Solanum peikuoense S.S.Ying in 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

30. Solanum peikuoense S.S.Ying in X.Aubriot & S.Knapp sp. nov.

Fig. 49

Diagnosis.

Like S. pseudosaponaceum , but with the upper surfaces of leaves glabrate and shiny, inflorescences forked but not many times branched, larger flowers corolla (2-2.4 cm diam. versus 1-1.5 cm diam.) and generally fewer seeds per berry (18-40 versus 25->100).

Type.

Taiwan. Southern Taiwan: Pingtung County, Wutai Hsiang , 13 Oct 1993, Y-R. Lin et al. 134 (holotype: HAST [29822]; isotype: BM [BM000846380], E [E00320675], MO [MO-3105792, acc. # 04669018]) .

Description.

Erect shrub to small tree, to 4 m, unarmed, less often armed with a few prickles. Stems erect, terete, unarmed or with a few scattered prickles, sometimes dark purple (Ku 1752), sparsely stellate-pubescent; prickles, if present, 0.1-0.3 cm long, straight, deltate, orange-yellow, glabrous; pubescence of mixed sessile and variously stalked porrect-stellate trichomes, the stalks to 0.1 mm long, the rays 6-8, 0.1-0.5 mm long, the midpoints absent or up to 0.1 mm long; new growth densely stellate-pubescent, the trichomes like those of the stems; bark of older stems glabrescent, reddish brown and shiny. Sympodial units plurifoliate, the leaves not geminate. Leaves simple, very shallowly lobed, the blades 11-18 cm long, 5.2-10 cm wide, ca. 1.5-2 times longer than wide, elliptic to somewhat ovate, widest at the middle, chartaceous, strongly discolorous, unarmed or more rarely armed along the principal veins with tiny awl-shaped prickles like those of the stems; adaxial surface dark green, almost completely glabrous to sparsely stellate-pubescent along the midrib and veins but with a few sessile porrect-stellate trichomes on the midrib and along the principal veins, the rays 6-8, 0.3-0.5 mm long, the midpoints ca. 0.4 mm long, approximately equal to the rays; abaxial surface similarly but more densely pubescent with sessile porrect-stellate trichomes along the veins; major veins 5-7 pairs sparsely pubescent especially abaxially, drying pale yellow abaxially; base acute to attenuate, usually somewhat oblique; margins shallowly lobed, the lobes 5-7 on each side, 0.5-1 cm long, deltate and apically acute, the sinuses extending up to ca. 1/4 of the distance to the midvein; apex acute to acuminate; petiole 1.5-3.5 cm long, 1/9-1/5 of the leaf blade length, unarmed or with a few awl-shaped prickles, and very sparsely pubescent with porrect-stellate trichomes like those of the stems. Inflorescences 1.5-3.5 cm long, internodal and lateral, forked, with 10-16 flowers, some of these borne below the branching point, only a few flowers open at any one time, sparsely pubescent with porrect-stellate trichomes like those of the stems; peduncle ca. 1.3 cm long; pedicels 1-1.2 cm long, ca. 1 mm in diameter at the base, ca. 1.2 mm in diameter at the apex, spreading and perhaps slightly nodding at anthesis, sparsely stellate-pubescent with porrect-stellate trichomes like the inflorescence axes, articulated at the base; pedicel scars irregularly spaced (1)4-5 mm apart. Buds pointed-ovoid, the corolla exserted from the calyx lobe acumens before anthesis. Flowers 5-merous, apparently all perfect. Calyx with the tube ca. 2 mm long, cup-shaped, tearing to form irregular lobes, the lobes ca. 1 mm long with an elongate acumen to 3 mm long, ca. 1 mm wide, sparsely stellate-pubescent to glabrescent. Corolla 2-2.4 cm in diameter, white or purple (Ku 1752), stellate, lobed ca. 2/3 of the way to the base, the lobes 8-10 mm long, 3-4 mm wide, spreading at anthesis, glabrous adaxially, glabrous or sparsely stellate-pubescent along the petal midribs abaxially. Stamens equal; anthers 5-7 mm long, ca. 1.5 mm wide, tapering, yellow, poricidal at the tips, the pores directed distally, not elongating to slits with drying; filament tube minute, glabrous and papery; free portion of the filaments ca. 0.5 mm long, glabrous. Ovary conical, glabrous; style ca. 10 mm long, straight, glabrous; stigma minutely capitate, the surfaces minutely papillose. Fruit a globose berry, 2-6 per infructescence, 1-1.3 cm in diameter, the pericarp smooth, red or black (Lin et al. 134), glabrous; fruiting pedicels 1-2.3 cm long, 1-1.2 mm in diameter at the base, ca. 2 mm in diameter at the apex, woody, erect or spreading, unarmed; fruiting calyx lobes not markedly expanding, 1/3 the length of the mature fruit, spreading, broadly deltate with a filiform acumen to 3 mm long, this usually breaking off. Seeds 18-40 per berry, 3-3.5 mm long, 2-2.7 mm wide, flattened-reniform, dull yellow, the surfaces minutely pitted, the testal cells with sinuate margins. Chromosome number: not known.

Distribution

(Fig. 50 ). Solanum peikuoense is endemic to the island of Taiwan, most collections are from the southern part of the island.

