BRAZIL • “Brasilia meridionalis”; s.d.; Sellow s.n.; lectotype (designated by Alves and Thomas 2015: 372): K [K000584438].

BRAZIL – Espírito Santo • Mun. Santa Teresa, 1.5 km N of São João do Petrópolis on ES-80, then 600 m W on dirt road and 300 m on foot to Reserva Valão São Bras; 19°48’10”S, 40°41’21.7”W; 160 m; 22 Sep. 2016; W.W. Thomas, M. R. Barbosa, F.Z. Saiter & E.F. Oza 16619; holotype: JPB [JPB63492]; isotypes: G, K, MBML, MO, NY, P, RB.

Rhynchospora barbosae is unique in having leaf blades less than 1 cm wide and nutlets 2.4–2.6 mm long.

Plants glabrous, rhizomatous, the rhizomes 2.5–4 mm in diameter, the internodes 1.5–6 cm. Culms arching, 30–56 cm long, 1–1.7 mm wide. Leaves basal or on basal portion of fertile culm, usually 3–6, the older leaves dying as culms mature; sheaths tight, 3–3.8 cm long, the summit of the sheath concave or “V” shaped; blades 29–57 × 0.8–0.9 cm, linear. Synflorescence a series of 3–4 inflorescences, each subtended by a leaf-like bract, the bracts at each more distal node diminishing in size, the basal bract with a sheath 12–15 mm long, the blade linear, 30–43 × 6–8 mm; inflorescences corymbose grouped into 2–3 basal longer lateral branches and 2–4 shorter distal branches forming a terminal cluster and comprising 17–35 spikelets, each lateral branch with 2–5 spikelets; lower lateral branches greatly exceeding the central axis; lowest inflorescence with central axis 50–56 × ca 0.5 mm long, the portion distal to the lowest lateral branch 13–25 mm long; basal lateral branch 20–39 × ca 0.2 mm long. Mature spikelets lenticular (slightly flattened), brown, ellipsoid to ovoid, 3–3.2(–4.2) × 2.3–2.5 mm, the basal 6–7 glumes distichous, carinate, cucullate, the apex acute and mucronate, the mucros separating from the glume below apex. Hypogynous bristles ca 1.7–1.8 mm long, densely short-plumose on the distal two thirds, sparsely so on the basal third. Nutlet broadly elliptic to broadly obovoid in outline, deeply ellipsoid to nearly globose, 2.4–2.6 × 1.8–1.9 mm, the summit straight to slightly arched, the persistent style base triangular, (0.9–)1.1–1.2 × 0.9–1 mm, the surface shiny, smooth to lightly and irregularly textured.

Rhynchospora barbosae is known from a single area of Atlantic Forest in the state of Espírito Santo, Brazil (Fig. 5). The only collections are from an intact tropical seasonal semi-deciduous forest (Thomas and Barbosa 2008) at 160 m on a forested slope, usually among rocks.

The species is named in honour of Dr Maria Regina de Vasconcellos Barbosa, a co-collector of the type. She is a Brazilian botanist and Senior Professor at the Federal University of Paraíba. She is a brilliant teacher and is an expert on the Rubiaceae and on the vegetation of north-eastern Brazil.

Rhynchospora barbosae is known from three localities in a ca 15 km strip of semi-deciduous forest in the municipality of Santa Teresa, Espírito Santo (Fig. 5). The Atlantic Forest of Brazil has been identified as one of the World’s biodiversity “hotspots” (Myers et al. 2000), in part, because of continuing deforestation. Overall, the Atlantic Forest has been reduced to less than 11 percent of its original extent (Ribeiro et al. 2009), with the dry forests suffering the most. The Extent of Occurrence for this species is 8.05 km², a value that would be considered CR. The Area of Occupancy is 12.0 km², a value just large enough that it would suggest that EN is the proper Red List category. The municipality of Santa Teresa, however, has been well collected and there are few remaining semi-deciduous forests in the region, and the little that is left is under pressure. While the species is collected from three localities, we consider them to comprise a single location. Since the location is unprotected and anthropogenic pressure on the semi-deciduous forests in the region is high, we assess R. barbosae as Critically Endangered: CR B1ab(iii).

