Endeostigmata

t

Taxonomy

Alycidae Canestrini & Fanzago 1877 (=Pachygnathidae Kramer 1877, Bimichaeliidae Womersley 1944Womersley 1944:
Womersley H. 1944. Australian Acarina, families Alycidae and Nanorchestidae. Transactions of the Royal Society of South Australia 68: 133–143.)

Diagnosis

Prodorsumprodorsum:
the dorsal surface of the propodosoma.
with 2 pairs 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).
(si, ve) and 3 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.
(se, in, exp); naso and median eye absent, one pair of lateral eyes. 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.
with teeth and lobe; 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 5 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.
; chelicerae chelate-dentatechelate-dentate:
pincer-like chelicerae with teeth.
, each with 1 setaseta:
(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.
. Opisthosomaopisthosoma:
(= abdomen) the posterior body division in arachnids; usually not distinct in mites because of the fusion of the opisthosoma with part of the prosoma to form the idiosoma.
hypertrichous; 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).
.

Remarks

This genus is poorly known, but is most similar to Amphialycus, which retains setae vi and a median eye (but without a distinct naso) and has 2 pairs of lateral eyes. Species of Alycus also have lost the median eye, but usually retain a vestigial naso and setae vi.

References

• Halbert 1920Halbert 1920:
  Halbert JN. 1920. The Acarina of the seashore. Proceedings of the Royal Irish Academy (Section B) 35 (7): 106-152.
• Zakhvatkin 1949Zakhvatkin 1949:
  Zakhvatkin AA. 1949. New representatives of apparently segmented mites (Acarina: Pachygnathidae). Entomologicheskoe Obozrenie 30: 291-297.