Rhynchospora seccoi C.S. Nunes, P.J.S. Silva Filho & A. Gil, 2019

Nunes, Clebiana De Sá, Filho, Pedro Joel Silva Da Silva, Thomas, William Wayt & Gil, André Dos Santos Bragança, 2019, Rhynchospora seccoi, a new species of Rhynchospora sect. Tenues (Cyperaceae) from Brazilian Amazon (Serra dos Carajás, Pará State), Phytotaxa 405 (2), pp. 91-100 : 92-97

Rhynchospora seccoi C.S. Nunes, P.J.S. Silva Filho & A. Gil , sp. nov. ( Figures 1 ; 2 D, E and 3 )

Type:— BRAZIL. Pará: Parauapebas, FLONA [Floresta Nacional] Carajás — Serra dos Carajás, Serra Norte N 3, coletado a margem do brejo na canga, 27 April 2015, fl., fr., C.S. Nunes, P.L. Viana, A. Gil, N.F. O. Mota & A.L. Ilkiu-Borges 21 (holotype: MG!; isotypes: BHCB!, IAN!, ICN!, RB!) .

Cespitose annual herbs, 5–47 cm tall. Culms 4–47 × 0.04–0.12 cm, ascending, flexuous, trigonous to obtusely trigonous in cross section, glabrous, green to stramineous when dry, sometimes longitudinally sulcate. Leaves 2.7–27 × 0.03– 0.11 cm, ascending, cauline, rarely basal and cauline, 1–2(3) per culm, sometimes the lowest ones with reduced blades; sheath 0.7–5.1 cm long, papyraceous, with the distal half membranaceous, glabrous, green, light brown, or brown to stramineous when dry, inner band glossy with reticulate cells; blades 2–22 cm long, papyraceous, longitudinally canaliculate, glabrous, green to stramineous when dry, adaxially 4–8 ribbed. Synflorescence comprising 1 terminal and 2–3 axillary, congested paniculodia; terminal paniculodium 0.8–2 × 0.7–1.8 cm; axillary paniculodia 0.7–1.4 × 0.5–1.3 cm; involucral bracts leaf-like 1–20 × 0.1–0.3 cm, reducing in size gradually toward the apex of the synflorescence, glabrous, green to stramineous when dry, sometimes with brown maculae on the inner band; branches slender and filiform, obtusely trigonous or subterete in cross section; spikelets 3.2–5.1 × 0.8–1 mm long, ovoid-lanceoloid to ellipsoid, grouped in fascicles; rachilla flexuous, canaliculate, glabrous; glumes 5–8, persistent in mature spikelet; the basal ones 4–6, 1.7–2.8 × 0.9–1.8 mm, fertile, ovate to oval-lanceolate, membranaceous, stramineous, glabrous, acute at apex, short-mucronate, margin not hyaline, midcosta green; the distal ones 1–2, 1–1.7 × 0.3–0.6 mm, sterile, lanceolate, membranaceous to submembranaceous, stramineous, acute at apex, short-mucronate, margin not hyaline, midcosta indistinct; perianth bristles absent; stamens 3, the filaments 1.5–2.5 mm long, the anthers 0.6 mm long; style bifid, 1.5–1.9 mm long. Nutlet 0.6–1.0 × 0.4–0.7 mm, turgid-biconvex, obovoid, rounded-obovoid or ellipsoid, stramineous to dark brown, the surface transversely rugose, with 8–10(12) transverse ridges comprised of vertically oriented linear cells, the apex rounded, the base acute-obtuse narrowing to a short stipe (ca. 0.05 mm long). Style-base ca. 0.1 × 0.2–0.4 mm, shallowly triangular, brown, shortly bilobed at base, the lobes not extending along the shoulders of nutlet.