BRAZIL – Espírito Santo • Mun. Santa Teresa, IFES Campus Santa Teresa, mata do São Brás, abaixo do ponto de captação de água, Folhas verdes escuras, rígida, dentro da mata, solo raso; 19°48’11”S, 40°41’20.4”W; 350 m; 2 Sep. 2015; E.F. Oza, F.Z. Saiter, F. Falk & J. Ribeiro 6; MBML [50636] • Comunidade do Milanês, São João de Petrópolis, propriedade de Thiago Rosado/IFES Santa Teresa, em grotão com solo profundo e muita matéria orgânica; 19°47’38.4”S, 40°39’54”W; 250 m; 6 Apr. 2016; E.F. Oza, F.Z. Saiter, F. Falk & J. Ribeiro 16; MBML [50637] • Várzea Alegre (Mata do Fausto, próximo ao colégio), interior de mata, ambiente seco; 27 Jul. 2000; V. Demuner et al. 1303; MBML [013251], NY • Escola Agrícola; 19°49’55.2”S, 40°36’46.8”W; 155 m; 4 Apr. 2003; P. Fiaschi et al. 1468; CEPEC, MBML [21036], NY, SPF [157828].

The only other species with large nutlets similar in size to those of Rhynchospora barbosae is R. calyptrocaryoides (R. Gross) W.W.Thomas with nutlets 2.4–3.2 mm long. Rhynchospora calyptrocaryoides, however, is a much more robust plant, with leaf blades 15–90 × 2–2.4 cm compared to 29–57 × 0.8–0.9 cm in R. barbosae. Rhynchospora macrantha (Kunth) W.W.Thomas has achenes that overlap in size with those of R. barbosae (2.1–2.6 × 1.5–2.1 mm vs 2.4–2.6 × 1.8–1.9 mm). It, however, is also much more robust and has large, open panicles with solitary spikelets at the end of each branch. The remaining species of Rhynchospora sect. Pleurostachys have achenes 0.8–2.4 mm long. See key to the species of R. sect. Pleurostachys below.

BRAZIL – Bahia • Mun. Poções. Fazenda Boa Esperança, 7.5 km S of Morrinhos (6.1 km E of Poções on road to Ilhéus) on forested slope; 14°36’40”S, 40°20’13”W; 7 Feb. 2004; W.W. Thomas, A.M. Amorim, P. Fiaschi., J.L. Paixão & S. Sant’Ana 13954; holotype: CEPEC [102299]; isotypes: K, MO, NY, RB [692412], RB [693118], US.

Rhynchospora hamadryadis is unusual in having mostly short, unbranched secondary axes branching off the primary axis of each synflorescence. Otherwise, it is similar to Rhynchospora panicoides Schrad. ex Nees.

Plants glabrous, rhizomatous, the rhizomes 1.5–2 mm in diameter, the internodes congested or occasionally to 6 cm. Culms slender and arching, 18–45 cm long, 0.7–1 mm wide. Leaves mostly or all basal; basal leaves 3–7, linear, the sheaths 2–3 cm long, often difficult to distinguish from blade, the blades 20–35 × 0.2–0.4 cm; cauline leaves 0–1, the sheath 15–20 mm long, the summit of the sheath concave. Synflorescence a series of 3–4 elongate, compact, corymbose inflorescences of 1–9 spikelets, each inflorescence subtended by a linear, leaf-like bract, the bracts at each more distal node diminishing in size; basal bract with the sheath 14–20 mm long, the blade 18–24 × 0.15–0.35 cm; terminal inflorescence largest, the primary axis 18–65 × 0.25 mm, the basal secondary axis longest, 70–110 × 0.3–0.4 mm, each secondary axis terminating in a cluster of 3–6 spikelets. Mature spikelets (without fruit deforming shape) brown, lenticular (slightly flattened), broadly obpyriform, 2.8–3.8(–4.5) × 2.2–2.6 mm, the basal 6–7 glumes distichous, carinate, cucullate, the apex acute, mucronate, the basal fertile glume ca 2.2–2.5 × ca 2.5 mm, the mucro ca 0.3–0.4 mm. Hypogynous bristles ca 2–2.5 mm long, two-thirds as long as to slightly exceeding the nutlet and style base, densely short-plumose on the distal two thirds, sparsely so on the basal third. Nutlet broadly to very broadly elliptic to obovate in outline, deeply lenticular, 1.7–2.4 × 1.45–1.7 mm, the surface golden tan and very lightly tuberculate, the summit slightly arched; persistent style base triangular, 0.4–0.5 × 0.6–0.7 mm, the surface dull grey and irregularly textured.

