally flattened, testa brownish with black and brown spots.

Etymology:— The specific epithet honours Cristiane Snak, an important Brazilian botanist, with immense contributions to studies within Leguminosae , particularly in the groups of Diocleae and Phaseolinae .

Phenology:—Collected with flowers in January, February, September, and October. Collected with fruits in January and February.

Distribution and habitat:— The new species is known only from the eastern region of Brazil, in the states of Espírito Santo and Minas Gerais ( Fig. 3 ), in fragments of humid forests at altitudes ranging from 510 to 1870 m above sea level. These forests are associated with granite and gneiss inselbergs. The new species may or may not be close to rivers.

The environmental niche modeling (ENM) ( Fig. 3 ) presented a reliable AUC value of 0.919. The variables that contributed the most were BIO 11 (mean temperature of the coldest quarter—37.7%), BIO 15 (precipitation seasonality of the driest quarter—34.8%), and BIO 10 (mean temperature of the warmest quarter—27.5%). With this set of selected variables, the produced model suggests a potential niche area different from the recorded occurrence area for the species. Among the collection sites, only the Parque Nacional do Caparaó shows a small overlap with a potential niche area. The main potential areas recovered are some small fragments located in the border region between the states of Minas Gerais, São Paulo, and Rio de Janeiro, Brazil, indicating that possibly the current collection points of Sigmoidotropis snakiae are relictual areas of a broader area. This increases the importance of the Parque Nacional do Caparaó and Parque Estadual do Forno Grande for the conservation of this species, even though they are not locations with current potential niches in the predictive model.

Conservation status:— The calculations performed in GeoCat showed values of EOO— 24,203 km ² and AOO— 24 km ², falling into the criteria B1ab(iii) [Vulnerable (VU)] and B2ab(iii) [Endangered (EN)], respectively, according to the IUCN. Assessing the occurrence of populations in nearby towns, but in areas limited mainly to rocky outcrops and possible proximity to rivers or wetter areas, as well as their occurrence in two conservation areas, such as the Parque Estadual do Forno Grande, Espírito Santo, and the Parque Nacional do Caparaó, Espírito Santo and Minas Gerais, in addition to what was demonstrated in the ENM showing the potential niche area different from its current distribution, we assessed the conservation status of the species as vulnerable (VU).

Additional specimens examined (Paratypes):— BRAZIL, Espírito Santo, Castelo, Parque Estadual do Forno Grande , trilha para o Forninho, floresta ombrófila densa altomontana com inselbergues, 1100–1400 m elev., 20°30ʹ58ʹʹS 41°05ʹ01ʹʹW, 12 February 2008 (fl., fr.), R. C. Forzza et al. 4962 ( RB 473339 ) ; trilha para o Forninho, floresta ombrófila densa altomontana com inselbergues, 1100–1500 m elev., 20°30ʹ58ʹʹS 41°05ʹ01ʹʹW, 14 October 2008 (fl.), R. C. Forzza et al. 5813 ( RB 485119 ) ; Muniz Freire, afloramento rochoso, inselberg ao lado da estrada na saída para Iúna, ca. 1, 5 km da cidade, 510–550 m elev., 20°27ʹ16ʹʹS 41°26ʹ16ʹʹW, 22 October 2019 (fl., fr.), D. R. Couto & C. N. Fraga 4944 ( RB 826014 ) . Minas Gerais, Água Boa, Serra da Grama, 1100 m elev., 18°06ʹ0.8ʹʹS 42°22ʹ59.8ʹʹW, 15 February 1992 (fl.), L. S. Leoni 1769 ( RB 741732 ) ; Alto Caparaó, estrada dentro do Parque Nacional do Caparaó , em um barranco do lado direiro, 1500 m elev., 20°24ʹ36.2ʹʹS 41°50ʹ60ʹʹW, 31 January 2024 (fr.), F. S. Santos et al. 147 ( HUEFS 277446 ) ; Parque Nacional do Caparaó, Vale Verde, floresta aluvial, ao longo do rio Caparaó , 20°25ʹ11.6ʹʹS 41°50ʹ46.2ʹʹW, 16 February 2000 (fl.), V. C. Souza et al. 23172 ( RB 741562 ) ; Parque Nacional do Caparaó , cresce ao lado da estrada sobre formação rochosa, 1500 m elev., 20°24ʹ36.2ʹʹS 41°51ʹ0ʹʹW, 25 January 1997 (fl., fr.), L. S. Leoni 3611 ( RB 741577 , 736609 ) ; Parque Nacional do Caparaó , Cachoeira Bonita, surge ao lado da estrada sobre barranco, 1870 m elev., 20°24’25.3”S 41°50’15.0”W, 10 January 2001 (fl.), L. S. Leoni 4567 ( RB 736616 ) ; Carangola, Furriel, área perturbada, cresce junto a pastagem, 20°41ʹ53.7ʹʹS 42°10ʹ32.1ʹʹW, 12 September 1993 (fl.), L. S. Leoni & L. C. Medeiros 2252 ( RB 741563 ) .

Notes:— Sigmoidotropis snakiae can be recognized as a twining vine with pubescent to tomentose branches, narrowly triangular stipules measuring (3–3.5)6.1–9 × 1–2 mm; normally lanceolate leaflets, pubescent to tomentose, papyraceous to chartaceous; large lilac flowers, measuring 26–26.5 mm long and 26.1–26.2 mm wide when open; standard approximately 29 × 33 mm, without callosity and with papillae present in the middle of the blade; wings approximately 34 × 29 mm, larger than the standard and diverging at approximately 45°, the right petal descending and the left one ascending, expanded at rounded apex.

Sigmoidotropis grandiflora is another species restricted to the eastern region of Brazil that may be mistakenly identified as S. snakiae , however, S. grandiflora is characterized by having keel wings larger than the length of the calyx tube, whereas S. snakiae has keel wings smaller or equal to the length of the calyx tube.

Figures

FIGURE 1. Sigmoidotropis snakiae. A. Part of a branch with leaves and inflorescence (SB = 3 cm); B. Open calyx; C. Standard petal (inner view); D. Wing petals (outer view); E. Keel (side view) (B–E SB = 20.4 mm); F. Androecium (SB = 21.2 mm); G. Gynoecium (SB = 19.2 mm); H. Legume (SB = 29.7 cm); I. Seed (SB = 3.7 mm). Drawn by K.A. Soares.

FIGURE 2. Sigmoidotropis snakiae. A. Environment where the plant is found; B. Leaves; C. Details of the indumentum on the young branch, stipule, and leaflets; D & E. Flowers of S. snakiae and S. speciosa respectively; F. Legume in the inflorescence. Photographs: A–D e F, by F.S. Santos; E, by CIAT 24312.

FIGURE 3. Sigmoidotropis snakiae. Geographical distribution in the States of Espírito Santo and Minas Gerais, Brazil (black circles in areas A and B). Area C represents the region with the highest potential niche, as identified by the environmental niche modelling.