Tetradenia tanganyikae Phillipson, 2008

Phillipson, Peter B. & Steyn, Catherine F., 2008, Tetradenia (Lamiaceae) in Africa: new species and new combinations, Adansonia (3) 30 (1), pp. 177-196 : 190-194

8. Tetradenia riparia (Hochst.) Codd

Bothalia 14 (2): 181 (1983); Codd, Flora of Southern Africa 28: 114 (1985). — Moschosma riparium Hochst. , Flora oder Allgemeine botanische Zeitung xxviii: 67 (1845). — Iboza riparia (Hochst.) N.E.Brown , in Thiselton-Dyer (ed.), Flora Capensis v. I. 300 (1910). — Type: South Africa. KwaZulu-Natal, VII.1839, Krauss 331 (holo-, K!; iso-, M!; MO [2 sheets]!).

Moschosma myriostachyum Benth. & Hook. f., Genera Plantarum 2: 1173 (1876). — Type: Malawi, Murchison (Kholombidzo) Falls, VII.1861, Meller s.n. (lecto-, K [2 sheets]!, selected here).

SELECTED REPRESENTATIVE MATERIAL. — Malawi. Shire Highlands , 6.IV.1906, Adamson 81 ( K, P) . — Michiru Hills, Balantyre district , 14.VII.1988, Banda & Tawakali 3332 ( K) . — Balantyre, Shiri Highlands , 6.VII.1879, Buchanan 159 ( K) . — No locality, 21.X.1905, Cameron 112 ( K, P) . — Eldorado Estate, Mlanye , 23.VIII.1960, Chapman 884 ( K) . — Southern Region, Mt Mulanje, foot Esperanza Estate , 25.VIII.1986, Chapman 7995 ( K, MO) . — Southern Region, Mt Mulanje massif low down the Likhubula Valley , 13.VIII.1987, Chapman 8780 ( K, MO) . — Mlanje, Close to Mozambique border, 26.IX.1948, Faulkner 302 ( K 2 sheets). — Nr. Blantyre, Shire Highlands, Last s.n. ( K) . — Murchison Falls , VIII.1861, Meller s.n. ( K) . — Livingston’s Zambesi Expedition , VIII.1861, Meller s.n. ( K) . — Mozamballa, Zambesi Expedition, Waller s.n. ( K) . — Mt Chiradzulu, Whyte s.n. ( K) .

Mozambique. No locality, 17.VI.1911, Dawe 384 ( K) . — No locality, Dawe s.n. ( K) . — Amalongas, Honey 742 ( K [2 sheets]). — Manica, E. Sofala, foot of Mt Zambe , S of Vila Peru, 15.VI.1959, Leach 9116 ( K) . — Manicae Sofala, near Vila de Manica, 7.VII.1969, Leach & Cannell 14250 ( K) . — Vallée du Muza, 8.VIII.1904, Vasse 4 ( P) . — Vallée du Muza, Vasse 52 ( P) .

