Chusquea fruticosa Pianiss., Santos-Gonç. & L.G. Clark, 2018

Pianissola, Evandro Machado, Parma, Daniele F., Santos-Gonçalves, Ana Paula & Clark, Lynn G., 2018, Two new species of Chusquea subg. Swallenochloa (Poaceae: Bambusoideae: Bambuseae) from Minas Gerais, Brazil, and complete description of C. caparaoensis, Phytotaxa 358 (3), pp. 235-250 : 239-240

Chusquea fruticosa Pianiss., Santos-Gonç. & L.G. Clark , sp. nov. ( Figs. 1 A ‒ E , 3 A ‒ E )

Type:— BRAZIL. Minas Gerais: Araponga, Parque Estadual da Serra do Brigadeiro, Pico do Soares, 1594 m, 20°43.294’S, 42°29.014’W, 15 June 2015 (fl.), Pianissola & Silva 116 (holotype VIC!, isotypes BHCB!, ISC!, RB!).

This species can be distinguished from other species belonging to the C. nudiramea informal group based on the following set of characters: subsidiary buds/branches flanking the central bud/branch; intravaginal branching; foliage leaf blades 2.6 ‒ 6.5 cm long, 0.2–0.4 cm wide and L:W = 10.3 ‒ 20 on vegetative branches, and 2.6 ‒ 4.2 cm long, 0.2 ‒ 0.4 cm wide and L:W = 6 ‒ 12 on reproductive branches.

Culms 0.8–1.8 cm in diameter, 1.8–4 m tall, caespitose, more or less erect, arching at the apex; internodes 7–14.7 cm long, terete to slightly flattened above the branch complement, glabrous, waxy. Culm leaves 13.2–19.5 cm long, caducous, the juncture of the sheath and blade abaxially an inverted shallow “V” to rounded; sheaths 8.9–12 cm long, 1.3 ‒ 3 times as long as the blade, more or less triangular, glabrous on both surfaces, the margins glabrous, sheath summit extension(s) absent; blades 3.5–9 cm long, triangular, erect, persistent, adaxially strigillose at the base, strigose at the apex, abaxially often strigillose at the apex and glabrous elsewhere or completely glabrous, midrib evident only toward the apex, apex navicular-mucronate, margins scabrous, base not pseudopetiolate; girdles 0.4 ‒ 2 mm long, glabrous; inner ligules 0.5–1.9 mm long, erose, ciliolate. Nodes slightly swollen; central bud triangular, flanked by (0–) 1 ‒ 3 subsidiary buds on each side; nodal line (sheath scar) more or less horizontal; supranodal ridge prominent. Branching intravaginal; central branch 26 ‒ 83 cm long, curving upwards and away from the main culm at a 10° ‒ 50° angle, rebranching; (0–) 2 ‒ 6 subsidiary branches per node, 8 ‒ 40 cm long, becoming shorter and less robust from the central branch, more or less erect, rebranching. Foliage leaves 4–12 (–16) per complement; sheaths deciduous, uniform in color, strigillose, nerves prominent, margins usually glabrous, rarely ciliate at the apex of young leaves, summit extension(s) absent; outer ligule less than 0.2 mm long, a minute rim, glabrous; inner ligule 0.3–0.9 mm long, rounded or more commonly truncate, usually finely ciliolate or glabrous; pseudopetiole 0.4–0.9 mm long, distinct, glabrous; blades 2.6–6.5 cm long, 0.2–0.4 cm wide and L:W = 10.3 ‒ 20 on vegetative branches, 2.6 ‒ 4.2 cm long, 0.2 ‒ 0.4 cm wide and L:W = 6–12 on reproductive branches, adaxially scaberulous over some veins, or completely glabrous, abaxially glabrous, not tessellate, striate, base asymmetric, cuneate-narrowly cuneate, apex navicular, short subulate, margins scabrous. Synflorescences (1.3 ‒) 1.9 ‒ 4 cm long, 0.4 ‒ 1.2 cm wide, paniculate, narrow, base retained within the subtending sheath; rachis angular, scaberulous to pubescent, not glaucous, branches angular, incanous to scaberulous, not glaucous; branches 1.2 ‒ 2.2 cm long, appressed; pedicels (1 ‒) 2 ‒ 3.5 (‒ 5) mm long, angular, scaberulous to pubescent, not glaucous. Spikelets 6 ‒ 7.1 mm long, 1.1 ‒ 1.9 mm wide, more or less terete, rarely falcate; glumes I and II with nerves absent, abaxially glabrous to (rarely) incanous, apically glabrous or ciliolate to ciliate, often glaucous; glume I 0.1 ‒ 0.5 mm long, less than 1 / 20 (‒ 1 / 14) the spikelet length, scalelike, truncate, acute or obtuse; glume II 0.2 ‒ 0.7 mm long, less than 1 / 10 (‒ 1 / 35) the spikelet length, apex acute, obtuse, or truncate; glumes III and IV abaxially (sparsely) scaberulous above the midvein, glabrous or incanous elsewhere, often partially glaucous, 3 (‒ 4)-nerved, keeled; glume III (3.3 ‒) 3.8 ‒ 5 mm long including the awn, 2.7 ‒ 4 mm excluding the awn, ½ ‒ ¾ the length of the lemma, awned or rarely short-awned, awn (0.4 ‒) 0.9 ‒ 1.5 mm long, adaxially puberulent for the upper ½, or less, becoming pubescent towards the apex, glabrous elsewhere, ciliolate or ciliate for the upper ½ of the margin, or less; glume IV 3.9 ‒ 5.6 mm long including the awn, 2.9 ‒ 4.5 mm long excluding the awn, 3 / 5 ‒ 4/ 5 times the length of the spikelet, apex awned, awn 0.9 ‒ 1.6 mm long, adaxially puberulent for the upper 2 / 3, becoming pubescent toward the apex, ciliate on the upper 2 / 3 or less; lemma 6 ‒ 7 mm long including the mucro, mucronate, (8 ‒) 9-nerved, keeled, abaxially scaberulous along the midvein, glabrous to incanous elsewhere, sometimes glaucous, adaxially puberulent on the upper 1 / 5 or less, or rarely pubescent, ciliolate or ciliate on the upper ½ of the margin, or less; palea 5.9 ‒ 7.1 mm long, subequal to the lemma, bimucronulate, abaxially incanous, sometimes the sulcus puberulent, adaxially pubescent on the upper 1 / 5, glabrous elsewhere, 4-nerved, 2-keeled, slightly sulcate from the base or more often sulcate from the middle portion, ciliolate on the upper ¼ of the margin or less. Lodicules 3, apically ciliate; the anterior pair 1 ‒ 1.5 (‒ 2) mm long, glabrous, the posterior one 1.1 ‒ 1.7 mm long, glabrous. Stamens 3; anthers 3 mm long, yellow. Fruit unknown.

