476 



UNITED STATES NATIONAL MUSEtTM BtJLLETIN 2 24 



Nerax, new genus 

 FiQTJBES 388, 740, 1381, 1390 

 Erax of American authors generally ; not Erax Scopoli, 1763. 



Type of genus: Asilus aestuans Lirme, 176", by 

 present designation. 



The species of Nerax are medium size to generally 

 large flies, composed of numerous species and species 

 gi-oups confined to the New World. They are readily 

 characterized by the prominent, bristle-covered gib- 

 bosity of the face, tlie numerous, stout bristles, the 

 tapered abdomen m which the male terminalia forms 

 a characteristic, enlarged, elongate, laterally com- 

 pressed and clublike structure. The fully inflated 

 scutellum sliould be noted. The posterior branch of 

 the third vein ends before, at or slightly beyond the 

 apex of the wing and near the base of tlie anterior 

 branch of the third vein there is often a spur vein with 

 the base itself formed like a crossvein, or this spur may 

 be quite absent and the base arising gradually. Length 

 12 to 35 mm. 



The decision as to a proper and satisfactoi-y name for 

 the very large, New World group of flies, which have 

 previously gone under the name of Erax Scopoli, 

 through an error of interpretation by Macquart, is 

 much involved. Hine, 1919, noted this situation with- 

 out rectifying it and without comment on the prior 

 claim of European species to the name Erax. Hine 

 designated an American species as type of genus for 

 Erax Scopoli, overlooking the fact that Coquillett, 1910, 

 had previously designated one of Scopoli's included 

 species as the type of genus of Erax Scopoli. I am 

 indebted to Mr. H. Oldroyd for calling to my attention 

 the confusion which has long existed with respect to 

 the European robber flies which have been currently 

 placed under the name ProtopJmnes Loew. 



For type of genus I choose Asilus aestuans Linne be- 

 cause it is a typical and ubiquitous species within the 

 genus, of wide range and can not be confused with 

 'Efferia Coquillett or other related genera. 



Eristicus Loew, 1848, is one of the names mentioned 

 for possible use for the New World flies formerly going 

 under tlie name Erax Scopoli. Loew included no spe- 

 cies by name under his genus Eristicus and on account 

 of preoccupation the name was changed by Osten 

 Sacken (1878) to Neoeristicus. Because Erkticus was 

 offered as a new name for a new group, and not as a 

 substitute name, or change of name, it is proper in this 

 case to affix to it the first suggested species which prop- 

 erly fits the description. The first person to properly 

 associate a species with the name Eristicus was Bellardi 

 (18G1) who, in his well known compendium on Mexican 

 and Central American Diptera, discussed the gi-oup of 

 flies at some length and described 14 species under tlie 

 name Erax Scopoli, and for each of these 14 he placed 

 after them in parentheses the term Erax Loew. He 

 followed these by 2 more species under Erax, namely 

 Erax nigripes Bellardi and Erax villosus Bellardi. 



Text-Figure 34. — Pattern of distribution of the cjenus Nerax Hull 



Bellardi clearly indicated that these 2 species were un- 

 like the first 14 species that he described, by placing 

 after them in parentheses 'EriMicus Loew'. This prior 

 use invalidates Coquillett's (1910) designation of ^raa; 

 amhiguus Macquart as type of genus of Eristicus on 

 hearsay evidence. This represents the first association 

 of a species with the genus Eristicus Loew, and one of 

 these 2 species is available for type of genus. I now des- 

 ignate Eristicus nigripes Bellardi the type of genus of 

 Eristicus Loew, which genus name was changed by 

 Osten Sacken to Neoeristicus. 



But these 2 species, Eristicus nigripes and villosus 

 belong in the same group of species as have, up until 

 this time, been placed in Bigot's genus Eicherax Bigot, 

 1857. Since Eicherax was completed by a named and 

 included species, Eicherax sitnplex Macquart, before 

 Eristicus was comiDleted by a named, associated species 

 by Bellardi, 1861, 1 conclude that it is proper to place 

 Neoeristicus in the synonymy of Eicherax. 



It is apparent that Eristicus Loew, 1848, changed by 

 Osten Sacken, 1878, to Neoeristicus on account of pre- 

 occupation of Eristicus, is not then available for the 

 New World species formerly going under the name 

 Erax. In 1910 Coquillett designated Erax harhatus 

 as the type of genus of Erax. This was the fifth species 



