Solanum pachyneuroides
Not known
Endemic to Cuba, known only from the eastern part of the island from pine woods at ca. 700 m elevation.
Solanum pachyneuroides is morphologically a member of the Leptostemonum clade (sensu Weese & Bohs, 2007), with prickles, stellate pubescence and presumably tapering anthers. Its relationships have not yet been assessed using molecular sequence data. Whalen (1984) did not include it in his conspectus of the prickly solanums.
Amshoff, G.J.H. 1954. Notes on some South American Solanaceae.
Acta Botanica Neerlandica 3: 417-420.
Whalen, M.D. 1984. Conspectus of species groups in Solanum subgenus Leptostemonum.
Gentes Herbarum 12 (4): 179-282.
Weese, T.L. & L. Bohs 2007. A Three-Gene Phylogeny of the Genus Solanum (Solanaceae)
Syst. Bot. 32(2): 445-463.
Solanum pachyneuroides is superficially similar to S. pachyneurum, with coriaceous leaves and prickly stems. The trichomes of the two species are markedly different, those of S. pachyneurum are sessile, somewhat lepidote and many-rayed, while those of S. pachyneuroides are stalked and only ever have 2-4 rays. Solanum pachyneuroides has fewer pairs of veins, and appears to have larger fruit. The winged pedicel seen in fruiting specimens is also distinctive, but flowering specimens of female plants have not been seen. The thick coriaceous leaves of S. pachyneuroides are also like those of S. gundlachii, another Cuban endemic, but that species has elongate, rather than short, inflorescences. The extremely rare and sympatric S. moense also resembles this suite of taxa, but it has denser, reddish rusty, long-stalked pubescence.
Solanum pachyneuroides appears to be dioecious, with different individual plants bearing markedly different types of inflorescences (as is seen in other dioecious species of Solanum such as S. polygamum, S. crotonoides and a number of Australian species). The isotype specimen of S. pachyneuroides at US is apparently a male plant, with branched inflorescences, while Wright 382 p.p. at K (an isotype of S. pachyneurum var. glabrescens) is a female, with an inflorescence (in fruit) consisting of a single flower arising from the stem. Amshoff (1954) also observed that the calyx in female flowers was pricklier than in male flowers, supporting his separation of S. pachyneuroides from S. pachyneurum where he observed no difference in what were previously said to be long- and short-styled flowers of the latter species.
In eastern Cuba, Solanum pachyneuroides is sympatric and easily confused with S. gundlachii, but the distinctive few-rayed large stellate trichomes of S. pachyneuroides are diagnostic. Inflorescences of S. gundlachii have both long- and short-styled flowers, but fruiting specimens are difficult to distinguish if care is not taken to observe trichomes.
Because the type of S. pachyneurum var. glabrescens, Wright 382, is a mixed collection, only some herbaria have type material of var. glabrescens, the majority of sheets are of S. pachyneurum s.s. The duplicate at K (K000196231) is the only one I have seen that consists of S. pachyneuroides, with one stem on the sheet (R hand stem) S. pachyneuroides and the L hand stem S. pachyneurum.
Solanum pachyneuroides is known only from a few collections, and its recollection should be a priority.