Solanum sulawesi X.Aubriot & S.Knapp, 2022

Aubriot, Xavier & Knapp, Sandra, 2022, A revision of the " spiny solanums " of Tropical Asia (Solanum, the Leptostemonum Clade, Solanaceae), PhytoKeys 198, pp. 1-270 : 1

42. Solanum sulawesi X.Aubriot & S.Knapp sp. nov.

Fig. 69

Diagnosis.

Like Solanum Solanum involucratum Blume, but differing in its lack of dense stellate pubescence on leaf blades and new growth, attenuate leaf bases, and fruiting calyces that are not accrescent.

Type.

Indonesia. Sulawesi: Sulawesi Utara, 220 km W. of Manado, 50 km inland from Pangi, on tributary of Sungai Ilanga , 350-750 m, 3 Mar 1990, J.S. Burley et al. 3625 (holotype: L [L.2882218]; isotypes: A, BO [n.v.], K [K000014635]) .

Description.

Shrubs to 1.5 m tall, strongly armed. Stems erect, terete, densely prickly, glabrous, purple (fide Burley et al. 3625); prickles 0.3-1 cm long, 0.1-0.25 cm in diameter at the base, straight, of many different sizes, pale yellowish tan; pubescence absent; new growth densely prickly and moderately stellate-pubescent with short-stalked porrect-stellate trichomes, the stalks ca. 0.2 mm long, the rays 4-6, ca. 0.5 mm long, the midpoints ca. 0.5 mm long, equal to the rays, the trichomes soon deciduous and the stems glabrate; bark of older stems pale tan. Sympodial units difoliate, the leaves not geminate. Leaves simple, shallowly lobed, the blades (5-)9-17 cm long, (4-)7.5-12 cm wide, 1-1.5 times longer than wide, broadly elliptic, chartaceous, concolorous, strongly armed along the midrib and major veins with straight prickles; adaxial surface glabrate, sparsely pubescent along the veins with scattered sessile porrect-stellate trichomes, the rays 4, 0.1-0.2 mm long, the midpoints 1-1.5 mm long, much longer than the rays; abaxial surface sparsely pubescent with multangulate stalked trichomes, the stalks to 0.5 mm long, the rays 8-10, to 0.5 mm long, irregular in size on a single trichome; major veins 5-6 pairs, densely prickly on both surfaces, the prickles ca. 40 per face, 0.3-1 cm long, straight; base attenuate; margins shallowly lobed, the lobes 5-6 on each side, 1-3 cm long, deltate, acute at the tips and occasionally somewhat bilobed, the sinuses ca. halfway to the midrib; apex acute to acuminate; petioles 2-4 cm long, 1/4-1/3 as long as the leaf blades, densely prickly and sparsely pubescent, the prickles like those of the stems and leaves, the pubescence of scattered stalked porrect-stellate-trichomes, the stalks to 0.5 mm, the rays 6-8, ca. 0.3 mm, the midpoints equalling the rays in length, soon deciduous and the petioles of older leaves glabrate. Inflorescences 0.5-3 cm long, internodal and lateral, unbranched, with 4-8 flowers, only 1 or 2 flowers open at any one time, glabrous except at the very tips, densely prickly, the prickles 2-3 mm long, straight; peduncle absent to 0.9 cm long, densely prickly; pedicels 0.5-0.6 cm long, ca. 0.5 mm in diameter at the base, ca. 1 mm in diameter at the apex, spreading and slightly nodding at anthesis, densely prickly and sparsely stellate-pubescent like the leaf adaxial surfaces, articulated at the base, the trichomes porrect-stellate, the rays 4-8, 0.2-0.5 mm long, midpoints not clearly differentiated from the rays; pedicel scars tightly packed and almost overlapping. Buds broadly ellipsoid and somewhat tapering, included in the calyx lobes until just before anthesis. Flowers 5-merous, apparently all perfect, but some distal flowers may be short-styled. Calyx with the tube 2-2.5 mm long, cup-shaped to slightly urceolate, abruptly narrowing to the pedicel and densely prickly, the lobes 4-6 mm long, ca. 2 mm wide, narrowly deltate, densely prickly on the midveins and sparsely stellate-pubescent abaxially with porrect-stellate trichomes like those of the pedicels. Corolla 1.4-1.8 cm in diameter, white, stellate, lobed 2/3 of the way to the base, interpetalar tissue minimal, the lobes 5-6 mm long, 2.5-3.5 mm wide, narrowly deltate, spreading at anthesis, mostly glabrous adaxially but with a few stellate trichomes at the tips, sparsely stellate-pubescent abaxially with densely tangled sessile trichomes where exposed in bud, these densest at the tips, a few tiny prickles along the petal midvein. Stamens equal; anthers 5-5.5 mm long, ca. 1.5 mm wide, tapering, yellow, densely papillate in the lower half, poricidal at the tips, the pores directed distally, not elongating to slits with drying; filament tube minute, glabrous; free portion of the filaments minute, glabrous, the anthers almost sessile. Ovary conical, densely pubescent with sessile porrect-stellate trichomes with tiny rays and elongate midpoints; style 6-6.5 mm long, glabrous; stigma strongly bilobed, the surfaces minutely papillose. Fruit a globose berry, several per infructescence, 1.5-2 cm in diameter, green (immature?), the pericarp thin and slightly shiny, evenly pubescent with porrect-stellate trichomes with 4-6 minute rays less than 0.1 mm long, the midpoints 3+-celled 1-2.5(-3) mm long; fruiting pedicels 0.8-1.1 cm long, ca. 2 mm in diameter at the base, abruptly enlarged at the apex to ca. 4 mm in diameter, woody, spreading to more or less deflexed from the weight of the berry; fruiting calyx accrescent, the lobes expanding to 7-8 mm long, reflexed and often breaking off. Seeds 50-100 per berry, ca. 2.5 mm long, ca. 2 mm wide, flattened reniform, yellowish tan or brown, the surfaces minutely pitted, the testal cells with straight or slightly sinuate margins. Chromosome number: not known.

