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Genus Psiguria in Family Cucurbitaceae

In botanical taxonomy, a genus (plural genera) is a rank used to group closely related species within a family. In the hierarchy, genus sits below family and above species.

Genera are defined by shared morphological, anatomical, and genetic characteristics (for example, features of flowers, fruits, seeds, or leaves) that indicate a close evolutionary relationship among the species they contain.

Each genus can include one or more species. Examples include Rosa (roses) and Solanum (nightshades, including tomato and eggplant).

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Genus Description

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Psiguria (author Neck.) is placed in Cucurbitaceae and broadly corresponds to the accepted genus Gurania as presently circumscribed in major checklists (POWO, 2024; WFO, 2024). Approximately 18 species are recognized, occurring from southern Mexico through Central America and across northern South America to Amazonian Brazil and the Guianas, with a few species extending to Bolivia and the Atlantic Forest of Brazil. The type for the generic name derives from an early Cucurbita concept and has not been stably linked to one of the modern segregates. Neotropical climbing vines growing in lowland moist to premontane forests, including secondary growth and forest edges, best characterize the complex.

The plants are dioecious, woody vines with axillary tendrils bearing discoid adhesive tips. Leaves are simple to shallowly lobed, ovate to broadly lanceolate, with a cuneate to truncate base and a fimbriate–serrulate margin; the indumentum is usually of short, often stellate hairs. Flowers are unisexual; staminate racemes are dense and many-flowered, pistillate flowers are solitary or few in axillary fascicles. The calyx has five narrow lobes, corollas are five-parted to the base with reflexed, yellowish to orange or red petals. The inferior ovary is bicarpellary with axile placentation and numerous ovules; the fruit is a fleshy, multi-seeded berry, typically orange to reddish when mature, with seeds embedded in juicy pulp. These traits together distinguish the group from most other Neotropical Cucurbitaceae with axillary tendrils and discoid adhesive tips, and from the closely allied segregates Anguria and Gurania sensu strictissimo by flower and fruit features as broadly interpreted (Keraudren, 1966).

Diversity concentrates in the Guianas and Amazon basin, with several regional endemics, and a secondary center in northern Central America. Typical habitats span lowland rainforests to lower montane forests, often in forest gaps and secondary growth; elevation generally ranges from sea level to around 1,500 m. Many species flower repeatedly through the year and are characteristic of early-successional habitats (Keraudren, 1966).

The complex is strongly hummingbird-pollinated, with pendulous, nectar-rich flowers aligned with avian pollinators; fruit are dispersed by birds and small mammals (Keraudren, 1966; Species 2000 & ITIS Catalogue of Life, 2024). In contrast to many Cucurbitaceae, anatomical studies have emphasized the discoid adhesive tips of the tendrils, a functional adaptation for climbing in forest settings (Barbosa et al., 2023).

Recent taxonomic work has converged on a broadened concept of Gurania that subsumes Psiguria and sometimes Anguria, reflecting limited morphological differentiation across segregates. Alternative treatments retain Psiguria as a genus or subgenus within Gurania, but molecular and morphological syntheses support the broader circumscription (Aahami et al., 2022; Barbosa et al., 2023; POWO, 2024). Disagreement persists at the sectional or subgeneric level within the complex, and nomenclatural alignment of the type element has not been conclusively resolved.

The vines are occasionally cultivated as ornamental climbers for their brightly colored flowers and fruits, but they have limited horticultural use and are not important in agriculture or timber. Invasive behavior is not widely reported (WFO, 2024).

Conservation status is unassessed for most taxa; habitat loss from deforestation and fragmentation across much of the Amazon and Guianas is a primary threat. Field-based revisions and targeted population studies are needed to evaluate threats and guide future conservation planning.

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