Abstract
Field-collected gynandromorph specimens of Chrysotus spectabilis (Loew) (Diptera: Dolichopodidae) from the Brazilian State of Paraná are described and illustrated, with special reference to their terminalia morphology and intersexual homology between sclerites. Based both on the position of the male clasping structures in the female gynander (arising dorsally from the acanthophorites) and the acanthophorites in the male gynander (arising from the genital capsule), it is argued that the “revised epandrial hypothesis” offers a more robust explanation for the male terminalia homology in Diptera than alternative hypotheses (namely, periandrial and hinge hypotheses). Additionally, the segmental origin of female acanthophorites is re-evaluated and assumed to be a product of fusion between tergites 9 and 10, rather than the tergite 10 only.
References
Aldrich J. M. 1896. Dolichopodidae. In: Williston, S.W. (Ed.), On the Diptera of St. Vincent (West Indies). Transactions of the Entomological Society of London, 1896, pp. 309–345, figs. 101–119.
Aldrich J. M. 1901. Supplement. Dolichopodidae. In: Godman, F.D. & Salvin, O. (Eds.) Biologia Centrali-Americana. London, pp. 333–366, pl. 6, figs. 7–24.
Becker T. 1922. Dipterologische Studien. Dolichopodidae. B. Nearktische und neotropische Region. Abhandlungen der zoologisch-botanischen Gesellschaft in Wien. 13 (1): 1–394.
Bickel D. J. 1994. The Australian Sciapodinae (Diptera: Dolichopodidae), with a review of the Oriental and Australasian faunas, and a world conspectus of the subfamily. Records of the Australian Museum Supplement 21, 394 pp.
Capellari R. S. & Amorim D. S. 2010. Re-description and new combination of five New World species of Chrysotus Meigen, with comments on the Neotropical genus Lyroneurus Loew (Diptera: Dolichopodidae). Zootaxa 2520: 49–65.
Cumming J. M. & Cooper B. E. 1992. A revision of the Nearctic species of the tachydromiine fly genus Stilpon Loew (Diptera: Empidoidea). The Canadian Entomologist 124(6): 951–998.
https://doi.org/10.4039/Ent124951-6
Cumming J. M., Sinclair B. J. & Wood D. M. 1995. Homology and phylogenetic implications of male genitalia in Diptera – Eremoneura. Entomologica Scandinavica 26: 121–151.
https://doi.org/10.1163/187631295X00143
Cumming J. M. & Wood D. M. 2009. Adult morphology and terminology. In: Brown BV, Borkent A, Cumming JM, Wood DM, Woodley NE, Zumbado MA (eds) Manual of Central American Diptera, Volume 1, NRC Research Press, Ottawa, pp. 9–50.
Engel M. S. 2007. A lateral gynandromorph in the bee genus Thyreus and the sting mechanism in the Melectini (Hymenoptera: Apidae). American Museum Novitates 3553: 1–11.
https://doi.org/10.1206/0003-0082(2007)3587[1:TNFODA]2.0.CO;2
Griffiths G. C. D. 1972. The phylogenetic classification of Diptera Cyclorrhapha, with special reference to the structure of the male postabdomen. Series entomologica 8. Dr. W. Junk, The Hague, 340 pp.
Griffiths G. C. D. 1983. Book review of “Chvala, M. 1983. The Empidoidea (Diptera) of Fennoscandia and Denmark. II. General Part. The families Hybotidae, Atelestidae and Microphoridae. Fauna Entomologica Scandinavica 12” Quaestiones Entomologicae 19(3/4): 483–485.
Griffiths G. C. D. 1984. Male genitalia in the classification of Chloropidae. Paper for discussion presented at the XVII International Congress of Entomology, Hamburg. 2 pp.
Griffiths G. C. D. 1996. Review of papers on the male genitalia of Diptera by D.M. Wood and associates. Studia dipterologica 3: 107–123.
Hennig W. 1976. Das Hypopygium von Lonchoptera lutea Panzer und die phylogenetischen Verwandtschftsbeziehungen der Cyclorrphapha (Diptera). Stuttgarter Beiträge zur Naturkunde Serie A 283: 1–63.
Kahanpää J. 2008. Nematode-induced demasculinisation of Dolichopus males (Diptera: Dolichopodidae). Zootaxa 1689: 51–62.
