Subcapitulum

Illustration of the gnathosoma, showing the subcapitulum.

The subcapitulum (from Latin sub, under and capitulum, small head), also known as infracapitulum,[1][2] hypognathum[3] or hipognatum, refers to the ventral part of the gnathosoma (the part of the body comprising the mouth and feeding parts)[4] or the fusion of the palpal coxae and the labrum (the upper or anterior mouthpart) complex[3] present in the mites on which the mouth, pedipalps (the second pair of appendages), lips and pharynx are located.[1] In its central part, the gutter hypostome (the anterior part of the subcapitulum) is formed, which in the forceps is transformed into a serrated pricking system.[4] The anterolateral parts of the subcapitulum may be equipped with corniculi (horn-like process) or rutella (the hypertrophied setae on the hypostome).[4] It is delimited by the capitular apodeme (an ingrowth of the exoskeleton), which separates it from the cheliceral frame.[1]

The function, morphology or definition of the subcapitulum can vary within the Acari clades. At the base of the hypostome, there can be sternal apophyses, which in Mesostigmata are formed in the tritosternum (the sternum of the third body segment).[4] The front edge of the subcapitulum can be provided with paralaciniae (a pair of small processes). In Oribatida, its basal section forms a mentum.[2] In some Actinotrichida, the dorsal part forms the neck.[1] In some Cheyletoidea and parasitic Myobiidae, the subcapitulum merges with the stylophore (chelicerae formed of fused cheliceral bases) to form a gnathosomal capsule. In some Prostigmata clades, a subcapitulum or the whole capsule is referred to as rostrum.[2]

References

  1. 1 2 3 4 Maggenti, Armand R.; Maggenti, Mary Ann (2005). Gardner, Scott L., ed. Online Dictionary of Invertebrate Zoology.
  2. 1 2 3 Walter, David E. (2005). "Glossary of Acarine Terms". Retrieved 2 September 2015.
  3. 1 2 Dunlop, Jason A. (2000). "The epistomo-labral plate and lateral lips in solifuges, pseudoscorpions and mites". Ekológia, Bratislava. 19: 67–78.
  4. 1 2 3 4 Czesław Błaszak, ed. (2011). "1". Zoologia. T. 2, cz. 1, Stawonogi: szczękoczułkopodobne i skorupiaki (in Polish). 2. Warsaw: Polish Scientific Publishers PWN. pp. 130, 142, 186–187, 204, 371. ISBN 978-83-01-16568-0.


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