Entada simplicata (Barneby) Sch.Rodr.

Rodrigues, Rodrigo Schütz & Flores, Andréia Silva, 2012, A new combination in Entada (Leguminosae) from Roraima, Brazil, Phytotaxa 39, pp. 47-50 : 47-49

Entada simplicata (Barneby) Sch.Rodr. & A.S. Flores, comb. et stat. nov. ( Fig. 1 , 2 )

Basionym:— Entada polystachya (L.) DC. var. simplicata Barneby (1996: 175)

Type:— BRAZIL. Roraima: Caracaraí, Estrada Perimetral Norte , 10 km do entroncamento com estrada Manaus- Caracaraí próximo a Novo Paraíso , 23 August 1987, Cid Ferreira 9220 (holotype INPA!, isotypes: NY [photo!], MG!, MIRR!) .

Entada simplicata , as here defined, is sufficiently different from other New World members of Entada Adans. (Leguminosae: Mimosoideae ) to be recognized as a distinct species. This species belongs to E. sect. Entadopsis (Britton) Brenan , because of its chartaceous and craspedial fruits and pleurogrammatic seeds up to 20 mm in diametre ( Brenan 1966). The other species of this section are E. polyphylla Bentham (1840: 133) , and E. polystachya (L.) De Candolle (1825: 425) .

Entada polyphylla and E. polystachya were considered as distinct species ( Bentham 1876, Britton & Rose 1928 [as Entadopsis polyphylla (Benth.) Britton (in Britton & Rose 1928: 191) and E. polystachya (L.) Britton (in Britton & Rose 1928: 191)], Macbride 1943, Brenan 1966) until the treatment of Barneby (1996). In his revision, Barneby (1996) treated E. polystachya as comprising three varieties: E. polystachya var. polystachya , E. polystachya var. polyphylla (Benth.) Barneby (1996: 175) , and E. polystachya var. simplicata Barneby (1996: 175) . The latter taxon was described by Barneby (1996) as new on the basis of a single flowering collection from Roraima State, northern Brazil.

Later, Barneby (2001) reconsidered Entada polystachya and E. polyphylla as separate species, as did Grimes (2002), and Forero & Romero (2009). The number of leaflets of longer pinnae is the most useful character to clearly distinguish E. polyphylla [(12–) 13–20 pairs] from E. polystachya (<11 pairs).

In the context of Entada taxonomy, the difference in the number of pinnae and leaflets is often employed as one of the most important features in recognizing species in Africa, Asia and South America (e.g. Brenan 1959, 1966, 1970, Barneby 2001, Tateishi et al. 2008, Forero & Romero 2009, Ohashi et al. 2010). In these papers, especially Brenan (1959, 1966, 1970), taxa which have discrete morphological differences in the number of pinnae and leaflets, in conjunction with other foliage (e.g. pubescence), inflorescence, floral, fruit and seed characters, were afforded specific rank.

During the course of a taxonomic study of Entada in Roraima State, Brazil, we made collections and observations of Entada in the field. In this Amazonian Brazilian State, only E. simplicata and E. polystachya have been recorded. One E. simplicata population and seven E. polystachya populations were visited in field. As a result, additional flowering specimens as well as the first fruiting specimen of E. simplicata became available from a new locality in Roraima. We also conducted morphology analyses based on collections at MIRR, INPA, IAN, MG, and UFRR. Additionally, digitalized images of selected specimens of E. polystachya from F and NY, representing specimens along its distributional range ( Barneby 1996) were analyzed.

Vegetatively Entada simplicata is markedly distinct from the other species of E. sect. Entadopsis . In E. simplicata are only 1–3 pairs of leaflets each (18–) 22–52 mm wide, while in E. polystachya , there are 5–11 pairs each 5–20 mm wide, and in E. polyphylla there are (12-) 13–20 pairs each <8 mm wide.

Herbarium studies indicate that Entada simplicata also differs from E. polystachya in a suite of fruit characters. Entada polystachya has wider fruits [(5)–5.5–9.3 mm)], as well as a longer funiculus (27–39 mm); in E. simplicata fruits are 3.8–5.3 mm wide and the funiculus is 13–17 mm long. However, E. simplicata has distinctly longer fruit stipes (25–36 mm long) than E. polystachya (8–21 mm long). A qualitative and clear-cut fruit character is the presence and composition of the mesocarp: in E. polystachya , the mesocarp is relatively thick over the seed chambers, and is composed of a conspicuous spongy layer; in E. simplicata , the mesocarp is absent, including around seed chambers. Moreover, a recent morphological study (Feitoza, Rodrigues & Flores, unpublished data) has revealed that E. simplicata also differs in its seed and seedling morphology, further suggesting that specific rank should be considered appropriate.

While Entada polystachya has the widest distribution of any Neotropical Entada , occurring from Western Mexico, Central America, Hispaniola, Puerto Rico, Lesser Antilles and tropical South America ( Barneby 1996, 2001), Entada simplicata is found only in Roraima State, Brazil ( Fig. 2 ). Field work and data from the few known specimens from Cachoeira do Roxinho region (Iracema municipality) indicate that E. simplicata inhabits margins of open pluvial tropical forests on rocky slopes. The type specimen, ca. 170 km SE from this region, was collected in roadside forests, on sandy or clay wet soils. On the other hand, data from field observations, herbaria and literature ( Lewis & Owen 1989, Barneby 2001) indicate that in Amazonia and Venezuelan Guayana E. polystachya usually grows in evergreen lowland forests or trackside scrublands, frequently along flooded riverbanks. However, especially in Central America and Mexico, it may also be found in disturbed forests, in dry to wet thickets ( Standley & Steyermark 1946) on rocky or sandy soils.

Additional specimens examined of E. simplicata : — BRAZIL. Roraima: Iracema, Cachoeira do Roxinho , 19 November 2008, Flores & Peixoto 2147 ( MIRR) ; Cachoeira do Roxinho , 02º18’N, 61º20’W, 14 September 2002, Pessoni & Silva 639 ( UFRR) ; Cachoeira do Roxinho , 21 August 2002, Pessoni et al. 574 ( UFRR) .

Figures

FIGURE 1. Entada simplicata. A. Leaf with 1 pair of pinnae (only one represented), each one with two 2 pairs of leaflets. B. Leaf with 3 pairs of pinnae (only one represented), each ones with 3 pairs of leaflets. C. Detail of a raceme, with two floral buds illustrated. D. Flower. E. Fruit (st: stipe). A from Pessoni 639 (UFRR); B–D from Pessoni 574 (UFRR); E from Flores & Peixoto 2147 (MIRR). Drawn by R.S. Rodrigues.

FIGURE 2. Distribution map of Entada simplicata.