Solanum memaoyanum 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 memaoyanum D. McClelland sp. nov. Figure 6

Diagnosis.

Like Solanum semisucculentum D.McClelland, but growing in the forest, a taller plant and with pubescent stems, leaves, and inflorescences.

Type.

New Caledonia. Nord: Contrefort ouest du Mé Maoya audessus de la Mine Emma, 1450 m, 23 Apr 1970 (fr), H.S. MacKee 21797 (holotype: NOU [acc. #017079]; isotypes: A, K [K000922612, K001155402], L [L0651810, L0651811], MO [acc. #2816917, barcode MO-2282963], NSW [acc. #594231], P [P00300081], U [U0182899]).

Shrub or small tree to 3 m tall with a trunk to 8 cm in diameter, the internodes to 2.8 cm long, unarmed. Stems densely pubescent with yellow-ferruginous, sessile porrect-stellate trichomes, the rays ca. 8, 0.05-0.1.5 mm long, the midpoint shorter than to more or less equal to the rays; new growth densely pubescent with sessile porrect-stellate trichomes on the veins and sparsely pubescent on the lamina, with minute glandular papillae to 0.04 mm long; bark of older stems brown, glabrescent. Sympodial units difoliate, the leaves not geminate. Leaves simple; blades 3.9-9.9 cm long, 2.0-3.3 cm wide, ca. 2.0-3.4 times as long as wide, lanceolate to elliptic, somewhat fleshy, discolorous, unarmed; adaxial surfaces sparsely pubescent, later glabrescent, the sessile porrect-stellate trichomes with (4-)8(-12) rays, 0.1-0.25 mm long, the midpoints shorter than to more or less equal to the rays; abaxial surfaces sparsely pubescent with sessile porrect-stellate trichomes, the rays 6-8, 0.1-0.2 mm long, the midpoint shorter than to more or less equal to the rays; principal veins 5-8 pairs, the midrib raised abaxially, distinct adaxially, the lateral veins weakly brochidodromous, raised abaxially, distinct adaxially; base rounded, equilateral or oblique; margins entire; apex acute to short-acuminate; petiole 1.0-2.2 cm long, 0.7-1.2 mm in diameter, channeled above, densely pubescent with sessile porrect-stellate trichomes like the stems. Inflorescence to 2.2 cm long, appearing lateral, extra-axillary, emerging from the upper 1/3 of the internode, unbranched, with 2-7 flowers, densely pubescent with sessile porrect-stellate trichomes; peduncle 0.8-1.7 cm long, 0.5-0.6 mm in diameter, unarmed; pedicels 0.7-1.3 cm long, 0.3-0.4 mm in diameter at the base, 0.6-0.9 mm in diameter below the calyx, bent to approximately 90° below the calyx, gradually increasing in diameter in the distal 1/4-1/2, sparsely pubescent, articulated at the base; pedicel scars congested to spaced 3.5 mm apart, rigid, in two rows. Buds ovate, the calyx densely stellate-pubescent, the lobe tips glabrous, the corolla densely stellate-pubescent abaxially where exposed in bud, strongly exserted from the calyx before anthesis. Flowers 5-merous, all perfect or apparently so (few flowering specimens have been collected). Calyx ca. 2.6 mm long, appearing nearly truncate with caudate lobe tips, the tube ca. 0.9 mm long, the lobes 1.4-1.7 mm long, the sinuses opaque when dry; splitting in the sinuses during fruit development and then the lobes deltate. Corolla ca. 2.4 cm in diameter, stellate, white, the interpetalar tissue well-developed, glabrous, the lobes ca. 0.8 cm long, 0.3 cm wide, triangular, spreading at anthesis, abaxially moderately pubescent, adaxially glabrous at the base with scattered pubescence towards the tips. Stamens equal; filament tube minute; free portion of the filaments ca. 1.7 mm long, glabrous; anthers ca. 5.1 mm long, 1.3 mm wide, tapering, straight, yellow, connivent, poricidal at the tips, the pores directed outward, extending around the tip edge. Ovary ca. 1.3 mm in diameter, globose, glabrous; style and stigma not seen. Fruit a globose juicy berry, 0.7-1.1 cm in diameter, red when mature, glabrous, the pericarp thin, glossy, translucent; fruiting calyx lobes 2.6-4.0 mm long, 1.7-3.8 mm wide, glabrous, reflexed; fruiting pedicels 1.3-2.6 cm long, 0.6-1.0 mm in diameter at the base, 1.7-2.5 mm in diameter below the calyx, gradually increasing in diameter in the distal 1/3-2/3, arching, glabrous to sparsely pubescent. Seeds 40-50 per fruit, 1.8-2.3 mm long, 2.2-2.6 mm wide, flattened-orbicular and notched at the point of attachment, yellow-tan when dry, the surface minutely and deeply pitted (cancellate), the testal cells somewhat sinuate in outline in the center, more straight-sided along the incrassate margins. Chromosome number not known.

Distribution and ecology

(Figure 7 ). Solanum memaoyanum is narrowly restricted to the mountain of Mé Maoya on the Grande Terre, New Caledonia, and grows in rainforest from 1,300 to 1,500 m elevation.

Phenology.

Known to flower in January and fruit in April and August.

Etymology.

This species is named after Mé Maoya, the mountain where the type was collected.

Preliminary conservation assessment

( IUCN 2019). EOO = 9.35 km2 [CR - Critically Endangered]; AOO = 12 km2 [EN -Endangered]. Solanum memaoyanum is known from only a few collections, all of which are in montane serpentine soil areas now highly disturbed by mining activities. Although the AOO suggests an assessment of EN, we suggest S. memaoyanum should be assigned a status of CR (B2a,b) due to its fragmented distribution and threats to its montane habitat.

Discussion.

Solanum memaoyanum is most similar to another new species described here, S. semisucculentum . Specimens here attributed to both were included in Heine’s (1976) concept of S. styraciflorum Schltr.; McClelland (2012) treats S. styraciflorum as a synonym of S. artense Montroux (see description of S. artense on Solanaceae Source, www.solanaceaesource.org). From herbarium material S. memayoanum appears to have fleshy leaves like S. semisucculentum , but it differs in having a taller habit (MacKee 21797 records the stems as being 8 cm in diameter), pubescent stems, leaves, and inflorescences, and seeds with a more deeply pitted (the lateral cell walls longer) surface. In addition, the habitat of the two species differs; Solanum memaoyanum grows in closed rainforest from 1,300 to 1,500 m elevation as opposed to S. semisucculentum , which grows in open shrubby habitat (maquis) and is typically not found above 700 m elevation. Solanum artense (incl. plants matching the protologue of S. styraciflorum ) is found below 250 m on calcareous soils, rather than the serpentine soils in mountainous regions on which both S. memaoyanum and S. semisucculentum are found.

Additional specimens examined.

New Caledonia. Nord: contrefort oest du Mé Maoya audessus de la Mine Emma, 1350-1500 m, 13 Jan 1970 (fl), H.S. MacKee 21422 (NOU, P); Mt. Mé Maoya, above Mine Emma, ca 27 air-km northwest of Bourail, ca. 1300 m, 8 Aug 1980 (fr), G. McPherson 2948 (MO, NOU, NSW, PTBG).

Figures

Figure 6. Solanum memoayanum D. McClelland (isotype MacKee 21797, P [P 00300081]). Reproduced with permission.

Figure 7. Distribution of Solanum memoayoanum and S. semisucculentum.