Atlas and biogeographic review of the North American mayflies (Ephemeroptera)

Robert Patrick Randolph, Purdue University

Abstract

An atlas detailing state and provincial distributions of 663 North American Ephemeroptera species is presented. Biogeographic affinities of 95 North American genera are discussed and their hypothesized origins reviewed. Historical events in regards to vicariance and dispersal were important factors influencing the evolution of the North American fauna. Lineages found in North America are a result of Northern Hemisphere vicariant events (e.g., plate tectonics) and periods of dispersalist invasion, notably via the Isthmus of Panama and Beringia. The North American fauna is composed predominantly of Nearctic endemics/relicts, and lineages with Laurasian or Neotropical affinities. Although Cloeodes and Ephoron are hypothesized to have a Gondwanan origin and invaded North America via the Neotropics and Laurasia, respectively. Caenis may be of ancient Pangean origin, and in North America may consist of elements of recent boreal and austral affinities. The Nearctic endemic/relict element is comprised of 33 genera, with Litobrancha and Siphloplecton considered relictual based on fossil evidence. Thirty-one North American genera are hypothesized to be of Nearctic origin, although Analetris and Baetisca, because of cladistic data, are relictual in the Nearctic. Thirty-seven genera have a Laurasian affinity and hypothesized origin. Afghanurus, Baetopus, and Cloeon are hypothesized to have an east Laurasian origin. Twenty-five North American genera have Neotropical affinities and hypothesized origin. Moribaetis, Varipes, Ableptemetes, Hydrosmilodon, and Euthyplocia occur only in the Neotropics, and most others are found mainly in southwestern North America, Callibaetis and Tortopus being notable exceptions. North American species are arranged under fifteen distribution patterns. It is evident there are distinct eastern and western faunas. One-hundred and sixty-one species are widespread Eastern, 36 are Northeastern, and 75 are Southeastern. Sixty-eight species are widespread Western, 100 are Northwestern, and 66 are Southwestern. Forty species are known only from Neotropical Mexico. Certain species have discontinuous distributions, which are either an artifact of incomplete collection data (e.g., Plauditus cestus) or true disjunctions resulting from events such as Pleistocene glaciation (e.g., Cinygmula subaequalis) or disjunction of specific habitats (e.g., Dolania americana). Remaining patterns comprise a small element of the North American fauna (12 species), including Northwest+Northeast, Far North+Northeast, East+Northwest, Far North+Northwest+Northeast, and Northwest+Northeast+Southwest.

Degree

Ph.D.

Advisors

McCafferty, Purdue University.

Subject Area

Entomology

COinS