Solanum vanuatuense D.McClelland, 2020

McClelland, Donald H. R., Nee, Michael & Knapp, Sandra, 2020, New names and status for Pacific spiny species of Solanum (Solanaceae, subgenus Leptostemonum Bitter; the Leptostemonum Clade), PhytoKeys 145, pp. 1-36 : 1

Solanum vanuatuense D.McClelland sp. nov. Figure 12

Diagnosis.

Like Solanum milnei Seem. and S. austrocaledonicum Seem., but differing in usually geminate, lobed leaves, smaller corolla and anthers, and strongly curved style.

Type.

Vanuatu. Efate: lower slopes of Pic Fatamalapa, 17°33'S, 168°22'E, 200 m, 15 Jul 1971 (fl, fr), P.S. Green 1103 (holotype: P [P00315286]; isotypes: A, K [K001155324], L [L0531790], NSW [acc. # 594210]).

Description.

Shrub to 2 m, the internodes to 5.1 cm long, unarmed. Stems densely pubescent with yellow to yellow-ferruginous, sessile and stalked porrect-stellate trichomes, the stalks of various lengths to 0.1 mm long, the rays 6-8, 0.2-0.3 mm long, the midpoint more or less equal to the rays; new growth densely pubescent with sessile or very short-stalked porrect-stellate trichomes and minute glandular hairs to 0.05 mm long; bark of older stems reddish brown. Sympodial units difoliate, the leaves geminate or not, if geminate the minor leaves 1/2-2/3 as large as the major leaves and similar in shape. Leaves simple or shallowly lobed; blades (major leaves) 4.9-11.2 cm long, 1.9-3.9 cm wide, 2.6-3 times as long as wide, lanceolate to ovate, chartaceous, discolorous; adaxial surfaces sparsely to moderately pubescent with short-stalked porrect-stellate trichomes, the stalks to 0.06 mm long, the rays 4-8, 0.15-0.25 mm long, the midpoint equal to or longer than the rays; abaxial surfaces sparsely to moderately pubescent with sessile or short-stalked porrect-stellate trichomes, the stalks to 0.3 mm long, the rays 4-8, 0.2-0.35 mm long, the midpoint equal to or longer than the rays; principal veins 4-6 pairs, the midrib raised abaxially and adaxially, the lateral veins weakly brochidodromous or semicraspedodromous, or craspedodromous in lobed leaves, raised abaxially, distinct adaxially; base rounded, typically oblique though occasionally equilateral; margins entire, sinuate, or shallowly lobed, the sinuses less than 1/4 of the distance to the midrib; apex acute or acuminate; petiole 6.2-16.8 mm long, 0.6-1.3 mm in diameter, densely stellate-pubescent with trichomes like those of the leaves, channeled above. Inflorescence to 8.9 cm, appearing lateral, extra-axillary, emerging from the middle or upper 1/3 of the internode, branched 1-3 times, with 60+ flowers, densely pubescent with sessile porrect-stellate trichomes; peduncle 0.3-1.9 cm long, 0.6-1.8 mm in diameter, unarmed; pedicels 0.7-1.0 cm long, ca. 0.3 mm in diameter at the base, 0.6-0.9 mm in diameter below the calyx, straight, not bent below the calyx or bent to approximately 90°, swelling more or less evenly from the base to the base of the calyx, densely pubescent, articulated at the base; pedicel scars congested to spaced 5.7 mm apart, overlapping to spaced 0.4 mm apart in the distal portion of the inflorescence, rigid, in two rows. Buds ovate, the calyx densely stellate-pubescent, the corolla densely stellate-pubescent where exposed abaxially, strongly exserted from the calyx before anthesis. Flowers 5-merous, all perfect or apparently so. Calyx 2.2-2.8 mm long, appearing nearly truncate with caudate lobe tips, the tube 0.5-0.9 mm long, the sinuses opaque when dry, the lobes 1.2-2.0 mm long, caudate, moderately to densely pubescent abaxially, glabrous adaxially, splitting in the sinuses during fruit development and then the lobes deltate. Corolla 1.1-1.3 cm in diameter, stellate, white, the interpetalar tissue well-developed, glabrous, the lobes 3.9-4.5 mm long, 2.2-3.5 mm wide, deltate, spreading at anthesis, adaxially glabrous or with a few scattered sessile porrect-stellate trichomes, densely pubescent abaxially. Stamens equal; filament tube minute; free portion of the filaments ca. 0.8 mm long, glabrous; anthers 2.5-2.9 mm long, 0.9-1.1 mm wide, markedly tapering, straight, yellow, spreading, poricidal at the tips, the pores directed dorsally, extending around the edge of the apex. Ovary ca. 0.6 mm, globose, moderately pubescent at the apex with simple glandular trichomes; style 5.6-6.4 mm long, ca. 0.2 mm in diameter, exserted from the anther cone, deflexed and emerging from between two adjacent stamens, filiform, curved or hooked at the apex, glabrous or sparsely pubescent on the basal 1/3 with simple glandular hairs; stigma 0.3-0.6 mm in diameter, capitate, minutely papillate. Fruit a globose juicy berry, 0.6-0.8 cm in diameter, apparently orange or red when mature, glabrous, the pericarp thin, glossy; fruiting calyx lobes 1.7-2.4 mm long, 1.3-1.5 mm wide, sparsely to moderately stellate-pubescent, appressed to the berry surface; fruiting pedicels 11.1-16.2 mm long, ca. 0.4 mm in diameter at the base, 1.3-1.7 mm in diameter below the calyx, straight, not bent below the calyx, gradually increasing in diameter in the distal 1/2-2/3, sparsely to moderately stellate-pubescent. Seeds 10-20 per fruit, 1.5-1.8 mm long, 1.5-2.0 mm wide, flattened-orbicular and notched at the point of attachment to flattened-reniform, red-brown when dry, the surface evenly reticulate, the testal cells with straight walls, the seed margins incrassate. Chromosome number not known.

