Nordic Journal of Botany

A new species of Zehneria (Cucurbitaceae) from Somalia

Mats Thulin

Thulin, M. 1996. A new species of Zehneria (Cucurbitaceae) from Somalia. - Nord. J. Bot. 16: 297-299. Copenhagen. ISSN 0107-055X.

The new species Zehneria somalensis, from shady limestone rocks in north-eastem Somalia, is described and illustrated.

M. Thulin, Dept of Systematic Botany, Uppsala Universiy, Villavagen 6, S-752 36 Uppsala, Sweden.

Introduction

The genus Zehneria Endl. was included in Melothria L. by Cogniaux (1916), but was reestablished by Jeffrey (1962) and now comprises about 35 species in the paleo- tropics (Jeffrey & Thulin 1993). The account of Zehne- ria for Flora of Somalia (Jeffrey & Thulin 1993) includ- ed two species, Z. scabra (L. f.) Sond., widespread in Africa and tropical Asia, and 2. anomala C . Jeffrey in Somalia and northern Kenya westwards to Niger and Chad, and in Arabia.

During field work in north-eastern Somalia in Janu- ary 1995 another species was found, which does not agree with any previously described taxon. This is de- scribed below as Z. somalensis.

Zehneria somalensis Thulin, sp. nov.

Type: Thulin, Dahir & Hassan 8975, Somalia, Sanaag Region, Karin Xaggarood, 10"58'N, 48"52'E, 10 Jan 1995 (UPS holotype, IT, K isotypes).

Species nova ab aliis speciebus monoicis filamentis longis et thecis arcuatis combinatione caulium glabronum cum foliis palmatim (3-)5-lobatis infra glabris, floribus femineis solitariis, et fructibus ellipsoideis rubris sem- inibus 4- 12 c. 4.4 mm longis differt. - Fig. 1.

Plant monoecious; stems herbaceous, up to several me-

Accepted 16- 10- 1995 0 NORDIC JOURNAL OF BOTANY

ters long, angular with green edges, trailing or hanging, glabrous. Leaves simple; blade broadly ovate-triangular in outline, 3-8 x 2.5-6.5 cm, palmately * deeply (3-)5- lobed, cordate at the base, scabrid with minute scattered stiff hairs above, glabrous or almost so beneath, lobes elliptic to lanceolate or ovate, acute, the central the larg- est; petiole 1.2-4.5 cm long, canaliculate above, gla- brous or almost so. Tendrils simple, glabrous, or sparse- ly hairy at the very base only. Male flowers 3-6 in axillary clusters; pedicels 10- 14 rnm long, glabrous; hypanthium campanulate, 2.5-3.2 mm long, pale green, glabrous outside, pilose inside; calyx-lobes (4-)5, trian- gular, c. 0.4 mm long; petals 5, white, triangular, c. 1.6- 2.8 x 1.6-2.4 mm, practically free, glabrous outside, hairy inside; stamens 3, filaments 1.5-2 mm long, insert- ed near base of hypanthium, sparsely hairy near middle, anthers all 2-thecous with somewhat exserted short ar- cuate thecae, disk flat, suborbicular and obscurely lobed. Female flowers solitary, coaxillary with the male flowers; pedicels 25-40 mm long, glabrous, thickened and articulated just below the flower; ovary fusiform, c. 6.5 x 1.5-2 mm, glabrous; hypanthium, calyx-lobes and petals * as in the male flowers; staminodes 3, c. 2 mm long, inserted near the base of the hypanthium, disk an- nular, surrounding the base of the style; style c. 3 mm long, with 2-lobed stigma. Fruit elliptic in outline, c. 13- 17 x 6-9 mm, apiculate, red when ripe, c. 4-12-seeded. Seeds ovate in outline, flattened, bordered, c. 4.4 x 3.2 x 1.5 mm, straw-coloured. - Fig. 1.

