From ZooTerms (Dictionary of Invertebrate Zoology)
phallobase (noun; Greek
phallos, penis;
basis, bottom): (
Arthropoda:
Insecta) Proximal part of the
phallus of males, a large
basal structure supporting the
aedeagus; a
thecal fold or
sheath around the
aedeagus;
basal phallic sclerites in the
wall of the
genital chamber.