Rhynchospora hamadryadis is known from three localities, all in the deciduous seasonal forest zone (Thomas and Barbosa 2008) at 495 to 900 m elevation in southern Bahia and adjacent Minas Gerais (Fig. 5). This is a low, open forest with many lianas and giant bromeliads. Locally, it is known as “mata de cipó” and is exceedingly scarce.

In Greek and Roman mythology, a hamadryad was a woodnymph bonded to a certain tree and who died when the tree died. Martius (1906) recognized five phytogeographic regions in Brazil and used Hamadryades to describe the seasonal arid vegetation of the interior of north-eastern Brazil.

Rhynchospora hamadryadis is known from three locations, all in the highly endangered deciduous seasonal tropical forest. It has an Extent of Occurrence of 659.5 km² and an Area of Occupancy of 16 km² (Fig. 5). Both values indicate that the species should be considered as Endangered: EN B1ab(iii)+B2ab(iii). While the known localities near Boa Nova are now part of the Refúgio de Vida Silvestre de Boa Nova and are probably protected, the location in Minas Gerais remains unprotected and a decline in the area, extent and/or quality of the habitat is therefore inferred.

BRAZIL – Bahia • Boa Nova, Fazenda Cotermaia, entrance 1.2 km E of Boa Nova on road to Dario Meira; 14°22.419’S, 40°11.305’W; 810 m; 18 May 2001; W.W. Thomas et al. 12493; CEPEC [89604], NY, SPF [205632] • 14°22.389’S, 40°11.309’W; 790 m; 25 Oct. 2001; W.W. Thomas et al. 12640; CEPEC [92010], NY • 3.3 km E of Boa Nova on road to Dario Meira; 14°22.983’S, 40°11.177’W; 850–900 m; 15 Oct. 2000; W.W. Thomas et al. 12286; CEPEC [89012], NY • 14°22.98’S, 40°11.17’W; 865 m; 20 Nov. 2000; S.C. Sant’Ana et al. 1017; CEPEC [86937], NY, SPF [205657] • Jequié, Serra do Castanhão, 14.5 km S of Jequié on BR116, then 7.2 km W; 13°56.522’S, 40°11.468’W; 775 m; 23 Oct. 2001; W.W. Thomas et al. 12547; CEPEC [91012], NY–3, SPF [205643]. – Minas Gerais • Salto da Divisa [on both sides of the state line with Bahia: Itagimirim], Estação Repetidora de Salto da Divisa [Serra do Bogodo], 7.1 km E of Salto da Divisa; 16°01’43”S, 39°55’17”W; 495 m, 31 Jan. 2004; W.W. Thomas et al. 13735; CEPEC [103138], NY, RB [686946].

Rhynchospora hamadryadis is unusual in having mostly short, unbranched secondary axes branching off the primary axis of each synflorescence. This gives the appearance of a narrow, elongate synflorescence. The only other species to have similar inflorescences is R. panicoides, a much more robust species; while R. hamadryadis has 1–9 spikelets per inflorescence, R. panicoides usually has over 30 per inflorescence. See key to the species of R. sect. Pleurostachys below.

