Aulonemia cincta P.L. Viana & Filg., 2014

Aulonemia cincta P.L. Viana & Filg. View in CoL , sp. nov. Figs. 1−2 View FIGURE 1 View FIGURE 2 .

Similis Aulonemiae aristulatae rhizomatibus amphipodialibus, paniculis laxis et spiculis 1.2–2 × 0.2–0.4 cm, sed spiculis muticis et laminis discoloribus absimilis. Ab omnibus speciebus congeneribus notis singulari cingulo praedita, i.e., expansione corticosa deorsum ad lineam nodalem, differt.

Type:— BRAZIL. Paraná: Morretes, Pilão de Pedra , 28 January 1982, Kummrow 1704 (holotype MBM! , isotypes MO-3238710 ! , MO-3803806 ! ).

Rhizomes amphipodial. Culms initially erect or decumbent, the erect ones becoming clambering on the neighboring vegetation, 1.5–4 m long, the decumbent ones forming new short-necked sympodial rhizomes on the nodes in contact with the ground, then becoming clambering and leaning on the adjacent vegetation; midculm internodes 4.5–22.2 × 0.2–0.4 cm, hollow, thick-walled, terete, glabrous to pubescent, green and mottled when young, becoming blackish with age, surface smooth, striate in dried material. Nodal line horizontal, expanded into a corky downward girdle about twice the diameter of culm, glabrous or pubescent, dark reddish and becoming pale with age; intranodal area 0.2–0.6 × 0.2–0.6 cm, glabrous to pubescent; supranodal ridge conspicuous; buds not seen. Branch complement consisting of a single branch, which can bear branchlets on its basal nodes. Culm leaves gradually differentiating into foliage leaves toward the culm apex, sheaths 4.5–7.3 cm long, glabrous to sparsely pilose on the base, green to pale brown, usually red-mottled; fimbriae 0.1–0.2 cm long; outer ligule present, minute, inner ligule 0.1-0.4 mm long, membranous-ciliolate; pseudopetiole 1–1.9 mm, glabrous abaxially, pubescent adaxially; blades 2.8–5.6 × 0.5–1 cm, linear-lanceolate to oval-lanceolate, reflexed, glabrous to puberulous adaxially, glabrous abaxially. Foliage leaves with sheath 5.2–9.5 cm long, glabrous, slightly carinate toward the apex, green to pale brown, usually red-mottled, margins glabrous, apical auricular extension inconspicuous, to 0.5 mm long; pseudopetiole 1.5–3.1 × 1–1.8 mm, pubescent adaxially, glabrous abaxially, reddish to pale green; fimbriae persistent, 0.15–0.25 cm long, erect, slightly undulated, terete, scaberulous, free or fused at the base forming minute auricles, dark red, becoming pale with age; outer ligule ca. 0.2 mm long, membranous-ciliolate; inner ligule ca. 0.2 mm long, membranous-ciliolate; blades 4.6–15.6 × 0.8–3.2 cm, ovallanceolate, patent, glabrous adaxially, sparsely sericeous abaxially, membranous to chartaceous, glaucous with a dark green marginal stripe abaxially, uniformly green adaxially, not tessellate, base asymmetrical, rounded to subcordate, apex acuminate, margins antrorsely scabrous. Synflorescence an open panicle 14.5–23.7 × 9.0– 21.3 cm, pyramidal; branches divergent; peduncle verruculose; pedicels 2–38 × ca. 0.1 mm, glabrous. Spikelets 1.2–2 × 0.2–0.4 cm, ellipsoid, laterally compressed, consisting of 2 glumes, 2–4 fertile anthoecia and 0–1 apical rudimentary anthoecium; glume I 2.8–3.2 mm long, 1-nerved, scaberulous, pale, apex long acuminate, awnless; glume II 6.4–7.3 mm long, 3–5-nerved, glabrous to sparsely puberulous abaxially, puberulous adaxially, pale, apex long acuminate, awnless; rachilla internodes 2.8–5.2 mm long, scaberulous; lemma ca. 9.2 mm long, 6–7-nerved, puberulous, pale brown, mottled, apex long acuminate, awnless; palea 6.8–7.9 mm long, 2-nerved, densely papillose between the keels and scaberulous toward the apex abaxially, not mottled, apex navicular. Lodicules elliptic to broadly oval, ciliate; anthers not seen; ovary 1.2–1.8 mm long, ellipsoid, pilose on the apex. Fruit not seen.