Distribution and Habitat: — Rhynchospora seccoi is endemic to the cangas of the Serra dos Carajás (Pará State), occuring in the municipalities of Parauapebas (Serra Norte), Canaã dos Carajás (Serra Sul, Serra do Tarzan and Serra da Bocaina), Curionópolis (Cristalino), and São Félix do Xingu (Serra de Campos and Serra Arqueada) ( Figure 4 ). These municipalities cover the mountain range of the Serra dos Carajás, also known as the Mineral Province of Carajás, that have characteristic rugged terrain culminating in isolated ferruginous rock plateaus ( Viana et al. 2016). It is found on the tops of the Serra dos Carajás, growing in the cangas, near wet meadows, lakes, lagoons, and other flooded areas ( Figure 2 A-C).

Preliminary Conservation Status: —According to the IUCN (2017) criteria, Rhynchospora seccoi must be considered Endangered [B2 ab (i, ii, iii)]. It has an area of occupancy (AOO) of 92 km ² occurring in five isolated and severely fragmented locations: one protected by the Campos Ferruginosos National Park (Serra da Bocaina and Serra do Tarzan), one in the National Forest of Carajás, threatened by intense mining activity (Serra Norte and Serra Sul), and three others not protected by conservation units (Serra de Campos, Serra Arqueada, and Cristalino). The decline of its area of occupancy and quality of habitat (ferruginous rock plateaus) is ongoing due to mining activities and plans in the whole Carajás region.

Etymology: —The epithet “ seccoi ” honors the Brazilian botanist Ricardo de Souza Secco. He began his research career in Serra dos Carajás ( Secco & Mesquita 1983), participating in the first collection of Rhynchospora seccoi , on May 13, 1982 (C.R. Sperling, R.S. Secco, M. Cordon, A.L. Mesquita, B.G.S. Ribeiro & L.R. Marinho 5615 - F, INPA, MG, NY, US). Along his successful and long career, he dedicated his studies to Amazonian plants, training master’s and doctoral students, and the curatorship of the Herbarium of the Museu Paraense Emílio Goeldi (MG) .

Taxonomic relationships: — Rhynchospora seccoi is characterized by being annual, often with cauline leaves, synflorescence comprising 1 terminal and 2–3 axillary paniculodia, a nutlet with a rounded apex, a nutlet surface with 8–10(12) transverse ridges comprised of vertically oriented linear cells, and a style-base that is brown, shallowly triangular, shortly bilobed at the base with lobes not extending along the shoulders of nutlet. Although neither is known from the Serra dos Carajás (see Nunes et al. 2016a), R. seccoi is similar to the widespread species R. tenuis and R. riparia ( Nees 1842: 120) Boeckeler (1873: 561) . They are similar by having longitudinally canaliculate leaves, lanceoloid, ovoid-lanceoloid to ellipsoid spikelets, mucronate glumes apex, and nutlets rugose, with transverse ridges.

Rhynchospora tenuis differs from R. seccoi by being perennial, having basal leaves, having a nutlet with an obtuse apex, having a nutlet surface with 5–8 transverse ridges, and a style-base 0.2–0.5 × 0.6–1 mm with lobes extending along the shoulders of nutlet ( Figure 5 ). Rhynchospora riparia differs from R. seccoi by being perennial, having basal leaves, having a nutlet with an obtuse-truncate apex and a truncate base, with 2 rounded protuberances on either side, having a nutlet surface with 4–6 transverse ridges, and having a style-base 0.1–0.5 × 0.6–1 mm, with lobes extending along shoulders of nutlet ( Figure 5 ) ( Table 1).

