TRABAJOS ORIGINALES

A new shrubby species of Nasa Weigend ser. Carunculatae (Urb. & Gilg) Weigend (Loasaceae) from the Amotape-Huancabamba Zone

Nueva especie arbustiva de Nasa Weigend ser. Carunculatae (Urb. & Gilg) Weigend (Loasaceae) de la Zona Amotape-Huancabamba

Tilo Henning¹ ; Asunción Cano^2,3 and Maximilian Weigend¹

1 Institut für Biologie - Systematische Botanik und Pflanzengeographie, Freie Universität Berlin, Altensteinstr. 6, 14195 Berlin, Germany.
2 Museo de Historia Natural, Universidad Nacional Mayor de San Marcos, Avenida Arenales 1256, Jesús María, Apdo. 14-0434, Lima 14, Perú. E-Mail: acanoe@unmsm.edu.pe
3 Instituto de Investigación de Ciencias Biológicas Antonio Raimondi, Facultad de Ciencias Biológicas, Universidad Nacional Mayor de San Marcos.

Abstract

Nasa is the largest genera in the Loasaceae family and it is particularly speciose in the Amotape-Huancabamba Zone of northern Peru. Nasa ser. Carunculatae is a group of four species, three of them endemic to the Amotape-Huancabamba Zone. Species in this group are characterized by their shrubby habit, deciduous leaves, and typical tilt-revolving flowers with white to greenish petals. In this work, we describe a new species of Nasa ser. Carunculatae from the southern limit of Amotape-Huancabamba area, La Libertad, Peru. The species differs from others in having much smaller and notably narrower leaves. Unlike all the other species of ser. Carunculatae, the entire distal portion of the stem is densely glandular. It is apparently most closely related to Nasa carunculata, a species known from inter-Andean valleys of Ancash and Ayacucho.

Keywords: Nasa sanagoranensis, Loasaceae, new species, La Libertad, Peru.

Resumen

Nasa es uno de los géneros más numerosos de la familia Loasaceae y en particular uno de los más especiosos en la zona de Amotape-Huancabamba. Nasa ser. Carunculatae es un grupo con cuatro especies, tres de las cuales son endémicas de la zona de Amotape-Huancabamba. Las especies de este grupo están caracterizadas por su hábito arbustivo, hojas deciduas y flores con pétalos blancos a verdosos del tipo con escamas florales que encierran al néctar y que obligan al polinizador a inclinarlas ("tilt-revolver flowers"). En el presente trabajo, nosotros describimos una nueva especie del grupo Nasa ser. Carunculatae, procedente del límite sur de la zona de Amotape-Huancabamba, La Libertad, Perú. La especie difiere por presentar hojas mucho más pequeñas y notablemente más angostas. A diferencia de las otras especies de la ser. Carunculatae, la porción distal del tallo es densamente glandular. Aparentemente está estrechamente relacionada a Nasa carunculata, una especie conocida de los valles interandinos de Ancash y Ayacucho.

Palabras clave: Nasa sanagoranensis, Loasaceae, nueva especie, La Libertad, Perú.

Introduction

Nasa is the largest genus of the family Loasaceae and comprises ca. 100 species (Weigend et al. 2006). It has its centre of diversity in Peru and especially in northern Peru and southern Ecuador, the so-called Amotape-Huancabamba Zone, where a particularly large number of narrow endemics occur, often known only from single localities (Dostert & Weigend 1999; Rodriguez & Weigend 2007; Weigend 2000, 2002; Weigend & Rodriguez R. 2002, 2003;Weigend et al. 1998, 2003). The infrageneric systematics of Nasa remain largely obscure and the morphological groups may not represent natural entities (Weigend & Gottschling 2006).

However, while the majority of taxa represent herbaceous plants, there are three morphologically comparatively well-defined species groups which include shrubby representatives. Two of them, Nasa ser. Grandiflorae (Urb. & Gilg) Weigend and Nasa ser. Alatae (Urb. & Gilg) Weigend have orange or yellow, campanulate corollas. The third shrubby group, Nasa ser. Carunculatae (Urb. & Gilg) Weigend has the typical tilt-revolver-flowers with white or bicolorous petals, which are common across the subfamily Loasoideae.

The representatives of ser. Carunculatae are much-branched from the base and have ovate, lobed leaves. Unlike all other species of Nasa, they are deciduous and loose most or all of their leaves at the end of the wet season (usually May/June). Nasa ser. Carunculatae was last revised in 2003 (Weigend et al. 2003), and four species were recognized, with a northernmost representative in the extreme South of Ecuador (N. connectans Weigend), two species in the Amotape-Huancabamba Zone [N. macrothyrsa (Urb. & Gilg) Weigend and Nasa usquiliensis Weigend, T.Henning & C.Schneid.] and another, widespread species in inner-andean valleys from northern Ancash to Ayacucho [N. carunculata (Urb. & Gilg) Weigend].