Comments: — Chusquea fruticosa is morphologically most similar to C. caparaoensis , because of their foliage leaf width and shape, but distinguishing these two species is easy ( Table 1). Chusquea fruticosa has an abaxially glabrous culm leaf sheath (versus scabrous), a central bud flanked by the subsidiary buds in a linear array (versus central bud subtended by the subsidiary buds in a constellate array), intravaginal branching pattern (versus extravaginal), foliage leaf blades 0.2 ‒ 0.4 cm wide (versus 0.18 ‒ 0.25 cm) and a L:W ratio = 10.3 ‒ 20 on vegetative branches (versus L:W = 21 ‒ 26.5), glume III (3.3 ‒) 3.8 ‒ 5 mm long and proportion of the spikelet ½ ‒ ¾ (versus 2.2 ‒ 3.9 mm long and proportion of the spikelet 2 / 5 ‒ 1 / 2) and glume IV 3.9 ‒ 5.6 mm long, with the awn 0.9 ‒ 1.6 mm long and the proportion of the spikelet 3 / 5 ‒ 4 / 5 (versus 2.8 ‒ 3.5 mm long, with the awn 0.4 ‒ 0.7 mm long and ½ ‒ 3 / 5 the proportion of the spikelet). The leaf shape and width can also resemble some individuals of C. mimosa , but its robust central bud subtended and encircled by the subsidiary buds is completely different from the slightly bigger central bud flanked by its subsidiary buds in C. fruticosa . The flanking subsidiary buds and intravaginal branching of C. fruticosa are typical characteristics found in the species placed in C. subg. Swallenochloa sect. Swallenochloa , but the deciduous sheaths of the foliage leaves of this species indicate a potential relationship with the species of the C. nudiramea informal group; for that reason we place this species in the C. nudiramea informal group, which will now include five species.

