Lycianthes, the third most species-rich genus in the Solanaceae, is distributed in both the New and Old Worlds and is especially diverse in Mexico. Here we provide an identification key, taxonomic descriptions, distribution maps, and illustrations of specimens, trichomes, flowers, and fruits for the 53 known Lycianthes taxa of Mexico and Guatemala. The new combination Lycianthes scandens (Mill.) M.Nee is made and replaces the name Lycianthes lenta (Cav.) Bitter, which is placed in synonymy. Within L. scandens, two varieties are recognized (Lycianthes scandens var. scandens and Lycianthes scandens var. flavicans (Bitter) J.Poore & E.Dean, comb. nov.). In addition, one new species (Lycianthes rafatorresii E.Dean, sp. nov.) is described from eastern Mexico, and 10 names (either recognized taxa or synonyms of recognized taxa) are lectotypified, including the names Solanum heteroclitum Sendtn., S. rantonnetii Carrière, and S. synantherum Sendtn. The species L. multiflora Bitter and L. synanthera (Sendtn.) Bitter are excluded from the treatment, as research indicates that they do not occur in Mexico and Guatemala, however full synonymy for both names is given.

Two cloud forest species of Lycianthes are newly described: L. breedlovei from the state of Chiapas, Mexico and L. fredyclaudiae from the state of Baja Verapaz, Guatemala. Both species have orange-brown, multangulate-stellate trichomes in which the rays of the trichome are rebranched, white to pale lilac flowers (with darker violet-purple lobes in L. breedlovei), and unequal stamens. Morphologically, they resemble L. hortulana of Honduras, but both new species have previously been misidentified as L. cuchumatanensis. This article provides species descriptions, maps of geographic distributions, drawings of trichomes, and images of the flowers and specimens of the two new species, as well as a comparison chart of morphological characters used to separate L. breedlovei and L. fredyclaudiae from similar species.

Rhizosphere microbiomes have received growing attention in recent years for their role in plant health, stress tolerance, soil nutrition, and invasion. Still, relatively little is known about how these microbial communities are altered under plant competition, and even less about whether these shifts are tied to competitive outcomes between native and invasive plants. We investigated the structure and diversity of rhizosphere bacterial and fungal microbiomes of native annual forbs and invasive annual grasses grown in a shade-house both individually and in competition using high-throughput amplicon sequencing of the bacterial 16S rRNA gene and the fungal ITS region. We assessed how differentially abundant microbial families correlate to plant biomass under competition. We find that bacterial diversity and structure differ between native forbs and invasive grasses, but fungal diversity and structure do not. Furthermore, bacterial community structures under competition are distinct from individual bacterial community structures. We also identified five bacterial families that varied in normalized abundance between treatments and that were correlated with plant biomass under competition. We speculate that invasive grass dominance over these natives may be partially due to effects on the rhizosphere community, with changes in specific bacterial families potentially benefiting invaders at the expense of natives.

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