Solanum umtuma Voronts. & S.Knapp, 2012

Vorontsova, M. S. & Knapp, S., 2012, A new species of Solanum (Solanaceae) from South Africa related to the cultivated eggplant, PhytoKeys 8, pp. 1-11 : 3-6

Solanum umtuma Voronts. & S.Knapp sp. nov. Figs 1 -3

Diagnosis.

Differs from Solanum cerasiferum Dunal by its cuneate to truncate leaf bases (versus short-attenuate leaf bases in Solanum cerasiferum ), ovate foliaceous calyx lobes 7-10 mm long with between 30-80 prickles at anthesis on long-styled flowers (versus deltate to long-deltate membranous calyx lobes 4-7 mm long with only 0-20 prickles on long-styled flowers of Solanum cerasiferum ); also differs from Solanum linnaeanum Hepper & P.-M.L.Jaeger by its shallow, obtuse to acute leaf lobes (versus deep, rounded leaf lobes in Solanum linnaeanum ).

Type.

South Africa. Eastern Cape: Elliotdale District, The Haven [32°14'S, 28°54'E], forest margin, flower white, 17 Nov 1966, J.L. Gordon-Gray 1017 (holotype: NU [NU-40255]).

Description.

Shrub, 0.5-1.5 m. Young stems erect, slender, moderately stellate-pubescent to glabrescent, with porrect sessile or variously stalked trichomes, the stalks to 0.2 mm long, the rays 6-8, ca. 0.2 mm long, the midpoints approximately the same length as the rays, armed with straight prickles 3-4 mm long, 1-2 mm wide at base, deltate, flattened, pale yellow-orange, glabrous, spaced 5-20 mm apart; bark of older stems glabrescent, green-brown to dark brown. Sympodial units plurifoliate. Leaves lobed; blades 8-20 cm long, 5-15 cm wide, 1.5-2 times longer than wide, elliptic, chartaceous, drying concolorous to weakly discolorous, green-brown, moderately stellate-pubescent on both surfaces, with porrect, sessile or stalked trichomes, the stalks to 0.2 mm long, the rays 6-8, 0.2-0.5(-0.8) mm long, the midpoints approximately the same length as the rays, with 5-20 prickles on both surfaces; the primary veins 4-6 pairs, the tertiary venation clearly visible abaxially and not visible adaxially; base cuneate to truncate; margins lobed, the lobes 3-4 on each side, 1-3 cm long, deltate, apically obtuse to acute, extending approximately 1/3 of the distance to the midvein, often with secondary lobing; apex obtuse to acute; petiole 1-3 cm long, approximately 1/6 of the leaf blade length, moderately stellate-pubescent, with 0-5 prickles. Inflorescences apparently lateral, 3.5-9 cm long, rarely branched, with 6-15(-20) flowers, 1-4 flowers open at any one time, weakly stellate-pubescent, with 0(-5) prickles; peduncle 1-3 mm long; pedicels 1-2.3 cm long in long-styled flowers, 0.8-1.2 cm long in short-styled flowers, erect to pendent, articulated at the base, moderately stellate-pubescent to glabrescent, with 0-20 prickles on long-styled flowers, unarmed on short-styled flowers; pedicel scars spaced 2-8 mm apart. Flowers 5-merous, heterostylous and the plants andromonoecious, with the lowermost 1-3 flowers long-styled and hermaphroditic, the distal flowers short-styled and functionally male. Calyx 11-22 mm long in long-styled flowers, 5-9 mm long in short-styled flowers, the lobes 7-10 mm long in long-styled flowers, 3-4 mm long in short-styled flowers, ovate and foliaceous in long-styled flowers, deltate in short-styled flowers, apically bluntly acute in long-styled flowers and acute to obtuse in short-styled flowers, moderately stellate-pubescent, with 30-80 prickles in long-styled flowers and 0-30 prickles in short-styled flowers. Corolla 2.5-3.3 cm in diameter in long-styled flowers, 1.5-2.5 cm in diameter in short-styled flowers, usually white or white with purple midveins, sometimes mauve, stellate, lob ed for 1/4-1/2 of its length, the lobes ca. 7 mm long, ca. 10 mm wide in long-styled flowers, 6-10 mm long and 5-8 mm wide in short-styled flowers, broad-deltate, spreading, sparsely stellate-pubescent abaxially, the trichomes porrect, sessile or stalked, the stalks to 0.2 mm, the rays 5-8, 0.2-0.4 mm long, the midpoints approximately the same length as the rays. Stamens equal, with the filament tube 1-3 mm long, the free portion of the filaments ca. 0.5 mm long; anthers 5-6 mm long in long-styled flowers, 4.5-5.8 mm long in short-styled flowers, connivent, tapering, poricidal at the tips. Ovary glabrous, with a few stellate trichomes towards the apex; style 1.1-1.2 cm long in long-styled flowers, stout, straight or gently curved, moderately stellate-pubescent for most of its length. Fruit a spherical berry, 1(-2) per infructescence, 2.7-3.5 cm in diameter, the pericarp smooth, dark green with pale green and cream markings when young, yellow at maturity; fruiting pedicels 2-3 cm long, 1.2-2.2 mm in diameter at base, woody, pendulous, with 0-20 prickles; fruiting calyx not accrescent, covering 1/4-1/3 of the mature fruit, reflexed, with 10-80 prickles. Seeds ca. 100-200 per berry, 2.7-3.5 mm long, 2-2.5 mm wide, flattened-reniform, orange-brown.