Etymology.

Solanum sulawesi is named for the island on which it appears to be endemic, Sulawesi, which is of an extraordinary composite geologic nature at the collision zone of the Asian, Pacific, and Australian tectonic plates ( Villeneuve et al. 2002).

Distribution

(Fig. 70 ). Solanum sulawesi is endemic to the Indonesian island of Sulawesi (previously known as Celebes under Portuguese colonial occupation); two collections are from the northern peninsula and the third from the southwestern peninsula of the island.

Ecology and habitat.

Solanum sulawesi has been collected in open areas in lowland tropical rainforest, from 350 to 750 elevation.

Common names and uses.

None recorded.

Preliminary conservation status

( IUCN 2019). Data Deficient (DD). The few collections, coupled with the possibility of more being uncovered as more specimens of S. involucratum are examined carefully, suggests that it is too early to assign a preliminary conservation status for this species.

Discussion.

Solanum sulawesi is morphologically similar to both S. involucratum and S. lasiocarpum , both of which have large, repand leaves and pubescent berries. It differs from S. involucratum in its calyx that is not accrescent in fruit, its glabrous stems and extremely sparsely pubescent leaves that are cuneate to attenuate and widest near the middle (versus truncate and widest near the base). Solanum lasiocarpum is a much more densely pubescent plant and is often completely unarmed. The leaves are more ovate in outline and more densely pubescent. The midpoints of the fruit trichomes in S. sulawesi are unusual in being 2-3-celled; those of both S. lasiocarpum and S. involucratum are single-celled. Fruits of S. sulawesi are smaller than those of S. Solanum lasiocarpum , and less densely pubescent.

We would have preferred to place the holotype for this species in a herbarium in Indonesia, but extensive searches in the herbarium at Bogor (BO; A. Kartonegoro, pers. comm.) failed to locate a duplicate of Burley et al. 3625, although one should be located there.

Material of S. sulawesi has not been included in molecular analyses but we suspect it will prove a member of a clade comprised of southeast Asian species and not a member of the largely American Lasiocarpa clade.

We have seen very few collections of S. sulawesi , but specimens of this species may have been previously identified as S. involucratum or S. lasiocarpum. These and unidentified collections in BO and other Indonesian herbaria are of particular interest and are a priority for examination.

Paratypes.

[also see Suppl. materials 1-3] Indonesia. Sulawesi: Sulawesi Tenggara, Southeast Celebes. Ladongi - Tirawuta - Kolaka [Kolaka Timur], 19 Oct 1978, Prawiroatmodjo & Maskuri 1356 (K, L); Sulawesi Utara, "Ins. Celebes: (Minahassa): N Celebes", 1888, Warburg 15844 (NY).

Figures

Figure 69. Solanum sulawesi X. Aubriot & S. Knapp - Herbarium specimen (holotype) collected in Indonesia in 1990 (Burley et al. 3625, L. 2882218). Photograph credit: Naturalis Biodiversity Center.

Figure 70. Distribution of S. sulawesi.