Cyperus tuckerianus L.P. Silva, Hefler & R. Trevisan, 2016

Pereira-Silva, Luciana, Hefler, Sonia Marisa & Trevisan, Rafael, 2016, Cyperus tuckerianus (Cyperaceae), a new species from the Central-West Region of Brazil, Phytotaxa 284 (3), pp. 218-224 : 219-222

Cyperus tuckerianus L.P. Silva, Hefler & R. Trevisan , sp. nov.

Type: — BRAZIL: Mato Grosso: Poxoréu : flooded site, 15°50’43”S 54°24.1’54”W, 16 January 2016, fl. and fr., L.P. Silva 119 (holotype FLOR!; isotypes UFMT!, RB!, NY!). ( Figures 1–2 )

Diagnosis: — Caespitose herb, annual to short perennial; 57.0–79.0 cm high, culm trigonous; inflorescence lax anthelodium simple or compound; vinaceous prophyll; spikelets digitiform or grouped in glomerules; spikelets 7.5–13.0× 2.3–3.2 mm; glumes 2.1–2.7 mm long; achenes obovoid to elliptic, biconvex.

Description: — Caespitose herb, annual to short perennial; 57.0–79.0 cm high, with thin roots 0.2–1.0 mm diam. Culm 43.5–67.5 cm long, 2.0–3.0 mm diam., trigonous, smooth, glabrous, acute angles, transverse septa absent. Leaf blade (1.5–) 2.3–31.5 cm × 3.4–5.0 mm, linear-lanceolate, flat, papyraceous-chartaceous, glabrous, greenish, with scaber antrorse in the apical portion of the margin and in the abaxial central vein, acute apex; basal leaves reduced to a sheath; leaf sheath 6.0–14.0 cm long, membranous to papyraceous, glabrous, grooved surface. Bracts of the inflorescence 3–4, (1.7–)2.5–24.0 cm × (1.1–)1.6–5.0 mm. Terminal anthelodium lax from simple to compound, 4.8–14.5 x 4.0–16.0 cm. Primary rays (2–)4–8; the basal one 3.5–12.0 cm long, surrounded by prophyllum 0.5–17.5 mm long, vinaceous. Secondary bracts inconspicuous. Secondary rays present or absent, 0.7–3 cm long, surrounded by vinaceous prophyllum, inconspicuous. Spikelets 7–25, digitiform or grouped in glomerules 1.1–2.5 × 1.5–3.5 cm. Spikelets 7.5–13.0 × 2.3–3.2 mm, narrow-elliptical to lanceolate. Rachilla 0.4–0.6 mm long, slightly flexuose, not articulate, not winged, visible or inconspicuous. Glume 9–22, 2.1–2.7 × 1.3–1.7 mm, 0.7–1.1 mm wide in side view, ovate-lanceolate, navicular, glabrous, brown-yellow to dark-gold, 5–6 veins (including the keel), keels usually greenish or sometimes with fine vinaceous lines, apex acute muticous; sterile glumes present or absent, membranous, vinaceous. Stamen 2, anthers 0.5–0.8 x 0.1–0.2 mm, yellow. Styles (0.3–) 0.5–1.5 mm long; stigmas 2, (1.1–)2.0– 3.5 mm long. Achene 1.1–1.3 × 0.7–1.0 mm, obovoid to elliptic, biconvex, apex slightly apiculate, dark-brown to black, surface puncticulate, shinny, completely covered by the glumes.

Distribution and habitat:— Presently this species is known only for the states of Mato Grosso and Mato Grosso do Sul in the Central-West Region of Brazil ( Figure 3 ). The specimens were collected in the phytophysiognomy Cerrado in humid flooded areas and also in the vegetation formation regionally known as vereda.

Etymology:— The specific epithet is given in honor of Dr. Gordon Charles Tucker, researcher of Eastern Illinois University, for his great contribution to the knowledge about genus Cyperus .