Distribution

( Fig. 3 ). Endemic to South Africa in KwaZulu-Natal and Eastern Cape provinces (most specimens from KwaZulu-Natal); 50-1300 m elevation. Solanum umtuma is limited to the Maputaland-Pondoland Floristic Region ( van Wyk and Smith 2001) and spans the Maputaland and Pondoland Centres of endemism.

Ecology.

Occasional on grassland, scrub, and forest edges, usually growing on sandy soil.

Etymology.

“Umthuma” is an isiXhosa vernacular name for many species of prickly Solanum ; in the Xhosa language the “th” is pronounced as “t”, so we have here written the epithet phonetically as " umtuma ". The epithet is used here as a noun is apposition and thus not latinized to agree in gender.

Preliminary conservation status.

Solanum umtuma is a species of open and somewhat disturbed habitats (as are many prickly solanum species) and occupies an area of approximately 8000 km2 and appears to be relatively evenly distributed within that area ( Fig. 3 ). Although not normally common where it occurs, it is not a species of immediate conservation concern.

Selected specimens examined.

South Africa. Eastern Cape: Transkei, outside Umtata [31°30'S, 29°00'E], 17 May 1975, M.N.M. Arnold s.n. (K [K000441994]); Port St Johns, 1 May 1899, E.E. Galpin 2869 (K [K000545863]); Port St. Johns, 21 Dec 1932, A.O.D. Mogg 1300 (K [K000545864]). -KwaZulu Natal: 50 km from Nongoma, 13 May 1975, M.N.M. Arnold 35934 (K [K000795077]); Berea, 1862, T. Cooper 1272 (BM [BM000887022], K [K000441992, K000441993]); Berea, 1862, T. Cooper 1273 (K [K000441998, K000441999]); Noodsberg, Feb 2002, T. Edwards 2973 (NU); location unknown, “Zululand”, received Jul 1865, W.T. Gerrard 295 (BM [BM000887021], K [K000795076]); Umhlanga Rocks, 2 Sep 1966, R.K. Grosvenor 168 (K [K000441995]); Weza forestry Area - beyond Lorna Doone [31°18'S, 29°57'E], 2 Jul 1986, P.E. Hulley 134 (NU); Mkambati, Mkambati Envi romental Education Centre, 6 Apr 1988, P.E. Hulley 230 (NU); Umgeni Park near Howick; Endulu Camp road, 18 Dec 1988, P.E. Hulley & T. Olckers 279 (NU); 11 km N of Butterworth, 27 Apr 1990, P.E. Hulley & T. Olckers 333 (NU); Vernon Crookes Nature Reserve, 27 Apr 1990, P.E. Hulley & T. Olckers 336 (NU); Umvoti, Umvoti valley S.W. of Mapumulo river bank, 9 Feb 1965, E.J. Moll 1538 (K [K000442000]); Swart Umfolozi, Mpembeni, 1257 m, 27 Jan 2005, L.S. Nevhutalu, LA. Nkuna, & E. van Wyk 921 (K [K000441997]); La Lucia, 14 Aug 1966, R.G. Strey 6750 (K [K000441991]); Umhlanga Rocks, on gentle slopes above Umhlanga Rocks Hotel, 30 Dec 1959, R.H. Watmough 461 (K [K000441996]); Ixopo, 22 Aug 1986, J.O. Wirminghaus s.n.(NU); Ngoye Forest, Zululand [28°50'S, 31°42'E], 17 Sep 1987, J.O. Wirminghaus 628 (NU).