Additional specimens examined (paratypes):— BRAZIL: Pará: Serra dos Carajás, 2 km west of AMZA camp N-5, Scrubby vegetation on ferric rock outcrops, 13 May 1982, C.R. Sperling, R.S. Secco, M. Cordon, A.L. Mesquita, B.G.S. Ribeiro & L.R. Marinho 5615 (F, INPA, MG, NY, US) ; Serra dos Carajás , 2 km west of AMZA camp N-5, 13 May 1982, C.R. Sperling, R.S. Secco, M. Cordon, A.L. Mesquita, B.G.S. Ribeiro & L.R. Marinho 5646 ( INPA, MG, NY) ; Canaã dos Carajás , S11-D, 6°24’30” S, 50°21’6” W, 836 m, 27 Jan 2012, L.V.C. Silva, M.O. Pivari, T.B. Jorge & M. Gontijo 1136 ( BHCB) ; Floresta Nacional de Carajás - Serra Sul - Corpos A, B e C, bordas das lagoas germinadas, Canga arbustiva, 6°20’59” S, 50°26’52” W, 752 m, 8 Dec 2007, N.F.O. Mota, P.L. Viana, L.V. Costa-Silva, L.C. Garcia, G.M. Maciel & D.F. Silva 1131 ( BHCB) ; Serra Sul , 6°20’26” S, 50°25’4” W, 820 m, 17 Feb 2010, M.O. Pivari, L.V.C. Silva & A.J. Arruda 1491 ( BHCB) ; S11 A, brejo entremeado por campo rupestre canga, 6°18’57” S, 50°26’43” W, 734 m, 22 Mar 2012, A.J. Arruda, P.L. Viana, F.M. Santos, T.J. Battituci & L.J. Arruda 1159 ( BHCB) ; Serra do Tarzan , 6°20’12” S, 50°9’12” W, 14 Mar 2009, V.T. Giorni, P.L. Viana, L.M. Versieux, L.C. Garcia & L.V.C. Silva 150 ( BHCB) ; Serra da Bocaina, campo graminoso sobre canga, 6°19’22” S, 49°55’41” W, 742 m, 11 Mar 2012, A.J. Arruda, L.V.C. Costa & N.F.O Mota 683 ( BHCB) ; Serra do Tarzan , 6°19’56” S, 50°8’57” W, 750 m, 24 May 2010, M.O. Pivari, L.V.C. Silva, A.O Santos & A.J. Arruda 1590 ( BHCB; MG) ; S11 A, brejo entremeado por campo rupestre canga, 6°19’5” S, 50°26’44” W, 735 m, 22 Mar 2012, P.B. Meyer, A.J. Arruda, P.L. Viana, F.M. Santos, T.J. Battituci & L.J. Arruda 1160 ( BHCB) ; Serra do Tarzan , 6°19’50” S, 50°10’15” W, 700 m, 14 Mar 2009, P.L. Viana, L.M. Versieux, L.C. Garcia, V.T. Giorni, L.V.C. Silva & D.S. Silva 4044 ( BHCB) ; FLONA Carajás, Serra dos Carajás , Serra Sul , Corpo D, 29 Apr 2015, C.S Nunes, P.L. Viana, A. Gil, N.F. O. Mota & A.L. Ilkiu-Borges 49 ( MG) ; FLONA Carajás, Serra dos Carajás , Serra Sul , Corpo D, 30 Apr 2015, C.S Nunes, P.L. Viana, A. Gil, N.F. O. Mota & A.L. Ilkiu-Borges 56 ( MG) ; FLONA de Carajás - Serra do Tarzan , campo graminoso, 6°20’12’’ S, 50°10’15’’ W, 733 m, 13 Apr 2016, B.F. Falcão, F.M.A. Peixoto, F.S.R. Pena, S. Sakagawa 342 ( MG) ; Canaã dos Carajás, Serra da Bocaina, Campo Graminoso / Lajedo , 6°18’54’’ S, 49°16’31’’ W, 222 m, 14 Apr 2016, B.F. Falcão, F.M.A. Peixoto, F.S.R. Pena, S. Sakagawa 369 ( MG) ; FLONA de Carajás - Serra do Tarzan, Campo graminoso, 6°18’53’’ S, 50°05’57’’ W, 727 m, 14 