Deguelia occidentalis (Ducke) A.M.G. Azevedo & R.A. Camargo, 2016

Camargo, Rodrigo A. & Tozzi, Ana Maria G. A., 2016, Taxonomic placement of Millettia occidentalis (Leguminosae, Papilionoideae), a rare liana from the Amazon Basin, Phytotaxa 261 (1), pp. 75-81 : 76-79

Deguelia occidentalis (Ducke) A.M.G. Azevedo & R.A. Camargo , comb. nov.

TYPE:— BRAZIL. AMAZONAS. Santo Antônio do Içá , Rio Solimões, 1 December 1948, R. L. Fróes 23680 (lectotype, here designated: IAN-42600!; isolectotypes: IAN-42600a!, K-921328!, NY-16337!) .

Basionym:— Millettia occidentalis Ducke, Bol. Técn. Inst. Agron. N. 28: 35. 1953.

Images:— Illustration: Figure 1 ; Representative specimen among the syntypes: Figure 2 ; Distribution map: Figure 3 .

Description:— Scandent shrubs to lianas, stems more or less sinuous, striate, slightly rufous-tomentose. Stipules small and caducous. Leaves imparipinnate, 5 leaflets, petiole 3.5–8.5 cm long and rachis 5.5–10 cm long, sparse rufous-tomentose; leaflets 8–19 × 5–12 cm, proximal pair smaller, elliptic to suborbicular, apex apiculate, base obtuse or rounded; petioles 5–7 mm long; stipels subulate, early caducous. Inflorescence pseudoracemose, 16–24 cm long, 1–2 pseudoracemes per node, rufous-sericeous, brachyblasts subconical, bearing more than 5 flowers each, usually lacking on the first 2–5 cm (1/4 to 1/5 of its length); pedicel 2–6 mm long, slender, rufous-sericeous, trichomes short; bracteoles, 0.5 mm, ovate. Calyx shortly 5-dentate, becoming dense dark pigmented below the teeth, towards the base, dorsally rufous-tomentose with short trichomes. Corolla white, membranaceous, glabrous, 0.8–1 cm; standard oblongorbicular, apex emarginated, base truncate; wing petals oblong, slightly falcate; keel petals oblong, slightly falcate. Stamens white, membranaceous, pseudomonadelphous before anthesis, splitting in two halves afterwards. Ovary short stipitate, dense rufous sericeous-villous, with 5–6 ovules; interstaminal disc 10-lobed, short; style slightly curved, glabrous (except on its base), stigma short. Legume 11.5–13 × 2–2.7 cm, oblong-linear, slightly falcate, base cuneate, narrow becoming broader towards the apex, apiculate, elastically dehiscent.

Vernacular name:— Timborana.

Typification notes:— The author described M. occidentalis based on 3 different collections, as cited in the protologue; A. Ducke s.n. RB 17222 , R. L. Fróes 23680 and R. L. Fróes 25583, and he mentions after the syntypes that the type specimen is located at IAN, but he doesn´t explicit which of the collections is the type. Although the author wrote down type in one of the specimens of R. L. Fróes 23680 ( IAN 42600 ), there is another specimen ( IAN 42600 a) from the same collection, with a mature valve attached to it, so we designated these specimens as lectotype and isolectotype. Ducke (1953) also mentioned that some of Fróes unidentified collections had been sent overseas to Kew and Utretch, from these collections we could only locate an isolectotype and a photo from one of the specimens ( R. L. Fróes 25583) at K. Recently , two syntypes and their images were also found, both available on their respective websites, R. L. Fróes 23680 located at NY and R. L. Fróes 25583 located at US ( Figure 2 ). Moreover, R. L. Fróes 25583 was also found at IAC .

