Arthroplea bipunctata is a of flatheaded mayfly in the Heptageniidae (sometimes historically placed in Arthropleidae). It is known from North America, with records from the Nearctic region. The species was described by McDunnough in 1924, originally as Cinygma bipunctata. Like other flatheaded mayflies, it belongs to a group adapted to clinging in fast-flowing waters.

Identification

Distinguished from other Arthroplea by the two-spot pattern referenced in its specific epithet. Flatheaded mayflies ( Heptageniidae) can be separated from other families by their flattened shape, with often meeting dorsally in males, and their clinging-adapted legs with robust claws. Within the , A. bipunctata would be distinguished from the more widespread A. by specific spot patterns and genitalic differences, though detailed diagnostic features require examination of .

Habitat

Freshwater lotic environments, specifically streams and rivers with moderate to fast current. Flatheaded mayflies are typically found clinging to rocks, woody debris, and other submerged substrates in well-oxygenated waters.

Distribution

North America; specifically recorded from the Nearctic region. Distribution details beyond this broad region are poorly documented in available sources.

Life Cycle

As with all mayflies, development includes aquatic nymphal stages and terrestrial winged stages. The nymphs are aquatic and undergo multiple instars before emerging as subimagos (duns) and then imagos (spinners). Specific details of voltinism, nymphal development time, and patterns for this are not documented.

Ecological Role

Nymphs function as herbivores- in stream , processing and organic matter. They serve as prey for fish and other aquatic . are non-feeding and primarily function in .

Similar Taxa

  • Arthroplea congenerThe only other in the Arthroplea; distinguished by genitalic and color pattern details
  • Other Heptageniidae genera (e.g., Heptagenia, Maccaffertium, Rhithrogena)Similar flattened body form and preferences; distinguished by wing venation, genitalia, and specific leg and gill

More Details

Taxonomic Note

There is historical inconsistency in placement. Some sources list Arthropleidae as the family, while modern classifications (GBIF, Catalogue of Life) place Arthroplea within Heptageniidae. The Arthroplea contains only two : A. bipunctata and A. .

Original Description

First described by James Halliday McDunnough in 1924 as Cinygma bipunctata, later transferred to the Arthroplea.

Data Availability

The is poorly represented in biodiversity databases, with only 5 observations in iNaturalist and limited specimen records, reflecting its apparently restricted distribution or undercollection.

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Sources and further reading