Material examined

One of us (AC) collected yet another species clearly belonging to this group in the Amotape-Huancabamba Zone in the Department La Libertad in June 2008 (Figure 1). The species was collected in the Sanagoran District (Prov. Sanchez Carrión, Depto. La Libertad) and is clearly closely allied to N. carunculata (Figure 5), but also clearly falls outside the range of that species and is here described as a species new to science. Nasa sanagoranensis sp. nov. can be easily distinguished from the previously known species of the group by its smaller leaves which are only shallowly lobulate, faintly serrate and shortly petiolate and its distinctly smaller flowers. To describe the new species a taxonomic treatment is given as well as an updated key for Nasa ser. Carunculatae.

Characteristics

The five species of the Nasa carunculata complex can be readily distinguished by morphological characters. The most easily observed characters are lamina shape and size, indumentum, flower (nectar scales, petals) and fruit morphology.

Growth habit. Nasa sanagoranensis is a deciduous, perennial shrub like the other members of Nasa ser. Carunculatae. It is the smallest species of this group, with its numerous erect to ascending stems reaching a height of only 50-60 cm (versus 100-200 cm in the other taxa).

Leaf morphology. Lamina shape and size are often taxonomically informative in Nasa ser. Carunculatae. Leaf margins are deeply lobulate with 4-7 coarsely serrate lobules on each side (N. macrothyrsa, N. usquiliensis and N. carunculata) or only shallowly lobulate (N. connectans). The lamina of N. sanagoranensis is ovate with a truncate to subcordate base and an acuminate apex. Nasa sanagoranensis has the narrowest leaves in the whole complex (and some of the narrowest in the genus), which are intermediate in lobule depth between the two types described above. With a leaf size of ca. 40-110 x 10-15 mm the leaves are also the smallest known from Nasa Ser. Carunculatae (the other species have leaves 80-170 (up to 400 in N. macrothyrsa) x 25-110 mm). The petioles are very short (4-5 mm versus 10-80 mm in the other species) and the bracts and upper leaves are subsessile.

Inflorescence morphology. Nasa sanagoranensis has terminal mono- or dichasia or few-branched thyrsoids with 5-8 pendent flowers as typical for N. ser. Carunculatae. More complex inflorescence branching as reported from N. macrothyrsa is absent.

Indumentum. In Nasa three basic types of trichomes are found (Doster & Weigend 1999): uniseriate gland-tipped trichomes, scabrid/glochidiate trichomes and stinging hairs (setae). Nasa sanagoranensis has dense indumenta of glochidiate trichomes on almost all parts of the plant. Scabrid trichomes are restricted to stem and adaxial leaf surface. Setae are generally scarce compared to other members of the complex. Reddish brown setae are found on stem, adaxial leaf surface and especially calyx and fruit. White setae are restricted to the abaxial leaf surfaces and distal parts of the stem. Uniseriate gland-tipped trichomes, usually rare and restricted to the petals in Nasa ser. Carunculatae, very densely cover all distal parts of Nasa sanagoranensis. The dense cover with glochidiate hairs and the abundance of uniseriate, gland-tipped trichomes in the inflorescence are unique in Nasa ser. Carunculatae.

Flower morphology. Nasa ser. Carunculatae has the typical tilt-revolver flowers morphology of Nasa, as described elsewhere (Weigend & Gottschling 2006: p. 125, Fig. 1) Overall morphology, shape and colouration of the flowers of Nasa sanagoranensis differ only marginally from the other species of the group. However, the flowers are strikingly small (ca. 20 mm in diam.) and are the smallest in the group and some of the smallest in the genus.

Distribution. Nasa sanagoranensis was collected close to the southernmost limit of the so called Amotape-Huancabamba Zone (Berry 1982, Ayers 1999, Young & Reynel 1997, Weigend 2002, 2004). This phytogeographical zone reaches from the Rio Jubones system in Ecuador to the Rio Chamaya system in Peru (Weigend 2004) and is a species rich area with an exceptional percentage of endemism (Young & Reynel 1997, Weigend et al. 2005a, b). Nasa sanagoranensis is the fourth species of Nasa ser. Carunculatae from the Amotape-Huancabamba Zone, only one species, N. carunculata, occurs outside this region. Nasa Ser. Carunculatae thus conforms to a pattern observed in numerous species groups such as Nasa ser. Grandiflorae, N. ser. Alatae and the N. stuebeliana group, but also in entirely unrelated plant groups such as Ribes, Passiflora, Urtica (Skrabal et al. 2001, Weigend 2002, 2004, Weigend et al. 2005b, Weigend et al. 2006). Figure 1.