Conservation status: —Based on the collection sites it was possible to calculate the Extent of Occurrence of 21,166 km 2 and Area of Occupancy of 12 km 2 for the species. According to the criteria proposed by IUCN (2016) and evaluation of the habitat available in the region, we can consider that C. tuckerianus is a species possibly not threatened (LC). The region where the species occurs needs an exploration with better distribution of collections. We believe that the species is under-sampled in the scientific collections and an effort to explore other areas will allow to determine the degree of threat of the species with more accuracy.

Additional collection (paratypes):— BRAZIL: Mato Grosso do Sul, Brasilândia, Reserva Cisalpina , between Brasilândia and Paulicéia, 21°15’27”S 51°57’41”W, 19 December 2012, fl. e fr., S.N. Moreira et al. 1303 (BHCB) ; Inocência: Fazenda Buriti, along the length of córrego São Pedro , 20°01’37.5”S 52°07’43.5”W, 11 February 2011, fl. e fr., V.J. Pott et al. 11239 (CGMS) .

Notes:— The material selected as holotype presents an elongation of the basal internodes of the culm ( Figure 2D ), however this does not seem to be the typical morphology of the species. It was observed during the collection of the material that the habitat had recently suffered a burial ( Figure 3A ), which induced the elongation of the structure. Another important aspect to mention is the classification of the species life cycle as annual to short perennial. In spite of its robust aspect, we noted the plant presented little input in the development of its vegetative part and a higher focus in its reproductive structures (inflorescence). We believe this fact is related to the short life cycle of the plant, nonetheless in order to confirm this information it would be necessary to follow the plant’s development through the year.

According to the classification of Kükenthal (1936), Cyperus tuckerianus belongs to the subdivision Isodiametrici Kükenthal (1936: 327) of subgenus Pycreus . This subdivision is characterized by achenes with the surface covered by hexagonal isodiametric cells ( Figure 1E ). However, it was not possible to place this species in any of the sections proposed by Kükenthal (1936) for subgenus Pycreus , because the species presents characteristics that fit obscurely either in section Propinqui (Kükenthal 1836: 342; Clarke 1908: 95) or in section Chrysanthi ( Clarke 1908: 95; Kern 1974: 648).

Within the species of subgenus Pycreus , C. tuckerianus seems to be closer to C. unioloides Brown (1810: 216) , C. lanceolatus var. compositus J. Presl & C. Presl (1828: 167) and C. lanceolatus var. subunioloides Kükenthal (1936: 351) (see Table 1).

Cyperus tuckerianus may be easily distinguished from C. unioloides by its shorter and narrower spikelets and shorter glumes, and the anthers which are shorter 0.5–0.8 mm (vs. 2.0– 2.4 mm in C. unioloides ).

Cyperus tuckerianus is distinguished from C. lanceolatus var. compositus by its longer and wider spikelet and longer glumes, and Kükenthal (1936) described the rays of this variety only 2.5 cm long (vs. rays 3.5–12.0 cm long in C. tuckerianus ).

Cyperus lanceolatus var. subunioloides presents similarities with C. tuckerianus , however Kükenthal (1936) described this variety with a lax anthela and with spikelet of 20 mm long (vs. 7.5–13.0 mm long in C. tuckerianus ). In the work of Corcoran (1941), the author comments that Cyperus lanceolatus var. subunioloides appears to be a form of C. lanceolatus Poir. (1806: 245) with wider spikelets, and that this difference is not enough to recognizing at the variety level . We observed a high resolution photograph of the holotype of Cyperus lanceolatus var. subunioloides and we agree with the conclusion of Corcoran (1941).

Figures

FIGURE 1. Illustrations of Cyperus tuckerianus (based on L.P. Silva 119). A. Habit. B. Spikelet. C. Achene. D. Surface of achene. E. Detail of surface of the achene with isodiametric cells and prominent silica bodies. Illustrated by Luciana P. Silva.

FIGURE 2. Photographs of Cyperus tuckerianus in its natural habitat in the state of Mato Grosso, Brazil. A. Habit. B. Inflorescence. C. Detail of the culm base (paratype). D. Detail of the elongated internode (black arrow) at the culm base (holotype). All photographs by Luciana P. Silva.

FIGURE 3. Distribution map of Cyperus tuckerianus in the Central-West Region of Brazil.