BRAZIL – Minas Gerais • Salto da Divisa [on both sides of the state line separating Bahia: Itajimirim]. Estação Repetidora de Salto da Divisa [Serra do Bogodo], 1.9 km S of road from Salto da Divisa to Itajimirim, 7.1 km E of Salto da Divisa; 16°01’43”S, 39°55’17”W; 495 m; 31 Jan. 2004; W.W. Thomas, A.M. Amorim, P. Fiaschi, J.L. Paixão & S. Sant’Ana 13748; holotype: CEPEC [102274]; isotypes: K, MO, NY, RB [686968], RB [696646].

Rhynchospora eremica is one of the smallest species in sect. Pleurostachys with culms no more that 30 cm long and leaves mostly under 20 cm long. Its short, broad leaves are unique among those species with basal leaves.

Plants glabrous, rhizomatous, the rhizomes congested, 2 mm in diameter, the internodes 0.5–1 cm. Culms arching, 22–30 cm long, 1 mm wide. Leaves basal 3–5, linear, the sheaths not seen, the blades 12–21(–45) × 0.5–1.2 cm, glaucous green above and below, flattened, midrib evident. Synflorescence a series of 3–6 corymbose inflorescences, each subtended by a leaf-like bract, the bracts at each more distal node diminishing in size; basal bract with sheath 10–22 mm long, the blade linear, 6–14 × 0.2–0.7 cm; inflorescences increasing in size and number of spikelets distally, each one of 3–9 spikelets, the primary axis 30–70 × 0.2 mm, the basal branches longest, 10–26 × 0.1–0.2 mm, with 2–3 spikelets, the shorter distal branches forming a terminal cluster of 2–4 spikelets. Mature spikelets dark brown, (measurements for those without maturing achenes distorting shape) lenticular, ellipsoid, 4–6.4 × 1.8–2.5 mm, comprising 20–30 glumes, the basal 3 glumes smaller, sterile, the fertile glumes ca. 2.6 × 1.5 mm, more or less distichous, carinate, cucullate, the apex acute, mucronate. Hypogynous bristles 0.6–2.0 mm long, half as long as to slightly exceeding the achene, densely short-plumose on the distal two thirds, sparsely so on the basal third. Nutlet circular to very broadly obovate in outline, deeply lenticular, 1.6–1.8 × 1.4–1.7 mm, the surface golden tan and very lightly rugulose to tuberculate, the summit slightly arched; persistent style base triangular, 0.4–0.5 × 0.5–0.8 mm, the surface dull grey and irregularly textured.

Known from a single collection on the Serra do Bogodó, a 490 m high hill with low, open deciduous seasonal tropical forest (Thomas and Barbosa 2008) surrounded by lower, ca 200 m elevation, flat, deforested land converted into pasture (Fig. 5). The Serra is on the state line separating the municipalities of Salto da Divisa in Minas Gerais and Itajimirim in Bahia.

The specific epithet comes from the Greek “eremos” meaning solitary and often is used in specific epithets to describe desert environments. Here, it describes the dry forest habitat, and that this species is known only from the type collection.

Two subsequent trips to the only known locality revealed no additional plants. Since the original collection, cattle were permitted to enter and graze, probably affecting the diversity of plants in the herbaceous layer of the forest. Rhynchospora eremica is sympatric with R. hamadryadis described above but has never been collected at other localities where the latter species occurs (Fig. 5). It was collected at a single unprotected locality that has since been altered, and has never been collected anywhere else, but we hope that additional exploration may reveal it in other locations. In addition, the deciduous seasonal tropical forest, is the most exploited and sensitive type of Atlantic Forest. Since R. eremica is only known from a single location and since we infer a decline in the area, extent and/or quality of the habitat as a result of grazing, the species is assessed as Critically Endangered: CR B2ab(iii).

Rhynchospora eremica is one of the smallest species in section Pleurostachys with culms only reaching 30 cm long. Of the smaller species with basal or mostly basal leaves, it is unique in having short, broad leaf blades (12–21 × 0.5–1 cm) and occurring in dry forests. See key to the species of R. sect. Pleurostachys below.