Discussion.

Solanum umtuma is a medium-sized subshrub with straight prickles, acute to obtuse leaf lobes, and large yellow fruits. It is almost certainly a close relative of the sympatric Solanum linnaeanum ; the two species share long, leafy, prickly calyx lobes on long-styled flowers and fruits and differ primarily in the shape of their leaf lobes. Solanum linnaeanum is immediately recognisable by its quite deeply incised leaves with rounded lobes; a few intermediate specimens of Solanum umtuma have somewhat rounded lobes, e.g. R.G. Strey 6750 (K000441991). Label data indicate that Solanum umtuma has white or only occasionally violet to mauve flowers, while Solanum linnaeanum always has purple flowers.

Solanum umtuma is morphologically very similar to Solanum cerasiferum and more superficially similar to other species with straight prickles and acute to obtuse leaf lobes, including the African highland Solanum dasyphyllum Schumach. & Thonn. ( Solanaceae Source 2011) and Solanum robustum H.Wendl. of the New World (see Nee 1999). It is not sympatric with any of those species, so confusion is only possible in the herbarium. Solanum umtuma can be distinguished from Solanum cerasiferum by its cuneate to truncate leaf bases (versus short-attenuate leaf bases in Solanum cerasiferum ), ovate foliaceous calyx lobes 7-10 mm long on long-styled flowers (versus deltate to long-deltate membranous calyx lobes 4-7 mm long on long-styled flowers in Solanum cerasiferum ), and the densely spiny calyx of long-styled flowers with ca. 30-80 prickles at anthesis (versus flower calyces with only 0-20 prickles at anthesis in Solanum cerasiferum ). Solanum dasyphyllum and Solanum robustum both have leaf blades that are markedly attenuate on the petiole and decurrent onto the stem, the stems are usually somewhat winged from these decurrent leaf bases. Solanum umtuma is sympatric with Solanum lichtensteinii and differs from it by its obtuse to acute leaf lobes (versus rounded leaf lobes in Solanum lichtensteinii ).

Specimens of Solanum umtuma have sometimes been annotated as " Solanum fuscatum L." or " Solanum ferrugineum Jacq." These names are both widely misapplied. No original material of Solanum fuscatum L. has been located and the application of this name has been in doubt ( Knapp and Jarvis 1990) and it has been proposed for rejection ( Knapp 2011). Solanum ferrugineum Jacq. is the accepted name for a member of section Torva from the New World; this species occurs from Mexico to Costa Rica ( Nee 1999; L. Bohs pers. comm.).

Figures

Figure 1. Solanum umtuma. A Habit with pronounced secondary leaf lobes and sparse prickles B Habit with few secondary leaf lobes and dense prickles C Calyx of a long-styled flower at anthesis D Fruiting branch E Porrect stellate trichome from the adaxial surface of a leaf. Scale bar: A, B, C = 3 cm; C = 1.5 cm; E = 0.5 mm. A, E from Gerrard 295; B-D from Arnold 35934. Drawn by Lucy T. Smith.

Figure 3. Distribution of Solanum umtuma (black circles) and its putative sister species Solanum linnaeanum (white circles) in southern Africa (specimen details for Solanum linnaeanum can be found on the Solanaceae Source website, http: // www. solanaceaesource. org).