Chamaecrista ipanorensis Rando & H.C. Lima, 2020

Rando, Juliana Gastaldello & Lima, Haroldo Cavalcante De, 2020, A new arborescent Chamaecrista (Leguminosae) from Amazon, Brazil, Phytotaxa 433 (2), pp. 161-166 : 162-164

Chamaecrista ipanorensis Rando & H.C. Lima , spec. nov. ( Fig.1 and 2 )

Diagnosis: Chamaecrista ipanorensis mostly resembles C. hymenaeifolia but differs in the length of pulvinus plus petiole, in the form and venation of leaflets. Chamaecrista hymenaeifolia has pulvinus plus petiole with 7–20 mm long, two or three pairs of leaflets, elliptical or ovate slightly falcate with acute apex, its venation is classified as craspedodromous-brochidodromous. Chamaecrista ipanorensis has pulvinus plus petiole with 21–39 mm long, has only two pairs of leaflets, however they are orbicular or obovate (mainly in the distal pairs), with obtuse or retuse apex, and its venation is classified as brochidodromous.

Type: – BRAZIL. Amazonas : São Gabriel da Cachoeira , Alto Rio Negro , Rio Uaupés , Ipanoré (“Ipanuré”), Estrada para Urubuquara, caatinga alta sobre solo arenoso, 17 November 1987 (fl), H. C. de Lima 3204, M. L. Kawasaki, J. Ramos, J. Guedes, R. P. de Lima & A. M. Neto (holotype: INPA 181577 !; isotypes: HUEFS 244640 , INPA 10296 !, INPAw 10296, MO, NY!, RB!, SPF!) .

Trees 16 m tall, DAP 12 cm; stems glabrous scarcely lenticellate. Stipules early- deciduous, not seen. Leaves 4-foliolate, leaflets opposite; pulvinus 3–4 mm long; petiole 18–35 mm long; rachis 2.5–3.5 cm long, glabrous; extrafloral nectary 2, impressed, 1–2 mm de diameter, one positioned close to the base of petiole from 2–5 mm of the pulvinus and the other placed below to distal leaflets, from 0.4–0.7 mm to the apex; petiolules 4.5–8 mm long, glabrous, blackened; leaflet blades 6–9 × 6.5–8 cm, orbicular or rarely obovate, glabrous on both surfaces, obtuse or retuse apex, rounded to slightly cuneate base; broquidodromous venation with detail of the perimarginal veins of marginal secondary type. Inflorescence racemes ramiflorous, 5-flowered; peduncle 4.4–6.0 mm long; Bracts early deciduous, not observed; extrafloral nectaries sparsely present on peduncles, concave and sessile; pedicel 2.5–2.9 cm long, pubescent; bracteoles subulate, 0.8–0.9 mm long, pubescent, ciliate; sepals triangular, acuminate, 2.6–3.2 mm long, pubescent externally, and glabrous internally, green to light yellow; 5 petals, oblong, cuneate base, rounded apex, 9– 1.1 cm long, yellow; stamens 10, homomorphics, 5–6 mm long, the filaments glabrous, the anthers entire pubescent; gynoecium 7–11 mm long, ovary ca. 4 mm densely strigose, style 3–6 mm sparsely strigose with golden trichomes. Fruit and seeds not observed.

The new species have been described after analysis of a collection performed in 1987 in São Gabriel da Cachoeira, Amazonas state, Brazil. After this, no specimens from other collections were found, which indicates that the new species has never been collected again, although this place was later visited by several botanists, which established tree inventories plots in the upper Rio Negro ( Stropp et al. 2011). The only known collection resulted in seven duplicates distributed to HUEFS, INPA (2 specimens and also a sample of wood - INPAw), MO, NY, RB and SPF. Rupert Barneby identified the specimen housed in NY herbarium as Chamaecrista hymenaeifolia (Benth. 1870:130) H.S. Irwin & Barneby (1982: 641) , and included a comment that it could be a distinct form “ forma foliolis orbiculatis ” pointing out the remarkable feature of this new species. Actually, these species share a similar number of leaflets (2 pairs or 3 in C. hymenaeifolia ), morphology and position of extrafloral nectaries that are impressed, and located on the petiole, distinctly below the first pairs of leaflets and not immediately below or between such as in the others species of the section, excluding C. polystachya (Benth. 1840: 77) H.S. Irwin & Barneby (1982: 641) ( Irwin & Barneby 1977, Coutinho et al. 2016). They also share a similar indumentum of anthers, which are all covered by pubescent trichomes, a common characteristic in the section but absent in C. polystachya . The morphology and position of extrafloral nectaries are also shared by C. polystachya , however it has more leaflets (2–4 pairs) with a distinct morphology. Chamaecrista ipanorensis is only known from the tree communities on white sand in the locality of Ipanoré, São Gabriel da Cachoeira. Chamaecrista hymenaeifolia has a more extensive distribution in the upper Rio Negro, but occurring simpatrically with C. ipanorensis in close areas around São Gabriel da Cachoeira, in white sand forest, or also classified as “campinarana” vegetation ( Fig. 3). Chamaecrista polystachya occurs in Savannas on the borders of Brazil and Venezuela. Here, we are proposing a new species based on differences in the form of leaflets, pattern of venation, and length of petiole ( Table 1).

Etymology:— The specific epithet “ ipanorensis ” refers to the locality where the species was collected, an area with high diversity and endemism in the northwest of the upper Rio Negro in the Amazon Basin.

Phenology:— Collected only with flowers in November.

Conservation status: —Following the recommendations of IUCN (2017) we assigned the Data Deficient category (DD). The new species is known only from one specimen, for this reason is difficult to make any further inference about its conservation status.

Figures

FIGURE 1. Chamaecrista ipanorensis. A. Flowering branch. B and C. Detail of the rachis showing the extrafloral nectaries, B. Between the terminal pair of leaftles and C. Between petiole and first pair of leaflets. D. Five petals and a stamen. From H.C. de Lima 3204, M.L. Kawasaki, J. Ramos, J. Guedes, R.P. de Lima & A.M. Neto (SPF). Drawn by Marcelo Tomé Kubo.

FIGURE 2. Chamaecrista ipanorensis. A. Leaflet and detail of its broquidodromous venation. From H.C. de Lima 3204, M.L. Kawasaki, J. Ramos, J. Guedes, R.P. de Lima & A.M. Neto (SPF). C. hymenaeifolia. B. Leaflet and detail of its craspedodromous-brochidodromous venation. From H.C. de Lima 3217, M.L. Kawasaki, J. Ramos, J. Guedes, R.P. de Lima & A.M. Neto (SPF). Drawn by Marcelo Tomé Kubo.