Allagoptera robusta R.C.Martins & Filg., 2015

Martins, Renata Corrêa, Filgueiras, Tarciso S., Graciano-Ribeiro, Dalva & Somavilla, Nádia Sílvia, 2015, A new species of Allagoptera (Arecaceae) from the Cerrado of central Brazil, Phytotaxa 197 (2), pp. 115-124 : 116-122

Allagoptera robusta R.C.Martins & Filg. sp. nov. ( Figs. 1 , 2B, 3–5, 6C , 7C )

Species nova affinis Allagoptera campestris (Martius) Kuntze pinnis aggregatis, discoloribus, rigidis, inflorescentia spiciformi, fructibus congestis, cellulis epidermidis faciei adaxialis 1-seriatis, parenchymate paliformi ad 6 cellulas praedito, fascibus vascularibus in 3 magnitudine, sed habitu solitario (versus habitu caespitoso), corona foliorum aperta (versus corona foliorum clausa), inflorescentiae rachis curvata in maturitate, 16–33 cm longa (versus inflorescentiae rachis recta in maturitate, 4.8–15 cm longa), hypodermidi faciei abaxialis 2–seriata (versus hypodermidi faciei abaxialis 1–seriata), fibris in mesophyllo serie continua in facie adaxiali et intercepta in facie abaxiali (versus fibris in mesophyllo serie intercepta in ambabus faciebus), fascibus vascularibus regulariter dispositis (versus fascibus vascularibus irregulariter dispositis) differt.

Type:— BRAZIL. Distrito Federal: Brasília, Park Way, Quadra 21, Conjunto 2, 15.533ºS, 47.557ºW, 1054 m, March 2011 (fl, fr), R.C. Martins 1131 (holotype UB!)

Acaulescent to short-stemmed palm, solitary, 0.25–1.5 m tall. Stem 0–25 × 15 cm. Leaves 3–6, 100–180 cm long; sheath 9–30 × 4.5 cm long; petiole 18.5–46 × 0.8–1.4 cm; rachis 68.5–98 cm long; pinnae (16–)48–76 (per side), inserted in groups of 2–8 in different planes; basal 17–41 × 0.2–1.5 cm, median 15–39.5 × 1–1.6 cm, apical 3.1–31 × 0.2–1.1 cm. Prophyll 15–26 × 1.5–3 cm. Peduncular bract 23–60 cm long, rostrum 1–5 cm long, 0.2–0.65 cm thick; inflorescence spicate, 16–70 cm long; peduncle 1.7–25 × 1–2.5 cm; rachis 16–33.5 cm long (9–14.5 cm pistillate portion + 5–7.5 cm staminate portion); rachillae null. Staminate flowers 0.8–1.5 × 1.5 cm; sepals joined at base, free at apex, margin entire or slightly ciliate on apex, 0.7–1 × 0.1–0.5 cm; petals free, margin entire, 0.5–2 × 0.35– 0.6 cm; stamens (7–)8–10(–11), 0.4–0.5 cm long, anthers straight, 0.2–0.45 cm long, filaments 0.2 cm long, pistillode inconspicuous, 1–5 lobed. Pistillate flowers 0.7–1.9 × 0.6–0.9 cm; sepals free, margin entire to irregular, 0.7–0.9 × 0.45–0.65 cm; petals free, margin entire to slightly ciliate, 0.7–0.9 × 0.65 cm; stigma trifid ca. 0.3 cm long; staminodal ring inconspicuous, 0.1 cm tall. Fruit obovoid, yellowish-green to orangish-green, 2.5–2.8 × 1.2–1.3 cm; seed 1.

Specimens examined: — BRAZIL. Distrito Federal: DF-100, May 1992. Dias 98 ( CEN) ; Ecopousada Terraviva , 15.404ºS, 48.115ºW, 1117 m, April 2008, Proença & Zanatta 3517 ( UB) ; Estação Ecológica do Jardim Botânico de Brasília , 15.521ºS, 47.507ºW, 1092 m, April 2011, Martins 1137, 1138 ( UB) ; Fazenda Água Limpa , 15.455ºS, 47.523ºW, 1086 m, February 1999, Martins 225 ( UB) ; May 1989, Scariot 549, 550 ( CEN) ; February 1987, Proença 683 ( UB) ; November 1982, Ratter et al. 4780 ( K, UB) ; October 1982, Ratter et al. 4712 ( UB) ; Park Way ( Q.21), 15.533ºS, 47.557ºW, 1054 m, March 1999, Martins 223, 240 ( UB) ; Park Way ( Q.18), 15.536ºS, 47.568ºW, 1062 m, September 2010, Martins 1094 ( UB). Goiás: Alto Paraíso , 14.075ºS, 47.303ºW, 1186 m, December 1965, Irwin et al. 9366 ( IBGE) ; Luziânia , 16.150ºS, 47.571ºW, 930 m, September 1978, Brandão 2098 ( PAMG) ; Mineiros , 17.341ºS 52.330ºW, 750 m, May 1992, Noblick 4871 ( K, UFG) .

Distribution and habitat: —Three populations were located in the state of Goiás (Alto Paraíso, Luziânia and Mineiros). The species is also found in preserved and remnant Cerrado areas of the Distrito Federal. In shaded environments, the stem can grow to 1 m tall, with a decumbent habit. In sunny environments, however, the stem remains almost completely underground.

Etymology: —The specific epithet refers to the robust appearance of this plant in the field.

Vernacular name:—(proposed here) licuri solitário.

Phenology: —Collected with flowers and fruits in the months of February, March, May, June, August, September, and November. It is important to note that flowers and fruits occur concomitantly.

