Southern African Loranthaceae and Viscaceae : new taxa * and new combinations

Two new genera are named: Pedistylis Wiens with the type species P. galpinii (Schinz ex Sprague) Wiens and Vanwykia Wiens with the type species V. remota (Bak. & Sprague) Wiens. Three new species and one new subspecies are described: Plicosepalus amplexicaulis Wiens, Tapinanthus crassifolius Wiens, Viscum oreophilum Wiens, and V. capense L.f. subsp. hoolei Wiens. The following nomenclatural changes are made: Actinanthella wyliei (Sprague) Wiens, Tapinanthus forbesii (Sprague) Wiens, T. leendertziae (Sprague) Wiens, T. kraussianus (Meisn.) Danser subsp. transvaalensis (Sprague) Wiens, T. natalitius (Meisn.) Danser subsp. zeyheri (Harv.) Wiens, Tieghemia bolusii (Sprague) Wiens and T. rogersii (Sprague ex Burtt Davy) Wiens.

This paper formalizes the new taxa and nomen clatural changes adopted in my recent taxonomic treatment of Loranthaceae and Viscaceae for the Flora of Southern Africa.Except for the recognition of the two families as distinct, the most dramatic change from Flora Capensis is the abandonm ent of the genus Loranthus (sens, lat.) in favour of a more restricted generic view involving the recognition o f 11 loranthaceous genera.In this view, Loranthus is a monotypic genus based on L. europaeus Jacq.
Long-standing controversy centres on the number of genera into which the family Loranthaceae (sens, sir.) should be divided.The extremes o f treatment are the 10 genera recognized by Engler [Pflanzenfam. 3,1: 117 (1894)] and the approximately 125 accepted by van Tieghem (in a series of papers in Bull.Soc. bot. Fr. in 1894-96).Danser in an excellent study [Verh. K. Akad. Wet., Sect. 2, 29(6): 1-128 (1933)] recognized 51 genera, but his treatm ent o f the New World groups was not critical.Probably the total number of loranthaceous genera will ultimately stabilize between 60 and 70.
Generic boundaries within Loranthaceae as here recognized are as significant as those in many families and surely more substantive than in some (e.g., Brassicaceae, Boraginaceae, Apiaceae).Contemporary monographic workers in the family have all adopted the restricted generic concept in Loranthaceae and floristic systematists are doing so with increasing frequency.With the exception o f the relictual terres trial root parasitic groups, the alternative is to recognize Loranthus as a single genus o f worldwide, pantropical, and south temperate distribution.A more detailed discussion of the problem will be published elsewhere.
With respect to Africa as a whole, Balle [Webbia 11: 541-585 (1956)] recognized 22 genera, which is a sound approximation.The southern African genera are defined on the bases of actinomorphy versus zygomorphy, choripetaly versus sympetaly, other obvious differences in floral and inflorescence charac ters, and variations in haustorial systems.The genera are in fact identifiable at a glance when the critical features are understood.
Large shrubs perhaps exceeding 2 m high, glabrous, older plants forming much enlarged (up to 1 m across!) haustorial connections with the host.Younger branches often densely lenticelled, the nodes of older branches usually greatly swollen.Leaves opposite-subopposite, mostly oblong, often slightly falcate, highly variable in length (50-) 70-80 (-120) X 10-20 mm, penninerved, veins often raised on the lower surface.Petioles 8-10 mm long.Inflorescences axillary or often in pairs on the swollen nodes o f older branches, 2(3)-flowered umbels, with stout peduncles and pedicels, each about 5 mm long.Flowers 5-merous, radially symmetrical (tube without a unilateral split).Corollas yellow, sympetalous, lobes reflexed and about as long as the tube.Mature buds 70-80 mm long.Filaments at m aturity curving outward about 90° or more, becoming reddish, attached at the base of the lobes.Styles bending downward near the apex in a broad curve for 180° or more (as a shepherd's crook), becoming reddish.Stigmas broadly ovoid.Berries ellipsoid, ca. 2 0 x 1 2 mm, yellow-green, with scattered warts.Flowering approximately February through April.n = 9 .
A monotypic genus narrowly restricted to the lowveld of the south-eastern Transvaal, and adjoining Swaziland and M ozambique; an isolated genus with out apparent close relatives.
M oderate to large shrubs perhaps 1 m or more high, spreading by haustoria-bearing surface runners.Stems stout and robust, leaf-bearing shoots 3-5 mm thick.Young branches densely short tomentose, older branches jglabrous.Leaves subopposite-alternate, rarely fascicled, mostly obovate, rounded apically, cuneate to the base, 50-60 x 30-40 mm, densely yellowish-white tomentose when young, glabrous and thickly coriaceous with age.Petioles 4-6 mm long.Umbels often fascicled on the swollen nodes of older branches, 3-6-flowered, completely covered by a dense yellowish-white tom entum at least 1 mm thick (the trichomes with whorls arising from a central axis).attached at the base of the corolla lobes, essentially erect, but curving inward to form a central, collective anther mass.Styles thickened and pubescent below, thinner and glabrous above.Stigmas ellipsoid.Berries unknown.
A genus with 1 (possibly 2) species in south-eastern Africa.Related to Septulina, Bakerella in Madagascar, and especially to the larger Asian genus, Taxillus.
The species is clearly distinguished from P. kalachariensis by the amplexicaul, sagittate leaves and basally whitish corolla.The species is also distinct from P. sagittifolius of eastern and north-eastern Africa, the latter having a differently coloured corolla and differently shaped, often fascicled leaves.

U T ).
Plants monoecious.Internodes often exceed 10 mm in length.

T
y p e .-Swaziland,near M babane, Compton 27859 holo.; (PRE, NBG).Parasitic on Pterocelastrus, the only known indige nous host (also on Prunus persica).Recorded from the highlands of Swaziland, the adjoining eastern Trans vaal and the Soutpansberg.