Melanism
Guides
Acanthoscelides quadridentatus
Acanthoscelides quadridentatus is a seed beetle (Bruchinae) native to the Americas with introduced populations in Australia and southern Asia. In its native Brazilian Cerrado range, it exhibits phenotypic plasticity with two distinct morphs: melanic individuals that are approximately 1.1-fold larger, and lighter, smaller individuals. The species is a specialist seed predator of Mimosa setosa, attacking both M. setosa var. paludosa and M. setosa var. setosa. Attacked seeds fail to germinate, making this beetle a significant mortality factor for its host plant.
Cyphostethus tristriatus
Juniper Shield Bug
Cyphostethus tristriatus, commonly known as the juniper shield bug, is a large shield bug in the family Acanthosomatidae. Native to the Palearctic region, it has been introduced and established in North America. The species exhibits intraspecific melanism, with a highly melanic morph documented in addition to the typical green coloration. It is associated with juniper as a host plant.
Oligia
Oligia is a genus of noctuid moths comprising over 60 described species distributed across Europe, the Americas, Africa, and Asia. Species are small to medium-sized moths typically associated with grassland habitats. Several species are economically significant as pests of forage grasses, while others have served as models for studying melanism evolution. Species-level identification often requires genitalia examination due to morphological similarity among closely related taxa.
Oligia strigilis
Marbled Minor
Oligia strigilis, the Marbled Minor, is a noctuid moth distributed across Britain, Europe, and Central Asia, with accidental introduction and rapid spread in northeastern North America. It is one of three similar Oligia species in the UK that require genitalia examination for reliable identification. The species has declined by 76% in Britain since the 1970s despite potential range expansion. Melanic forms occur frequently and have been of significant evolutionary interest.
Oreoneta
A genus of dwarf spiders (family Linyphiidae) established in 1894, comprising approximately 30 species distributed across cold-temperate and Arctic regions of the Northern Hemisphere. Most species inhabit high-latitude or high-altitude environments. The genus was revised extensively by Saaristo & Marusik in 2004, resulting in numerous new species descriptions.
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