South Africa. Insuzi Valley between Nkandhla and Ntingwe, 13.VI.1946, Acocks 12721 ( K) . — Stanger , 5 miles from Doornkop Sugar Mill, Archibald 14 ( PRE) . — 9 km W of Nkandhla nr. Nsuzi river , 13.VI.1946, Codd 1407 ( K) . — Transvaal , Soutpansberg, 20.VIII.1955, Codd 8398 ( K) . — Prov. Natal , district Umzinta, 9.VII.1955, Codd 8576 ( K) . — Natal , Kranskop , between Kranskop and Tugela Bridge, Compton 19756 ( NBG) . — Northern Transvaal , Lake Funduzi, mountainside, Crocker s.n. ( J) . — Natal , Nkandla district , Insuzi River valley, Edwards 1472 ( PRE) . — Natal , Oribi mountainside near Hell’s Gate, Glen 407 ( J) . — Natal , Pinetown district, 22.VI.1970, Hilliard 5060 ( K) . — Transvaal , Barberton , Plaston, granite outcrops, Holt 310 ( PRE) . — Zoutpansberg , near Entabeni , 20.VIII.1930, Hutchinson & Gillett 4319 ( K [2 sheets]). — Bothas Hill, Natal, 3.IX.1930, Hutchinson 4686 ( K) . — Natal , Pietermaritzburg , Cato Ridge district , Craiglea, Jacobsen 3334 (49) ( PRE) . — Transvaal , Pilgrims Rest district , Mala Mala near Skukuza, Johnson 448 ( NBG) . — Natal , Port Shepstone , Oribi Gorge, Johnson 934 ( NBG) . — Natal , Eshowe , Umhlatuzi Swamp, Kotze 41 ( PRE) . — Natal , 27.VI.1957, Leach 8112 ( K, PRE) . — Natal , Ifafa, moist ground river bank, Moss 19003 ( J) . — Swaziland , Mvangatini, Murdoch 82 ( PRE) . — Natal , Echanga, Noel s.n. ( GRA) . — Natal , Weenen district, Pentz 348 ( K, PRE) . — Transvaal , Phalaborwa Water Board, 16 km S of Phalaborwa, Retief 465 ( PRE) . — Natal , Station Dumisa, 20.VI.1909, Rudatis 657 ( K, P) . — Ellesmere , 30.IX.1909, Rudatis 723 ( P) . — Natal , Alexandra district, 1.VII.1910, Rudatis 1048 ( K, PRE) . — Transvaal , Letaba , Central Hill , Westfalia, Scheepers 993 ( SRGH, PRU) . — Inanda Location , 13.VII.1969, Strey 8758 ( K) . — Inanda Location , 13.VII.1969, Strey 8759 ( K, PRE, SRGH) . — Gibraltar cliffs, 20.VI.1972, Strey 10967 ( K, PRE, SRGH) . — Inanda Location , 13.VII.1969, Strey Dec-23 ( K) . — Natal , Port Shepstone , Oribi Gorge Nature Reserve , Vassilatos and Mantell 543 ( J) . — Natal , Eshowe, Venter 1675 ( PRE) . — Natal , Ngotshe district , Lebombo Mountains , Majozini, Ward 4193 ( PRE) . — Prov. Zululand , Bartlow Combine, 8.VII.1960, Ward Jun-09 ( K) . — Inanda , Natal, Wood 141 ( K) . — Natal , VIII.1886, Wood 1001 ( K, P) . — Natal , 1.VII.1908, Wood s.n. ( P) . — Natal , Durban, Wood 43198 ( SAM) .

Swaziland. Manzini, Bulunga Point , forest margin, Compton 32116 ( PRE) . — Utondozi , 11.VII.1957, Compton 26962 ( K) . — Hlatikulu, Mamitu River , Compton 27950 ( PRE) . — Mankaiana, Filmerton , riverside bush, Compton 28920 ( PRE) . — Ingwavuma Poort , 18.VII.1960, Compton 30095 ( K) . — Mankaiana, Ntondozi , 27.VI.1963, Compton 31652 ( K, PRE) . — Hlatikulu, Pierce 53 ( PRE) .

Zimbabwe. No locality, IX.1930, [van Sow] 28924 ( K) . — Salisbury district , 15.VII.1974, Biegel 4514 ( K) . — Salisbury , 22.IX.1974, Biegel 4629 ( K) . — Salisbury district , 15.VII.1974, Biegel 4805 ( K) . — Chimanimani Mountains , 22.VIII.1966, Bisset CH 3 ( K) . — Above Mutare on road to Vumba Mountain, 3.VIII.1988, Carter & Coates-Palgrave 2131 ( K) . — Inyanga , Hondi Valley, Chase 1595 ( K) . — Umtali , Christmas Pass, 17.IX.1948, Chase 1624 ( K) . — Inyanga district , 4.VIII.1950, Chase 2854 ( K) . — Umtali district , 18.VIII.1953, Chase 5055 ( K, MO) . — Wuton Farm , Odzi River, Umtali district, 29.VII.1970, Chase 8616 ( K, MO) . — Driespanberg Pass between Chipinga and Birchenough Bridge, 17.IX.1975, Plowes 7149 ( K) . — Melsetter district , Bridal Veil Falls, near Melsetter village, 21.IX.1960, Rutherford-Smith 132 ( K) . — Chirinda Rhodesia , 24.XI.1905, Swynnerton 244 ( K) . — No locality, IX.1930, Van Sow 28924 ( K) .

