The genus Physalis is instantly recognizable to anyone who has peeled the papery husk from a ground cherry or a golden berry. Its signature feature is an inflated fruiting calyx, a lantern-like envelope that completely encloses the fleshy berry within. Roughly 90 species belong to the genus, all native to the American continent, and Mexico stands as its primary center of diversity and endemism, harboring more than 60 native species, of which about 59 percent are found nowhere else. Some members, such as the husk tomato Physalis philadelphica and the golden berry Physalis peruviana, carry enormous economic and cultural weight across the globe. Yet despite this familiar fruiting architecture, the internal classification of Physalis has long frustrated taxonomists, because high phenotypic plasticity and overlapping diagnostic characters blur the boundaries between species.

It was during recent botanical explorations in Querétaro that researchers encountered populations of a perennial Physalis growing in secondary vegetation and disturbed areas of xerophytic scrub, often sheltered beneath the canopy of Neltuma laevigata. At first glance, the plants suggested an affinity with Physalis longifolia or Physalis caudella. But closer inspection revealed a remarkable combination of vegetative traits: leaves that are completely sessile, meaning they attach directly to the stem without a petiole, and stems clothed in exceptionally long, multicellular, eglandular trichomes, hair-like structures that reach up to 3.5 millimeters in length. Detailed morphological comparisons against herbarium specimens and specialized literature, backed by molecular evidence, confirmed that these populations represent a species new to science.

The formal diagnosis separates Physalis mahindae from its lookalikes on several fronts. Where Physalis longifolia stands erect with glabrous or short-haired stems and petiolate leaves up to 12 centimeters long, the new species adopts a slightly prostrate habit, bears densely pubescent stems armed with trichomes up to 3.5 millimeters, and carries sessile, lanceolate to linear-lanceolate leaves that can stretch to 18 centimeters. The reproductive structures diverge just as sharply: the corollas feature broad interpetalar tissue, the tissue between petal segments, which is absent in its relatives, and the flowering calyx lobes spread conspicuously behind the corolla as five elongated, narrowly triangular tips. The berries are larger, roughly 15 millimeters in diameter compared with 10 millimeters in P. longifolia, while the seeds are smaller, measuring about 1.5 millimeters against 2 millimeters.

The full description paints a portrait of a stout, rhizomatous herb standing 60 to 70 centimeters tall, with longitudinally angled stems and geminate leaves, paired leaves of unequal size, the smaller one about a quarter the size of its partner. The flowers are solitary in the leaf axils, with campanulate-rotate corollas 9 to 12 millimeters across, yellow and marked with five brown-purplish maculae at the base, a classic Physalis signature. Anthers are yellow with purple filaments, the stigma capitate to slightly clavate, and the fruiting calyx is 10-costate, meaning it bears ten ribs, measuring 25 to 35 millimeters long and nearly 18.5 millimeters wide, its acuminate lobes almost filiform and entangling among themselves. The globose berry matures from green to yellow or orange, entirely enclosed by the accrescent calyx, and holds numerous kidney-shaped yellow seeds. Flowering and fruiting run from September to January.

To verify the taxonomic novelty, the team conducted an exhaustive comparative review, examining physical herbarium specimens from three institutions, MEXU, IBUG, and QMEX, supplemented by high-definition digital images from MO and collections available through JSTOR Global Plants. They built a comparative table pitting the new species against five morphologically similar relatives: Physalis acutifolia, P. caudella, P. cinerascens, P. gracilis, and P. longifolia. The holotype, collected in October 2021 at Parque El Batán in the municipality of Corregidora at 1,844 meters elevation, was deposited at the Luz María Villarreal de Puga herbarium at the Universidad de Guadalajara, with isotype duplicates sent to the Jerzy Rzedowski herbarium at the Universidad Autónoma de Querétaro.

Molecular phylogenetic analysis added an unexpected twist. The researchers extracted DNA from silica gel-dried tissue and herbarium specimens, amplified the second intron of the nuclear LEAFY gene, a marker widely used in Solanaceae systematics, and sequenced three individuals of the new species alongside 51 sequences gathered from GenBank. The phylogeny, inferred under Maximum Likelihood in IQ-TREE using the GTR + I + G evolutionary model with 1,000 ultrafast bootstraps, placed Physalis mahindae as the sister species to P. gracilis with strong support, a bootstrap value of 95. That pair, in turn, shares its most recent common ancestor with a clade containing P. peruviana, and the whole group is sister to P. longifolia. The surprise is biogeographic: neither P. peruviana, native to South America, nor P. longifolia, distributed northward in the United States and Canada, occurs naturally in Mexico, making the evolutionary neighborhood of this Querétaro endemic rather unexpected.

The authors caution that the reconstruction rests on a single nuclear marker, and single-gene trees can sometimes fail to reflect the true species tree. They frame the grouping as a preliminary hypothesis rather than a definitive evolutionary placement. Still, the LEAFY sequences demonstrate that the new species carries a divergent molecular signature, and future phylogenomic studies with expanded population-level sampling are expected to resolve its history more fully. For now, the molecular data complements the morphological evidence used to delimit the taxon.

Conservation prospects are grim. Only two populations of Physalis mahindae are currently known, and although the species may occur in other patches of xerophytic scrub in the surrounding region, more exploration is needed. Using the GeoCAT geospatial assessment tool, the team calculated an Area of Occupancy of just 4 square kilometers, based on a standard 2-by-2-kilometer grid, and an Extent of Occurrence of 82 square kilometers, drawn as a minimum convex polygon around all known occurrence points. Under criterion B of the IUCN Red List guidelines, which concerns geographic range, both values fall below the thresholds of 10 and 100 square kilometers respectively, placing the species squarely in the Critically Endangered category, coded CR B1+B2ac(ii, iii).

The species is named in honor of Mahinda Martínez y Díaz de Salas, an eminent Mexican botanist recognized for her outstanding contributions to the taxonomy of Physalis. Beyond the honorific, the discovery carries a broader message: even in a genus as well studied as this one, dedicated fieldwork in Mexico continues to yield previously undescribed species, reinforcing the country’s status as the main center of diversification for the group. The description of Physalis mahindae increases the known species diversity of the genus in Mexico and underscores the urgent need for floristic and systematic research in the region, before the two fragile populations that anchor this new branch of the nightshade family tree slip away unnoticed.

Subject of Research: Taxonomy and molecular phylogenetics of the new endemic plant species Physalis mahindae (Solanaceae) from Querétaro, Mexico

Article Title: Physalis mahindae (Solanaceae), a new endemic species from Querétaro, México

Article References: Herrera-García, J. A., Vargas-Ponce, O., Sandoval-Padilla, I., & Zamora-Tavares, P. (2026). Physalis mahindae (Solanaceae), a new endemic species from Querétaro, México. Discover Plants, 3(1), Article 467. https://doi.org/10.1007/s44372-026-00930-4

Image Credits: AI Generated

DOI: 10.1007/s44372-026-00930-4

Keywords: Physalis mahindae, Solanaceae, new species, Querétaro, Mexico, endemism, LEAFY gene, phylogenetics, IUCN Red List, Critically Endangered, xerophytic scrub, plant taxonomy