Eriosema grearii Cândido & Fort., 2016

Cândido, Elisa Silva, Vargas, Wanderleia De, Vatanparast, Mohammad, Mansano, Vidal De Freitas, Machado, Silvia Rodrigues & Fortuna-Perez, Ana Paula, 2016, A New Species of Eriosema (Leguminosae, Papilionoideae, Phaseoleae) from Mato Grosso do Sul, Brazil, with a Secretory Structure Novel to the Genus, Phytotaxa 263 (2), pp. 122-130 : 123-127

publication ID	https://doi.org/ 10.11646/phytotaxa.263.2.4
persistent identifier	https://treatment.plazi.org/id/A93787D0-184C-181C-FF00-FA94FBEB509C
treatment provided by	Felipe
scientific name	Eriosema grearii Cândido & Fort.
status	spec. nov.

Treatment

Eriosema grearii Cândido & Fort. View in CoL -Perez, spec. nov. ( Fig. 1 View FIGURE 1 )

Morphologically similar to Eriosema heterophyllum and differing from it mainly by free stipules (vs. joined in E. heterophyllum ), membranaceous leaflets (vs. papyraceous to cartaceous) with secretory-base trichomes (vs. absence of secretory-base trichomes), flowers distributed along the inflorescences axis (vs. congested at its apex) in inflorescences not opposite the leaves (vs. opposite).

Type:— BRAZIL. Mato Grosso do Sul: Municipality of Ponta Porã. Cabeceira do APA, 23°53’S ; 55°46’W, 16 October 1980, J. G. Guimarães 1196 (holotype HRB!) .

Subshrub ca. 0.25 m tall, stems erect, unbranched, striated, velutinous-tomentose. Stipules 5–9 × 2–4 mm, free, elliptic, lanceolate to ovate, apex acute, persistent, externally tomentose. Stipels absent. Leaves unifoliolate, petioles 8–10 mm long. Leaflets 3–7 × 2–4 cm, adaxial and abaxial surfaces pilose, with glands, elliptic to obovate, apex mucronate, base attenuate, margins entire. Racemes on the lower third of the stems, not opposite the leaves, 6–10 flowers, flowers distributed along the inflorescence axis, racemes (including peduncle) 7–15 cm long, villous, pedicels 3–5 mm long, flowers 6–13 mm long. Calyx 5–lobed, villous, margins entire, 5–veined; tube 3–4 mm long, two vexillar lobes 2–4 mm long, three carenal lobes 3–8 mm long; corolla yellow, the standard 9–12× 8–10 mm (excluding claw), orbicular, multi-veined, apex retuse or slightly emarginate, base auriculate, auricles 1 mm long, adaxial surface pubescent, abaxial surface villous; claw 2–4 mm; wing petals 6–10 × 2.5–5 mm (excluding claw), oblong to obovate, apex rounded, glabrous, slightly auriculate; claw 2 mm long; keel petals 6–10 × 3–5 mm (excluding claw), falcate to obovate, apex rounded, glabrous to pilose at the apex in both surface; claw 2–4 mm long; stamens 12–14 mm long, anthers uniform; ovary 5 mm long, villous; style 10 mm long, curved, stigma minute. Fruit not seen.

Distribution and Habitat: —The taxon is known from a single collection in the municipality of Ponta Porã, in the Cerrado region of Mato Grosso do Sul, Brazil ( Fig. 4 View FIGURE 4 ). The area is a disturbed grassy cerrado, with red latosol and stony soils, and liable to frequent fires.

stereomicroscope.

Phenology: —The species was collected with flowers in October.

Etymology: —The epithet honors Dr. John Grear, U.S. scientist who published a monograph for the American species of Eriosema and described several new species of the genus.

Conservation Status: —Despite an intensive fieldwork and herbaria study, no other specimens of the new species but that in the type location was found, suggesting a narrow geographical distribution with high degree of vulnerability. However, for the assignment of a conservation status our data are insufficient, therefore, in accordance with the IUCN Red List criteria ( IUCN 2014), the species must be considered Data Deficient (DD).

Taxonomic Comments: — Eriosema grearii resembles E. heterophyllum Benth. but is easily differentiated by its free stipules (vs. joined), membranaceous leaflets (vs. papyraceous to cartaceous), the calyx divided into two parts, one of two lobes of the same size and the other of three carenal unequal lobes, with one much higher than the rest ( Fig. 1E View FIGURE 1 ) (vs. calyx with all lobes of the same size), lax flowers ( Fig. 1A View FIGURE 1 ) distributed along the inflorescences axis (vs. flowers concentrated at the apex), inflorescence not opposite the leaves ( Fig. 1A View FIGURE 1 ) (vs. opposite), and leaflets with secretory-base trichomes (vs. absence of secretory-base trichomes).

Secretory Structure Study: — Eriosema grearii exhibits a peculiar type of trichomes on the abaxial leaflet surface, referred to here as secretory-base trichomes and reported for the first time for the Phaseoleae ( Fig. 2 A–D View FIGURE 2 ), as well as spherical capitate trichomes ( Fig. 2 E–F View FIGURE 2 ), and vesicular glands ( Fig. 2 G View FIGURE 2 ), with idioblasts in the mesophyll ( Fig. 2 E, G View FIGURE 2 ).

The vesicular glands have bulky heads and one-celled peduncles embedded in the epidermis depressions ( Fig. 2 G View FIGURE 2 ). The spherical capitate trichomes have seven-celled heads with inconspicuous ( Fig. 2 E View FIGURE 2 ) or conspicuous ( Fig. 2 F View FIGURE 2 ) stalks not inserted in the epidermis depressions.

The secretory structures, referred here as secretory-base trichomes and observed for the first time in Phaseoleae ( Fig. 2 A–D, H View FIGURE 2 ), are multicellular, unbranched, uniseriate trichomes, comprised of an elongated, acuminate apical cell with tick and lignified walls, two intermediate cells with thick unlignified walls, and a large, hexagonal basal cell ( Fig. 2 C View FIGURE 2 ). The basal cell shows a reduced cytoplasm and one large vacuole filled with a flocculent material, stained pink by toluidine blue ( Fig. 2 D View FIGURE 2 ).

In contrast, Eriosema heterophyllum shows bulky capitate trichomes with large heads and one-celled peduncles embedded in the epidermis depressions ( Fig. 3 A, D View FIGURE 3 ) besides non-glandular multicellular unbranched uniseriate trichomes with one elongated acuminate apical cell and one basal cell ( Fig. 3 A–C, E View FIGURE 3 ).