In the Serra do Mar mountain range in the Brazilian states of Paraná, Santa Catarina and São Paulo. Solanum apiahyense is a rare and inconspicuous shrub of the understory and edges of well preserved and secondary fragments of the montane Brazilian Atlantic rainforest (Floresta Ombrófila Densa of IBGE 2012; Mata Atlântica), from 600 to 900 m. Although most collections are from well preserved sites, S. apiahyense is not exclusively associated with shaded environments. The species is also found along unpaved roadsides close to the type locality.
Solanum apiahyense is a species of uncertain relationships, and is possibley sister to the Geminata clade (see Commentary).
Solanum apiahyense, described more than a century ago (Witasek 1910), has not been assigned to any infraspecific group of Solanum so far. Recent phylogenetic analysis using molecular data (Giacomin 2015) has shown it to be closely related to S. trachytrichium, which was previously assigned to the Geminata clade (Knapp 2002, 2008) and to its own subsection when originaly described (subsect. Silicosolanum Bitter; Bitter 1919). Bitter (1919) based this on the unusual trichome morphology of hooked cells arising from a flattened multicellular base that give the leaves a feeling of sandpaper in herbarium specimens. Although molecular data support a close relationship between S. apiahyense and S. trachytrichium, the affinities of this clade are not clear-cut. Data from combined markers place it as sister to all other Geminata clade species, but with low support. In analyses of individual markers, it emerges as sister to either the Brevantherum or Geminata clades depending upon the marker used (Giacomin 2015).
Morphologically both taxa are easy to distinguish from most other Geminata species, and have the following assemblage of characters: both are small shrubs with leaves mostly not geminate, they have leaf trichomes with an expanded multicellular base and relatively large flowers (>1.5 cm in diameter). Among them, Solanum apiahyense and S. trachytrichium are easy to distinguish: S. trachytrichium has a unique scabrous indumentum on the leaf surfaces and stems, composed of short unicellular hooked trichomes on a mound-like multicellular base, while in S. apiahyense the surface is not rough to the touch, and although some trichomes with multicellular bases can be seen on leaves, these are translucent, very long (about 2 mm) and mostly 5-7-celled. These long trichomes of S. apiahyense are easily seen on the new growth, while S. trachytrichium trichomes are not visible to the naked eye. In addition, the flowers of S. apiahyense are slightly smaller, 1.5-1.7 cm in diameter versus 1.6-2.2 cm in S. trachytrichium.
In the past, the epithet S. apiahyense has been applied to more than one species of the S. inornatum group (part of the Brevantherum clade; Giacomin and Stehmann 2014) by various Solanum taxonomists, although they are now known to not be closely related. Although members of the S. inornatum group (e.g., S. inornatum Witasek, S. bradei Giacomin & Stehmann and relatives) and S. apiahyense are similar in habit and in having pubescence of long, translucent trichomes, they can be readily distinguished by close examination of the trichomes; those of S. apiahyense are multicellular with 5-7(8) cells while those of members of the S. inornatum group are mostly 3-celled (probably representing modified stellate hairs, Giacomin and Stehmann 2014). Fruiting specimens of S. apiahyense have peduncles longer than 1 cm and the pedicels are strongly apically expanded and constricted just beneath the calyx lobes (see Figure 1C in Knapp et al. 2015), while in the species of the S. inornatum group species, the peduncles do not exceed 1 cm and the pedicels are never apically expanded with a distal constriction. Examination of trichomes with a 10× hand lens will allow easy identification of both flowering and fruiting material.
The type material found at WU (Puiggari 3711) consists of a single sheet, and does not match the photograph of a dried specimen in the original publication (Witasek 1910: tab. 30, fig. 2). It should therefore be treated as an isotype (Mentz & Oliveira 2004). As no further material could be found in other possible herbaria where J.I. Puiggari deposited his collections, the specimen at WU is here designated as a lectotype.
Bitter G (1919) Solana nova vel minus cognita XVII. Repertorium Specierum Novarum Regni Vegetabilis 16: 10-15.
Giacomin LL (2015) Solanum L. clado Brevantherum (Solanaceae): Sistemática e Diversidade. Ph.D. Dissertation, Universidade Federal de Minas Gerais, Brazil.
Giacomin LL, Stehmann JR (2014) Three new species of Solanum (Brevantherum Clade) endemic to the Brazilian Atlantic Forest. PhytoKeys 38: 69-87.
Instituto Brasileiro de Geografia e Estatística (IBGE) (2012) Manual técnico da vegetação brasileira. 2 ed. Instituto Brasileiro de Geografia e Estatística, Rio de Janeiro, 1-271.
IUCN Standards and Petitions Subcommittee (2014) Guidelines for using the IUCN Red List Categories and Criteria. Version 11. Prepared by the Standards and Petitions Subcommittee. Downloaded from http://www.iucnredlist.org/documents/RedListGuidelines.pdf on 12 Nov 2014.
Knapp S (2002) Solanum section Geminata (G. Don) Walpers (Solanaceae). Flora Neotropica 84: 1-405.
Knapp S (2008) A revision of the Solanum havanense species group (section Geminata (G. Don) Walp. pro parte) and new taxonomic additions to the Geminata clade (Solanum: Solanaceae). Annals of the Missouri Botanical Garden 95(3): 405-458.
Knapp S, Giacomin LL, Stehmann JR (2015) New species, additions and a key to the Brazilian species of the Geminata clade of Solanum L. (Solanaceae). PhytoKeys 47: 1-48.
Witasek J (1910) Solanaceae. Denkschriften der Kaiserlichen Akademie der Wissenschaften, Wien. Mathematisch-Naturwissenschaftliche Klasse 79: 40-375, t. 27-31.
Based on IUCN (2014) guidelines - Endangered (EN) B1; B2 ab (ii, iii, iv). EOO 3,208 km2 (EN); AOO 16 km2 (EN). Although the species occurs in a wide latitudinal range, it is locally rare, and is known from only six localities. None of the known populations are from within protected areas.