Chusquea fruticosa was included in Silva et al. (in press), a floristic treatment of the bamboos of Parque Estadual da Serra do Brigadeiro, as C. aff. caparaoensis .

Phenology: —Some flowering individuals were found in two populations, at the Serra das Cabeças and Pico do Soares, but most of the individuals were seen in the vegetative phase. For this reason it is not possible to conclude whether a gregarious flowering event was starting or whether the observed flowering was sporadic. These populations must be continually monitored in the future in order to understand the flowering cycle of this species.

Geographic distribution and habitat: — Chusquea fruticosa occurs in high elevation grasslands, in transitional vegetation to high elevation grasslands and above rocky outcrops in the Serra do Brigadeiro ( Fig. 5 ). Several populations have been collected along the isolated inselbergs ranging in elevation from 1580 to 1980 m. No records of this species were found in the herbaria we visited, so we regard this species as endemic to the Serra do Brigadeiro.

Conservation status: —We applied the IUCN (2016) criteria and propose an IUCN red list category of vulnerable (VU = D2) given that the number of locations in the same conservation unit is only five.

Etymology: —The specific epithet “ fruticosa ” refers to the shrubby appearance of this species.

Additional specimens examined: — BRAZIL: Minas Gerais: Araponga, Parque Estadual da Serra do Brigadeiro, Pico do Pato , alto do Pico , 26 June 2013, Parma et al. 27, 28 and 30 (ISC, VIC) and 29 (VIC) ; Pico do Boné , 1642 m, 20°40’44.1”S, 42°27’41.9”W, 5 December 2013, Pianissola 28 (VIC), ibid., 1709 m, 20°40’47.8”S, 42°26’41.1”W, 5 December 2013, Pianissola & Parma 33 (VIC) ; Laje do Ouro , 1501 m, 3 March 2015, Silva & Costa 138 (VIC) ; Pedra do Pato , 1840 m, 20°44.967’S, 42°28.424’W, 13 April 2015, Pianissola & Silva 83 and 84 (VIC) ; ibid., 1840 m, 20°44.955’S, 42°28.429’W, 13 April 2015 (fl.), Pianissola & Silva 85 and 86 (VIC) ; ibid., 1861 m, 20°44.9985’S, 42°28.319’W, 13 April 2015, Pianissola & Silva 87, 88, 89 and 90 (VIC) ; Fazenda do Brigadeiro, em montanha ao lado do Rochedo , 1618 m, 20°37’18.41”S, 42°25’10.39”W, 15 April 2015, Pianissola & Silva 100 (VIC) ; ibid., 1610 m, 20°37’18.37”S, 42°25’10.39”W, 15 April 2015, Pianissola & Silva 101 (VIC) ; ibid., 1581 m, 20°37’19.64”S, 42°28’8.96”W, 15 April 2015, Pianissola & Silva 103 (VIC) ; Serra das Cabeças, Mamute , 1666 m, 20°41.355’S, 42°28.549’W, 10 July 2015 (fl.), Pianissola & Silva 104A, 104B and 105 (VIC) .

Figures

FIGURE 1. Chusquea fruticosa and Chusquea caparaoensis. A–E Chusquea fruticosa (Pianissola & Silva 116) A. Culm leaf. B. Branch complement. C. Bud complement. D. Flowering branch with foliage leaves and inflorescence. E. Spikelet. F–I Chusquea caparaoensis (F, Pianissola et al. 132 (VIC); G. Pianissola et al. 80, H–I Pianissola et al. 81) F. Seedling. G. Bud complement. H. Flowering branch with foliage leaves and synflorescence. I. Spikelet. Illustration by Reinaldo Pinto.

FIGURE 3.A–E Chusquea fruticosa.A. Habitat. B. Habit.C. Culm leaves.D. Branch complements and foliage leaves.E. Synflorescences and foliage leaves. F–J Chusquea caparaoensis. F. Habitat and habit. G. Branching pattern and foliage leaves. H. Synflorescence and foliage leaves. I. Dead culms. J. Seedling. Photos by Evandro Pianissola.

FIGURE 5. Geographic distribution of Chusquea fruticosa, C. caparaoensis and C. imbricata. The red circle represents the distribution of both Chusquea fruticosa and C. imbricata in the Parque Estadual da Serra do Brigadeiro. The blue square represents the distribution of Chusquea caparaoensis in the Parque Nacional do Caparaó. The gray area represents the Atlantic Forest domain.