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This species is accepted, and its native range is Brazil (Tocantins).

[KBu]

Araújo D., Medeiros Antar G., Lombardi J. A. 2016. Dioscorea compacta (Dioscoreaceae), a new endangered dwarf species from the Jalapão region, Tocantins, Brazil. Kew Bulletin 71: 27. DOI 10.1007/S12225-016-9635-8

Conservation
There are few known populations of Dioscorea compacta, three registered inside a perimeter of 15 km and another 60 km away. They cover an EOO of 314 km2, with an AOO of 16 km2 (cell size of 4 km2); both values are below the threshold for Endangered in the IUCN (2012) conservation status assessment, 5000 km2 and 500 km2, criteria B1 and B2 respectively. The cerrado of Jalapão is under the increasing threat of burning where the surrounding areas are turned into cattle ranches or grain plantations. Most of the threats come from less than 100 km to the east, in the northwestern state of Bahia.
Ecology
Between 500 and 600 m a.s.l. in dry soils of sandy open cerrado vegetation. Its known populations are currently under protection of JPA. According to collectors and published literature (Schimidt et al. 2007), dry season fires are very common in the Jalapão region and is hard to find areas unburned for more than 3 years. Thus, Dioscorea compacta may be resistant to fires, surviving due to its underground system.
Morphology Leaves
Leaves alternate, entire; petiole to 0.5 cm long; blade 3 – 4.5 × 0.8 – 2.5 cm, bright green above, pale green below, membranaceous, ovate to lanceolate, base cordate, apex acute, veins 3 – 7, prominent on abaxial suface
Morphology Reproductive morphology Fruits
Capsules 8 – 9 × 6.8 – 7 mm, light green when immature, brownish when mature, rounded-obovate in outline, 3-winged, two seeds per locule; seeds spheroidal, wings absent, testa dark brown, colliculate
Morphology Reproductive morphology Inflorescences
Staminate inflorescences to 6.5 cm long, branched main axis bearing cymes with highly reduced internodes, 1 – 7 flowers per node, bracts 2.5 – 3 mm long, lanceolate, right curved, mucronulate; flowers sessile, bracteoles 1.5 – 2.5 × 0.5 – 0.8 mm, ovate, apex rounded, mucronulate, perianth tubular, 3 mm long, green, white at apex, tepals free at the middle, 1.3 – 1.5 × 0.5 – 0.8 mm, oblong; stamens 3, base connate, inserted at the base of the perianth, filaments c 1 mm long, anthers basifixed, extrorse, staminodes 3, alternate with stamens; pistillode 0.2 – 0.3 mm, terete, columnar, apically 3-lobed Pistillate inflorescence to 0.5 cm long, simple, compact, one per node; bearing up to 7 sessile flowers, 4 mm long, one per node of the rachis, bracts two, 2 – 3 × 0.5 – 0.7 mm, narrowly ovate; perianth campanulate, tepals free, 1 × 0.5 mm, mostly whitish, ovate, acute, ovary 3-carpellate, style c 1 mm long, columnar, trifid at the apex, each branch 2-lobed; staminodes 3, c 0.1 mm long, antheriform; ovary 3-angled, carpels fusion conspicuous
Morphology Stem
Stems, to 40 cm long, slender, initially erect, then prostrate, sometimes climbing, dextrorse
Note
A dwarf species, similar to D. sphaeroidea R. Couto & J. M. A. Braga based on dimensions and fruit/seed morphology, but differing on filament length, 0.5 mm in D. sphaeroidea and 1 mm in D. compacta; pistillode shape, flattened and columnar; style length, 0.5 mm and 1 mm, respectively. In contrast, the Dioscorea anomala complex and D. perdicum have circular wings in their flattened seeds. However, the same author stated that seeds with such wings can glide in very light air but are less effective in strong wind, which is the prevailing condition in those environments. Non South American wingless seeded species are zoochoric (Wilkin pers. comm.) and the carunculate seeds of Epipetrum (Viruel et al. 2010) in South America are suggested to be the same. On the other hand, once D. compacta is fruiting in the last month of the rainy season, the rounded colliculate light seeds probably still depends on the wind for dispersal, instead of flying, rolling or even being carried by small streams among the bushes. We noticed predation of the staminodes in many staminate flowers, which can be confusing for proper determination but calls attention to an interesting feature for the study of the plant-predator/pollinator relationship. At first sight, Dioscorea compacta resembles the dwarf occasional climbers D. anomala, D. maianthemoides and D. stenophylla, herein called D. anomala complex, but is clearly distinct by the number of stamens, number of staminodia in the pistillate flower and the seed shape. Another dwarf, D. perdicum is similar because of its short inflorescences and 3-staminate flowers, but distinct because of the absence of either pistillodia or staminodia in staminate and pistillate flowers, respectively. Besides D. compacta, the only Brazilian species that combine dwarf growing and spherical unwinged seeds in 3-winged capsules — as appear in some Epipetrum — is the recently discovered D. sphaeroidea. In Mexico, D. minima and D. multinervis are very similar to D. compacta due to its short pistillate inflorescences and spheroid rugose seeds, but distinct by the absence of staminodia in the staminate flower. The tubers of neotropical dwarf species are perennial and the aerial stem is dextrorse, so this may place them in the second of two New World clades as shown by Wilkin et al. (2005). A more focused phylogenetic approach is necessary to understand the rise of dwarf Dioscorea in the Neotropics. We named this species “compacta” for its compact growth and inflorescences, especially the pistillate ones.
Phenology
Flowering and fruiting during the wet season, between November and February.
Type
Type: Brazil, Tocantins: Mateiros: Estação Ecológica Serra Geral do Tocantins, caminho para o rio Verdinho, G. Antar, H. Antar & Nascimento 731 (holotype SPF; isotype K).
Vegetative Multiplication Tubers
Underground system an ovoid-conical tuber 1.5 × 1.0 cm, with a single aerial stem, light brownish periderm and white inside

Native to:

Brazil North

Dioscorea compacta D.Araújo appears in other Kew resources:

First published in Kew Bull. 71(2)-27: 2 (2016)

Accepted by

  • Govaerts, R., Nic Lughadha, E., Black, N., Turner, R. & Paton, A. (2021). The World Checklist of Vascular Plants, a continuously updated resource for exploring global plant diversity. https://doi.org/10.1038/s41597-021-00997-6 Scientific Data 8: 215.

Literature

Kew Bulletin

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Kew Backbone Distributions
The International Plant Names Index and World Checklist of Selected Plant Families 2021. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
© Copyright 2017 World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0

Kew Bulletin
Kew Bulletin
http://creativecommons.org/licenses/by-nc-sa/3.0

Kew Names and Taxonomic Backbone
The International Plant Names Index and World Checklist of Selected Plant Families 2021. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
© Copyright 2017 International Plant Names Index and World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0