Apr 2016, B.F. Falcão, F.M.A. Peixoto, F.S.R. Pena, S. Sakagawa 368 ( MG) ; FLONA de Carajás - Serra dos Carajás , Lajedo, S 11A, beira da estrada que corta a lagoa do cromossomo, 6°20’58’’ S, 50°26’57’’ W, 710 m, 15 Feb 2016, B.F. Falcão, F.M.A. Peixoto, F.M.G. Santos, S. Sakagawa 65 ( MG) ; Serra da Bocaina, Lajedo com campo graminoso, 6°18’11’’ S, 49°53’57’’ W, 724 m, 16 Apr 2016, B.F. Falcão, F.M.A. Peixoto, F.S.R. Pena, S. Sakagawa 387 ( MG) ; Serra da Bocaina, Campo Graminoso / Campo Brejoso , 6°18’31’’ S, 49°54’06’’ W, 706 m, 18 Apr 2016, B.F. Falcão, F.M.A. Peixoto, F.S.R. Pena, S. Sakagawa 419 ( MG) ; FLONA de Carajás - Serra dos Carajás , Lajedo, S 11A, drenagem seca sob canga, 6°19’23’’ S, 50°27’02’’ W, 715 m, 20 Feb 2016, B.F. Falcão, F.M.A. Peixoto, F.M.G. Santos, S. Sakagawa 130 ( MG) ; FLONA de Carajás - Serra dos Carajás, Vegetação Rupestre Arbustiva, S 11C. Borda de estrada em área úmida, 6°22’00’’ S, 50°23’05’’ W, 741 m, 21 Feb 2016, B.F. Falcão, F.M.A. Peixoto, F.M.G. Santos, S. Sakagawa 129 ( MG) ; FLONA de Carajás - Serra dos Carajás , Campo Brejoso, S 11C, beira de estrada com drenagem e água corrente, 6°22’38’’ S, 50°23’00’’ W, 713 m, 22 Feb 2016, B.F. Falcão, F.M.A. Peixoto, F.M.G. Santos, S. Sakagawa 128 ( MG) ; FLONA de Carajás - Serra dos Carajás, Borda entre Campo Brejoso e Mata Baixa , S11B, 6°20’34’’ S, 50°25’08’’ W, 723 m, 23 Feb 2016, B.F. Falcão, F.M.A. Peixoto, F.M.G. Santos, S. Sakagawa 127 ( MG) ; FLONA de Carajás - Serra dos Carajás , Lajedo, S 11B, 6°20’33’’ S, 50°25’29’’ W, 730 m, 24 Feb 2016, B.F. Falcão, F.M.A. Peixoto, F.M.G. Santos, S. Sakagawa 126 ( MG) ; FLONA de Carajás - Serra do Tarzan, Campo Brejoso, Borda de brejo, transição para lajedo, 6°20’12’’ S, 50°09’51’’ W, 739 m, 21 May 2016, B.F. Falcão, F.M.A. Peixoto, F.M.G. Santos, S. Sakagawa 540 ( MG) ; Área da Mina do Sossego, Vegetação Rupestre Aberta afloramento rochoso, possivelmente granito, em frente a barragem, 6°27’52’’ S, 50°05’22’’ W, 284 m, 22 May 2016, B.F. Falcão, F.M.A. Peixoto, F.M.G. Santos, S. Sakagawa 539 ( MG) ; FLONA de Carajás - Serra do Tarzan, Campo brejoso com população de buritirana ao centro, 6°19’58’’ S, 50°09’45’’ W, 740 m, 29 May 2016, B.F. Falcão, F.M.A. Peixoto, F.M.G. Santos, S. Sakagawa 273 ( MG) ; Serra da Bocaina, Campo Graminoso, Em transição com Lajedo , 6°18’46’’ S, 49°53’16’’ W, 713 m, 30 May 2016, B.F. Falcão, F.M.A. Peixoto, F.M.G. Santos, S. Sakagawa 305 ( MG) ; Serra da Bocaina, Campo Brejoso , 6°18’48’’ S, 49°53’17’’ W, 712 m, 31 May 2016, B.F. Falcão, F.M.A. Peixoto, F.M.G. Santos, S. Sakagawa 304 ( MG) ; FLONA