Key to the species of Nasa ser. Carunculatae

1. Petioles less than 7 mm long, lamina 4-9 (-12) cm long (on vegetative shoots and below inflorescence). 2

2. Leaves always at least slightly rugose, narrowly triangular to ovate (> 25 mm wide); petals 14-19 mm long. N. carunculata

2. Leaves flat, shallowly lobulate and narrow (< 20 mm wide); petals 8-11 mm long. N. sanagoranensis sp. nov

1. Petioles 15-40 (-80) mm long, lamina 10-20 cm long (on vegetative shoots and below inflorescence). 3

3. Floral scales 5-6 mm long, red and dark yellow; petals 12-17 mm long; fruiting pedicels ca. 10 mm; only S Ecuador. N. connectans

3. Floral scales 8-11 mm long, red and white or greenish white; petals 20-30 mm long; fruiting pedicels 20-30 mm, only N Peru. 4

4. Petals ca. 9 mm deep, claw ca. 7 mm long; floral scales dorsally with two red transversal stripes (scale neck, callus); leaves abaxially whitish from scabrid trichomes ca 0,5-0,75 mm long. N. macrothyrsa

4. Petals 5-7 mm deep, claw ca. 4 mm long; floral scales dorsally with three red transversal stripes (scale neck, callus, nectar sacs distally); leaves abaxially green with glochidiate trichomes ca 0,25-0,5 mm long. N. usquiliensis

Formal Taxonomy

Nasa sanagoranensis T. Henning, M. Weigend & A. Cano, sp. nov.

(Figs. 2 A-J, 3, 4)

TYPE: Peru. Dept. La Libertad. Prov. Sanchez Carrión. Ditrito Sanagoran. Rocky slope, 2727-2739 m, 0813625-9137456, 05.06.2008, A. Cano & N. Valencia 18448 (holotype: USM, Isotypes BSB, HUT).

Haec species N. carunculatae affinis, sed ab ea foliis multo angustioris, indumento glanduloso, atque corolla minora differt.

Coarse perennial shrub 50-60 cm tall, with numerous stems from base, these basally decumbent, up to > 6 mm thick near base, sparsely covered with reddish brown setae 1,5-2 mm long and densely covered with glochidiate trichomes. Petioles 4-5 mm long, sparsely setose, upper leaves subsessile; lamina elongate, 40-110 mm long, 10-15 mm wide, base cuneate to rounded, margin entire to shallowly lobulate with 4-7 lobules on each side, each 2-5 mm long and 5-10 mm wide, coarsely serrate; abaxial surface covered with few pale setae 1-1,5 mm long and very densely covered with glochidiate trichomes 0,25-0,5 mm long, adaxial surface covered with reddish brown setae 2-2,5 mm long, scabrid trichomes 0,5-0,75 mm long and shorter glochidiate trichomes.

Flowers in a terminal mono- or dichasia or few-branched thyrsoids up to 35 cm long overall, with 1-3 monochasial branches and 5-8 pendent flowers per branch; bracts lanceolate, shallowly serrate, approximately 5-10 mm long, 2-3 mm wide; pedicels ca. 5-8 mm long; calyx very densely covered with glochidiate trichomes and reddish brown setae , tube conical, 3 x 3 mm, calyx lobes acuminate from widely ovate base, ca. 4 mm long, ca. 2 mm wide; petals deeply cymbiform, 8-11 mm long, 3-4 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, pure white; nectar scales ovate, narrowed above, ca. 4 mm long, ca. 3 mm wide, base incurved, back with two elliptical, confluent nectar sacs at base, these distally red, with 3 vertical grooves below neck and with 3 united or separate carunculae (fragmented callus) ca 1,5 mm from scale neck, neck conspicuously thickened, slightly recurved, without filaments, laterally protracted into two small erect wings ca. 1 mm long and 0,5 mm wide; staminodia 2 per scale, ca. 5 mm long, base slightly dilated, filiform above, sparsely papillose to epapillose white; stamens with filaments 7-9 mm long, white, anthers 0,5 mm long and wide, yellowish brown. Fruit a widely cylindrical capsule with persistent calyx lobes, pedicel erect, ca. 25 mm long, capsule 8-15 mm long and ca. 8 mm wide at apex. Figure 2, 3 and 4.

Acknowledgments

We thank Golder Associates Peru S. A. and the Barrick Lagunas Norte Mining Company for the logistic support during field work. Similarly, we thank Niels Valencia, Blanca León, Mónica Arakaki and María I. La Torre for reviewing the manuscript. Also, we thanks to José Roque for your help with the figure 1. Financial support for the first author (TH) by the NaFöG is gratefully acknowledged. We want to express our gratitude to Kristin Hardge for providing the drawing.

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Presentado: 02/09/2009
Aceptado: 09/11/2009
Publicado online: 12/01/2010