| Schizophora | |
|---|---|
 | |
| Marsh fly (Sciomyzidae) | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Diptera |
| Suborder: | Brachycera |
| Infraorder: | Muscomorpha |
| Clade: | Eremoneura |
| (unranked): | Cyclorrhapha |
| Section: | Schizophora Becher, 1882 |
| Subsections | |
TheSchizophora are asection oftrue flies containing 78 families, which are collectively referred to asmuscoids, although technically the term "muscoid" should be limited to flies in the superfamilyMuscoidea; this is an example of informal, historical usage persisting in the vernacular. The section is divided into two subsections, theAcalyptratae andCalyptratae, which are commonly referred to asacalyptrate muscoids andcalyptrate muscoids, respectively.
The defining feature of the Schizophora is the presence of a special structure used to help the emerging adult fly break free of thepuparium; this structure is an inflatable membranous sac called theptilinum that protrudes from the face, above theantennae. The inflation of the ptilinum (using fluidhemolymph rather than air) creates pressure along the line of weakness in the puparium, which then bursts open along the seam to allow the adult to escape. When the adult emerges, the fluid is withdrawn, the ptilinum collapses, and the membrane retracts entirely back inside the head. The large, inverted, U-shaped suture in the face through which it came, however, is still quite visible, and the name "Schizophora" ("split-bearers") is derived from this ptilinal or frontal suture. The term was first used byEduard Becher.
In contrast to eggs of other arthropods, most insect eggs are drought-resistant, because inside the maternalchorion, two additional membranes develop from embryonic tissue, theamnion and theserosa. This serosa secretes acuticle rich inchitin that protects the embryo against desiccation. In the Schizophora, however, the serosa does not develop, but these flies lay their eggs in damp places, such as rotting organic matter.[1]
The absence of schizophoran flies fromCretaceous rocks implies that they likely rapidly diversified during theCenozoic, with the first appearance of the group during the earlyPaleogene,[2] around 53 million years ago, with it being estimated that they split off from other flies around 66-65 million years ago.[3]