The post-spiracular seta and sensillus in the Mallophaga (Insecta)

Attention is drawn to the presence in some species of Ischnocera (Mallophaga) of sensilli on the turgum of the abdomen, which are here called post-spiracular sensilli. The sensilli may lie posterior to the margin of the turgal plates and be associated with the post spiracular setae, when in this position they are here called adjacent sensilli. When the adjacent sensilli are actually touching the alveoli of the post-spiracular setae, they are called contiguous sensilli. The sensilli may lie on the turgal plate and may not be associated with any setae; in this position they are said to be not adjacent. In some cases the presence or absence of adjacent sensilli is a useful systematic character.