Etymology: —The epithet refers to the peculiar girdle of this plant, a corky expansion of the leaf sheath in the nodal line, which is persistent in mature culms.

Comments: — Aulonemia cincta is a graceful thin-stemmed viny bamboo with culms not wider that 4 mm. The plants can propagate via new sympodial rhizomes, which originate from nodes of decumbent culms that touch the ground, in an amphipodial pattern, a feature also described by Soderstrom (1988) for the Mexican Olmeca fulgor (Soderstrom 1988: 22) Ruiz-Sanchez et al. (2011: 93) , and also found in Aulonemia aristulata , from Brazil (Viana 2010), and the two other congeners described in this paper. This feature seems to optimize vegetative propagation of these rapidly-growing bamboos, which are typically associated with forest borders and clearings.

As in many other species of the Arthrostylidiinae , the blades of A. cincta are conspicuously bicolored: vivid green on the adaxial surface and bluish glaucous on the abaxial side, due to wax deposition on the epidermis, except for a conspicuous marginal green stripe ( Fig. 2F View FIGURE 2 ). Another interesting feature of the new species is the contrasting color pattern of some vegetative structures in young culms compared to the same structures in the old culms. In young branches, culms and leaf sheaths are greenish, usually red-mottled ( Fig. 2C,E,G View FIGURE 2 ), the girdle in the nodal line is dark red ( Fig. 2E View FIGURE 2 ), pseudopetioles are vivid red, sometimes pale greenish, and fimbriae are dark red, almost black ( Fig. 2G View FIGURE 2 ). With age, the culms become typically shiny blackish or brownish, the sheaths become pale ( Fig. 2D View FIGURE 2 ), as well as the girdle and the cluster of fimbriae.

The amphipodial rhizomes, the clambering culms, and the open panicles with divergent branches suggest affinities with Aulonemia aristulata and the two other new species described in this paper ( A. prolifera and A. soderstromii ). However, A. cincta can be easily distinguished from A. aristulata by its glumes and lemmas with apexes acuminate to long acuminate (obtuse and awned in A. aristulata ). When compared to A. prolifera and A. soderstromii , A. cincta is clearly differentiated by its hollow and thick-walled culm internodes (whereas both A. prolifera and A. soderstromii have solid culms). Additionally, A. cincta has bicolored leaf blades (green on the adaxial surface and bluish glaucous with a marginal green stripe on the abaxial side) while A. aristulata , A. prolifera and A. soderstromii have concolor blades, uniformly green on both sides ( Table 1 View TABLE 1 ).

Among all described species of Aulonemia , A. cincta can be recognized by its typical girdle, consisting of a downward corky expansion of the leaf sheaths that remains in the nodal line after leaf senescence ( Figs. 1A View FIGURE 1 , 2D,E View FIGURE 2 ). A similar trait is also found in Arthrostylidium scandens McClure (1964: 4) , from northern South America ( Judziewicz & Clark 1993), and Atractantha cardinalis Judziewicz (1992: 170) , from Bahia state in Brazil.

Because of its graceful habit and colorful vegetative structures, this species has potential ornamental value, although little information about growing Arthrostylidoid bamboos is available in the literature.

Phenology: —Only the type collection, gathered in 1982, is known in flower. There is not enough information to estimate the life cycle of this species.

Distribution and habitat: —Known only from the type locality, in the state of Paraná, situated in the Serra do Mar at altitude around 700– 800 m.s.m. It was first collected by Kummrow in 1982 (type collection) and collected again by the senior author of this paper 28 years later in the same locality. In this area, patches of Aulonemia cincta were found associated with borders and clearings of the evergreen montane forests.

Conservation status: —Probably critically endangered (CR B1a). Known only from the type locality, where it is quite rare. During at least three weeks of extensive fieldwork in the area, no more than ten clumps were located. These were confined to an area no larger than 3 km 2 (Viana 2010). We recommend that additional efforts to find more populations of this threatened species be made.

Additional specimens examined: — BRAZIL. Paraná: Morretes, estrada de terra próximo à BR 277 , 25°36'25"S, 48°56'55"W, 870 m, 1 August 2010 (veg), P.L. Viana & N.F.O. Mota 4401 ( BHCB, IBGE, ISC, MBM, MG, NY, RB, SP, UWSP) GoogleMaps .