Paspalum cangarum C.O. Moura, P.L.Viana & R.C. Oliveira, 2018

Moura, Clapton Olimpio De, Viana, Pedro Lage & Oliveira, Regina Célia, 2018, A new species of Paspalum (Poaceae, Panicoideae, Paspaleae-Recta group), from the cangas of the Serra dos Carajás, Pará, Brazil, Phytotaxa 357 (3), pp. 213-219 : 214-216

Paspalum cangarum C.O. Moura, P.L.Viana & R.C. Oliveira , sp. nov. ( Figs. 1 , 2 ).

Morphologically similar to Paspalum brachytrichum , from which it mainly differs by having 8 to 23 racemes, the proximal branches 7.0– 10.7 cm long, pedicels 0.8–1.5 mm long and spikelets 1.9–2.2 mm long.

Type:— BRAZIL. Pará: Parauapebas, Floresta Nacional de Carajás, Serra Sul, Campo úmido metalófilo (canga), 732 m, 06°23’32.6”S, 050°22’04.6”W, 17 March 2011, R. C. Oliveira, W. O. O. Edward, L. Tyski, D. F. Silva 2595 (holotype UB 173916!, isotype MG!).

Caespitose perennial. Culms 90–140 cm tall, erect, internodes glabrous, nodes glabrous to densely pubescent, trichomes ca. 2.0 mm long, white. Sheaths 8.0–20.0 cm long, usually longer than the internodes, pilose or glabrous on the abaxial surface, trichomes usually concentrated in the proximal region, up to 4.0 mm long; collar glabrous or with few trichomes, with different color (yellowish to brownish) or inconspicuous. Ligules membranous, 0.3–0.5 mm long, ciliate, cilia ca. 3.0 mm long; auricles absent. Blades 4.5–45 × 0.1–0.3 cm, folded or occasionally flat, linear, base slightly narrower than the sheaths; apex acute, the adaxial surface glabrous or papillose-pilose, abaxial surface glabrous or with trichomes up to 5 mm long, papillose-pilose. Synflorescences terminal, long exserted or included in the sheaths, pyramidal (proximal branches longer than the distal one); racemes 8 to 23, 1–10.7 cm long. Rachis membranous, ca. 0.5 mm wide, glabrous or papillose-pilose, terminating in a spikelet; pedicels solitary 0.8–1.5 mm long, glabrous. Spikelets solitary, 1.9–2.2 × 0.8–1 mm, elliptic, dorsiventrally compressed; lower glume absent; upper glume 1.8–2.1 × 0.8–1 mm, membranous, slender, 5-nerved, nerves conspicuous, midnerve present, usually smaller than the upper anthecium, glabrous; lower lemma 1.9–2.2 × 0.8–1 mm, membranous, 3 or 5-nerved, nerves conspicuous, midnerve present, glabrous; upper anthecium 1.9–2.1 × 0.8–1 mm, cartaceous, stramineous, glabrous, papillose, slightly shiny; lodicules 2, ca. 0.2 mm long; stamens 3, anthers purple. Caryopsis ca. 1.2 × 0.5 mm, elliptic or orbicular, hilum elliptic.

Etymology: —The specific epithet refers to the “canga” vegetation, where the species is believed to be endemic.

Distribution and habitat: — Paspalum cangarum is found in open areas upon the canga vegetation, occurring in open grasslands associated with iron-rich soils. It is endemic to Serra dos Carajás , Pará, Brazil, where it was gathered only in the Serra Sul (S11) and Serra da Bocaina plateaux ( Fig. 3 ).

According to the label of the holotype, Parauapebas is the city of the first record; however, the geographic coordinates indicate that the original collection was taken in the neighbouring city, Canaã dos Carajás .

Conservation Status: —According to the IUCN Red List criteria (IUCN 2012), Paspalum cangarum should be classified as endangered, based on the extent of occurrence (EOO) estimated as 727 km 2 and of area of occupancy (AOO) estimated as 144 km 2. The population recorded in the Serra da Bocaina is protected because it is located within the recently created Campos Ferruginosos National Park, a full protection conservation unit. However, the populations of Serra Sul (S11 plateau), located within the limits of the Carajás National Forest, are threatened by mining activities, since this category of conservation unit in Brazil allows sustainable exploration of its natural resources, such as mining ( MMA 2014) ( Fig. 3 ), and canga vegetation is usually associated with iron deposits ( Jacobi et al. 2007, Viana et al. 2016).