Distribution and ecology

(Figure 13 ). Solanum vanuatuense occurs on several islands in the Vanuatu archipelago; it is reported as growing in grass or low herbage, seaside, and on outcroppings of limestone from sea level to 200 m elevation.

Phenology.

Known to flower and fruit February, July, and October-November.

Etymology.

This species is named for island state of Vanuatu.

Preliminary conservation assessment

( IUCN 2019). EOO = 45,572 km2 [LC - Least Concern]; AOO = 40 km2 [EN -Endangered]. Although Solanum vanuatuense occurs on six islands in the archipelago, its coastal habitat is almost certainly threatened by human activities. We assign a preliminary status of EN (B2a,b) due to the fragmented nature of populations on different islands and threats to coastal habitats.

Discussion.

Specimens of Solanum vanuatuense were included in the sympatric S. milnei Seem. ( Seemann 1866) in the original description of the latter; it differs from that species in its smaller flowers and geminate leaves that are often lobed. Solanum vanuatuense is also similar to S. austrocaledonicum Bitter of New Caledonia and Vanuatu from which it can be distinguished by its geminate leaves that are often deeply lobed, its deltate calyx lobes (rather than long apiculate on a truncate rim) and small flowers. Solanum vanuatuense and S. austrocaledonicum co-occur on the island of Anatom (Schmid 5149 is S. vanuatuense and Schmid 5149b is S. austrocaledonicum - both specimens mounted on P00315283).

Additional specimens examined.

Vanuatu. Anatom: entre Umetch et Aneghowhat, 12 Feb 1986 (fl, fr), Bourdy 442 (K, P); sin. loc., (fl) McGillivray s.n. (BM); secteur de Umec [Umetch], Nov 1974 (fl, fr), Schmid 5149 (P). Efate: Port Vila, Oct 1883 (fl, fr), Levat s.n. (P). Erromango: entre Cook Bay et Ipota, ca. 5 m, 25 Jul 1983 (fl, fr), Cabalion 2247 (K, P); tableland, 600 ft, 26 Jul 1930 (fl), Cheeseman 38 (K). Espiritu Santo: Hog Harbour, 24 Nov 1933 (fl, fr), Baker 58 (BM). Futuna: “tableland”, Dec 1858 (fl, fr), Milne 391 (K). Pentecost Island: north end, ca. 1972, Walsh 208 (NSW).

Figures

Figure 12. Solanum vanuatuense D. McClelland (holotype Green 1103, P [P 00315286]). Reproduced with permission.

Figure 13. Distribution of Solanum vanuatuense.