Endeostigmata

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Taxonomy

Grandjeanicidae Kethley, 1977

Diagnosis

Prodorsumprodorsum:
the dorsal surface of the propodosoma.
with 1 pair of filiform trichobothriatrichobothrium:
(pl. trichobothria) (= bothridial sensillum) an often elaborately modified seta set in a cup-like base; forms include filiform, ciliate, pectinate or variously thickened or clubbed (bat-like to globose or capitate).
(bo) and 4 pairs of setaeseta:
(pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
(exp absent); naso well developed and bearing setae ro; median and lateral eyes absent. Subcapitulumsubcapitulum:
(also infracapitulum) the venter of the capitulum; the ventral faces of the fused palpcoxae; apparently formed independently in the two superorders of mites.
with 3 pairs of adoral setaeseta:
(pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
and 2 pairs of hypostomal setaeseta:
(pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
; rutellarutellum:
(pl. rutella) In Sarcoptiformes, the hypertrophied setae on the hypostome, often toothed; not to be confused with a corniculus (although possibly a homologue).  In Astigmata, the rutellum may be referred to as a pseudorutellum, although it is the same structure.  Various forms of rutella are recognized, including the atelebasic and pantelebasic.
slender, distally dentate; chelicerae chelate-dentatechelate-dentate:
pincer-like chelicerae with teeth.
, each with 2 setaeseta:
(pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
. Bodybody:
the idiosoma of mites.
globular with 3–4 pairs of pilosepilose:
with a covering of hairs or hair-like processes.
-acicular setaeseta:
(pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
in row c, and 11 pairs of pilosepilose:
with a covering of hairs or hair-like processes.
and truncate setaeseta:
(pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
in rows d–h; 3 pairs of genital papillaegenital papillae:
 1-3 pairs of extrusible finger-like to button-like projections, usually retracted into in the genital vestibule of acariform mites; sometimes formed as sessile disks around the genital opening; thought to be osmoregulatory structures; modified or multiplied and dispersed over the body in many freshwater mites.  Genital papillae are absent in the larva, but may be added ontogenetically: protonymphs have one pair, deutonymphs two pairs, and tritonymphs (and adults) three pairs.  The tritonymphal pair of papillae is often lost.  The serially homologous Claparède's organ is usually present in the larvae (and prelarvae) of mites exhibiting genital papillae in nymphs and adults (Oudeman's Rule).
; 8 pairs of genital setaeseta:
(pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
; ovipositorovipositor:
an extrusible organ for laying eggs.  Female oribatids have a well developed ovipositor that ends in three finger-like projections.  Ovipositors are less well developed or absent in other mites.
, eugenital setaeseta:
(pl. setae, from L. = bristle) cuticular process composed of a hollow shaft (sometimes filled with a refractive material) produced from a membranous socket (the alveolus); the hair-like, spine-like, branched or variously expanded structures on the surfaces of the legs and body.  Most setae function as mechanoreceptors, but others (e.g., solenidia) are chemoreceptors or have unknown or ambiguous functions.
present. Pretarsustarsal apotele:
(also pretarsus) the most distal segments of legs and palps bearing the claws and empodium
I without claws or empodiumempodium:
(pl. empodia) an unpaired structure arising between the tarsal claws, ranging from pad-like to claw-like and often bearing structures such as tenent hairs, dense setulae, or taking the form of a featherclaw (Eriophyoidea)..
, but with auditory complex and flagellum. Gut boluses of fungal material and/or arthropod cuticle often present. Males unknown.

Remarks

These mites are relatively rare and primarily tropical in distribution. Legs I are used as antennae, and the complex arrangement of setalsetal:
of or pertaining to a seta.
structures distally on tarsustarsus:
(pl. tarsi) the subdistal leg segment between the tibia and the pretarsus (apotele).
I has been interpreted as an auditory-stridulatory complex (Coineau and Theron 1997). The gut contents of the specimens from Queensland contain some fungal matter, but mostly consist of the cuticle of small mites, especially Immature Oribatida (Walter 2001Walter 2001:
Walter DE. 2001. Endemism and cryptogenesis in ‘segmented’ mites: A review of Australian Alicorhagiidae, Terpnacaridae, Oehserchestidae and Grandjeanicidae (Acari, Sarcoptiformes). Australian Journal of Entomology 40: 207-218.).

Similar taxa

The globular body and highly modified legs I are reminiscent of Sphaerolichus, but the long flagellum, single prodorsal sensillus, and array of pilose, cuneiform opisthosomal setae are distinctive.

References

• Kethley 1977bKethley 1977b:
  Kethley JB. 1977b. The status of Hybalicus Berlese, 1913 and Oehserchestes Jacot, 1939 (Acari: Acariformes: Endeostigmata). Fieldiana Zoology 72 (4): 59-64.
• Kethley 1982dKethley 1982d:
  Kethley JB. 1982d. Endeostigmata. pp. 118-120. In: Parker SP, ed. Synopsis and classification of living organisms, Vol. 2. McGraw-Hill, New York.
• Kethley 1990aKethley 1990a:
  Kethley JB. 1990a. Acarina: Prostigmata (Actinedida). pp. 667-756. In: Dindal DL, ed. Soil biology guide. John Wiley & Sons, Brisbane.
• Theron 1974Theron 1974:
  Theron PD. 1974. Hybalicidae, a new family of endeostigmatic mites (Acari: Trombidiformes). Acarologia 16: 397-412.