Mimosa longepedunculata Taubert, Bot. Jahrb. Syst.

Borges, Leonardo Maurici & Pirani, José Rubens, 2014, When the old guys knew better: The true identity of Mimosa longepedunculata and reestablishment of M. tocantina (Leguminosae, Mimosoideae), Phytotaxa 181 (5), pp. 261-278 : 272-273

Mimosa longepedunculata Taubert, Bot. Jahrb. Syst. 21: 432. 1896.

Lectoype (designated by Borges & Pirani 2014):— BRAZIL. Goiás: Habitat in valle fluvii Passa Tempo in ditione Maranhao superioris , September 1892, fl., fr., E. Ule 2830 ( HBG! [also annotated as “7”; “im Thale des Passa Tempo”] ; isolectotypes: P! [only annotated as “7”; “ Serra dos Viadeiros; no Valle do Passa Tempo ”], R! [two sheets annotated only as “7”; one indicated as “ im Thale des Passa Tempo obere Paranangebiet ”, the other: “Serra dos Viadeiros; no Valle do Passa Tempo”] ).

Figs. 1–6 ; 10 .

Treelets to 3 m, leaves congested, forming a lax rosette at tip of dichotomous branches with irregularly exfoliating peridermis. Indumentum composed of simple trichomes, filiform and abundant glandular capitate setae that make the plant viscous; all ochraceous and patent, but the trichomes lighter than the setae and the filiform setae somewhat sinuous. Branches, stipules, leaf axes and peduncles hirsute; leaflets ciliate, all with the triple indumentum; trichomes 0.2–0.3 mm long, filiform setae 1–5 mm long, glandular setae 0.3–1.2 mm long, only the shorter and more delicate setae present on leaflets, pulvinolules with a higher concentration of indumentum. Leaves 14–19-jugate; stipules 9–15 mm × 2.5–4 mm, narrowly triangular, slightly acuminate, caducous or persistent even in the trunks; petioles 33–75 mm long, 1.5–2 mm diam., grooved or not on adaxial surface, the dilated pulvinus 2–3 mm long; rachis 16.7–25.2 cm long, 1–1.6(–2.5) mm diam., grooved on adaxial surface and randomly bearing a spiculate projection ca. 0.5 mm long between pinnae pairs, terminal projection 4–5 mm long, linear; basal rachillas 22–48 mm long, medial rachillas 53– 105 mm long, distal rachillas 60–98 mm long, all 0.3–0.5 mm diam., 10–25 mm apart, the distance decreasing toward the apex of the rachis; leaflets 4–7 × 1–1.7 mm, 21–27 pairs on basal rachillas, 35–41 pairs on medial rachillas, 35–38 pairs on distal rachillas, 0.7–2 mm apart, narrowly-oblong, straight to falcate, apex acute, base oblique, subcordate, rounded acroscopically, rounded-truncate basioscopically, veins 4–6-palmate, primary and secondary ones prominent on abaxial surface, but sometimes on both faces, secondary veins sometimes as prominent as the primary ones, paraphyllidia absent. Glomerules 13–22 × 15–20 mm, spherical, 2-axillar to an almost fully developed leaf, hence somewhat included in the foliage, but visible trough the not densely congested leaves; peduncles 20.5–23 cm long, 1.2–2 mm diam., enlarging (probably also extending further) with development of fruits; floral bracts (3.7–)5–7 × 1–1.5 mm, narrowly acute-spatulate to fusiform, tomentose with filiform setae 1.2–2 mm long, and glandular setae 0.3–0.7 mm long; flowers 4-merous, diplostemonous; pedicel 0.1–0.2 mm long; calyx 0.3–0.9 mm long, shallowly cupulate, with 4 lobes 0.2–0.4 × 0.5–0.8 mm, triangular, sometimes irregular or absent, rim ciliate with thick and plane (rarely terete) setae 1.1–3.5 mm long, and less frequently also with glandular setae ca. 1.5 mm long, tube glabrous; corolla 6.5–8.3 mm long, narrowly infundibuliform or tubular, lobes 1.1–2 × 0.9–1.3 mm, ovate, mucronate, 1-nerved (vein apex sometimes branching), tomentose and completely concealed by filiform setae ca. 0.4–0.5 mm long, tube glabrous; filaments ca. 20–23 mm long, glabrous, fused 0.8–2.5 mm at base, white; anthers ca. 0.6 mm long, glabrous; ovary 0.3–1.7 × 0.5–0.7 mm, narrowly oblong, laterally compressed, tomentose with filiform setae ca. 0.8 mm long, stipe 0.8–1 mm long, glabrous; style ca. 25 mm long, glabrous; stigma porate, glabrous. Fruit a sessile unjointed craspedium 26–42 × 9–18 mm, narrowly-oblong to oblong, coriaceous, castaneous, apex acute to rounded, aristate, base cuneate, strigose with filiform setae with bulbous base 1–2.5 mm long, the long ones surrounded by small ones in a concentric pattern that does not completely conceals the surface, glandular setae 0.3–0.5 mm long present in margins, but usually not on valves, when present, generally concentrated near the margins; replum 0.8–3.2 mm wide; mm; seeds 3.9–5 × 3.3–3.5 mm, ovate to suborbicular, castaneous, pleurogram present.