de Carajás - Serra dos Carajás , vegetação rupestre aberta, S11B, lajedo, 6°20’31’’ S, 50°25’32’’ W, 730 m, 31 May 2016, B.F. Falcão, F.M.A. Peixoto, F.M.G. Santos, S. Sakagawa 325 ( MG) ; Curionópolis, Cristalino, Vista do Platô do Cristalino , 06°27’42.4”S, 49°40’55.9” W, 06 Apr 2017, R.M. Harley, A.M. Giulietti, M.G.C. Nogueira & C.W. Maurity 58120 ( MG) ; Parauapebas [Marabá], Serra dos Carajás. N-4, mina piloto para exploração de ferro, 15 Mar 1984, A.S.L. da Silva, N.A. Rosa, R.P. Bahia & M.R. Santos 1845 ( MG) ; [Marabá], Serra dos Carajás. N-4, próximo a transição para a mata, 19 Mar 1984, A.S.L. da Silva, N.A. Rosa, R.P. Bahia & M.R. Santos 1903 ( MG) ; [Marabá], Serra dos Carajás, mina Norte 1, 19 Apr 1985, N.A. Rosa & M.F.F. da Silva 4693 ( MG) ; [Marabá], Serra Norte. Arredores da estrada para N-1, 17 May 1982, R. Secco, C. Sperling, M. Cordon, B.G. Ribeiro, A. Mesquita & Marinho 231 ( MG) ; Parauapebas, FLONA de Carajás - Serra dos Carajás , Campo graminoso/lajedo, N8, 6°10’57’’ S, 50°08’27’’ W, 716 m, 20 May 2016, B.F. Falcão, F.M.A. Peixoto, F.M.G. Santos, S. Sakagawa 523 ( MG) ; FLONA de Carajás - Serra dos Carajás , lajedo, N8, 6°11’08’’ S, 50°08’23’’ W, 729 m, 20 May 2016, B.F. Falcão, F.M.A. Peixoto, F.M.G. Santos, S. Sakagawa 522 ( MG) ; FLONA de Carajás - Serra dos Carajás, Lajedo em meio ao campo graminoso, presença de poços d’agua, N6, 6°07’48’’ S, 50°10’36’’ W, 693 m, 26 Mar 2016, B.F. Falcão, F.M.A. Peixoto, F.M.G. Santos, S. Sakagawa 248 ( MG) ; FLONA de Carajás - Serra dos Carajás, lajedo, N4WS, borda de campo brejoso (lagoa Isoetes ), 6°06’08’’ S, 50°11’12’’ W, 708 m, 26 Mar 2016, B.F. Falcão, F.M.A. Peixoto, F.M.G. Santos, S. Sakagawa 247 ( MG) ; FLONA de Carajás - Serra dos Carajás , Mata Baixa, N 5, 6°06’54’’ S, 50°08’07’’ W, 626 m, 25 Mar 2016, B.F. Falcão, F.M.A. Peixoto, F.M.G. Santos, S. Sakagawa 221 ( MG) ; FLONA de Carajás - Serra dos Carajás , Lajedo, N 5, presença de poças de água, 6°07’19’’ S, 50°08’06’’ W, 620 m, 25 Mar 2016, B.F. Falcão, F. M.A. Peixoto, F.M.G. Santos, S. Sakagawa 220 ( MG) ; FLONA de Carajás - Serra dos Carajás , Campo Graminoso, N 1, beira de estrada em água corrente, 6°01’39’’ S, 50°17’09’’ W, 700 m, 22 Mar 2016, B.F. Falcão, F.M.A. Peixoto, F. M.G. Santos, S. Sakagawa 195 ( MG) ; FLONA de Carajás - Serra dos Carajás , Vegetação Rupestre Arbustiva, N 1, 6°01’57’’ S, 50°17’24’’ W, 686 m, 22 Mar 2016, B.F. Falcão, F.M.A. Peixoto, F.M.G. Santos, S. Sakagawa 194 ( MG) ; FLONA de Carajás - Serra dos Carajás, Serra Norte N3, coletado a margem do brejo na canga, 27 Apr 2015, C.S