Nasa urubambensis T.Henning & M.Weigend, 2011

Henning, T. & Weigend, M., 2011, Two new species of Nasa (Loasaceae) from Andean South America, Phytotaxa 26, pp. 1-8 : 6-8

Nasa urubambensis T.Henning & M.Weigend , spec. nov. ( Figs. 1 , 4 )

Plantae erectae, ramosae, usque ad 50 cm altae. Caulis basi ad 3–4 mm diametro, setis flavescentis, glandulis et pilis scabridis brevissimis obtectus. Folia alterna, lamina ovata vel rhomdoidea, basi cuneata, apice acuminata, margine irregulariter lobata, lobis 1–2(–3) in uno latere, ovatis margine serratis. Calyx tubo turbinato, lobis ovatiacuminatis, 4 mm longis et 2 mm latis; corolla expansa; petala alba, oblonga, cymbiformia, 6–7 mm longa, 2–4 mm lata, dente triangulari in utrisque lateribus 2–3 mm a basi remoto provisa, dorso esetosa, glandulosa et dense pilis scabridis instructa.

TYPE:— PERU. Dept. Cusco: Prov. La Convencion. Dist. Ocobamba, Paccha, Bosque secundario, W 13°03´30´´ S 072°17´20´´, 2460–3200 m, 25 September 2006, L. Valenzuela, G. Calatayud & E. Suclli 7728 (holotype HUT, isotypes B, MO).

Annual herb 40–50 cm tall, with numerous stems from base, 3–4 mm thick near base, covered with reddish brown setae 2–3 mm long, densely covered with very short glochidiate and scabrid trichomes <1 mm long and short, uniseriate gland-tipped trichomes, especially towards the apex. Petioles 10–20 mm long, sparsely setose, lamina of basal leaves rhombic, 60–80 mm long and 50–60 mm wide, shallowly, irregularly lobed with 1–2 (–3) lobules on each side, upper leaves ovate to elongate 20–30 mm long, 10–20 mm wide, base cuneate, margin entire, coarsely serrate; abaxial surface covered with few reddish setae 1.0– 1.5 mm long and densely covered with glochidiate trichomes 0.25–0.50 mm long, adaxial surface set with few reddish brown setae 1–2 mm long and scabrid trichomes <0.5 mm long. Flowers in a terminal mono- or dichasia or few-branched thyrsoids up to 30 cm long overall, with 1–3 monochasial branches and 4–12 pendent flowers per branch; bracts lanceolate, shallowly serrate, 10–20 mm long, 2–4 mm wide; pedicels ca. 5–10 mm long; calyx very densely covered with glochidiate trichomes and reddish brown setae, tube conical, 2 × 2 mm, calyx lobes acuminate from widely ovate base, ca. 4 mm long, ca. 2 mm wide; petals deeply cymbiform, 6–7 mm long, 2– 4 mm deep, base unguiculate and abruptly widened into two small, triangular teeth 2–3 mm from base, densely covered with glochidiate hairs and uniseriate gland-tipped trichomes on back, white; nectar scales ovate, narrowed above, ca. 3 mm long, ca. 2 mm wide, base incurved, with 3 vertical grooves below neck, back with two round, confluent nectar sacs at base, neck conspicuously thickened, slightly recurved, without filaments, laterally protracted into two small erect wings ca. 0.5 mm long and wide; staminodia 2 per scale, ca. 3 mm long, base slightly dilated, filiform above, densely papillose white; stamens with filaments 5–6 mm long, white, anthers 0.5 mm long and wide, yellowish brown. Fruit an erect, cylindrical capsule with persistent calyx lobes, pedicel erect, ca. 20 mm long, capsule 14–17 mm long and ca. 5 mm wide at apex.

Distribution:—The species is so far only known from two, nearby (~ 16 km) collections from the Cordillera Urubamba northeast of the Urubamba-valley in the Department Cusco, Province La Convención ( Fig. 1 ).

Habitat:—Referring to the notes made by the collectors, N. urubambensis can be found in either disturbed primary forest (remnants) or secundary woodland. This and the elevation range of 2000–3000 m is typical for species of Nasa , as described above.

Affinities:—At first glance, the two collections differ dramatically in terms of leaf shape and size and overall habit. One specimen is stifly errect with small thin leaves, whereas the other collection is a branched compact plant with larger and broader leaves. An identical flower and capsule morphology and the virtually same geographical origin indicate that these morphological differences are of little systematic value and are rather a result of different microclimatic conditions at the respective locations. Plants that are exposed to full sunlight and the resulting drought in the inner-Andean valleys tend to have smaller leafs and are less branched than individuals that grow in semi-shade under moister conditions. Nasa urubambensis seems to be able to complete its lifecycle at different, even disturbed sites (landslides/rockslides, road margins, crop plantations) which is typical for Nasa species in general and the N. poissoniana group in particular. Nasa urubambensis especially resembles N. ferruginea due to its small flowers and similarities in habit and leaf morphology. But, unlike N. ferruginea its nectar scales are uniformly pale yellow and the plants are only sparsely setose. In the province of La Convención, only two other species of the group are found, namely N. raimondii and N. vargasii . Both can easily be distinguished from N. urubambensis by their bicolorous nectar scales (white or yellow resp. with red markings) and divergent leaf morphology (see: Henning & Weigend 2009), with rhombic leaves, that are irregularly shaped and shallowly lobed ( N. urubambensis ) vs. widely ovate ( N. vargasii , N. raimondii ) with either a broader, subpalmately lobed lamina ( N. vargasii ) or an only shallowly lobulate, regular serrate lamina ( N. raimondii ). The latter differs even more dramatically by its broadly amplexicaul bracts which are always petiolate in N. urubambensis ( Fig. 4 ).

Etymology:—Species delimitation in Nasa is usually based rather on a unique combination of frequently observed characters than on clear morphological autapomorphies. Since the new Nasa shows no single striking character, but can easily be distinguished from the other species found in that region, we called it ‘urubambensis’ after the Cordillera where it has been collected twice. This area of course is named after the Urubamba-river and its valley, which is the natural limit of the Cordillera in the south and east.

Additional specimen examined (paratype):— PERU. Dept. Cusco. Prov.. La Convencion: Dist. Huayopata, Inkatambo, bosque primario intervenido, W 13°03´24´´ S 072°26´00´´, 2100 m, 29 April 2007, L. Valenzuela, B. Rado, R. Valenzuela & L. Gamarra 9663 (B, HUT, MO).

Figures

FIGURE 1: Distribution map for the two new species of Nasa.

FIGURE 4: Nasa urubambensis. A. Flowering shoot. B. Basal leaf. C. Flower, frontal view. D. Petal. E. Nectar scale, dorsal view. F. Ditto, lateral view. G. Staminode. H. Fruit. Drawn from Valenzuela et al. 7728 (A (apical parts), C–H) and 9663 (A (basal parts), B). Drawing prepared by T. Henning.