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This species is accepted, and its native range is Madagascar.
A specimen from Kew's Herbarium

[KBu]

Anna Haigh, Wilkin, P., & Rakotonasolo, F. (2005). A New Species of Dioscorea L. (Dioscoreaceae) from Western Madagascar and Its Distribution and Conservation Status. Kew Bulletin, 60(2), 273-281. Retrieved from http://www.jstor.org/stable/4110936

Conservation
Least Concern (IUCN 2001). As Dioscorea bosseri has wide area of occurrence, there is no evidence of population decline and it can grow in disturbed areas such as clearings and degraded forest, it is probably not threatened.
Distribution
Dioscorea bosseri is found in Western Madagascar, from Tulear to Ankarana. There is an outlying collection from Mandoto. D. bemarivensis has a similar distribution, but is also found further south in Toliara Province.
Ecology
Deciduous forest, often in gaps, clearings or on forest margins, on both sand and limestone- derived substrates.
Morphology General Habit
A slender twining vine to c. 2 m, stems annual
Morphology General Indumentum
Indumentum present, very variable, consisting of sparse simple hairs to 0.1 mm long, cylindrical with a clavate apex, translucent to slightly brown on petioles, petiolules and inflorescences; on leaflet margins and occasionally on veins on the underside of leaflets, the indumentum consists of flattened, deltoid, translucent modified hairs
Morphology Leaves
Leaves alternate, trifoliolate, sometimes bearing pusticulate scales, usually drying dark olive green/grey above, paler below; anterior leaflet 3-nerved (outer 2 nerves slightly weaker than central), 21 - 70 x 7 - 35 mm, ovate to elliptic with a short-acuminate to narrowly deltoid forerunner tip; posterior leaflets 20 - 56 x 10 - 38 mm; petioles 2 - 14 mm long, canaliculate on adaxial surface, colour as leaves, very small pulvinus present at base, no apical pulvinus visible in herbarium specimens, petiolules 0.1 - 5 mm long, canaliculate on adaxial surface; cataphylls present, to 0.75 mm long, base ovate, clasping stem, apex tripartite, 2 lateral acumina to 1.25 mm long, terminal acumen to 2.5 mm long; lateral nodal flanges absent (i.e. nodes lacking stipule-like structures sensu Burkill 1960)
Morphology Reproductive morphology Flowers
Male flowers lax, pedicellate and almost invariably solitary; pedicels 1.1 - 2.6 mm long, floral bracts 1 - 1.6 mm long, lanceolate with an acuminate apex, bracteole as bract but smaller; tepals inserted on a 0.7 - 1.2 mm diam. flat, discoid torus, fleshy in rehydrated material, yellow- green, free, two whorls only slightly differentiated, outer tepals 1.1- 1.5 x 0.7- 1.3 mm, ovate, apex obtuse to acute, inner tepals 1.0 - 1.5 x 0.8 - 1.4 mm, more broadly ovate, apex as outer whorl; stamens subsessile, inserted in 2 triangular whorls on torus surface, anthers 0.2 - 0.3 mm long, elliptic to oblong; stylode scarcely visible Female flowers with floral bracts c. 1.3 mm long, lanceolate with an acuminate apex; ovary c. 4- 6.5 mm long, 3-angled, elliptic in outline; tepals 6, ovate, apex obtuse to acute, whorls only slightly differentiated, outer whorl 1.2 - 1.5 x 0.7 - 1.0 mm, inner whorl 1.2 - 1.3 x 0.8 - 1.1 mm, more broadly ovate; staminodes sessile, visible as paired tubercles, c. 0.1 mm in diam., inserted on torus around stylar column base; styles fused into a broad column with broad stigmatic surfaces 0.5 - 0.7 mm in width, each surface pyriform in outline, apex deflexed
Morphology Reproductive morphology Fruits
Capsules (all submature) 11 - 14 x 16- 20 mm, reflexed, broadly orbicular in outline, base truncate to retuse, apical sinus absent to 0.9 mm, fruiting pedicels to 3.0 mm long
Morphology Reproductive morphology Inflorescences
Inflorescences 1 - 2 per axil, male to 18.5(- 22.3) cm long, racemose, simple or occasionally bifid (Wilkin et al. 1144); peduncle 3 - 12 mm long, axis pale green, 2.7 - 17.3(- 21.3) cm long; female to 14.4 cm long, spicate, simple
Morphology Reproductive morphology Seeds
Seeds elliptic-lenticular, c. 3 mm long; wing extending all around seed margin, no mature seeds seen.
Morphology Stem
Stems left-twining, terete, longitudinally sulcate when dried, unarmed, pale green with some pink pigmentation, diameter to 1.1 mm; bulbils occasionally present in axils, 2 - 4 mm in diam., irregularly globose, yellow- green, (only seen in Wilkin et al. 1144)
Note

The name of the new taxon is in honour of Jean Bosser who collected several specimens of it between 1964 and 1970. He annotated Bosser 19980 with ways in which it differs from Dioscorea bemarivensis, and these observations have been shown to be the main distinguishing features of the new species. Bosser 19980 was also selected as the type because it is the most complete and representative specimen available.

Dioscorea bosseri is found in scattered populations throughout the same area as those of D. bemarivensis. This extensive co-occurrence suggests that sympatric speciation may have occurred in these two species. The collecting locality of Decary 15242 (Mandoto) is noteworthy as it appears to be above 1000 m in elevation, where evergreen, central highland vegetation would be encountered. All the other specimens of D. bosseri were collected in deciduous lowland forest. However, the locality given on the specimen label is not specific, and it may be that it was collected at a lower altitude on the way from Mandoto to Miandriavazo. It appears unlikely that D. bosseri would tolerate a moist, evergreen forest environment given that it is usually found in gaps, clearings or on forest margins and appears to be light-demanding.

