Texas caeninae (Ephemeroptera: Caenidae), with description of a new species

The subfamily Caeninae is examined with respect to its distribution within the state of Texas. Texas fauna includes Amercaenis ridens (McDunnough), Caenis amica Hagen, C. arwini, new species, C. bajaensis Alien and Murvosh, C. hilaris (Say), C. diminuta Walker, C. latipennis Banks, and C. punctata McDunnough. The report of C. diminuta represents a new state record. Some 26 new county records are provided for all species except C. bajaensis, and new Texas biotic province records are established for C. amica (Chihuahuan), C. arwini (southwestern Balconian), C. diminuta (Austroriparian and Texan), and C. hilaris (Kansan). Species ranges within and without the state are discussed. The highly distinctive C, arwini is described from a substantial series of larvae that demonstrate structural affinities primarily with C. bajaensis.