Ecology and habitat.

Solanum peikuoense grows in broadleaf, coniferous or mixed broadleaf-coniferous forests, often along roadsides or in open areas, from 1,200 to 2,000 m elevation.

Common names and uses.

None recorded

Preliminary conservation assessment

( IUCN 2019). Vulnerable (VU [B1,2a,bi,ii,]. EOO (10,013 km2, VU); AOO (44 km2, EN). Solanum peikuoense is a single island endemic with a small extent of occurrence. It is found in at least one protected area (Dawushan National Park), so is likely to be protected in the future.

Discussion.

Solanum peikuoense is a distinctive plant, and unlikely to be confused with any other species in the region. It is a member of the Torva clade (see Aubriot et al. 2016a) and is morphologically similar to other southeast Asian members of the group such as S. poka , S. pseudosaponaceum and S. torvoideum (and the introduced S. torvum ). Its shiny, almost glabrous mature leaves and stems distinguish it from any of these species, all of which are densely pubescent. It can be distinguished from the introduced S. torvum in the shiny leaves with acute to acuminate (rather than acute to truncate) apices, and its red or black berries (versus dirty green-yellow in S. torvum ); S. peikuoense also lacks the characteristic simple glandular trichomes found in the inflorescence axes of S. torvum . Some collections (e.g., Ku 1752) mention dark purple stems and purple flowers; other gatherings record the flowers as white.

Although a single gathering (Ying s.n.) in a single herbarium (NTUF) was cited in Ying (1997:14), the word type or holotype, or its equivalent was not used. This is contrary to Art. 40.6 of the “Code” ( Turland et al 2018) and renders " Solanum peikuoensis S.S.Ying" not validly published. We validate this name here and cite as type material a gathering for the same area that is widely distributed and has both flowers and fruits.

Paratypes.

[also see Suppl. materials 1-3] Taiwan. Chiayi Hsien: Chiayi, Arisan, Kagi, common around Funkiko, 25 Jan 1918, Wilson 9657 (A). Hualien Hsien: Tungnengkao, Panpien, 20 Apr 1927, Saito 6965 (A). Kaohsiung Hsien: Teng-chu, 22 Jan 1972, Hsu 13689 (A); Tengchih, 17 Nov 1992, Huang et al. 15850 (A); Taoyuan Hsiang, along Southern Cross-Island Hwy, between Lanya and Likuan, 27 Jun 2000, Lin 405 (CAS, HAST); Taoyuan Hsiang, near road mileage sign 13 km on Meilan Forest Road, 10 May 1994, Liu et al. 427 (HAST); Taoyuan Hsiang, Shihshan Forest Road 9.7 km, 21 May 1997, Peng 16833 (HAST); Taoyuan Hsiang, Tengchih, 28 Jun 2000, Wang 4317 (HAST); Kaohsiung Hsien, Taoyuan Hsiang, Tengchih, 29 Jun 2000, Wang 4376 (HAST, PE); Taoyaun Hsiang, Tengchih, 24 Jul 2004, Wang et al. 11628 (HAST). Nantou Hsien: Hsinyi Hsiang, Shenmu village, 31st forest compartment, 19 Apr 1984, Peng 6576 (HAST); Jenai Hsiang, 9-10K, 22 Apr 2000, Wang 5514 (HAST). Pingtung Hsien: Wutain Hsiang, Hsiaogueihu forest road, 3 May 2003, Ku 1752 (HAST). Taichung Hsien: Hoping Hsiang, Chia-yang to Tsui-luan, 7 May 1997, Lin et al. 938 (HAST); Hoping Hsiang, Tahsuehshan Forest Road, 30 Sep 2006, Lu 12541 (HAST); Tainchung Hsien, Hoping Hsiang, Tahhuehshan 200 forest road 30K, 28 Feb 2001, Wang & Li 4720 (HAST, PE); Hoping Hsiang, on Hsuehshan Forest Road, at road mileage sign 28.2 km, 5 May 1999, Wu 1273 (A, HAST); Hoping Hsiang, Pei-ko-ta-shan, 1 Aug 1996, Ying s.n. (HAST). Taitung Hsien: Haituan Hsiang, Hungshih Forest Road, near road marker 9.5 km, 1 Mar 2000, Liu 1369 (HAST); Peinan Hsiang, LiChia Forest Road, between road marker 19 km and 22 km, 25 Jul 2008, Lu 16536 (HAST); Yenping Hsiang, Yenping Forest Road, 24 Dec 2000, Yang s.n. (HAST); Chin-shui-ying, 18 Sep 1998, Yang 23750 (HAST).

Figures

Figure 49. Solanum peikuoense S. S. Ying A herbarium specimen collected in Taiwan in 1993 (Lin et al. 134, BM 000846380) B old stem and prickles (field photograph, unvouchered, Taiwan) C detail view of leaf base and petiole (field photograph, unvouchered, Taiwan) D detail view of inflorescence and open flower (field photograph, unvouchered, Taiwan) E detail view an infructescence (field photograph, unvouchered, Taiwan). Photograph credits: A CC-BY, © copyright The Trustees of the Natural History Museum, London B-E M. - I. Weng.

Figure 50. Distribution of S. peikuoense.