Chaetotaxy – Introduction
Chaetotaxy generally refers to the arrangement of macrotrichia (setae and setulae) on certain body areas. Especially important are those forming stable patterns in numbers, position, and orientation. Chaetotaxy is used enormously in the taxonomy of adult ‘higher’ flies (i.e. Acalyptrate+Calyptratae). A lot of handy chaetotaxy characters can be gleaned from the interactive keys linked in the Diptera Resources page. The two aspects shortly treated in the links below are both dorsal, thus readily captured in field macro photography, and are some of the most productive for taxa separation in this group.
Notes on ‘macrotrichia’….
Macrotrichia generally refers to all thickened hairs, both long and short. The stronger, and typically longest, macrotrichia are called setae (often bristles in older literature), with the smaller undifferentiated macrotrichia called setulae (or hairing) — there’s no definitive sorting between setae and setulae, and sometimes certain seta are weak enough to be lost in the setulae, but generally the two forms are easy to recognise with little practice.
.
Chaetotaxy — Dorsocentrals (& Acrostichals)
Chaetotaxy — Fronto-orbitals
