A chromosomal investigation of some British Cantharidae (Coleoptera)

The karyotypes of 20 species of Cantharidae occurring in the British Isles are described and illustrated, 19 of which are hitherto unrecorded. These are Cantharis cryptica Ashe, Cantharis fusca Linnaeus, Cantharis lateralis Linnaeus, Cantharis livida Linnaeus, Cantharis nigra (Degeer), Cantharis nigricans (O. F. Müller), Cantharis pallida Goeze, Cantharis pellucida Fabricius, Cantharis rufa Linnaeus, Cantharis rustica Fallén, Cantharis thoracica (Olivier), Rhagonycha fulva (Scopoli), Rhagonycha lignosa (O. F. Müller), Rhagonycha limbata Thomson, Rhagonycha lutea (O. F. Müller), Rhagonycha testacea (Linnaeus), Silis ruficollis (Fabricius), Malthinus seriepunctatus Kiesenwetter, Malthodes dispar (Germar) and Malthodes minimus (Linnaeus). The main findings were as follows: (1) Cantharis, Rhagonycha and Silis have karyotypes of six pairs of autosomes plus sex chromosomes, which are X0 (male), XX (female). (2) Malthinus and Malthodes differ from the other genera in having only five pairs of autosomes. (3) The chromosome complement of Silis differs from those of the other genera studied in having a variable number of B-chromosomes in individuals from the same population. (4) The karyotypes of the Rhagonycha species show a degree of uniformity in the relative chromosome lengths, centromere positions and C-banding patterns. (5) The karyotypes of the Cantharis species are much more distinct from each other where these characteristics are concerned. (6) Maturation of the gonads takes place in the late larval stage. (7) The segregation of the X chromosome of Cantharis rufa during meiosis is pre-reductional.