Allotanaupodidae

Zhang, Zhi-Qiang & Fan, Qing-Hai, 2007, Allotanaupodidae, a new family of early derivative Parasitengona (Acari: Prostigmata), Zootaxa 1517, pp. 1-52 : 5-6

Allotanaupodidae fam. nov.

Diagnosis

The same as that for the superfamily.

Type genus

Allotanaupodus gen. nov. (by present designation).

Etymology

Derived from the type genus.

Remarks

This new family, as the name implies, is most similar to another early derivative family Tanaupodidae of the superfamily Tanaupodoidea. It is also similar to Johnstonianidae (placed by Welbourn, 1991 in his Trombiculoidea) in some aspects. Allotanaupodidae fam. nov. can not be placed in any of the four superfamilies of Trombidiina sensu Welbourn (1991), although it is a member of Trombidiina without question. Thus it is provisionally placed in its own superfamily within Trombidiina.

This new family is characterized by a number of interesting features, some shared with other early derivative Parasitengona and others unique. A detailed analysis is presented below.

Prodorsal trichobothria in the adults and deutonymphs. In Erythraeina, the Erythraeoidea has two pairs of trichobothria within well-developed sensory areas and the Calyptostomatoidea has one pair. Most Trombidiina have a single pair of trichobothria within a pair of well-developed sensory areas. Some Johnstonianidae (e.g. Diplothrombium ) have two pairs of trichobothria within well-developed sensory areas. Allotanaupodidae fam. nov. is unique among terrestrial Parasitengona in the complete loss of both trichobothria and associated sensory areas. In early derivative terrestrial Parasitengona , the presence of two pairs of trichobothria is assumed to be the plesiomorphic condition (the outgroup Anystidae , for example, has two pairs). Newell (1957) noted the tendency toward the loss of the anterior pair of trichobothria in some Johnstonianidae (and also Tanaupodidae ). In Allotanaupodidae fam. nov., the posterior pair of the trichobothria is also lost. It should be noted that the complete loss of trichobothria is also seen in most water mites, with few exceptions (e.g. Hydrophantoidea and Stygothrombidoidea).

Prodorsal plate. The broad prodorsal plate in adults and deutonymphs in this family resembles those present in most larval Trombidiina. This plesiomorphic condition is shared by adults and deutonymphs of other early derivative groups such as Tanaupodidae (e.g. Lassenia ) and Johnstonianidae (e.g. Johnstoniana ) ( Newell 1957). In most derived Trombidiina, the prodorsum is dominated by the crista metopica and the prodorsal plate is often restricted to areas close to the crista .

Crista metopica . Most Trombidiina have well-developed crista metopica with associated sensory areas. The absence of a well-developed crista metopica is seen in some Trombellidae , some Johnstonianidae and Audyanidae . The crista metopica in the new family is a simple linear rod. A similar condition is seen in the early derivative Tanaupodidae , although the latter has a pair of trichobothria.

Hysterosomal dorsal setae and plates. The simple setae arising from small plates in the new family resemble those seen in larval Trombidiina and in the adults and deutonymphs of some other early derivative Trombidiina ( Tanaupodidae and Johnstonianidae ). The new family differs from the last two families in the presence of at least one pair of plates in each of the C to H rows with multiple setae (although this is not seen in Paratanaupodus ).

Number of genital acetabula in adults. The number of genital acetabula is typically one pair in protonymphs, two pairs in deutonymphs and three pairs in tritonymphs/adults in the Acariformes (Grandjean- Oudemans rule). The number of genital acetabula is quite variable in water mites ( Cook 1974) and also shows some variation in Erythraeina and Trombidiina. In Erythraeina, the adults of Calyptostomatoidea retain the deutonymphal condition of having two pairs of genital acetabula. In Trombidiina, parallel evolution is seen in Allotanaupodidae fam. nov. and some Trombellidae such as Neonothrothrombium and Durenia ( Robaux 1968) and Charadracarus of Johnstonianidae ( Newell 1960) .

Palptarsus. The palptarsus in the new family is short, its length similar to its diameter or slightly longer. In most other Trombidiina, the palptarsus is elongate (much longer than diameter). A correlated character is the subdistal insertion of the palptarsus on the ventral surface of the tibia in the new family. In other Trombidiina, the palptarsus is inserted proximally or near the middle on palptibia, and the elongate palptarsus and the distal part of the palptibia (including the tibial claw) form a thumb-claw complex. In the new family, the palptarsus is short and it thus can only form a thumb-claw complex by subdistal insertion.

The above analysis shows that the monophyly of Allotanaupodidae fam. nov. is supported by the following synapomorphies in adults/deutonymphs: (1) absence of trichobothria and sensory areas, (2) the presence of one or two pairs of plates with multiple setae on C to PS rows of dorsal hysterosoma, (3) the presence of only two pairs of genital acetabula in adults, and (4) palptarsus distally inserted on the palptibia.