EMENDED DESCRIPTION

Dioecious shrub 2(-3) m tall, with indument of long (0.8-1.5 mm) eglandular and short to medium (0.1-0.5 mm) glandular trichomes. Stems sparsely hispid with mainly glandular and scattered eglandular trichomes; longer eglandular trichomes present at the nodes. Leaves triangular to ovate; blade up to 100 × 75 mm, serrate to the base, teeth oblique triangular, ± 5 × 6 mm, apex acute, base cordate to truncate, hispid at first, but becoming sparsely hispid or nearly glabrous with short glandular and long eglandular trichomes above, similar beneath, but denser along the midrib, veins and margins and sometimes with sparse honey-coloured sessile glands; petioles c. 1/2 as long as the leaf blade; hispid like the stems. Inflorescence often very large, especially the male, branches sparsely hispid like the stems; bracts somewhat persistent, c. 2 × 1 mm, finely and sparsely glandular hispid on the outer surface and the margins, spikes very lax (male) or dense (female), the terminal spikes (on well-developed inflorescences) usually> 8 (male) or c. 1.5 cm (female) long, internodes> 4 (male) or ± 1 mm (female) long. Male flowers long pedicellate (> 0.7 mm); female flowers short pedicellate (0.3 mm). Calyx c. 0.7 (male) or 0.6 mm (female) long, sparsely and finely hispid, sometimes with scattered pale yellow or honey-coloured sessile glands, the lobes often tinged white to purple; fruiting calyx to 2.2 mm, lobes 0.7 mm long. Corolla broadly funnel-shaped, usually pale lilac, mauve or occasionally white, sparsely and finely pubescent outside; corolla tube narrow at the base and expanding abruptly beyond the calyx mouth, ± 1.6 (male) or 1.1 mm (female) long, with a ring of long hairs in the throat; lobes slightly spreading, glabrous inside and sparsely pubescent outside, sometimes with scattered sessile glands; lower lobe 1.8 (male) or 0.8 mm (female) long; lateral lobes shorter. Stamens with purple anthers. Style branched purple. Nutlets ellipsoidal ± 0.75 × 0.35 mm.

REMARKS

Tetradenia riparia occurs from the eastern parts of South Africa as far south as the KwaZulu-Natal South Coast, northwards through Swaziland, southern Mozambique and eastern Zimbabwe as far north as southern Malawi, from near sea-level in the south of its range to about 1500 m asl further north. Flowering is recorded mainly from May to September. The range of T. riparia overlaps with those of a number of other species ( T. bainesii , T. brevispicata and T. galpinii ), but it generally occurs at lower elevations or in more humid habitats. Within the genus, it represents the extreme in dimorphism between the male and female flowers and inflorescences.

Male plants in flower are easy to distinguish from those of any other species because of the relatively large flowers on long pedicels borne in large, lax inflorescences. The corolla of the male flowers is also a distinctive shape: it is broadly funnel-shaped, with the tube expanding abruptly beyond the calyx mouth from the narrow base, whereas in other species the corolla tube expands much more gradually from the base. Specimens lacking male flowers are sometimes difficult to place with certainty, but the species does have a unique suite of vegetative characters. Tetradenia riparia is most similar to T. galpinii , and apart from the characteristics of the male inflorescences mentioned above, the two taxa can be distinguished by their stem indument, comprised of mainly glandular trichomes in T. riparia and a more equal mixture of glandular and eglandular trichomes in T. galpinii , and by the petioles being generally ± 1/2 as long as the leaf blades in T. riparia as compared with ± 1/3 as long in T. galpinii .

