Maccaffertium meririvulanum

Maccaffertium meririvulanum is a species of flatheaded mayfly in the family Heptageniidae. It was first described by Carle and Lewis in 1978.^[2] This species is native to North America, where it is found in freshwater habitats such as streams and rivers with moderate to fast-flowing water.^[3]

Maccaffertium meririvulanum belongs to the genus Maccaffertium, which is part of the subfamily Heptageniinae within the family Heptageniidae. The genus was previously included in the broader genus Stenonema, but was revised based on phylogenetic studies of morphological characteristics.^[4]

This species is distributed in North America, with occurrences confirmed in the United States.^[1][5] Like other members of the Heptageniidae family, it is typically associated with lotic ecosystems water bodies with continuous flow where nymphs adhere to substrates such as rocks and gravel.

Mayflies, including M. meririvulanum, undergo incomplete metamorphosis, progressing from egg to aquatic nymph, and finally to a short-lived winged adult. The nymphs of this species are dorsoventrally flattened, an adaptation for clinging to rocks in fast-flowing water. They are detritivores and grazers, feeding on algae, microorganisms, and organic debris, and serve as an important food source for fish and other aquatic predators.^[3]

As of now, Maccaffertium meririvulanum has not been evaluated by the IUCN Red List and does not have any specific conservation status. However, like many aquatic insects, its presence and population density can serve as bioindicators of water quality and ecosystem health.^[2]