Solanum mariae Saerkinen & S.Knapp, 2015

Saerkinen, Tiina, Gonzales, Paul & Knapp, Sandra, 2015, Four new non-spiny Solanum (Solanaceae) species from South America, PhytoKeys 44, pp. 39-64 : 52-56

Solanum mariae Saerkinen & S.Knapp sp. nov. Figs 7 -8

Diagnosis.

Like Solanum caripense Dunal, but differing in having distinctive calyx lobes 2.0-2.5 mm long and 1.8-2.0 mm wide, broadly ovate in shape and spreading in buds and flowers, and in having fruits fully enclosed in an accrescent calyx.

Type.

Peru. Cajamarca: Prov. San Marcos, Dist. Chancay, 14 km from San Marcos, just S of Chancay, on road from San Marcos to Cajabamba, 7°24'20"S, 78°07'05"W, 2606 m, 9 May 2013 (fl,fr), S. Knapp, T. Särkinen, H.M. Baden, P. Gonzáles & E. Perales 10571 (holotype: USM; isotypes: BM [BM001034677], CPUN, E [E00700640], HUT, MOL).

Description.

Trailing herbs, stems to 20-30 cm tall arising from woody trailing stems that root at nodes, the individual stems up to 5 m long. Stems terete, 1.5-2.5 mm in diameter, moderately to densely pubescent with spreading bayonet hairs (uniseriate, 2-celled hairs with an elongate, thicker-walled basal cell capped by a short acuminate cell) and with simple, 2-4-celled uniseriate glandular-tipped finger hairs c. 0.5 mm long; new growth densely pubescent with trichomes like those of the stems; bark of older stems grey-brown, smooth. Sympodial units plurifoliate, not geminate. Leaves simple, 1.4-3.5 cm long, 1.0-1.6 cm wide, ovate-lanceolate; adaxial surface moderately pubescent with bayonet hairs like those on the stems, and with simple, 2-celled uniseriate glandular-tipped hairs c. 0.3 mm long; abaxial surface more densely pubescent with trichomes like those of the upper surface; primary veins 4-6 pairs; base acute to obtuse; margins entire; apex rounded; petiole 0.5-1.2 cm long, moderately to densely pubescent with trichomes like those of the stems. Pseudostipules in pairs, simple, 5 mm long, 3 mm wide, ovate-lanceolate, tip acute, resembling leaves in shape and appearance. Inflorescences 1.5-2.7 cm long, lateral and internodal, simple, with 3-5 flowers in the distal half, moderately to densely pubescent with spreading trichomes like those of the stems; peduncle 0.4-1.6 cm long; pedicels 0.6-0.7 cm long, ca. 0.3 mm in diameter at the base and apex, straight, curved at the tip, articulated at the base; pedicel scars spaced ca. 1 mm apart. Buds globose, the corolla only exerted from the calyx tube just before anthesis. Flowers 5-merous, all perfect; calyx tube ca. 1.5-2.0 mm long, the lobes 2.0-2.5 mm long, 1.8-2.0 mm wide, broadly deltate, with acute apices, spreading in bud and flower, moderately to densely pubescent; corolla 1.2-1.5 cm in diameter, shallowly stellate, white, lobed halfway to slightly less than halfway to the base, the lobes ca. 4-5 mm long and 4-5 mm wide, spreading at anthesis, moderately to densely pubescent abaxially with trichomes like those of the stem, glabrous adaxially; filament tube minute, glabrous; free portion of the filaments ca. 1.0-1.2 mm long, glabrous; anthers 2.7-3.0 mm long, ca. 2.5 mm wide, ellipsoid, yellow, poricidal at the tips, the pores lengthening to slits with age; ovary conical, glabrous; style 5-6 mm long, exerted 1.5-2.0 mm beyond the anther cone, glabrous; stigma clavate, minutely papillate, yellow-green in live plants. Fruit (immature) an ellipsoid berry, 8-9 mm long and 6.8 mm wide when developing, with the mesocarp ca. 0.2 mm wide, green, fully enclosed in the accrescent calyx, glabrous, mature fruits not seen; fruiting peduncle 1.3-2.2 cm long; fruiting pedicels 1.8-2.3 cm long, 0.3-0.5 mm in diameter at the base and 0.5-1.8 mm at apex, reflexed 180° in fruit; fruiting calyx 8-9 mm long, 3.5-4.0 mm wide and still developing, appressed to and enclosing the entire berry, the calyx lobes spreading at the mouth of enclosing tube. Seeds 30-40 per berry, 1.2-1.5 mm long, 1.0-1.2 mm wide, flattened-reniform, yellowish, the surfaces minutely pitted, the hilum positioned laterally in the middle, the testal cells pentagonal in outline.

