PROC. ENTOMOL. SOC. WASH. 111(1), 2009, pp. 57-67 TRICORYTHODES MINUTUS TRAVER, A NEW SYNONYM OF TRICORYTHODES EXPLICATUS EATON (EPHEMEROPTERA: LEPTOHYPHIDAE) DAVIDE. BAUMGARDNER Department of Entomology, Texas A&M University, College Station, Texas 77843-2475, U.S.A (e-mail: [email protected]) Abstract.-Based upon a study of adults, larvae, and reared adults from throughout North and Central America, Tricorythodes minutus Traver, 1935 is shown to be a junior synonym of Tricorythodes explicatus (Eaton, 1892) (n. syn.). Previous characters postulated to separate the two species are shown to be variable and unreliable. This study has clearly revealed the presence of a single, widespread and morphologically variable species distributed throughout much of western, central, and northeastern North America and northern Central America. Key Words: Ephemeroptera, Leptohyphidae, Tricorythodes explicatus, Tricor­ ythodes minutus, taxonomy Among Nearctic Tricorythodes, the justify the synonymy of T. minutus with exact identities of T. explicatus (Eaton) T. explicatus. and T. minutus Traver have remained vague and uncertain. Although Kilgore MATERIALS AND METHODS and Allen (1973) and Allen and Murvosh Collections (and their acronyms) ( 1987) described the larval stages of these housing materials used in this study two species and contrasted their larval include: The Natural History Museum, characters, much taxonomic confusion London (BMNH), C.P. Gillette Muse­ still remained. The possibility that these um of Arthropod Diversity, Colorado two species might be synonymous has States University, Ft. Collins (CSU) and been mentioned in the literature several Texas A&M University, College Station times (Lugo-Ortiz and McCafferty 1995, (T AMU). In material examined sum­ McCafferty et al. 1997, Baumgardner maries, larval collections are abbreviat­ and Bowles 2005). After an extensive ed by the capital letter "L," preceded by study of numerous specimens from the number of specimens examined. throughout North and Central America Collectors are identified by the follow­ (which included larvae and reared ing initials: DEB (David E. Baumgard­ adults), it is apparent that both are the ner); BCK (Boris C. Kondratieff). Legs, same species. The purpose of this paper gills, and mouthparts of over 40 speci­ is to trace the historical taxonomy of the mens were removed and mounted on two species (and two associated species slides for detailed study. Figures were synonymized with T. minutus), and drawn using a camera lucida. Global positioning measures are given in longi­ * Accepted by David R. Smith tude/latitude coordinates as degrees, 58 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON minutes, seconds. Seta] descriptive ter­ labeled as such in The Natural History minology follows Baumgardner and Museum. Ulmer (1920) established the Avila (2006). genus Tricorythodes and designated Tri­ corythus explicatus as the type species. RES UL TS AND DISCUSSION Banks (1903) documented the species for Tricorythodes explicatus was described the first time in the United States from by Eaton (1892), as Tricorythus explica­ Arizona, and McDunnough (1931) listed tus, based upon a series of adults it as occurring in Texas and Wyoming in collected by Herbert Knowles Morrison the United States and Saskatchewan and (1854-1885) from "N. Sonora, Mexico." Alberta in Canada. Traver (1935) ques­ However, it appears highly likely that the tioned the identification of the specimens type series was collected from the Gra­ from Canada, while Allen and Murvosh ham Mountains north of Fort Huachuca (1987) considered them to be T minutus. in extreme southern Arizona (Selander Spieth (194 I) indicated that the species and Valurie 1962). Morrison was a occurred as far north as Yellowstone professional collector who collected in Park in Wyoming. Allen and Murvosh Arizona in I 880 and 1882 (Essig 1931 ). (I 987) described the larval stage of T Horn (1886) notes that "The collection explicatus based upon specimens collect­ made by Morrison teaches very little. ed from what they believed was the type How far he went below the boundary I locality of the species in Sonora, Mexico. do not know, although my series was They also included a taxonomic key to purchased as from Arizona purely, and separate T explicatus from T minutus. the same series is quoted by the authors Tricorythodes minutus was described of the "Biologia" as from northern by Traver (1935) from adults from the Sonora." It appears that perhaps Morri­ Provo River in Utah. It was distin­ son, as a commercial collector, labeled guished from other known Tricorythodes his specimens from extreme southern adults on the basis of coloration (paler Arizona as being from northern Sonora than T stygiatus McDunnough) and (Mexico) so that he could then sell them lack of black maculation on the femora to the Biologia researchers as being from and tibiae (present on T allectus (Need­ their area of interest. To the American ham)) and from T texanus Traver due to scientists, he apparently gave them the its much darker coloration and more correct Arizona