Oxalis ferae, 2005

LLORENS, L., GIL, L., CARDONA, C., FRANQUESA, M. & BOI, M., 2005, A new species of Oxalis section Corniculatae (Oxalidaceae) from the Balearic islands, Botanical Journal of the Linnean Society 148 (4), pp. 489-493 : 489-493

OXALIS FERAE LLORENS, GIL & CARDONA SP. NOV.

Diagnosis: Herba repens prostrata; radix palaris gracilis, diametro 3– 4 mm; omnes partes glabrescentis, pilis plerumque antrorsis. Stipulae apice truncato. Petiolus (1-) 2–5 (-8) cm longus. Foliola latissime obovata, 2–6 mm longa, 2.7–8 mm lata, quaeque apice bilobato. Inflorescentiae unifloribus. Sepala oblonga, 3–4 mm longa. Petala 8.5–12 mm longa. Capsula obloida, 5.5–7 mm longa, 3.3–3.6 mm lata, pilis patentibus, apice abrupte attenuato. Semina compressa late obovata, 1.5–2 mm longa, 1.2–1.4 mm lata; testa 3–6 porcata, cristis distinctis.

Description: Prostrate creeping herb; taproot slender, 3.0– 4.1 mm diameter; roots develop at some nodes of the primary branches; primary branches elongate, up to 30 cm, glabrous or with occasional antrorse hairs; secondary branches often present, slightly hairy, with hairs (0.25–0.40 mm long) as for the primary branches. LEAVES 3-foliolate, sparsely hairy on the upper surface of the lamina, often more dense on the margin of each leaflet and densely hairy on the midrib of the lower surface, and on the petiolules; STIPULES obtuse on apex, with long hairs on margin; PETIOLE (1–)2–5(-8) cm long, subglabrous with some antrorse hairs; LEAFLETS broadly obovate, 2.1–6 mm long, 2.7– 8.0 mm wide (length to width ratio 0.7–0.8), bilobed (sinus 0.35–1.20 mm long; 1/7–1/5 of the longest of the leaflet), midrib whitish. INFLORESCENCE 1-flowered. SEPALS oblong 3–4 mm long, 0.9–1.1 mm wide, 3.2– 4.2 mm long in fruit, surface and margins with some hairs, pilose base, with apical tuft of hairs. PETALS 8.5–12.0 ¥ 4.0– 4.5 mm, yellow. STAMENS ten, alternately long and short; filaments glabrous or almost glabrous. CAPSULE obloid, 5.5–7.0 mm long, 3.3– 3.6 mm diameter (length to width ratio 1.5–1.7), longitudinally ribbed, covered with short hairs, distal half purple tinged when young, with abruptly attenuate and persistent styles. SEEDS 1–3 per locule, laterally flattened, broadly obovate in outline, very flattened, 1.5–2.0 mm long, 1.2–1.4 mm wide, 0.6– 0.7 mm thick, with 3–6 distinct ridges on both surfaces, dark purple-brown when dry ( Figs 1–11 ).

Type: Mallorca: Balearic Islands, Es Rafal d’Ariant , 11.ix.2003, altitude 90 m. Legit. Cardona, Franquesa, Gil et Llorens (Holotype: herb. Llorens-Gil; isotype: BC 862019 s.n.) .

Distribution and habitat: North-west Mallorca mountain range, between 80 and 120 m altitude. Colonizing humid and shadowy places, with little human disturbance but that are subjected to grazing (usually by sheep and goats). It occurs in clay-rich or sandy soils, usually gravelly, developed on out-crop areas of the Triassic (Keuper) or Liassic geological periods. It is an element of the cormophyte perennial pastures of a variable nitrophilous character, rich in Balearic or Tirrenic endemic species, such as Erodium reichardii , Sibthorpia africana , Scutellaria balearica , Carex rorulenta , Micromeria filiformis , Aetheorhiza bulbosa ssp. willkommii , Aristolochia bianorii , and Delphinium pictum .

Conservation status: At present, according to the IUCN Species Survival Commission (2001) categories this species should be regarded as – vulnerable VU (D 1+2).

AFFINITIES

The classification and the relationships within the species of Oxalis section Corniculatae present several difficulties and are inadequately known ( Conn & Richards, 1994; Turner, 1994). Eiten (1955, 1963), Navas (1976), Lourteig (1979), and Conn & Richards (1994) provide considerable information about the section. According to these authors, characteristics which provide the most taxonomic information are: growth type; type of indumenta of branches and fruits; and shape and size of capsule and seeds. Using such attributes, O. ferae shows important differences compared to the other species of the section ( Table 1 ).

Oxalis ferae is clearly different from O. corniculata (sensu stricto), O. exilis and O. stricta by its caespitose and stoloniferous habit, by being glabrescent (pubescent in O. corniculata and O. stricta ), in having uniflorous inflorescences (1–8-flowered in O. corniculata ; 1–5-flowered in O. stricta ), and by having larger corollas, and especially by its smaller obloid or obloidcylindrical fruits (1.5–2.0 times as long as wide in O. ferae and 5 times as long as wide in O. corniculata ) that are covered by short, patent hairs (not long, appressed and retrorse as in O. corniculata ). There are also major morphological similarities between O. ferae and O. parvifolia DC. (= O. filiformis Kunth ; O. gyrorrhiza Bertero ) of South America, but they differ especially in the pilosity of the calyx and leaves, the size of the flowers (bigger in O. parviflora ) and more particularly in the morphology and size of the fruits (cylindric-lanceolate and 3–4 times longer than wide in O. parviflora ).

Figures

Figure 1. Oxalis ferae sp. nov. Collection details. A, habit. B, pedicel with fresh fruit. C, dry fruit. D, dehiscent fruit with seeds. Scale bar = 2 cm.

Figures 2–10. SEM pictures of Oxalis ferae sp. nov. Collection details. Fig. 2. Glabrescent floral peduncle. Scale bar = 100 Mm. Fig. 3. Undersurface of leaflet. Scale bar = 1 mm. Figs 4–5. Petiolule. Scale bars: Fig. 4 = 1 mm; Fig. 5 = 200 Mm. Fig. 6. Midrib of undersurface of leaflet. Scale bar = 500 Mm. Figs 7–10. Seeds. Scale bars = 500 Mm.

Figure 11. Collection details. Fruits of Oxalis corniculata L. (left) and Oxalis ferae sp. nov. (right). Scale bar = 5 mm.