Abdomens: The rear and usually the longest (ten-segmented in mayflies) portion of an insect's body, to which the tails are attached.
Instar: Many invertebrates molt through dozens of progressively larger and better-developed stages as they grow. Each of these stages is known as an instar. Hard-bodied nymphs typically molt through more instars than soft-bodied larvae.
Monotypic: a taxonomic level containing a single lower level. Example - a genus consisting of a single species.
Thoracic: The thorax is the middle part of an insect's body, in between the abdomen and the head, and to which the legs and wings are attached.