Comanthera borbae A.C.S. Pereira & Giul., 2016

Pereira, Ana Carina Silva, Ribeiro, Patrícia Luz & Giulietti, Ana Maria, 2016, Comanthera borbae (Eriocaulaceae): a new species endemic to the Northern portion of the Chapada Diamantina, Bahia, Brazil, Phytotaxa 270 (1), pp. 25-32 : 26-30

Comanthera borbae A.C.S. Pereira & Giul. , sp. nov. ( Figures 1A–P ; 2A–D ;– 3 ).

Type:— BRAZIL. Bahia: Campo Formoso, Serra do Curral Frio, road from Delfino (Municipality Umburanas) to Boa Vista, ca. 8 km after Lajes dos Negros, 10º21’58,7’’S, 41º11’54,5’’W, 25 September 2004, Pereira et al. 110 (holotype HUEFS!, isotypes ALCB!, BM!,CEPEC!, F!, K!, NY!, RB!, SPF!).

Comanthera borbae differs from all other species of this genus in Bahia, by the cushion habit with the aerial stem covered by the persistent leaves. It is similar to C. pignalii due to a lanate indumentum of white trichomes on leaves and scapes, and to the shape of the capitulum, but differs by the type of trichomes, size of flowers, petal indumentum and involucral bracts in relation to size of the flowers.

Perennial herbs 15–30–(35) cm tall, caespitose. Stem 1.5–3× 1.3–1.5 cm, rhizome erect or slightly oblique, sparsely pilose or glabrous, basal part buried in sand, covered by the persistent and revolute leaves, roots appearing at the stem base, with narrow white spongy cortex and light brown medulla, aerial parts with young leaves. Leaves 8–11× 0.8– 1.1mm, spirally arranged in a rosette, erect when young, becoming deflexed, persistent, linear, narrower towards the base, coriaceous, apex obtuse, adaxial surface of limb plane, glaucous (bluish “in vivo”), densely lanate, covered with white, adpressed malpighiaceous trichomes with two long tapered arms and a short basal cell, scattered from the apex to the base, the 1/3 lower region of the limb also with associated filamentous trichomes, ca. 0.7mm long, senescent leaves becoming glabrescent; abaxial surface of limb with thickened veins, covered by lanate indumentum, with white filamentous trichomes, with ovoid basal cell and 1–2 terminal long cells, also with adpressed malpighiaceous trichomes, which are persistent on the senescent leaves; margins ciliate, with the apical 2/3 with malpighiaceous, adpressed cilia, and the basal 1/3 with filamentous, patent cilia, ca. 0.7mm long; sheath 1–1.5 mm wide, persistent on the stem, expanded, with membranous margins, ciliate, filamentous trichomes ca. 0.7mm long, adaxial surface glabrous, abaxial surface with sparse malpighiaceous trichome. Spathes 2–3.5 cm long, coriaceous, densely lanate, covered with white adpressed malpighiaceous trichomes, apex 2-divided, membranous. Scapes 1–4 per rhizome, terminal or rarely lateral, 12–32 cm long, erect, six-costate, densely pilose, on the intercostal area, with patent filamentous and adpressed malpighiaceous trichomes. Capitula 4–6 mm high × 5–9 mm in diameter, radiate later becoming hemispherical, receptacle densely tomentose, with erect and slightly curled trichomes, persistent during fructification; each capitulum with ca. 30 staminate and ca. 15 pistillate flowers. Involucral bracts in 6–7 series, exceeding the flower length by 1 mm in the young capitulum; bracts of the outer series cream-coloured, oblong-elliptic, 1.2–1.5× 0.7 mm, apex obtuse, pubescent on the abaxial surface; bracts progressively changing towards the inner series to white, spathulate, apex round, and with glabrous surface, bracts of the innermost series obovate, 3.5–3.9× 1.4–1.7 mm, longer than the flowers, apex round, hyaline, membranous, glabrous, deflexed in the dispersion phrase. Floral bracts absent. Staminate flowers ca. 2mm long; pedicels ca. 0.5 mm long; sepals ca. 1 mm long, united up to the lower third of their length, elliptic, apex obtuse, hyaline, membranous, glabrous; anthophore absent; petals ca. 1.5 mm long, united up to half their length, elliptic, apex obtuse, hyaline, membranous; stamens slightly exserted; pistillode ca. 0.4 mm long. Pistillate flowers ca. 2.2 mm long; pedicel ca. 0.4 mm long, elongating up to 1 mm at seed dispersion phase; sepals ca. 1.3 mm long, free, imbricate, concave, elliptic, apex obtuse, hyaline, membranous, glabrous; petals ca. 1.8 mm long, united only in the median region, hyaline, membranous, glabrous, lobes with round apices; styles united, ca. 0.2 mm long, stigmatic and nectariferous portions both inserted at apex, stigmatic portion ca. 1.2 mm long, nectariferous portion ca. 0.4 mm long. Seeds ca. 0.5 mm long, elliptic, rugose.