Paratypes:— BRAZIL. Pará: Canaã dos Carajás, Serra Sul, S 11 A, Campo graminoso sobre canga, 737 m, 6°18’57”S, 50°26’43”W, 21 March 2012, P. L. Viana, F. Marino, A. J. Arruda, T. B. Jorge, P. B. Meyer 5251 ( BHCB) ; S11 A, Campo graminoso, 717 m, 6°19’05”S, 50°26’45”W, 15 January 2016, B. F. Falcão, F. M. A. Peixoto, F. M. G. Santos, S. Sakagawa 64 ( MG) ; S11 B, Lageado associado a campo graminoso, 715 m, 6°21’17”S, 50°23’50”W, 17 February 2016, B. F. Falcão, F. M. A. Peixoto, F. M. G. Santos, S. Sakagawa 107 ( MG) ; S11 B, Campo rupestre, 724 m, 6°21’05”S, 50°23’43”W, 31 March 2016, B. F. Falcão, F. M. A. Peixoto, F. M. G. Santos, S. Sakagawa 322 ( MG) ; S11 C, Vegetação rupestre, 699 m, 6°23’01”S, 50°23’08”W, 16 March 2009, P. L. Viana, L. M. Versieux, L. C. Garcia, V. T. Giorni, L. V. C. Silva, D. F. Silva 4080 ( BHCB) ; S11 D, Campo graminoso sobre canga, 733 m, 6°23’40”S, 50°21’51”W, 20 March 2012, P. L. Viana, F. Marino, A. J. Arruda, T. B. Jorge, P. B. Meyer 5225 ( BHCB) ; estrada S11 D até S11 A, vegetação de campo rupestre (canga), 6°22’17”S, 50°23’04”W, 23 March 2015, L. C. Lobato, F. Peixoto, L. V. Ferriera, A. Rodrigues 4412 ( MG) ; Serra da Bocaina, Campo graminoso/lageado, 721 m, 6°19’11”S, 49°55’26”W, 18 June, 2016, B. F. Falcão, F. M. A. Peixoto, F. S. R. Pena, S. Sakagawa 412 ( MG) ; Serra da Bocaina, Campo graminoso, 723 m, 6°19’12”S, 49°55’27”W, 19 April 2015, B. F. Falcão, F. M. A. Peixoto, F. M. G. Santos, S. Sakagawa 439 ( MG) .

Taxonomic relationships: — Paspalum cangarum is morphologically similar to Paspalum brachytrichum and can be distinguished by the characteristics listed in Table 1. Chase (1939) treats P. brachytrichum as a member of the informal group Recta, comprising plants apparently rare with culms slender, simple; blades slender, folded; and spikelets glabrous or nearly. Within the group Recta, P. brachytrichum and the new species described are the only ones with solitary spikelets. Both species occurs in canga vegetation; however, P. brachytrichum is endemic to Minas Gerais state.

Figures

FIGURE 1. Paspalum cangarum: A. Habit. B. and C. Racemes with solitary spikelets, B.; abaxial view, C. adaxial view. D. Upper floret, upper lemma view. E. Upper glume. F. Upper floret, palea view. G. Lower lemma. Scale bar: A = 1 cm; B–G = 1 mm. Drawn from the holotype. Illustration by Isabela Couto.

FIGURE 2. Paspalum cangarum in its habitat: A. Canga vegetation, on the ironstone outcrops. B–C. Detail of the synflorescence. D. Raceme with spikelets showing anthers and stigmas. E. Proximal portion of a raceme. F. Spikelets in detail.

FIGURE 3. Distribution map of Paspalum cangarum. The dark lines indicate the Carajás National Forest (FLONA Carajás) and the Campos Ferruginosos National Park (PARNA Campos Ferruginosos); red circles are occurrence sites; black patches, canga plateaus; grey, mining pits.