Lathyrus ibicuiensis M.L. Abruzzi de Oliveira, 2015

De Oliveira, Maria De Lourdes A. A., Miotto, Silvia T. S. & Iganci, João R. V., 2015, Lathyrus ibicuiensis (Fabaceae, Faboideae), a new species endemic to Southern Brazil, Phytotaxa 204 (1), pp. 91-94 : 91-93

publication ID	https://doi.org/ 10.11646/phytotaxa.204.1.9
persistent identifier	https://treatment.plazi.org/id/03DD87FE-3430-FF89-4DC8-F8C2A9DDD157
treatment provided by	Felipe
scientific name	Lathyrus ibicuiensis M.L. Abruzzi de Oliveira
status	sp. nov.

Treatment

Lathyrus ibicuiensis M.L. Abruzzi de Oliveira View in CoL , sp. nov. ( Fig. 1 View FIGURE 1 )

Lathyrus ibicuiensis is similar to Lathyrus linearifolius Vogel in having simple tendrils, but differs by having ovate to lanceolate stipules (vs. semisagittate stipules), by highly ramified branches (vs. slightly branched), and by elliptic, oblong to rarely obovate leaflets (vs. linear-elliptic leaflets).

“Type: — BRAZIL. Rio Grande do Sul: Itaara, Reserva Biológica do Ibicuí Mirim, no campo dos Barcelos, 3 October 1989 (fl, fr), M.L. Abruzzi 1798 (holotype HAS!, isotypes K!, RB!).”

Subshrubs up to 70 cm tall, pubescent, notdark when dried. Branches angular, not winged. Leaves with one pair of leaflets, tendrils simple, sometimes very short, setaceous. Stipules two, free, ovate to lanceolate, apex acuminate, (0.7) 1–1.7 cm long, pubescent. Petiole 0.3–1 cm long. Leaflets 3.4–6.3 × 0.5–1.1 cm, elliptic, rarely oblong to obovate, pubescent on both surfaces, prominent veins on the abaxial surface; apex slightly acuminate to mucronate, base cuneate; margin pubescent. Racemes terminal, pluriflorous, 14–28 cm long, with 6–16 flowers; peduncle 8–23.5 cm long, striated, pubescent. Pedicel 0.2–0.5 cm long, pubescent. Corolla light purple, 1.8–2 cm long; calyx green, 0.8–1 cm long, pubescent, 5–laciniate, unequal, the lower three triangular, with 0.3–0.5 cm long, the upper two with converging apices and broad bases, ca. 0.1 cm long. Corolla glabrous; standard ca. 1.8 × 1.4–1.5 cm, obovate, apex emarginate, with wide claw; wings 1.7–1.8 cm long, claw narrow to slightly curved, ca. 0.35–0.7 cm long; keel petals falcate, 1.3–1.4 cm long, claws narrow, 0.3–0.65 cm long. Stamens 10, monadelphous, (1.5–) 1.8–2 cm long, glabrous; anthers dorsifixed ca. 0.05 cm long. Ovary linear, sericeus; style 0.5–0.6 mm long, stigma spatulate, glabrous. Legumes immature linear, pubescent, ca. 3.8 cm long.

Distribution and habitat:— Lathyrus ibicuiensis is only known from the Reserva Biológica do Ibicuí Mirim, Itaara, at the central region of Rio Grande do Sul state, Brazil. The species inhabits grasslands located on slopes of rocky hills ( Fig.2 View FIGURE 2 ).

Etymology: — the epithet refers to the valley of the Ibicuí-Mirim River, where the species was found.

Conservation status:— CR (D). According to the IUCN (2001) criteria and guides, Lathyrus ibicuiensis is a rare and critically endangered species because it is only known from one location and few observed specimens.

Similarities to other species:— Lathyrus ibicuiensis is similar to L. linearifolius Vogel (1839: 28) by having simple tendrils. It differs from that species by its ovate to lanceolate stipules (vs. semisagittate stipules), highly ramified branches (vs. slightly branched), and elliptic, oblong to rarely obovate leaflets (vs. linear-elliptic leaflets), as well as in its geographic distribution. The new species is restricted to Central Rio Grande do Sul, in rocky fields, while L. linearifolius is widely distributed in Southern Brazilian highland grasslands and coastal vegetation. It also differs from L. macrostachys Vogel (1839: 23) and from L. nervosus Lamarck (1788: 708) because these species have ramified tendrils. Mature legumes were not observed. The new species is rare and was found only in the typical locality, even after field trips to similar habitats and surrounding areas.

Additional specimens examined (paratypes):— BRAZIL. Rio Grande do Sul: Itaara, Reserva Biológica do Ibicuí Mirim , no campo dos Barcelos, 3 October 1989 (fl.), N. Silveira 6868 ( HAS) ; ibid., N. Silveira 6937 ( HAS) .