PROC. ENTOMOL. SOC. WASH. 101(1), 1999. pp. 1-25 EGG ARCHITECTURE OF NAUCORIDAE (HETEROPTERA): INTERNAL AND EXTERNAL STRUCTURE OF THE CHORION AND MICROPYLE Robert W. Sites and Becky J. Nichols Enns Entomology Museum, Department of Entomology, University of Missouri, Co-lumbia, MO 65211, U.S.A. (e-mail:
[email protected]) Abstract. — The chorion and micropyles of 27 species of Naucoridae, including 21 spe-cies of Ambrysus, are described and each description is supported with scanning electron micrographs. Photomicrographs of thick sections through the chorion or micropyle of 10 of these species also are presented. Chorionic sculpturing differs interspecifically in Am-brysus and based on the species studied, eggs of Ambrysus, Limnocoris, and Pelocoris have 2-3 micropyles. Key Words: Egg, chorion, micropyle, Naucoridae The Naucoridae (sensu lato), or creeping water bugs, comprise 394 described species worldwide (see La Rivers 1971, 1974, 1976; Polhemus and Polhemus 1982, 1988, 1994; Nieser et al. 1993; Liu and Zheng 1994; Polhemus 1994; Nieser and Chen 1996). As is typical among insect families, the adults have received the greatest amount of morphological research; accord-ingly, taxonomic treatments emphasize adult characters. Although nymphal stages have been described for several species of Naucoridae, details of egg structure largely have been ignored. Line diagrams from light microscopy have been presented for a few species; however, elucidation of fine detail is not possible with this technique. Recent reports for several species [Ambry-sus lunatus Usinger (Sites and Nichols 1990), Cryphocricos hungerfordi Usinger (Sites and Nichols 1993), Pelocoris poeyi Guerin Meneville (Sites 1991), and several species of South American Ambrysus and Pelocoris (Lopez Ruf 1989)] have included scanning electron micrographs that have re-vealed interspecific differences in chorionic patterns. Eggs of most naucorid species, for which oviposition is known, either are adhered to plants (exophytic oviposition) or to rock substrata (Hinton 1981). For example, eggs of A. lunatus are adhered to plants (Sites and Nichols 1990), Ambrysus mormon Montandon to pebbles (Usinger 1946), Aphelocheirus aestivalis (Fabricius) proba-bly to rocks (Larsen 1927), C. hungerfordi to rocks (Sites and Nichols 1993), Lacco-coris limigenus Stal to hard substrata (Clarke and Baroudy 1990), Naucoris ma-culatus F. to plants (Lebrun 1960), and Pel-ocoris femoratus (Palisot de Beauvois) to plants (Torre Bueno 1903, Hungerford 1927, McPherson et al. 1987). More spe-cifically, P. femoratus eggs are glued to leaf-lets of Nitella and other aquatic plants with a "fairly generous quantity of white adhe-sive" (Hungerford 1927). In contrast, the oviposition of Ilyocoris cimicoides (L.) is endophytic, inserting eggs into submergent plant tissue (Cobben 1968), such as into stems of Ranunculus or water peppermint (Rawat 1939). Eclosion occurs through the anterior pole and, generally, a crescentic slit is made
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