Kotrba M. 2000. 1.3. Morphology and terminology of the female postabdomen. In: Papp L & Darvas B (eds) Contributions to a manual of Palaearctic Diptera (with special reference to flies of economic importance). Volume 1. General and Applied Dipterology. Science Herald, Budapest: pp. 75–84.
Loew H. 1861. Neue Beiträge zur Kenntniss der Dipteren. Achter Beitrag. Programme der Königlichen Realschule zu Meseritz 1861: 1–100.
Loew H. 1874. Ueber einen Zwitter aus der Ordnung der Dipteren. Zeitschrift für die Gesammten Naturwissenschaften 44: 75–79.
McAlpine J. F. 1981. 2. Morphology and terminology – adults. In: McAlpine JF, Peterson BV, Shewell GE, Teskey HJ, Vockeroth JR & Wood DM (coords.) Manual of Nearctic Diptera, Volume 1. Agriculture Canada Monograph 27, Ottawa, pp. 9–63.
Narita S., Pereira R. A. S., Kjellberg F. & Kageyama D. 2010. Gynandromorphs and intersexes: potential to understand the mechanism of sex determination in arthropods. Terrestrial Arthropod Reviews 3: 63–96.
https://doi.org/10.1163/187498310X496190
Pollet M. A. A., Brooks S. E. & Cumming J. M. 2004. Catalog of the Dolichopodidae (Diptera) of America North of Mexico. Bulletin of the American Museum of Natural History 283: 1–114.
https://doi.org/10.1206/0003-0090(2004)283<0001:COTDDO>2.0.CO;2
Ringdahl O. 1949. Notizen zur Familie Dolichopodidae (Diptera). Opuscula Entomologica 14: 53–59.
Robinson H. & Vockeroth J. R. 1981. Dolichopodidae. In: McAlpine, J.F., Peterson, B.V., Shewell, G.E., Teskey, H.J., Vockeroth, J.R. & Wood, D.M. (Co-ords.) Manual of Nearctic Diptera, Volume 1. Agriculture Canada Monograph, 27, pp. 265–639.
Sinclair B. J. 2000. 1.2. Morphology and terminology of Diptera male terminalia. In: Papp L & Darvas B (eds) Contributions to a manual of Palaearctic Diptera (with special reference to flies of economic importance). Volume 1. General and Applied Dipterology. Science Herald, Budapest: pp. 53–74.
Sinclair B. J. & Cumming J. M. 2006. The morphology, higher-level phylogeny and classification of the Empidoidea (Diptera). Zootaxa 1180: 1–172.
Sinclair B. J., Cumming J. M. & Brooks S. E. 2013. Male terminalia of Diptera (Insecta): a review of evolutionary trends, homology and phylogenetic implications. Insect Systematics & Evolution 44: 373–415.
https://doi.org/10.1163/1876312X-04401001
Thomson C. G. 1869. 6. Diptera. Species nova descripsit. In: Kongliga Svenska Vetenskaps-Akademien, Kongliga svenska fregatten Eugenies resa omkring jorden. Pt. 2: Zoologie, Sec. 1: Insekter, Stockholm, pp. 443–614.
Ulrich H. 1974. Das Hypopygium der Dolichopodiden (Diptera): Homologie und Grundplanmerkmale. Bonner zoologischer Monographien 5: 1–60.
Ulrich H. 1976. Morphology of the dolichopodid hypopygium and its significance for a phylogenetic system of that family (Diptera). Paper presented at the XV International Congress of Entomology, Washington, D. C. 5 pp. + 5 figs.
Ulrich H. 1977. Abwandlungen im Baum des Dolichopodiden-Hypopygiums (Diptera) – I: Medetera truncorum Meigen. Bonner zoologische Beiträge 28(3–4): 412–420.
Ulrich H. 1983. Abwandlungen im Baum des Dolichopodiden-Hypopygiums (Diptera) – II: Thinophilus flavipalpis (Zetterstedt). Bonner zoologische Beiträge 34(1–3): 395–404.
Wahlgren E. 1912. Diptera, 1. Orthorapha, 2. Brachycera, Fam. 25–26 (Dolichopodidae, Lonchopteridae). Svensk Insektfauna 11: 1–179.
Zatwarnicki T. 1996. A new reconstruction of the origin of eremoneuran hypopygium and its implications for classification (Insecta: Diptera). Genus 7: 103–175.