Abstract
The New World species of the subgenera Allotrichoma Becker and Neotrichoma (new subgenus) are revised, including a phylogenetic analysis of the species groups and subgenera within the genus Allotrichoma. For phylogenetic perspective and to document the monophyly of the genus Allotrichoma and its included subgenera and species groups, we also provide a cladistic analysis of genera within the tribe Hecamedini. The ingroup included seven exemplar congeners from within Allotrichoma. Outgroup sampling included exemplars of other genera within Hecamedini and from the putative sister group, Lipochaetini, and to root the analysis, we used an exemplar of the tribe Discocerinini. Analyses with successive weighting and implied weighting recovered a monophyletic Allotrichoma and indicated clades within the genus. Eight new species are described (type locality in parenthesis): Allotrichoma bifurcatum (Utah. Utah: Lake Shore (40°06.9'N, 111°41.8'W; 1370 m)), Allotrichoma dynatum (Oregon. Benton: Finley National Wildlife Refuge (44°24.6'N, 123°19.5'W)), Allotrichoma occidentale (Oregon. Lake: Lakeview (44 km E; Drake Creek; 42°11'N, 119°59.3'W)), Allotrichoma robustum (California. Kern: Kern River (35°16.1'N, 119°18.4'W)), Allotrichoma sabroskyi (New Mexico. Sandoval: La Cueva (Junction of Highways 126 and 4; 35°52'N, 106°38.4'W; 2342 m)), Allotrichoma wallowa (Oregon Baker: Goose Creek (35 km E Baker City; 44°49.2'N, 117°27.79'W; 825 m)), Allotrichoma baliops (Florida. Monroe: Key West (Willie Ward Park; 24°32.9'N, 81°47.9'W)), and Allotrichoma insulare (Dominica. Cabrits Swamp (15°35'N, 61°29'W)). Within Allotrichoma, we recognize three subgenera of which one, Neotrichoma (type species: Allotrichoma atrilabre), is newly described. All known species from the New World are described with an emphasis on structures of the male terminalia, which are fully illustrated. Detailed locality data and distribution maps for the New World species are provided. A lectotype is designated for Discocerina simplex Loew and a neotype is designated for Allotrichoma bezzii Becker. Allotrichoma filiforme Becker, Allotrichoma trispinum Becker, and Allotrichoma dahli Beschovski are reported as new synonyms of Allotrichoma simplex (Loew) and Allotrichoma yosemite Cresson is a new synonym of Allotrichoma atrilabre Cresson. We also clarify the status of previously described species, including those with Holarctic distributions. For perspective and to facilitate genus-group and species-group recognition, the tribe Hecamedini is diagnosed and a key to included genera is provided.
Highlights
A few genera of shore flies (Diptera: Ephydridae) have greater species diversity in the Old World than in the New and have the extant diversity in the New World primarily found in temperate areas of the Nearctic Region, sometimes exclusively so
Based on specimens collected in Italy, Becker described A. bezzii, a species that we have discovered in the Nearctic Region, and to have a Holarctic distribution
Among the seven species reported from the Nearctic Region, Wirth (1965) listed two, A. laterale (Loew) and A. trispinum Becker, with Holarctic distributions
Summary
A few genera of shore flies (Diptera: Ephydridae) have greater species diversity in the Old World than in the New and have the extant diversity in the New World primarily found in temperate areas of the Nearctic Region, sometimes exclusively so Examples of these distributional and diversity patterns within shore flies are the genera Ephydra Fallén (Wirth 1971, 1975) and Allotrichoma Becker. The latter genus, Allotrichoma, is the subject of this revision, and why and how its distributional pattern developed and what the New World species-level diversity is have in part prompted this research. This global approach was done in an effort to adhere to the recommendations of Schmid (1979) and Schefter (2005), i.e., “Recognition of monophyletic groups of species as genera without reference to the world fauna might engender taxonomic inflation at the generic level and thereby erode the cognitive value of the genus.”
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