Ipomoea maranhensis D. Santos & Buril, 2020
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publication ID |
https://dx.doi.org/10.3897/phytokeys.151.49833 |
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persistent identifier |
https://treatment.plazi.org/id/0A828ABD-A6B9-5E9E-B154-0A6283A26D3D |
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treatment provided by |
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scientific name |
Ipomoea maranhensis D. Santos & Buril |
| status |
sp. nov. |
Ipomoea maranhensis D. Santos & Buril sp. nov. Figs 1 View Figure 1 , 2 View Figure 2
Type.
Brazil. Maranhão: município de Mirador, Ibipira, Parque Estadual do Mirador, 06°22'01"S, 44°22'00"W, 11 April 1998 (fl.), L.P. Félix et al. 8136 (holotype HUEFS38133, isotype HST8028).
Diagnosis.
Ipomoea maranhensis differs morphologically from I. burchellii Meins. by its twining habit (vs. subshrubs), lanceolate (vs. oblong), long-acuminate (vs. acute) and densely sericeous (vs. hirsute) sepals.
Description.
Vine, internodes 1-5 cm long, latex absent; stem pubescent with whitish trichomes. Leaf blade 3.3-7 × 0.9-2.3 cm, oblong, base cuneate, rounded to subcordate, apex obtuse, acute, apiculate, margin entire, pubescent on both surfaces, discolor, whitish on abaxial face, brochidodromous, 6-10 pairs of secondary veins, main vein prominent; petiole 2-3 mm long, canaliculate, pubescent, nectary near the apex of the petiole. Inflorescence of dichasial cymes reduced, bracteolate in the axils of the upper leaves, with 3-7 flowers; peduncle 2-3 mm long, pubescent; bracts 1.7-2 × 0.5-0.8 cm, elliptical, base cuneate, apex obtuse, pubescent, foliaceous, discolor; pedicel 2-4 mm long, pubescent; bracteoles 0.9-1.6 cm long, lanceolate, oblong, base truncate, apex acute, obtuse, margin entire, pubescent. Sepals all equal, 1.7-2.3 × 0.4-0.5 cm, lanceolate, base cuneate, apex long-acuminate, margins non-membranous, densely sericeous on the adaxial surface of the sepals, whitish. Corolla ca. 4 cm long, ca. 4.5 cm diam, infundibuliform, tube ca. 1.6 cm long, rose with whitish tube, midpetaline bands area sericeous externally. Stamens ca. 3 cm long, included, unequal, pilose at the base, anthers ca. 4 mm long, oblong, white. Ovary ca. 4 mm long, conical, glabrous, 4 locule; style ca. 2 cm long, glabrous; stigma bi-globose, papillose. Fruit unknown.
Anatomical description - petiole and leaf blade.
Petiole epidermis uniseriate with juxtaposed cells, parenchyma with isodiametric cells, prominent/concave main rib shape, U-shaped vascular bundles. Leaf epidermis uniseriate, mesophyll dorsiventral with crystallized idioblasts (druses), palisade parenchyma with one to two layers of elongated cells more evident on the adaxial surface, spongy parenchyma with three to four layers of round cells with sinuous anticlinal walls; glandular trichomes on both leaf surfaces.
According to the anatomical analysis, we observed that I. maranhensis and I. burchellii share mesophyll with crystallized idioblasts (druses) and petiole parenchyma with isodiametric cells. However, I. maranhensis is distinguished from I. burchellii by a prominent/concave main rib shape (vs. convex/flat main rib shape in I. burchellii ), U-shaped vascular bundles (vs. V-shaped), glandular trichomes spread on both leaf surfaces (vs. only on abaxial one) and dorsiventral mesophyll (vs. isobilateral) (Fig. 3 View Figure 3 ) (Table 2 View Table 2 ).
Phenology.
Collected with flowers in April.
Distribution and habitat.
Ipomoea maranhensis is known only from two disjunct populations between the municipality of Mirador, in the Mirador State Park (area of 4370 km2) and the municipality of Carolina, in the National Park Chapada das Mesas (CMNP, area of 1600 km2) (Fig. 4 View Figure 4 ). In both areas this species grows on quartzite soils associated with Cerrado vegetation at 186-345 m elevation, average temperature of 26 °C and annual precipitation between 1250-1500 mm ( Alcântara 2004; IBAMA 2013). The occurrence of this new species in the National Park Chapada das Mesas and in the Mirador State Park emphasizes the importance of these protected areas for the preservation of this taxon in the Cerrado domain.
Etymology.
The specific epithet refers to Maranhão state, where the type specimens were collected.
Additional specimens examined.
Brazil. Maranhão: Carolina, Parque Nacional da Chapada das Mesas, 345 m elev., 7°14'14"S, 46°58'50"W, 07 April 2017 (fl.), R.V.C. Saraiva 107 (SLUI 5037); Parque Nacional Chapada das Mesas, accesso no Km 596 da BR - 230, 7 km E em estrada vicinal, 290 m elev., 7°07'33"S, 47°22'13"W, 12 April 2016 (fl.), M.F. Simon et al. 2921 (CEN 95523).
Conservation status.
We categorized this species as Endangered (criteria EN) according to B1 (EOO <5000 km2) and B2ab (ii, iii) (AOO <500 km2) from IUCN (2019). Although populations of I. maranhensis occur in protected areas, this species is threatened due to the reduction of its habitat because of anthropogenic fires lit by small communities who remove vegetation with fire for subsistence agriculture in the Cerrado sensu stricto and Cerradão formations ( Ribeiro and Walter 2008). According to Estivalet (1997), prostrate or climbing plants seem to be more prone to burning than upright species, whose growth points are more protected inside the clump.
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