THE RELATIONSHIP BETWEEN THE VENTRAL NERVE CORD, BODY SIZE AND PHYLOGENY IN GROUND BEETLES (COLEOPTERA, CARABIDAE)

The ventral nerve cord in the family Carabidae (considered in the widest sense! exhibits variations in the degree of fusion of thoracic and abdominal ganglia. There are usually three discrete thoracic ganglia and between one and seven discrete abdominal ganglia, the number differing between tribes. Of the 44 tribes and 177 species examined, 38 tribes contained species showing no differences in the degree of ventral nerve cord consolidation. However, the remaining six tribes showed variations in the degree of ventral nerve cord consolidation between genera (Lebiini, Cychrini, Nebriini, Scaritini, Licinini and Brachinini), whilst one genus showed variations between species (Leistus, Nebriini). No variation in ventral nerve cord consolidation was observed in conspecifics. The degree of ventral nerve cord consolidation is inversely proportional to overall body length. With respect to phylogeny, the degree of consolidation of the nerve cord docs not consistently support the traditional Carabinae‐Harpalinae subfamily division. However, the Harpalinae always have four or less discrete abdominal ganglia (with the sole exception of the Broscinij, whilst the Carabinae exhibit almost the whole range of variations. Thus the Harpalinae (or the major pari of it) may be a monophyletic group, but this is not true of the Carabinae. Trends in the degree of ventral nerve cord consolidation for the various tribes were noted, and phylogenetic implications were evaluated wherever possible. Copyright © 1990, Wiley Blackwell. All rights reserved