Nunes, P.L. Viana, A. Gil, N.F. O. Mota & A.L. Ilkiu-Borges 21 ( MG) ; FLONA de Carajás - Serra dos Carajás, Serra Norte N2, coletada em canga úmida, 28 Apr 2015, C.S Nunes, P.L. Viana, A. Gil, N.F. O. Mota & A.L. Ilkiu-Borges 28 ( MG) ; FLONA de Carajás - Serra dos Carajás, Serra Norte N1, coletado na margem do brejo a beira da estrada do aeroporto no N1, 28 Apr 2015, C.S Nunes, P.L. Viana, A. Gil, N.F. O. Mota & A.L. Ilkiu-Borges 36 ( MG) ; FLONA de Carajás - Serra dos Carajás , trilha da lagoa da mata, acesso próx, a portaria N5, coletada a beira da lagoa da mata, 30 Apr 2015, C.S Nunes, P.L. Viana, A. Gil, N.F. O. Mota & A.L. Ilkiu-Borges 63 ( MG) ; FLONA de Carajás - Serra dos Carajás , trilha da lagoa da mata, acesso próx, a portaria N5, coletada em canga aberta a beira da trilha da lagoa da mata, 30 Apr 2015, C.S Nunes, P.L. Viana, A. Gil, N.F. O. Mota & A.L. Ilkiu-Borges 66 ( MG) ; Serra dos Carajás. Lagoa do Platô N6, 10 Mar 2010, L.C.B. Lobato, L.V. Ferreira, P. Prestes & D. Cunha 3876 ( MG) ; São Félix do Xingu, Serra dos Carajás , Serra de Campos , SF1, canga de campo brejoso, 6°23’33” S, 51°54’2” W, 626 m, 9 Apr 2017, M. Pastore, A.M. Giulietti, M.G.C. Nogueira, R.M. Harley & C.W. Maurity 621 ( MG) ; Serra dos Carajás, Serra de Campos , SF1, canga de campo brejoso, 6°23’33” S, 51°54’2” W, 626 m, 9 Apr 2017, M. Pastore, A.M. Giulietti, M.G.C. Nogueira, R.M. Harley & C.W. Maurity 630 ( MG) ; Serra dos Carajás, Serra de Campos , SF1, Lagoa na canga, 6°23’33” S, 51°54’2” W, 626 m, 9 Apr 2017, M. Pastore, A.M. Giulietti, M.G.C. Nogueira, R.M. Harley & C.W. Maurity 643 ( MG) ; [Ourilândia do Norte], Serra Arqueada , vegetação de canga, 6°31’24” S, 51°12’49” W, 418 m, 23 Apr 2017, T. Silva, P.L. Viana, C.W. Maurity, G.E.A. Fernandes & A.R. Silva 93 ( MG) .

Figures

FIGURE 1. Rhynchospora seccoi. A. Habit. B. Partial synflorescence. C. Spikelet. D. Basal glume. E. Nutlet. Illustration by João Silveira based on the holotype Nunes et al. 21 (MG).

FIGURE 2. Rhynchospora seccoi. A–C. Habitat. D–E. Detail of the paniculodium. Photos by (A, B, C) P.L. Viana; (D, E) C.F. Hall.

FIGURE 3. Holotype of Rhynchospora seccoi (C.S. Nunes, P.L. Viana, A. Gil, N.F.O. Mota & A.L. Ilkiu-Borges 21 - MG).

FIGURE 4. Distribution map of Rhynchospora seccoi in cangas of Region of Carajás. The red circles, collection sites; green circle, holotype site; yellow patches, canga plateaus.

FIGURE 5. Scanning Electron Micrographs (SEM) of nutlets. A. Rhynchospora seccoi (Nunes et al. 21 MG). B. Rhynchospora tenuis (Davidse et al. 17560 - MG). C. Rhynchospora riparia (Glaziou 15591 - MG).