Distribution.

Endemic to Peru; growing along north facing banks in loamy soils in along roadsides, not in full sun, associated with Lycianthes lycioides (L.) Hassl. ( Solanaceae ) and various grasses; only known from a single population at 2,600 m elevation from San Marcos Province in the Department of Cajamarca.

Ecology.

Flowering and fruiting April-May.

Etymology.

The species is named after biologist Maria Baden who collected the first specimen in Cajamarca in 2013 with the authors. Many of the collections made in our field trips in Peru since 2006 would not have been made without her, and to honour the number of hours spend on plant spotting from fast moving vehicles and driving carefully through recent landslides, we name this shy and stunningly beautiful Solanum species in her honour.

Conservation status.

The IUCN (2010) threat status of Solanum mariae is here considered of critically endangered (CR) based on only a few known occurrence points near Chancay in the San Marcos province, Department of Cajamarca, Peru, with AOO of 4 km2. The species appears to have specialist habitat requirements, preferring north-facing shady cliff sides. The known populations are both small, and vulnerable to grazing pressures.

Specimens examined.

PERU. Cajamarca: Prov. San Marcos, c. 14 km from San Marcos towards Cajabamba, 7°24'20"S, 78°07'05"W, 2604m, 25 Apr 2013, T. Särkinen & H. M. Baden 46 51 (USM).

Discussion.

Solanum mariae can be easily distinguished from other section Basarthrum species based on the large, broadly ovate and spreading calyx lobes in flower that become to enclose the entire fruit that are not known from any other species of the section. Further distinguishing characters include the combination of trailing stems that root along nodes, the relatively dense pubescence of long, 2-4-cellular glandular-tipped finger hairs throughout the plant, and the strictly simple leaves. In Peru, the species is most similar to Solanum caripense Dunal and closely allied species, but differs in having simple leaves combined with the glandular-tipped finger hairs throughout mature plants and larger calyx lobes that are spreading in flower and are accrescent and enclose the fruit. Anderson and Bernardello (1991) provide a key to the members of series Caripensia Correll to which the new species clearly belongs based on morphology.

Based on the style extension well beyond anthers in the newly described species, Solanum mariae is likely to be self-incompatible. Style extension has been found to indicate self-incompatibility in sect. Basarthrum in previous studies (e.g., Anderson 1979).

The trailing growth form of the new species, where roots are formed at leaf nodes, has been observed in other members of sect. Basarthrum , as well as in the closely related sect. Anarrhichomenum Bitter ( Tepe et al. 2012), whose members are distinguished from those of sect. Basarthrum by the presence of pseudostipules, winged seeds, and fruits maturing red or orange.

The central Andes region is a centre of diversity for Solanum sect. Basarthrum (Stern et al. 2008; Anderson 1979; Anderson et al. 2006; Särkinen et al. in prep.), and the new species described here adds to the growing list. Solanum mariae remains poorly understood based on our two collections from the single known population from the San Marcos Province of the Department of Cajamarca. No further specimens have been seen in local herbaria in Trujillo and Cajamarca. The locality lies within the watershed of the Río Marañón, and further field work in the same watershed in the Province of San Marcos is a priority in order to increase knowledge of this rare species, including the morphology of the fully mature fruits.