PROC. ENTOMOL. SOC. WASH. 86(2), 1984, pp. 354-357 CYTOGENETIC STUDY IN MALES OF NEARCTIC GENERA OF GERRIDAE (HEMIPTERA: HETEROPTERA) Diane M. Calabrese and Peter Tallerico (DMC) Department of Biology and The Wildlife Sanctuary, Dickinson College, Carlisle, Pennsylvania 1 70 1 3; (PT) Nursing Department, Pennsylvania State Uni-versity, University Park, Pennsylvania 16802. Abstract.— Chromosome numbers and sex chromosome mechanisms deter-mined on the basis of study of spermatogenic tissue are reported for six species ofGerridae: Ncogcrris hesione {Kirka\dy) {6, N = 1 1 + XO), Metrobates hesperius (Uhler) (3, N = 12 + XY), Rhcumatobates rileyi rileyi Bergroth (3, N = 9 + XY), Trcpobatcs pictus (Herrich-Schaeffer) (3, N = 1 2), Limnoponis notabilis (Drake and Hottes) and L. canaliculatus Say (3, N = 9 + XY). A preliminary pattern of correspondence emerges when chromosome numbers and sex determination mechanisms are superimposed on a phylogcnetic reconstruction for the Gerridae. Here we report chromosome numbers and sex determination mechanisms for representatives of five genera of Gerridae (Hemiptera: Hetcroptera), including three for which such information has not yet been published. We also comment on the apparent congruence between cytogenetic and morphological characters in the family. Many concepts have been associated with congruence: stability in classification, stability with addition of characters, stability with addition of groups; but there is no general agreement on a definition (cf Rohlf and Sokal, 1980; Schuh and Polhemus, 1980; Mickevich, 1978). Ultimately, congruence refers only to cor-respondence. We compare chromosome numbers and sex determination mech-anisms among genera we studied in the context of a phylogcnetic reconstruction of the genera produced by one of us (Calabrese, 1980). Materials and Methods Neogerris hesione (Kirkaldy) was collected in southern Florida, Metrobates hes-perius Uhler, Rhcumatobates rileyi rileyi Bergroth and Trcpobatcs pictus (Herrich-Schaeffer) were collected in Cumberland County, PA. Limnoporus canaliculatus Say was collected in central Florida by A. Zera. Limnoporus notabilis Drake and Hottes was collected in Haney, British Columbia by John Spence. At least five specimens of each species were field-fixed (1 5 ml glacial acetic acid, 45 ml absolute ethanol, 5 ml. acetone). Within two weeks testes were dissected out of males. Each testis was stained for 3-5 minutes with a drop of lacto-proprio orcein. A standard squash was made. Slides were sealed in temporary mounts and scanned for figures at 40 x . Metaphase I figures found were photographed at about 1 500 X under oil with a Bausch and Lomb (B&L) phase contrast microscope
BioStor