This species can be distinguished from Dioscorea bemarivensis by the presence of trifoliolate leaves on all parts as opposed to pentafoliolate leaves at least towards the stem base in the latter. If basal leaves are not present, a combination of other characters must be used to distinguish the two. In D. bossed the petioles and petiolules are short (2 - 14 mm and 0 - 5 mm respectively), the leaves dry dark olive- green and the flowers are large (male outer tepal width 1.1 - 1.5 mm). In D. bemarivensis the petioles and petiolules are long (7 - 64 mm and 1 - 27 mm respectively), the leaves usually dry a paler brighter green and the flowers are small (male outer tepal width 0.4 - 0.8 mm). If female plants are encountered, it appears that the apical sinus of the capsule is 0 - 0.9 mm deep in D. bosseri and 1.2 - 4.1 mm deep in D. bemarivensis, but this needs to be confirmed through study of mature capsules of D. bosseid.

There is a third species of Dioscorea in Madagascar with compound leaves throughout which is D. quartiniana A. Rich, this has simple hairs, and a dense male inflorescence in which the flowers and axis are concealed by floral bracts. Its seed is winged at the base only. Dioscorea mamillata Jum. & H. Perrier and D. perpilosa H. Perrier both possess densely bristly- pubescent leaves which are compound towards the stem base but entire on upper and fertile shoots.

Type
Madagascar, Toliara Province, lisiere est de la forêt du Zombitsy, Sakaraha, fl. 22 Feb. 1970, Bosser 19980 (holotypus P; isotypus MO).
Vegetative Multiplication Tubers
Tuber largely unknown (some underground parts present in Wilkin et al. 1144: small crown 9 mm in diam., epidermis pale brown, parenchyma white, subtending thick lateral roots, possibly leading to terminal tubers)
Vernacular
Elakelaky (Sakalava, Leandri 830), but this name is also used for Dioscorea bemarivensis according to Burkill & Perrier (1950). The more common Sakalava name for D. bemarivensis in the authors' experience is Trengytrengy or Kitengytengy.

[KBu]
Use
The tuber is probably edible like that of Dioscorea bemarivensis (Burkill & Perrier 1950) but it is unlikely to be greatly sought after.

Native to:

Madagascar

Dioscorea bosseri Haigh & Wilkin appears in other Kew resources:

Date Reference Identified As Barcode Type Status
Jan 1, 2012 De Block et al. [2259], Madagascar K000524398
Wilkin, P. [1144], Madagascar K000523659
Hanitrarivo, R.M. [HRM 216], Madagascar K001171777
Gautier, L. [4517], Madagascar K000523558
Nusbaumer, L. [968], Madagascar K000523559
Labat, J.N. [2110], Madagascar K000523657
Ranirison, P. [682], Madagascar K000523556
Decary, R. [15242], Madagascar K000728248
Wilkin, P. [1144], Madagascar K000523658
Ranarivelo, T. [RTI 581], Madagascar K001171778
Hanitrarivo, R.M. [HRM 051], Madagascar K001171780
Wilkin, P. [1144], Madagascar K000523660
Bolliger, R.F. [RFB 190], Madagascar K001171779

First published in Kew Bull. 60: 276 (2005)

Accepted by

  • Govaerts, R., Wilkin, P. & Saunders, R.M.K. (2007). World Checklist of Dioscoreales. Yams and their allies: 1-65. The Board of Trustees of the Royal Botanic Gardens, Kew.

Literature

Kew Bulletin

  • --- & Perrier de la B athie, H. (1950). Dioscoréacées. In: H. Humbert (ed.), Flore de Madagascar et des Comores. Museum National d'Histoire Naturelle, Paris.
  • Burkill, I. H. (1960). The organography and the evolution of the Dioscoreaceae, the family of the yams. J. Linn. Soc., Bot. 56: 319 - 412.
  • Harold, A. S. & Telford, M. (1990). Systematics, phylogeny and biogeography of the genus Meilita (Echinoidea: Clypeateroidea). J. Nat. Hist. 24: 987 - 1026.
  • Holmgren, P. R. & Holmgren, N. H. (1990). Index Herbariorum. Part 1: the Herbaria of the World. $8@th$ Edition. NYBG Press, New York.
  • IUCN (2001). IUCN Red List Categories: Version 3.1. Prepared by the IUCN Species Survivial Commission, Gland, Switzerland & Cambridge, U.K.
  • Jumelle, H. & Perrier de la Bathie, H. (1910). Fragments biologiques de la Flore de Madagascar. Ann. Mus. Colon. Marseille, sér. II. 8: 423.
  • Raleigh, R. E., Ladiges, P. Y., Entwisle, T. J. & Drinnan, A. N. (1995). Morphometric studies of the genus Tasmannia ( Winteraceae) in Victoria, Australia. Muelleria 8 (2): 235 - 256.
  • Sokal, R. R. & Rohlf, F. J. (1995). Biometry. Third edition. W. H. Freeman & Co., San Francisco.
  • Tyteca, D. & Dufrene, M. (1994). Biostatistical studies of Western European Allogamous populations of the Epipactis helleborine (L.) Crantz species group (Orchidaceae). Syst. Bot. 19 (3): 424 - 442.
  • Wilkin, P. (1999). A morphometric study of Dioscorea quartiniana A. Rich. (Dioscoreaceae). Kew Bull. 54: 1 -18.
  • Wuster, W., Otsuka, S., Malhotra, A. & Thorpe, R. S. (1992). Population systematics of Russell's viper: a multivariate study. Biol. J. Linn. Soc. 47: 97 - 113.

Herbarium Catalogue Specimens
Digital Image © Board of Trustees, RBG Kew http://creativecommons.org/licenses/by/3.0/

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