| dc.description.abstract | Larvae of Ithycerus are described for the first time. Ten
instars are identified with the possibility of more to be found.
The pupa remains unknown. Spiracular air tubes and orifices show
allometric growth and this, combined with body and head capsule
measurements, is used to separate instars. Female and male
reproductive systems are described. Females have two ovarioles
per ovary. Adult and larval stages have four cryptonephric
Malphigian tubules in the digestive tract. Adult and larval
nervous systems appear to be primitive in possessing long connectives
between ganglia. The first instar larva of Arrhenodes
minutus (Drury) is described for the first time. The first
illustrations of Antliarrhinus larvae are included. Ithycerus
noveboracensis (Forster) has a two year life cycle at least and
possibly three. Adults do not overwinter.
Three families of woody plants are associated with Ithycerus,
the Betulaceae, Juglandaceae and Fagaceae, with a preference for
species of Fagaceae. Adults are also occasionally found on
introduced fruit trees (Rosaceae). There is no obvious courtship
in Ithycerus. Oviposit!on takes place in soil; eggs are laid singly
and covered with fecal matter. The larvae feed on the vascular
cambium of the roots of host plants.
Several grooming movements and modes new for Coleoptera
were discovered in Ithycerus and include bilateral fore-mid leg
rub, mid-hindleg rub (third mode), bilateral hindleg rub (third
mode), simultaneous fore-midleg rub (one side), mid-hindleg rub
(other side) and flagellum extend. Female A. minutus rapidly
flutter the tips of their antennae against the tip of the rostrum
to dislodge wood particles trapped there while drilling egg holes.
Evidence is presented for the possibility of evolution of
three forms of Ithycerus in pleistocene refugia. The family
Ithyceridae is maintained on the basis of new characters, primarily
larval. The family is viewed as the most primitive of the four
apionid-like families recognized in this study, the others being
Brenthidae, Antiiarrhinidae status nov. and Apionidae. The family
Antiiarrhinidae is placed near Apionidae. Adult and larval ventral
nervous systems are discussed in light of their possible value as
phylogenetic indicators. An evolutionary sequence is postulated
for the numbers and positions of sensilla on the labra of larvae. | |