Examined specimens: — BRAZIL. Goiás: Alto Paraíso de Goiás, Estrada Alto Paraíso, Terezina , 10 October 1979 (fl, fr imm), E.P. Heringer 2435 ( IBGE, K!, UB!, UEC); Alto Paraíso de Goiás, Estrada Alto Paraíso de Goiás– Nova Roma, à 3,2 km da saída de Alto Paraíso , 14º06’21.6” S, 47º29’18.6” W, 1110 m, 1 November 2012 (fl, fr), L.M. Borges et al. 915 ( SPF!; duplicates to be distributed to HBG, K, P, NY, RB, UB); Alto Paraíso de Goiás, Estrada Alto Paraíso de Goiás–Nova Roma, ca. de 3 km da saída de Alto Paraíso , aprox. 14º06’21” S, 47º29’18” W, 1110 m, 16 February 2012 (fr), L.M. Borges et al. 989 ( SPF!; duplicates to be distributed to K, NY) .

Distribution and habitat: — Mimosa longepedunculata is known to occur in the hills surrounding part of Passatempo Stream and São Bartolomeu River, at Chapada dos Veadeiros, where it inhabits an area of cerrado with sandy soil around 1100 m in elevation. Although the areas are near water bodies, it is unlikely that the species occurs in proper riverine environments. Taubert (1896) indicates the collection site as being at the surroundings of the upper Maranhão River, but the type held at R indicates the collection site as the Paranã River region (“obere Paranangebiet”).

Flowering and fruiting: —The species was collected with flowers and fruits in September and November, and with fruits only in February.

Conservation status: —According to GeoCAT analysis results (EOO = 0 km 2; AOO = 4 km 2 [consequence of the cell size of 2 km 2 used; if the “auto value” option of the GeoCAT tool is used, the AOO value is zero), the species may be classified as Critically Endangered. However, since only four collections of the species are known, the data may be considered insufficient, resulting in the categorization of this species as Data Deficient (DD).

Etymology: —The epithet makes reference to the long peduncles of the species, which are not exclusive to it, but very distinctive among other taxa within Mimosa ser. Pachycarpae .

Notes: —As stated above, the particular morphological features of Mimosa longepedunculata do not allow its inclusion in any particular groups defined by Barneby (1991) for M. ser. Pachycarpae. This may reflect a bias in the subjective choice of characters defining groups in Barneby’s classification. On the other hand, it may reflect the evolutionary history of M. ser. Pachycarpae. The existence of such a group with wide morphological variation, but also with closely similar species occurring sympatrically, poses a problem for the assumption of speciation processes based on reproductive isolation. It may be that M. ser. Pachycarpae is an example of how developmental recombination may play an important role in species diversification (see West-Eberhard 2005). Thus, the chimera-like morphological pattern seen in M. longepedunculata , coupled with the consequent impossibility to ascribe it to a proper group, may have its origins in phenotypic accommodation.

Figures

FIGURE 1. Mimosa longepedunculata. A. Habit. B. Trunk with persistent stipules. C. Branch with filiform (Fs) and glandular (Gs) setae. D. Branch with dehiscent peridermis. E. Globose immature glomerule. F. Glomerule with expanded white filaments. G. Fruits. (Borges 915, SPF).

FIGURE 2. A–C; E–G. Mimosa longepedunculata. D. M. tocantina. A. Flower. B. Calyx with truncate rim (same scale as D). C. Lobate calyx. D. Calyx (same scale as C). E. Floral bract (abaxial surface). F.Floral bract (adaxial surface). G. Detail of the rachis surface showing the triple indumentum of trichomes and both filiform and glandular setae.

FIGURE 3. Lectotype of Mimosa longepedunculata. (Ule 2830 [=Ule 7], HBG 506643). Image used with permission and provided by the Herbarium Hamburgense (HBG).

FIGURE 4. Isolectotype of Mimosa longepedunculata (Ule 7 [=Ule 2830], P 03150238). Image used with permission and provided by the Muséum National d’Histore Naturelle (P).

FIGURE 5. Isolectotype of Mimosa longepedunculata. (Ule 7 [=Ule 2830], sheet 1, R 00000324). Image used with permission and provided by the Museu Nacional Herbarium (R).

FIGURE 6. Isolectotype of Mimosa longepedunculata. (Ule 7 [=Ule 2830], sheet 2, R 00000324a). Image used with permission and provided by the Museu Nacional Herbarium (R).

FIGURE 10. Northeastern Goiás area, Brazil. Range of Mimosa longepedunculata (○) and M. tocantina (▲). The boundaries of the Goiás State (thick line) and the municipalities (thin line) of occurrence are indicated.