Apinagia brejoagrestinensis A. S. Tavares & M. Sobral-Leite, 2015

Tavares, Aldaléa S. & Sobral-Leite, Marcelo, 2015, Apinagia brejoagrestinensis (Podostemaceae): a new rheophyte from the Atlantic Forest of northeastern Brazil, Phytotaxa 220 (1), pp. 61-68 : 62-65

Apinagia brejoagrestinensis A. S. Tavares & M. Sobral-Leite , sp. nov. ( Figs. 2 , 3 , 4 , 5 )

Type:— BRAZIL. State of Pernambuco: Agreste pernambucano, Gado Bravo Mountain Range (Serra do Gado Bravo), boundary between the municipalities of Caruaru and Agrestina, Mentirosos Stream, Flecheiras Farm, 08°23’25”S, 36°59’30.0”W, 501 m, 18 November 2007, M. Sobral-Leite 527, B. Maciel & P. Gomes (holotypus UFP 50258!, Fig. 2 , isotypus FLOR 57647!).

Paratypes:— BRAZIL. State of Pernambuco: Agreste pernambucano, Gado Bravo Mountain Range (Serra do Gado Bravo), boundary between the municipalities of Caruaru and Agrestina, Mentirosos Stream, between Caruaru and Agrestina, 08°23’25”S, 36°59’30.0”W, 501 m, 09 October 2011, M. Sobral-Leite 1252, A. Almeida, B. Sobral Leite & P. Gomes ( UFP 66884! FLOR 57648!).

Affinity:— Due to its thallus similar a stem, filamentous leaves and introrses stamens, characteristics of Euapinagia Tulasne ( Tulasne 1852, Van Royen 1951), Apinagia brejoagrestinensis is placed within this section. The new species is morphologically similar to A. glaziovii (Warm.) P.Royen ( Van Royen 1951: 46), A. guyanensis (Pulle) P.Royen ( Van Royen 1951: 37), and A. riedelii (Bong.) Tul. ( Tulasne 1849: 98), but differs from congenerics by floral traits ( Table 1), in particular the pilosity of flowers.

Description: —Rheophyte annual herbs of medium size, 15–50 cm in length. Stem flattened, flexuous, 10–30 x 0.5–1 cm. Leaves dichotomously branched; leaves pinnatifid; petiole cylindrical, 3–5 cm in length; pinnae repeatedly bifurcated, last divisions capillaceous, 3–8 cm in length, base fleshy from which flowers emerge, 2–7 x 3–5 cm. Flowers in fascicles at base of branches; spathella ovate, ovary, apex, 2.7–7.5 x 1–3 mm, provided with unicellular trichomes, brown, in larger number close to the apex; pedicel, 6–14 mm in length; tepals, 5–8, oblong, 1–1.5 x 0.5 mm, apex acute, provided with unicellular trichomes on the upper margin and apex, whorlled; stamens, 3–5, 5–7 mm in length; arranged unilaterally; filament, 3–5 mm in length, anther oblong, 2.5–3 x 0.5 mm, apex obtuse, base sagitate, dehiscence introrse; ovary oblong, 2.5–3 x 1–2 mm, without ribs, sessile; carpels 2, locule 1; placentation central-free, ovules 280–512 per ovary; style short; stigmas 2, oblong-subulate, glabrous, 1.5–2 mm in length. Capsule, 6–costate, ribs distinct ( Fig. 3 ).

Phenology:— The floral buds of Apinagia brejoagrestinensis appear submerged and the floral anthesis is only in the air, from late August to early November, in the beginning of the dry season in the region, when the ebb of the river begins. Its fruiting lasts from October to November and seed dispersal occurs in November, in the middle of dry season.

Distribution and habitat:— Apinagia brejoagrestinensis is known from the Mentirosos River, located between the municipalities of Caruaru and Agrestina.The Mentirosos River is an annual affluent of the Una River, which belongs to the homonymous river basin and drains a vast extension of one of the largest Landscape Units of Northeastern Brazil, the Borborema Plateau ( Fig. 1B ). Apinagia brejoagrestinensis occurs adhered to granitic rocks of the riverbed in an intermittent narrow river reach of rapids, with transparent waters ( Fig. 4A–B ), where it is the only submerged rheophyte.

