The antenna usually lies in an antennal groove. Some authors call it also the antennal fossa. The antenna is composed of three segments, the first, the second and the club of the antenna. The club is composed of 9 individual segments, in some species several of those segments can be fused together [taxonomical importance].
The eye of the flea is mostly nothing more than a chitin-layered protuberance. ESEM pictures suggest, that there is superficially no compound eye structure retained.
It is the palp bearing lobe of the maxilla. The whole maxilla actually includes the maxillary palps, the maxillary lacinia [sometimes also called maxillary stylet], the epipharynx and the labial palp.
3 to 5 segmented [taxonomical importance] part of the maxilla.
The genal process is a posterior prolongation of the head, which may or may not narrow to a sharp tip. Sometimes the structure is more ventrally or posteriorly elongated, in which case it is referred to as genal lobe.
The frons is the frontal part of the head. Many authors also include in this term a structure called clypeus. It is only visible in light microscopy [inside structure] and is a portion of the anterior part of the frons, where the cibarial dilatator muscles are attached.
This term denotes the posterior part of the head [see also head, integricipit/ fracticipit]
Fine ridges in the bulga. These corrugations are filled with secretion from the spermathecal glands in mature fleas, and the sperms are packed tightly between those ridges.
The spermatheca is part of the female reproductive organs. It is the place, where the sperms are stored, after they entered through the spermathecal duct [D]. Sometimes the spermatheca is paired [taxonomical importance]. It is a cuticular organ. When an egg passes along the oviduct, stored sperm from the spermatheca is released and moves into the bursa copulatrix. A ring of glands is surrounding the bulga and secrets nutrient material into the lumen, before the organ receives sperm.