Nord. J. Bor. 16(3) 1996 297

Fig. 1. Zehneria somalensis, from Thulin, Dahir & Hassan 8975. - A: Node with leaf, tendril, young fruit and male flowers, x 0.8. - B: male flower, opened up, x 6. - C: female flower, x 3 . - D: female flower, opened up, x 6. - E: seed, x 5.

Distribution and habitat. Zehneria somalensis is known only from the type locality in the eastern part of the Cal

Somalia, where it grows on the limestone escarpment

in its small subglobose fruits on pedicels only up to 4.5 mm long.

to be z. parvifolia (Cogn.) J. H. Ross in Mozambique

Range in the Sanaag Region in north-eastern Elsewhere in Africa the most similar species appears

facing the Gulf Of Aden* Only a sing1e population was seen, flowering and fruiting in profusion* the plants

and Natal (Jeffrey 1978). This is monoecious with gla- brous Stems and palmately 5-lobed leaves, but differs

hanging over a vertical rock-face in shade at c. 1600 m altitude. The surrounding vegetation is an evergreen bushland with Buxus hildebrandtii, Juniperus procera, Pistacia aethiopica and Acokanthera schimperi.

markedly from z. somalensis, for example in its glo- bose, bluish fruits with much smaller seeds.

The determination of the two collections of Z. scabra cited from Somalia by Jeffrey & Thulin ( I 993) is not

Taxonomic remarks. Z. somalensis, with its long fila- ments and arcuate thecae, belongs to the same group of species that includes, among east and north-east African species, the widespread Z. scabra, Z. emirnensis (Bak.) Keraudren in Tanzania and Madagascar, and Z. oli- gosperma C. Jeffrey in East Africa and Malawi. These three species are, however, all dioecious in contrast to the monoecious Z. somalensis. With its fairly few-seed- ed fruits Z. somalensis agrees best with Z. oligosperma, but apart from being monoecious, it differs from this al- so in its distinctly palmately lobed leaf-blades, c. 0.4 mm long calyx-lobes (versus 0.7-1.2 mm long), solitary female flowers (not in 2- 18-flowered clusters), fusiform (not subglobose) ovaries, and ellipsoid (not globose) fruits.

Z. anomala, along with Z. scabra the only species that was previously known from Somalia as well as from the Arabian peninsula, differs strongly from Z. so- malensis in its woody stems, in its filaments inserted near the middle of the hypanthium, its obscure disk, and

quite certain. The leaf-shape agrees fairly well with that of Z. scabra, but the undersides of the leaves and the stems are glabrous. This is very unusual for Z. scabra, but instead agrees with Z. somalensis. The specimens are both male and seem to represent a dioecious species as Z. scabra, but they could possibly also represent a monoecious species as Z. somalensis, where the female flowers were not collected. Both collections originate from Surud Mt in northern Somalia, and from a habitat very similar to that of Z. somalensis. Further studies in the field are needed to show whether the Surud popula- tion is conspecific with Z. scabra or 2. somalensis, or whether it represents a third taxon.

Acknowledgements - This paper is part of the Flora of Somalia project supported by SAREC. 1 am indebted to Louise Petrusson for the drawing.

298 Nord. J . Bol. 16(3) 1996

References Cogniaux, A. 1916. Cucurbitaceae-Fevilleae et Melothrieae. -

Engl. Pflanzenr. IV.275.1: 1-277. Jeffrey, C. 1962. Notes on Cucurbitaceae, including a pro-

posed new classification of the family. - Kew Bull. 15:

- 1978. Cucurbitaceae. - In: E. Launert (ed.), Flora Zambe- siaca 414-499. Flora Zambesiaca Managing Committee, London.

- & Thulin 1993. Cucurbitaceae. - In: M. Thulin (ed.), Flora of Somalia, vol. 1: 216-240. Royal Botanic Gardens, Kew.

337-371.

Nord. 1. Bot. 16(3) 1996 299

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