Oxalis morronei Alicia López & Múlgura, 2011

López, Alicia & Múlgura, María Ema, 2011, A new species of Oxalis section Palmatifoliae (Oxalidaceae) from southern Argentina, Phytotaxa 33, pp. 41-45 : 41-44

Oxalis morronei Alicia López & Múlgura , sp. nov., Fig. 1 A–K

Ad Oxalidem squamoso-radicosam affinis, sed foliolis quadratis apice emarginato et margine pilosulo et undulato differt.

Type:— ARGENTINA. Santa Cruz: Dpto. Lago Buenos Aires. Ruta Provincial 41, camino de Los Antiguos a Paso Río Roballos , 47º57´49´´S, 71º50´10´´W, 1,247 m, 9 January 2011. L . Zavala, D. Degenaro, C . Guerreiro, A. López & H. Illarraga 204 (holotype SI!) .

Herb 4–5 cm. Rhizomes 4–5 mm diam. with sparse ramifications, covered with thick scales; scales spirally imbricate, whitish, conical, with dark spot at apices; roots fibrous, adventitious, profusely branched. Leaves usually between 2 and 6 per plant. Stipules 2.0– 2.5 mm long, hyaline, fully adnate to the petiole, narrowed toward the apex. Petioles 4–5 cm. Blades with 10–12 leaflets: leaflets 3.5–4.0 × 4.5–5.0 mm, sessile, square, folded, bases slightly cordate, margin wavy, ciliate, apices deeply emarginate, venation pinnate, glabrous on both surfaces. Flowers solitary, peduncle 4–5 cm, glabrous, bibracteolate; bracteoles up to 2 mm, hyaline, ovate, acute, sheathing, adnate at the base, glabrous, pedicel 3 mm, pubescent. Sepals 5.0–5.5 × 2.0– 2.5 mm, pubescent externally, glabrous inside. Petals 1.5–2.0 × 0.5–1.0cm, pink to violet with purple streakes. Long stamens with dorsal teeth and multiseriate hairs with warted wall on the abaxial edge. Short stamens glabrous. Fruits not seen.

Distribution and habitat:— Only known from “camino de Los Antiguos a Paso Río Roballos” ( Fig. 2 A– B ). The species grows in the shelter of rocks, in rocky and sandy soils, on slopes with western exposure, near a stream. The location corresponds to the confluence of two phytogeographical provinces: the Alto-Andina and the Sub-Antartic ( Cabrera & Willink 1980). Oxalis morronei is associated with Festuca L., Nassauvia darwinii (Hook. & Arn.) O.Hoffm. & Dusen , Lathyrus magellanicus Lam. , Calceolaria uniflora Lam. , and Oxalis adenophylla Gillies ex Hooker & Arnott (1832: 165) .

Etymology:— The new species is dedicated to Dr. Osvaldo Morrone (1957–2011), a memorable member of the Instituto de Botánica Darwinion.

Observations:— This new species had been found in sympatry with O. adenophylla , but its particular morphology of the leaflets allows easy distinction in the field. This species is similar to O. squamoso-radicosa Steudel (1856: 443) , O. laciniata Cavanilles (1799: 7) , and O. loricata Dusén (1901: 247–270) in the presence of a horizontal rhizome with fleshy scales, and differs from O. adenophylla , O. enneaphylla Cavanilles (1799: 7) , and O. loricata in the absence of linear leaflets. Despite this Oxalis morronei differs from the other members of O. section Palmatifoliae in having square leaflets with slightly cordate bases, wavy and ciliate margins, deeply emarginate apices. For a more comprehensive comparison of the species in O. section Palmatifoliae we refer to Table 1 .

Figures

FIGURE 1. Oxalis morronei. A. General aspect of the plant. B. Abaxial face of the leaflet. C. Adaxial face of the leaflet. D. Leaflet. E. Immature fruit. F. Calix. G. Base of the petiole. H. Stamens. I. Long stamen. J. Detail of the hair of the long stamen. K. Detail of the rhizome. (Drawn from the holotype, Zabala et al. 204, SI).

FIGURE 2. Photographs of Oxalis morronei in its natural habitat. A. Camino de Los Antiguos a Paso Río Roballos. B. Detail of flower and leaflets.