Etymology: —The specific epithet honors Prof. Dr. Eduardo Leite Borba (Universidade Federal of Minas Gerais, Brazil) who initiated a line of research on the population biology of plants endemic to “campo rupestre” vegetation when he worked at the Universidade Estadual de Feira de Santana (2001–2005), supervising a number of post-graduate students.

Notes on taxonomic affinities: — Comanthera borbae belongs to C. subg. Comanthera , and the features distinguishing this subgenus from C. subg. Thysanocephalus are: leaves with malpighiaceous trichomes; capitula radiate, campanulate, or hemispherical; the innermost involucral bract series (rarely) equal to or (frequently) surpassing the flowers; bracts from the outer series with a different colour from the bracts of the inner series; pistillate flowers with imbricate sepals; and pedicels elongating when fruiting is in the seed dispersion phase ( Andrade et al. 2010, Parra et al. 2010, Echternacht et al. 2014). The new species is similar to C. pignalii , sharing the same general whitish appearance due to a lanose indumentum of white trichomes on leaves and spathes, and to the shape of the capitulum; but it differs by having two types of trichomes (malpighiaceous and filamentous) in the leaves and spathes, by the involucral bracts much longer than the flowers, those of the outer series oblong-elliptic and by smaller staminate and pistillate flowers (2–2.2 mm), these with glabrous petals. C. pignalii only has malpighiaceous trichomes, involucral bracts with the same size as the flowers, those of the outer series circular to obovate; bigger staminate and pistillate flowers (3.2–5.2 mm), these with petals hairy on both faces at the middle portion.

The individuals of Comanthera borbae have part of the stem and roots buried in the white, unstable sands, on the hills where the species occurs, leaving the small white plants hardly visible. This habit is similar to C. pignalii , recently described from the municipality of Jacaraci (Echternacht 2014), and C. floccosa ( Moldenke 1980:478) Parra & Giulietti ( Parra et al. 2010: 1144) from Serra do Açuruá in the municipality of Gentio do Ouro, a rare species only known from two collections ( Giulietti et al. 2009).

Distribution and habitat: —So far this species is only known from rocky outcrops with “campo rupestre” vegetation on sandy soils on the hills surrounding the municipalities of Campo Formoso (part of the “Mesoregião do Vale Sanfranciscano”, IBGE 1990) and Sento Sé (part of the “Mesoregião do Centro Norte Baiano”, IBGE 1990), in Northern Bahia, at the semiarid region of Northeastern Brazil. The entire extension of the Espinhaço Range in Bahia has been referred to as the Chapada Diamantina ( Figure 3 ), from Rio de Contas municipality in the South, to the municipalities of Umburanas (especially the mountains near Delfino), Sento Sé and Gentil do Ouro. So, we reinforce our argument that this delimitation has been widely used throughout Brazil, even if it has not been used by IBGE (1990), which relies on a delimitation based on municipalities.

