Hectopsyllidae is a small family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 of flea

Flea

Flea is the common name for insects of the order Siphonaptera which are wingless insects with mouthparts adapted for piercing skin and sucking blood...

s, containing only the chigoe flea

Chigoe flea

The chigoe flea or jigger is a parasitic arthropod found in most tropical and sub-tropical climates, not to be confused with the larval form of Trombiculidae found in more temperate climates. In Brazil, the parasite is referred to as bicho-de-pé . At 1 mm long, the chigoe flea is the smallest...

s and the sticktight fleas. They were formerly known as Tungidae, and by authorities that demote the Pulicoidea to family rank

Taxonomic rank

In biological classification, rank is the level in a taxonomic hierarchy. Examples of taxonomic ranks are species, genus, family, and class. Each rank subsumes under it a number of less general categories...

 they are treated as subfamily Hectopsyllinae (formerly Tunginae). Only 2 genera

Genera

Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...

 with some handfuls of species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 are placed here nowadays, making further subdivision of the family unnecessary.

These fleas usually parasitize terrestrial

Terrestrial animal

Terrestrial animals are animals that live predominantly or entirely on land , as compared with aquatic animals, which live predominantly or entirely in the water , or amphibians, which rely on a combination of aquatic and terrestrial habitats...

 mammal

Mammal

Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s, and in a few cases bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s and bat

Bat

Bats are mammals of the order Chiroptera "hand" and pteron "wing") whose forelimbs form webbed wings, making them the only mammals naturally capable of true and sustained flight. By contrast, other mammals said to fly, such as flying squirrels, gliding possums, and colugos, glide rather than fly,...

s. The females are by and large immobile and will remain attached to the same place for prolonged periods of time, possibly until they die. Hectopsylla narium was found to live inside the nostril

Nostril

A nostril is one of the two channels of the nose, from the point where they bifurcate to the external opening. In birds and mammals, they contain branched bones or cartilages called turbinates, whose function is to warm air on inhalation and remove moisture on exhalation...

s of the Burrowing Parrot (Cyanoliseus patagonus patagonus).

The closest living relatives of the Hectopsyllidae are the common fleas, Pulicidae

Pulicidae

Pulicidae is a flea family in the order Siphonaptera....

. The Hectopsyllidae differ from these by the following characteristics:

• Antenna
  Antenna (biology)
  Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....
  
  l club with punctiform sensilla
  Sensilla
  A sensillum is an insect sensory organ protruding from the cuticle, or sometime lying within or beneath it. Sensilla are divided in chemical, mechanical , thermal and visual....
  
  
• dorsal
  Dorsum (biology)
  In anatomy, the dorsum is the upper side of animals that typically run, fly, or swim in a horizontal position, and the back side of animals that walk upright. In vertebrates the dorsum contains the backbone. The term dorsal refers to anatomical structures that are either situated toward or grow...
  
   and medial seta
  Seta
  Seta is a biological term derived from the Latin word for "bristle". It refers to a number of different bristle- or hair-like structures on living organisms.-Animal setae:In zoology, most "setae" occur in invertebrates....
  
  e on the abdominal terga of the female reduced
• Left and right sensilia separated midways and with 8 sensory pits
• Proximal arm of ninth sternite
  Sternum (arthropod)
  The sternum is the ventral portion of a segment of an arthropod thorax or abdomen.In insects, the sterna are usually single, large sclerites, and external...
  
   lobe-shaped
• Well-sclerotized
  Sclerosis (medicine)
  In medicine, sclerosis refers to the stiffening of a structure, usually caused by a replacement of the normal organ-specific tissue with connective tissue.Types include:...
  
   and crisply outlined lateral lamina of the aedeagal
  Aedeagus
  An aedeagus is a reproductive organ of male insects through which they secrete sperm from the testes during copulation with a female insect...
  
   apodeme

In addition, they have reduced setae on the antennal flagellum, but this may be an adaptation bearing little phylogenetic information.