The relatively narrow concept of T. riparia adopted here contrasts with that of Codd (1983). He interpreted this species as highly variable and widespread in distribution – extending from South Africa to Ethiopia, and he placed most of the previously described taxa from Africa into synonymy under this species. Codd (1985) noted that his concept of T. riparia “includes a good deal of variation in leaf size, shape and pubescence but no pattern emerges and so infraspecific taxa are not upheld”.We disagree with this view, and believe that patterns of variability do exist, and that these are correlated with ecogeographical distribution. Furthermore, coherent entities can be defined on this basis, which are appropriately placed at the species level.Consequently we have redefined T. riparia , and we segregate six additional species. Four of these already have available epithets: T. bainesii , T. galpinii , T. multiflora and T. urticifolia , and two others are described as new species: T. discolor and T. tanganyikae .

The name Moschosma myriostachya Benth. has generally been equated with T. riparia in the literature. It is based on two syntypes, both collected in Malawi by C. J. Meller during Livingstone’s Zambezi Expedition. The first, collected in August 1861 at Murchison (Kholombidzo) Falls, is a male specimen of T.riparia ; the second, collected in September 1861 at Mount Chiradzulu (Zomba Peak), is a female specimen of T. discolor . We select the former as the lectotype of M. myriostachya because it is well-preserved and copious (it is mounted on two separate sheets at Kew), and so that the name will continue to fall into synonymy under T. riparia . Selecting the other syntype would make the name M. myriostachya available for the new species described here as T. discolor , but this could lead to confusion.

Plants of T. riparia , most commonly males, are cultivated as garden ornamentals in many tropical and subtropical countries, including in a number of African countries outside of its natural range.

9. Tetradenia tanganyikae Phillipson , sp. nov. ( Fig. 3 )

Frutex indumento sparso, inflorescentiis-masculis densis, differt a Tetradenia urticifolia floribus majoribus et indumento brevi.

TYPUS. — Zambia. Abercorn district , Ndundu, 1740 m, Richards 12917 (holo-, K!) .

PARATYPES. — Malawi. Brachystegia woodland, 24.VII.1946, Brass 16909 ( K, MO) . — Kabumba River, 22 km S of Engucwini in road from Rumpi to Kafukule , 6.VII.1970, Brummitt 11838 ( K) . — North end of Nyika Plateau and adjacent area, 10.VIII.1972, Brummitt & Synge WC 190 ( K) . — No locality, Pawek 3629 ( K) . — Nkhata Bay at Chikale Beach , 13.VIII.1972, Pawek 564OB ( K) . — Masuku Plateau, Whyte , 300 ( K) .

Tanzania. No locality, 1.VIII.1965, Beecher 50 ( K) . — Rungwe district Tukuyu , 20.VII.1932, Davies ( K) . — Dept. of Agriculture , 10.IX.1932, Davies D. 222 ( K) . — 1.V.1935, Emson 393 ( K) . — S Highlands Province , 11.XII.1932, Geilinger 2162 ( K) . — Iringa Prov. - Mbozi , 30.VIII.1933, Greenway 3642 ( K) . — Kwiro , 1.VII.1960, Haerdi 565/0 ( K) . — Nr. Pasagulu 10 m N of Kasogi , 6.VIII.1959, Harley 9173 ( K) . — Nr. Pasagulu, 10 m N of Kasogi , 7.VIII.1959, Harley 9197 ( K) . — Kabesi , 4.IX.1958, JeffordT.G.& Newbould 2328 ( K) . — Mpanda district, Mahali Mts Nr Kasangazi, 24.VII.1958, Juniper & Jefford 226 ( K) . — Mbeya Mountain Range , 16.VI.1999, Kayombo 2381 ( K, MO) . — Loweau plateau [?] N of Lake Leyessa [? illegible notes, just a guess], Lawson, Oct-80 ( K) . — Ufipa, on escarpment, near Muburu River, Ruhwa Rift valley , growing next to river, 3.XII.1936, Lee L.V. 10 ( K) . — Iringa Region, Nr. Milo , 3.IX.1986, Linder 3860 ( K) . — Pungaluma Hills above Mshewe Village , 20.XII.1989, Lovett & Kayombo 3390 ( K, MO) . — Kasangazi , Kigoma district, 30.VII.1958, Mahinde 186 ( K) . — Mahali Mountains, Ujamba , 23.VIII.1958, Newbould & Jefford 1734 ( K) . — Kasieha Valley, Mahali Mountains , 20.VII.1959, Newbould & Harley 4504 ( K) . — Kungwe Mountain Selimweguru, 24.VII.1959, Newbould & Harley 4611 ( K) . — Ruhudje , 26.VIII.1931, Schlieben 1142 A ( K, P) . — Bergwesen , 24.IX.1910, Stolz 295 ( K) .