Taxonomic notes:— Deguelia compromises a morphologically diverse neotropical genus from tribe Millettieae , that can be easily distinguished from its closest neotropical allies by the inflorescence type. It compromises trees to lianas with a variable number of leaflets, the indumentum of the corolla varies considerably and can be either present adaxially or abaxially or totally absent, fruits can be either indehiscent to lately or elastically dehiscent with few to many seeds. Ducke (1953) describes three or five leaflets for M. occidentalis (= D. occidentalis ) in the protologue but in all specimens examined only five was observed and in some cases the proximal pair of leaflets was missing but the scar was evident, as shown in the illustration ( Figure 1 ). This could have led to some misinterpretations, so the number of leaflets is here updated to only five. Deguelia occidentalis flowers resembles D. scandens Aublet (1775: 750) and D. negrensis ( Bentham 1860: 107) Taubert (1891: 387) , as they share glabrous, whitish flowers ( Table 1). This rare species also presents a similar leaftlet number to the latter, which also suggests that it can be closely related to these species.

Distribution:— Brazil, Amazonas state in Santo Antônio do Içá, only known from this locality ( Figure 3 ).

Habitat:— Amazon domain, on “terra firme” forests, which are non-flooded and have nutrient-poor clay soils. Deguelia occidentalis can be considered endemic to a small area in the state of Amazonas ( Brazil), as specimens only have been collected at one municipality, near the junction of Rio Içá and Rio Solimões, occurring usually on the high lands.

IUCN conservation assessment:— Endangered (EN). Although might be a lack of field work in the area, speculations supported by the available data can provide a preliminary conservation assessment based on criteria B; geographic range (extent of occurrence, area of occupancy and number of locations), but this species can be moved to a higher or lower threatened category. Besides, it has only been collected in the past century and further field effort is needed in search of recent material to gather more information on Deguelia occidentalis so other criteria can also be evaluated, regarding the conservation of this species. The number of locations (3) and the AOO or area of occupancy (12.000 km 2) suggests that this species should be placed in the Endangered category, but the extent of occupancy (EOO) can only be extrapolated due to the lack of precision of the specimens presented. Three different scenarios are possible and were evaluated through GeoCAT tool, a first very optimistic and mostly improbable hypothesis suggests this species as Vulnerable (VU), with no more than 5,900 km 2, which triangulates all the municipality and proposing that the specimens were collected on the boundaries of the municipality and further apart from each other, considering the borders of Peru and Colombia as a range of occurrence and this category should be discarded once specimens are cited to occur only on the high forests and the habit is fragmented along the extent with some flooded forests also present. A second scenario and more plausible is predicted around 3,000 –4,000 km 2, which triangulates between the borders of São Paulo de Olivença and União, from the margins of Rio Solimões to the high forests above Rio Içá and suggests this species as Endangered. Although the latter is the most suitable scenario for this species, a third scenario can be speculated which covers mostly the forests above Rio Iça, close to the junction with Rio Solimões (around 50– 90 km 2) that would place this species as Critically Endangered (CR), according to the EOO, but this hypothesis must be taken with regards due to the uncertainty of the data available. As the number of locations, the AOO and the most possible scenario for the EOO are in agreement we propose Deguelia occidentalis as Endangered, as a preliminary assessment until further analysis.

Additional specimens examined:— BRAZIL. AMAZONAS. Santo Antônio do Içá , 27 September 1906 (fl.), A. Ducke s.n. RB 17222 ( RB, IAN, photo UEC) ; Santo Antônio do Içá , Rio Içá, 30 October 1949 (fl., fr.), R. L. Fróes 25583 ( IAN, IAC, US, photo K) .

Figures

FIGURE 1. A. Flowering branch (proximal pair of leaflets is missing). B. Flowering bud. C. Calyx opened out. D. Standard. E. Wing petals. F. Keel petals. G. Staminal tube and pistil. H. Staminal tube, opened. I. Pistil (from Ducke s.n. RB 17222, drawn by Esmeralda Zancheta Borghi).

FIGURE 2. Fruiting stage specimen among the syntypes cited in the protologue, R. L. Froes 25583 (US).

FIGURE 3. Distribution map for Deguelia occidentalis. Neotropical region is presented on the lower left and the Brazilian states which are covered by the Amazonian domain (a total of nine) are highlighted in a gray layer.The Amazonas state is emphasized on the upper right corner and a hydrology layer was added for the Amazonian domain, showing distribution of D. occidentalis, with three points near to the junction (middlemost point) of Rio Solimões (major river right below the lowest point) and Rio Iça (crossing the upper point).