Herbertia amabilis Deble & F. S. Alves, 2013

Deble, Leonardo Paz & Alves, Fabiano da Silva, 2013, Herbertia amabilis Deble & F. S. Alves (Iridaceae), a new species from Brazil, Candollea 68 (1), pp. 133-137 : 134-136

Herbertia amabilis Deble & F. S. Alves , spec. nova ( Fig. 1 , 2 ).

Typus: BRAZIL. Rio Grande do Sul: Júlio de Castilhos, “no campo, entre gramíneas, no solo argiloso, flores brancas” , 29°18’43’’S 53°49’39’W, 23.XII.2010, fl. fr., L. P.Deble 12721, A.S. de Oliveira-Deble, J. N. C. Marchiori & F. S. Alves (holo-: SI!; iso-: CTES!, ICN!).

Species nova ab Herbertiae lahue subsp. amoenae affinis, sed magna statura (30-40 cm alta vs 8-15 cm alta), foliis longioribus et anguste linearis (18-35 cm longis, 0.3-0.5 cm latisvs 8-15 cm longis, 0.4-1 cm latis),ovarium obovatoclavatum, 3.5-5 mm longum (versus obovato-oblongum, 6-8 mm longum), tepala exteriora albida, (vs coeruleo-violacea),tepalainteriora albida et lutea (vs atro-violacea), optime distincta.

Plants up to 30-40 cm high, subterranean stems 10-20 cm long. Bulb ovoid, 18-24 mm wide, sometimes prolonged in a short collar. Leaves 2, plicate, narrowly linear, 18-35 cm long, 0.3-0.5 cm wide. Spathes 2-4, herbaceous, pallid-green, bivalved, two-flowered, pedunculate, peduncles 4-8.5 cm long; lower valve 2.3-3.4 cm long, the upper 3.5-4.5 cm long, both with membranous edges; pedicel filiform, 4-5 cm long. Flowers predominately white, radially symmetrical, 3.5-4 cm diam. Tepals whorls sharply dissimilar: outer tepals obovate, 18-21 mm long, 9-12 mm wide, white, with yellow dots scattered in the proximal half, and a yellow medial stripe at the base; inner tepals oblanceolate, 5-6 mm long, 1.3-1.8 mm wide, white, with a yellow macula in medial portion, apex long attenuate, acuminate, reflexed. Filaments entirely united in a column, 4.2-4.8 mm long, yellowish along the column; anthers linear, yellow, curved at dehiscence, 7-7.5 mm long; pollen yellow. Ovary obovate-clavate, 3.5-5 mm long, 1.8-2.5 mm wide. Style 9-9.5 mm long; style arms channeled, 4.5-5 mm long, at the apex bifid for 1.8-2.2 mm, the divisions divaricate, recurved, apically stigmatic. Capsules broadly oblong-clavate, 9-11 mm long, 4.5-5 mm wide. Seeds oblong to obconical, angular, reddish-brown, epidermis striate, 1.5-2 mm long.

Etymology. – The specific epithet means kind, delicate and refers to the pretty and delicate flowers of the new species.

Distribution and ecology. – Herbertia amabilis is a narrow endemic of central Rio Grande do Sul State, where just two populations are known. Plants grow in grasslands on clay soils in the hydrographic basin of the Guassupi river southwest of Júlio de Castilhos city ( Fig. 3 ).

Phenology. – Flowering and fruiting occur during December.

Conservation. – During the review of herbaria, no exsiccates of H. amabilis were found. The only known collections are those made by the authors and here cited. The extent of occurrence of H. amabilis comprises less than 100 km 2 and the populations size are smaller than 10 km 2; only two populations are know and with few individuals. Furthermore, agriculture, and urban expansion affect directly the range of the species. Due to the rarity, fragmentation of populations, and observed threats, it seems prudent to include H. amabilis in a preliminary status of Critically Endangered category of the IUCN Red List of Endangered plant species according to the following criteria “CR B1, 2a, b; D” ( IUCN, 2011).

Taxonomical note. – Herbertia amabilis by its androgynoecium filaments entirely united forming a column, its ascendant style arms, and the size of flowers is most closely related with H. lahue subsp. amoena , but can be segregated by the following features: robust habit (30-40 cm vs 8-15 cm), narrowly linear leaves, with 18-35 cm long, 0.3-0.5 cm wide (vs linear-lanceolate leaves, with 8-15 cm long, 0.4-1 cm wide), style arms at the apex recurved (vs not or slightly recurved), and ovary obovate-clavate, 3.5-5 mm long (vs obovate-oblong, 6-8 mm long). Additionally, the flowers are predominately white (vs blue-violet, rarely white in atypical individuals occurring among normal ones), with a yellow macula in medial portion of inner tepals (vs without yellow macula). Herbertia crosae , another close species differs by purple dots along the column of androgynoecium filaments (vs without purple dots), free apically up to 1 mm long (vs entirely united), and smaller anthers (4-5 mm vs 7-7.5 mm long). Herbertia darwinii has androgynoecium features similar with the new species, but its differs by large 4-5.7 cm wide, blue-violet flowers, ovary 6- 8.5 mm long, and leaves 1-2 cm wide.

Paratypus. – BRAZIL. Rio Grande do Sul: Júlio de Castilhos, “no campo, entre gramíneas, no solo argiloso, flores brancas” , 29°18’43’’S 53°49’39’W, 23.XII.2010, fr, L. P. Deble 12722, A. S. de Oliveira-Deble, J. N. C. Marchiori & F. S. Alves ( CTES!).

Figures

Fig. 1. – Herbertia amabilis Deble & F. S. Alves. A. Plant; B. Spathe with flower; C. Spathe with capsules; D. Lateral view of flower; E. Flower with tepals removed showing the androgynoecium; F. Inner tepals; G. Capsule; H. Seeds; I. Medial portion of leaf; J. pical portion of leaf. [Deble 12721 & al., SI] [Drawn by L. Paz Deble]

Fig. 2. – Herbertia amabilis Deble & F. S. Alves. A. Lateral view of flower; B. Upper view of flower; C. Flower, capsules and general habit; D. Distal portion showing spathe with flower and capsules. [Deble 12721 & al., SI] [Photos: L. Paz Deble]

Fig. 3. – Geographical distribution of Herbertia amabilis Deble & F. S. Alves.