Zambia. Fort Jameson , 1.VI.1958, Fanshawe 4560 ( K) . — Abercorn-Tunduma Road , 70 miles towards Tunduma, 5.VIII.1949, Greenaway 8377 ( K) . — Nr Abercorn , on the slopes of Sunzu, 1.VI.1955, Lawton 215 ( K) . — Ndcondu , 12.IX.1969, Sanane 946 ( K, P) . — Without locality, Modesty Sanane 947 ( K [2 sheets]; P) .

DESCRIPTION

Dioecious aromatic (citronella-scented) shrub 1.5- 5 m tall; with white or colourless indument of mainly short (± 0.1 mm) and long (± 1 mm) eglandular and medium (± 0.3 mm) glandular trichomes. Stems brown, the scars of fallen leaves hardly raised, hispid with patent medium-length glandular and also usually long eglandular trichomes, and a ring of longer (± 1.5 mm) eglandular trichomes at the node.Leaves ovate; blades <150 × 110 mm, margins shallowly serrate to crenate along their entire length, the teeth broadly triangular ± 4 × 8 mm, shortly rounded or pointed, occasionally with smaller teeth on their margins, apex acute, base rounded, sparsely pubescent with medium-length glandular and eglandular trichomes above, sparsely woolly with matted long fine eglandular trichomes present mainly near the veins, and with scattered pale honey-coloured sessile glands beneath; petioles ± 1/2 the length of the leaf blade, hispid like the stems. Inflorescence often very large, branches moderately to densely villous with mainly medium-length glandular trichomes; bracts caducous, ± 1 × 1.5 mm, moderately and rather evenly pubescent with short eglandular trichomes on the outer surface and the margins, spikes dense, the terminal spikes (on well-developed inflorescences) usually> 3 (male) or> 1.5 cm (female) long, internodes ± 2-3 (male) or 1 mm (female) long, the axes somewhat or completely hidden by the flowers at anthesis. Flowers subsessile to shortly (<0.3 mm) pedicellate. Calyx ± 0.5 × 0.6 mm (male) or 0.8 × 0.7 mm (female), pubescent with short trichomes and with copious pale yellow sessile glands, lateral sepal-pairs shortly divided, fruiting calyx ellipsoid ± 2 mm long, lobes ± 0.3 mm long. Corolla white, or (less commonly) pink; tube glabrous in throat, pubescent outside, ± 1.2 (male) or 1.4 mm (female) long; lobes slightly spreading, glabrous inside and pubescent outside (except at margins), lower lobe ± 1.2 (male) or ± 0.6 mm (female) long, lateral lobes shorter. Stamens protruding ± 2 mm, anthers ± 0.3 mm diameter, pink. Style ± 2.2 mm long, purple, drying honey-coloured, lobes ± 0.7 (female) or 0.2 mm (male) long. Nutlets yellow-brown, narrowly ellipsoidal, ± 0.8 × 0.3 mm.

REMARKS

Tetradenia tanganyikae is confined to the mountains of southwestern Tanzania, northern Malawi and adjacent parts of Zambia, with many of the known specimens collected inTanzania near to LakeTanganyika.The species is known from forest, woodland and bushland, mainly along streams and rivers between 1200-2000 m asl, and it is sometimes cultivated locally as a hedge. It has been recorded in flower from May to November.Label data on several collections report that the plant has a scent of “citronella”, but at least one reports “unscented leaves”.

This new species can be distinguished from all other members of the genus by the combination of dense male and female inflorescences, relatively short sparse indument on its stems and leaves, and medium-sized flowers, larger than those of T. urticifolia , a species that also occurs in Tanzania and with which it could be confused.

Figures

FIG. 3. — Tetradenia tanganyikae Phillipson, scanned image of holotype,Richards 12917 (K), from Ndundu in Mbala (Abercorn) district at 1740 m in Zambia.