Uses: —The sweet flesh of the mature fruit and the seeds may be eaten in natura. In the Park Way region of the Distrito Federal, the vegetation in public spaces near buildings is frequently removed. However, a few A. robusta individuals are incidentally preserved in these locations, rendering the plant visually conspicuous and highlighting its ornamental value. The discolorous leaves confer special aesthetic appeal to this plant, contributing to its potential use in regional landscaping projects.

Comments: — Allagoptera robusta can be distinguished by the solitary habit, open crown, and inflorescence rachis conspicuously curved at maturity. The typical robust appearance of this species can be observed in the group of structures near the ground: leaf sheaths, prophylls, peduncular bracts, and peduncles.

The species was found in four localities in the Distrito Federal (DF) besides the municipalities in the state of Goiás (Alto Paraíso, Luziânia, and Mineiros), in Cerrado sensu stricto and campo sujo and as a remnant in deforested areas. Allagoptera robusta is similar to A. campestris in having rigid pinnae in different planes, but differs in its solitary habit (vs. caespitose in A. campestris ), open crown (vs. closed crown) ( Fig. 2), ramenta absent (vs. present), tomentose peduncle (vs. glabrous peduncle), inflorescence rachis 16–33.5 cm long (vs. 4.8–15 cm) and petals of pistillate flowers 7–9 × 6.5 mm (vs. 4–6 × 3 mm). In Distrito Federal and northeastern Goiás, A. robusta and A. campestris occur sympatrically in Cerrado sensu stricto and campo sujo. Their underground stems represent a remarkable adaptation against occasional fires in the Cerrado.

In the past, the new species has been confused with A. leucocalyx , both in herbarium specimens and in the literature ( Moraes 1996, Martins & Filgueiras 2006). Allagoptera robusta differs from A. leucocalyx by its solitary habit (vs. cespitose in A. leucocalyx ), ramenta absent (vs. present) and its occurence in gallery forests (vs. cerrado s.s). A comparison of related species is presented in Table 1.

The anatomical description of A. robusta with A. campestris and A. leucocalyx revealed that the three species were similar in many aspects. The three of them have a thick cuticle, uniseriate epidermis with common triangular or rectangular epidermal cells on the adaxial surface and square cells on the abaxial surface, stomata with internal and external stomatal ridges, abundant on the abaxial surface and rare on the adaxial one ( Fig. 6B ). In addition, the hypodermis occurs on both sides of the foliar pinnae, formed primarily by parenchyma cells with cellulosic walls, and a few with lignified walls ( Fig. 6 ), and the mesophyll is homogeneous and formed by palisade parenchyma ( Fig. 6A ). The vascular bundles present up to three orders of branches, with sclerenchyma extensions in the sheath of the only on the abaxial surface of third-order bundles, and on both surfaces in second- and first-order bundles ( Fig. 6 ); in this region there are a few stegmata cells containing druse-like silica bodies ( Fig. 6B ). In all three species, the main vein is prominent on the adaxial surface, and the vascular system is surrounded by fibers ( Fig. 7 ). The epidermal cells of the abaxial surface are papillose ( Fig. 7 ), and the vascular bundles are collateral, with phloem separated by parenchyma or sclerenchyma. Hypodermal cells elongated in the longitudinal axis occur at the junction of the blade with the main vein of the abaxial surface, forming an expansion tissue with two layers ( Fig. 7A,B,C ), as described by Tomlinson (1990). Despite the above descriptions show many similarities among the species, the anatomical traits employed for the differentiation of this species are exposed in the Table 2. The analysis of the epidermis under SEM revealed the presence of trichomes on the adaxial surface of A. campestris and A. leucocalyx , while no trichomes were observed in A. robusta .

Some cells of the hypodermis of the central vein of Allagoptera robusta and A. campestris have thickened and lignified walls, forming a uniseriate or biseriate layer, which may also be triseriate in A. campestris ( Fig. 7A ). On the abaxial surface of A. leucocalyx , there is a ramenta with up to six rows of cells with a wall that is thickened at the base, converging toward a row of cells with thin walls ( Fig. 7B ).

Figures

FIGURE 1. Allagoptera robusta. A. Habit; B. Foliar rachis and insertion of pinnae; C. Pinna apex; D. Inflorescence with open staminate flowers; E. Pistillate flower; F. Sepals of pistillate flower; G. Petals of pistillate flower; H. Gynoecium with trifid stigma; I. Staminate flower; J. Calyx of staminate flower; K. Corolla of staminate flower; L. Androecium; M. Fruit. (Martins 1131). Illustrator: Renato Moraes.

FIGURE 6. Cross-section of pinna (blade region). A. Allagoptera campestris (Martins 228); B. Allagoptera leucocalyx (Martins 1093); C. Allagoptera robusta (Martins 1131). Scale bars: A. 100μm, B. 50 μm, C. 100 μm. Legends: fi: fibras, ade: adaxial face epidermis, abe: abaxial face epidermis, sb: silica bodies, st: stomata, ext: extension of sheath vascular, hp: hypodermis, sr: stomatal ridges, vb1 (1st order vascular bundle), vb2 (2nd order vascular bundle), vb 3 (3rd order vascular bundle).

FIGURE 7. Cross-section of pinna (region of the main vein). A. Allagoptera campestris (Martins 228); B. Allagoptera leucocalyx (Martins 1093); C. Allagoptera robusta (Martins 1131). Scale bars: A. 100μm, B. 200 μm, C. 100 μm. Legends: et: expansion tissue, pc: papillose cells, ra: ramenta.