Separation of two species standing as Helophorus aquaticus (L.) (Coleoptera, Hydrophilidae) by banded chromosome analysis

Abstract

Abstract. Methods are described for making chromosome preparations from developing embryos of Helophorus, for producing C‐ and G‐banding, and for staining the nucleolus organizer with silver. These methods are used to compare the karyotypes of two species currently included in H.aquaticus (L.). It is shown that these species differ because of reciprocal translocations between some chromosomes, and that they would therefore be unable to produce fertile hybrids. Morphological differences in the male and female genitalia are described, and the range of aedeagal variation shown by each species is established by reference to chromosome preparations from testis. Reference to the relevant type specimens shows that the two species are H.aequalis Thomson and H.aquaticus (L.). The latter is not a British species. Differences in the egg cocoons and third instar larvae are described. The present distributions and Pleistocene histories of the two species are described.

Loss of Y chromosome may be a synapomorphy of the tribe Lepturini (Coleoptera: Cerambycidae: Lepturinae)

“…After one change of fi xative, the cells were spread on wet and cold slides or conserved in the tube for a few days at 6°C before use. Slides were stained with Giemsa, photographed and C-banded according to Angus (1982). This technique was used for both adults and larvae.…”

Evolutionary Dynamics of <i>Tropisternus</i> Karyotype (Coleoptera: Hydrophilidae: Hydrophilini) from Southern Brazil

“…In the genus Anacaena, five species with different karyotypes were found: (Shaarawi and Angus 1991). However, most Hydrophilidae species studied to date show a karyotype of 2n=16+XY, with sex chromosomes associated in a parachute configuration (Angus 1982, Shaarawi 1989. Tropisternus mutatus sapucay cytogenetic data corroborate the diploid number of most specimens of the family.…”

“…There are few cytogenetic studies specifically for the family Hydrophilidae, and most of them refer to the counting of the diploid number and identification of the sex chromosome system (Smith 1953, Angus 1982, 1988, Shaarawi and Angus 1991. These studies reveal a frequent karyotype 2n=16+XY for the family.…”

Etude chromosomique de seize espèces ou sous-espèces de Cetoniini (Coleoptera: Scarabaeidae: Cetoniinae) d’Europe

“…Le chromosome X est acrocentrique. Chaque paire peut être identifi ée par sa taille, la position du centromère et le marquage de l'hétérochromatine et de l'euchromatine, après traitement approprié (Angus 1982). Ses chromosomes , très semblables à ceux de l'espèce suivante, ne sont pas montrés ici.…”