Additional specimens examined to other species of Apinagia : ― Apinagia glaziovii (Warming) P.Royen. BRAZIL. Minas Gerais: Caraça, 720 m, 18°47’16.0”S 45°26’32.0”W, 13 june 1884, Glaziou 15444 (holotype P, isotype F, isotype US). Apinagia guyanensis (Pulle) P.Royen. SURINAME.Alto Taponahony: Cachoeira Grandafoetoe, Versteeg 808 (holotype K, isotype U). BRAZIL. Amapá: Rio Amapá Grande, 27 august 1992, Tavares, A.S. & Jégu, M. 601 (INPA). Pará: Oriximiná, Rio Paru do Oeste, Cachoeira Chuvisco, 100 m, 0°11’00.0”S 56°02’00.0”W, 7 september 1980, Ferreira, C.A.C. 2230 (INPA 96493). Pará: Oriximiná, Rio Cachorro, próximo a Cachoeira São Pedro (Cachoeira Alta), 100 m, 0°53’00.0”S 57°13’00.0”W, 25 august 1980, Ferreira, C.A.C. 8037 (INPA 143880). Pará: Oriximiná, Rio Trombetas, Cachoeira Porteira, ilha em frente ao Acampamento da Gutierrez, 100 m, 1°45’56.0”S 55°51’58.0”W, 2 july 1980, Ferreira, C.A.C. 1260 (INPA 94635). Pará: Almeirim, Rio Jari, Cachoeira de Santo Antônio, 27 july 1983, Rankin, J.M. 404 (INPA 111506). Pará: Oriximiná, Rio Paru do Oeste, Cachoeira Chuvisco, 100 m, 0°11’00.0”S 56°02’00.0”W, 7 september 1980, Ferreira, C.A.C. 2252 (INPA 96471). Pará: Oriximiná, Rio Cachorro, Cachoeira do Varador, 23 km NW da Cachoeira Porteira, 100 m, 1°45’56.0”S 55°51’58.0”W, 20 june 1980, Martinelli, G. 7123 (INPA 101705). Pará: Almeirim, Rio Jari, Cachoeira de Santo Antônio, 27 july 1983, Rankin, J.M. 403 (INPA 111507). Pará: Oriximiná, Rio Paru do Oeste, Cachoeira Chuvisco, 100 m, 0°11’00.0”S 56°02’00.0”W, 7 september 1980, Ferreira, C.A.C. 2224 (INPA 96465). Apinagia riedelli (Bongard) Tulasne. BRAZIL. São Paulo: Rio Tietê, august, Riedel 392 (holotype P). Goiás: Rio Caretão, Weddell 2090 (K; P). Rio de Janeiro: Rio Negro, 5 june 1887, Glaziou 13141 (F, P).

Etymology:— The specific epithet brejoagrestinensis was chosen because the species occurs in a vegetation refuge, denominated ‘Brejo de Agrestina’ (Agrestina Swamp), which is recognized as a Brejo de Altitude (sensu Vasconcelos-Sobrinho 1949). These refuges are remains of the Montane Atlantic Forest in areas of the Brazilian semiarid, where the predominant vegetation in lowlands is steppic savanna (locally known as caatinga) ( Vasconcelos-Sobrinho 1949, Veloso et al. 1991).

Discussion:— Based on the reference work by Van Royen (1951), Apinagia brejoagrestinensis could be confounded with A. glaziovii , A. guyanensis , or A. riedelii , for their thin and leaves dichotomously branched. A. glaziovii and A. riedelii differs from A. brejoagrestinensis by terminal flowers at the top of the branches and emarginate stigmas. Apinagia riedelli also differs by its 3–4 lanceolate tepals in incomplete whorl and 2–3 stamens. A. glaziovii still diverge from A. brejoagrestinensis by its triangular tepals and 5–6 stamens ( Van Royen 1951). Although A. guyanensis presents a vegetative morphology and the site of flower insertion similar to A. brejoagrestinensis , A. guyanensis has pedicels 20–120 mm long (versus 5–15 mm in A. brejoagrestinensis , Table 1), 6–20 lanceolate tepals, 6–25 stamens and stigmas filiforms and connate until close to the apex ( Van Royen 1951, Tavares 1997, Tavares et al. 2006), reinforce that it is another species. Finally, the unicellular trichomes on the spathellas and tepals of A. brejoagrestinensis ( Fig. 5A–B ) are differential and exclusive diagnostic characters of this species, which were reported for the genus for the first time.

Conservation status based on IUCN’s criteria:— Due to the record of a single population with few individuals (<200 ind.) in a short river reach (<100 m 2), A. brejoagrestinensis fits in the category vulnerable to extinction (VU) according to IUCN (2011). The type locality is severely deforested and the Una River and its affluents are dammed along their entire extension, threatening the survival of the new species.

Figures

FIGURE 1. Distribution of Apinagia brejoagrestinensis. A. South America highlighting (square) the northeast of Brazil. B. Northeastern Brazil, highlighting the Borborema Plateau (striped area) and municipality of Agrestina, near the locality of A. brejoagrestinensis (●). C. Riacho Mentirosos, locality of the new species and municipality of Agrestina (●).

FIGURE 2. Holotype of Apinagia brejoagrestinensis (UFP 50258).

FIGURE 3. A–N. Apinagia brejoagrestinensis (based on the holotype and paratype).A. Stem flattened, flexuous, evidencing the leaves of fleshy base from which emerge the flowers. B. Detail of the dichotomously branched leaf. C. Detail of the leaf axil evidencing the flower buds. D. Flower bud at the moment of rupture of the spathella during the beginning of the anthesis. E. Enlarged detail of the spathella trichomes. F. Fleshy base of the leaves showing developed flowers. G. External view of the flower in anthesis. H. Internal view of the flower in anthesis. J. Tepals. K. Enlarged detail of the tepal trichomes. L. Stamens of oblong anthers. M. Developed capsule. N. Dehiscent capsule, showing two persistent valves.

FIGURE 4. Apinagia brejoagrestinensis. Type locality, life form, and close-up of the flowers.A. Reach of rapids where the species occur (white arrows). B Life form of the plant in the beginning of flowering, in the dry season. C. Close-up of the flowers in anthesis.

FIGURE 5. Apinagia brejoagrestinensis. Optical micrograph of the spathella and its unicellular trichomes.A. General view of the spathella and its unicellular trichomes. B. Detail of the unicellular trichomes on the spathella.