locality. Despite this shallow excavation of the apical margin apparent error in labeling, Essig ( 1931) of the styliger plate. Kilgore and Allen considered Morrison one of the greatest (1973) described the larval stage of T American entomological explorers, with minutus and listed it as occurring extensive collections made throughout throughout Arizona and New Mexico. the western and southeastern United Among characters they listed for the States. Morrison contracted a fatal case larvae of T minutus were a 3-segmented of dysentery on his last collecting trip to maxillary palp, presence of long margin­ Key West, Florida in 1885 (Essig 1931). al setae on the femora, abdominal terga The original brief description by Ea­ 7-9 with well-developed posterolateral ton (1892) focused upon coloration and projections, and operculate gills pale included two figures, one of the wing and with black markings (Kilgore and Allen one of the forceps (without the penes). I 973: fig. 37). Tricorythodes minutus was Since a holotype was not designated in subsequently reported from throughout the original type series, Kimmins (1934) western North America (Allen and Mur­ designated a specimen from this series as vosh 1987, McCafferty et al. 1993, Lugo­ the lectotype. This specimen is clearly Ortiz and McCafferty 1995, Mccafferty VOLUME 111, NUMBER 1 59 et al. 1997). It has also been reported varieties occurring in what would nor­ from north central and northeastern mally be considered the range of T North America (Alba-Tercedor and explicatus or T minutus, and can find Flannagan 1995, Randolph and McCaff­ no reliable characters in the adult stage erty 1998). separating the two species. Two other species of Tricorythodes, T As no characters were found to fa/lax Traver and T fallacina McDun­ separate the two species in the adult, nough, had previously been synonymized the larval stages of each species were with T minutus. Tricorythodes Jal/ax was examined. Although the key of Allen and described by Traver (1935) from adults Murvosh (1987) and characters given for from California, and its overall similarity the larval stage of T minutus by Kilgore to T explicatus was noted by Traver who and Allen (1973) appear to offer many distinguished it by its paler coloration. distinguishing characters, these charac­ Edmunds et al. (1976) synonymized T ters proved unreliable and sometimes Jal/ax with T. minutus because the two incorrectly applied. species completely intergraded along the Firstly, Kilgore and Allen (1973) borders of California, Oregon, and indicated that T minutus possessed a 3- Washington. They considered T. Jal/ax segmented maxillary palp, whereas Allen a "clinal variant" of T. minutus. and Murvosh (1987) indicated that T Tricorythodes fallacina was described explicatus possessed a 2-segmented max­ by McDunnough (1939) from adults illary palp. Examination of numerous from British Columbia, Canada. The larvae from throughout the reported new species was considered a "smaller, range of T minutus showed that all more northerly species" within the T possessed a 2-segmented maxillary palp explicatus complex. McDunnough ( 1939) with a single apical seta (Fig. 1); howev­ considered T explicatus to be a large er, some individuals possessed a weakly dark species occurring in Texas and developed articulation near the base of adjoining regions and T. Jal/ax a smaller, the second segment, giving the appear­ paler western species. Traver (1935) and ance of a 3-segmented maxillary palp McDunnough (1939) noted that all three (Fig. 2). This condition of a weakly species shared morphological characters articulated palp has been demonstrated such as the type and shape of genitalia for other leptohyphid mayflies such as and a shallow excavation of the apical Vacupernius packeri (Allen) (Baumgard­ margin of the styliger plate. Edmunds ner 2003) and some South American and Allen (1957) synonymized T falla­ Tricorythodes (Molineri 2002). None of cina with T minutus without comment. the larvae examined possessed a 3- However, this synonymy appears to be segmented maxillary palp; all possessed well justified on the basis of discussion a 2-segmented maxillary palp, with given in Edmunds et al. (1976) discussing about 10% of the larvae having traces the clinal variants of T fa/lax, T. of the weakly developed articulation. fallacina, and T. minutus. Secondly, Kilgore and Allen (1973) Thus, characters used to separate the indicated that T minutus possess well­ adult stages of T explicatus from T developed posterolateral projections on minutus are few and based upon differ­ abdominal terga 7-9, whereas in T. ences in overall size and coloration. I explicatus, terga 7-9 lacked well-devel­ have examined long series of adults from oped posterolateral projections (Allen western North America, Mexico, and and Murvosh 1987). However, examina­ Guatemala which would be attributed to tion of numerous larvae throughout the T. explicatus and T minutus, including reported range of T. explicatus clearly L' 60 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON I~ .· .. · .· ... : .• 6 2 Figs.