The populations of Comanthera borbae are small and the individuals are clustered together forming cushions. The major part of the Campo Formoso and Sento Sé municipalities are low-lying (up to 615m) and covered by Caatinga (deciduous dry forest), with associated hills, with altitudes of 920–1250m. These mountains function as isolated islands, suitable for the establishment of “campos rupestres” (see Rapini et al. 2008), where this new species were found.

Conservation status: — Comanthera borbae is here considered as Endangered (EN) ( IUCN 2014), having a total area of occupancy and extent of occurrence of less than 500 km ² ( Figure 3 ). The populations of this new species are separated from those of C. floccosa by about 150 km, and from C. pignalii by more than 500 km. The white sand habitats where these species occur in the Chapada Diamantina and its outskirts in Bahia are rare, occurring in disjunct areas associated with the “campo rupestre” vegetation inside the Caatinga Dominium. These areas are also much threatened by the extraction of sand, used for construction ( França et al. 2013, Echternacht et al. 2014). We already know that the areas where these three species occur suffer seriously from sand extraction for building, and in the case of C. pignalii , where the population occurs near a village, from trampling, as people frequently walk through it ( Echternacht et al. 2014).

The populations of Comanthera borbae and C. floccosa occur in very isolated areas in the higher part of the mountains, surrounded by much lower areas, supporting Caatinga vegetation. The two known populations of C. borbae would be protected with the creation of the proposed National Park of the “Boqueirão da Onça”, with an estimated area of 800,000 hectares, waiting to be approved. This would include all the mountain regions of five municipalities near the São Francisco river: Campo Formoso, Juazeiro, Sento Sé, Sobradinho and Umburanas. Apart from the exuberant flora, with many species considered to be endemic, the area also supports a unique fauna, which includes jaguar, deer, foxes, armadillos, including the three-banded armadillo (tatu-bola) and many rare and endemic species of birds, reptiles, amphibians and insects ( Siqueira Filho et al. 2014).

Additional specimens examined (paratypes): — BRAZIL. Bahia: Campo Formoso, road from Delfino (Umburanas) to Campo Formoso , Lagoa da Barra , 8,7km on the road to Boa Vista , 10º21’41”S 41º 11’44” W, 925 m, 28 June 2004, Machado 227 (HUEFS) ; 10º21’53”S 41º 11’48” W, 14 March 2010, Moraes & Machado 3036 (HUEFS). Sento Sé, Serra da Imbaúba , 10º20’55,60”S 41º 25’56.60” W, 1218 m, 22 September 2006, Siqueira Filho et al. 1839 (HUEFS, HVASF) ; 10º20’01”S 41º 25’53,40” W, 1249 m, 15 May 2010, Fontana et al. 6715 (HUEFS, HVASF).

Figures

FIGURE 1. Comanthera borbae. A. Habit; B. Dorsal leaf surface; C.Ventral leaf surface; D–E. Involucral bracts of the outer series; D. Abaxial pubescent surface; E. Adaxial glabrous surface; F–I. Involucral bracts of the inner and the innermost series; F. Abaxial pubescent surface of the inner series; G–I.Adaxial glabrous surface of the inner and the innermost series, changing the size and form; J–K. Staminate flowers;J. Flowerwith calyxand corolla;K.Gamosepalous calyx;L–O.Pistillate flower;L.Flower with calyxand corolla; M.Dialisepalous calyx showing corolla; N. corolla of the pistillate flower; O. One sepal; P. Seed (Drawn from the holotype by Carla de Lima).

FIGURE 2. Diagnostic vegetative characters for Comanthera borbae. A. Leaves in rosette; B. Abaxial surface of the leaf blade showing malpighiaceous trichomes; C. Adaxial of the leaf blade showing filamentous trichomes especially at the base, and filamentous trichomes on the spathe; D. Filamentous trichomes on the scape (Photo by A.C.S. Pereira).

FIGURE 3. Geographic distribution of Comanthera borbae in the Northern portion of the Espinhaço Range in Bahia, Brazil.