Endeostigmata and Sphaerolichida introduction

Taxonomy

The Endeostigmata (cohort Pachygnathina of Krantz 1978Krantz 1978:
Krantz GW. 1978. A manual of acarology [2nd ed.]. Oregon State University Book Stores, Corvallis.) was proposed by Grandjean (1937) for a cluster of early derivative acariform mites that he believed linked the Oribatida to the Prostigmata. Over the next few years Grandjean studied several genera of PACHYGNATHIDAE (now ALYCIDAE) in detail and proposed three (ALICORHAGIIDAE, TERPNACARIDAE, NANORCHESTIDAE) of the 10 currently recognized families. Subsequent work by Kethley (1977) (OEHSERCHESTIDAE, GRANDJEANICIDAE), Coineau and Theron (1983)Coineau and Theron (1983):
Coineau Y, Theron P. 1983. Les Micropsammidae, n. fam. d’Acariens Endeostigmata des sables fin. Acarologia 24: 275–280. (MICROPSAMMIDAE), Kethley (1989)Kethley (1989):
Kethley J. 1989. Proteonematalycidae (Acari: Acariformes), a new mite family from fore-dune sand of Lake Michigan. International Journal of Acarology 15 (4): 209–217. (PROTEONEMATALYCIDAE), and Lindquist and Palacios-Vargas (1991)Lindquist and Palacios-Vargas (1991):
Lindquist EE, Palacios-Vargas JG. 1991. Proterorhagiidae (Acari: Endeostigmata), a new family of rhagidiid-like mites from Mexico. Acarologia 32 (4): 341–363. (PROTERORHGAGIDIIDAE) raised the number of endeostigmatanendeostigmatan:
a member of the Endeostigmata; characteristic of or belonging to the Endeostigmata.
families to nine. Additionally, NEMATALYCIDAE Strenzke (1954) now is considered to be a member of the Endeostigmata (Evans 1992Evans 1992:
Evans GO. 1992. Principles of Acarology. CAB International, Wallingford, UK.).

Synonymies & other confusions. Although traditionally the Endeostigmata has been treated as a primitive group of Prostigmata, its affinities lie with the oribatid mites in the acariform order Sarcoptiformes. The exceptions are two of Grandjean’s families, SPHAEROLICHIDAE and LORDALYCIDAE, that are now placed in the Sphaerolichida as a sister group to the Prostigmata (OConnor 1984). In addition to the problem with higher-level placement, the Endeostigmata is rich in other nomenclatorial confusions. For example, the first nominate family, PACHYGNATHIDAE Kramer (raised to accommodate members of the genus Pachygnathus Dugês) is a junior homonym of a spider family of the same name (based on Pachygnatha, and the spider family itself a junior synonym of Tetragnathidae). PACHYGNATHIDAE is best referred to ALYCIDAE (Judson 2000Judson 2000:
Judson M. 2000. Nomenclatorial problems assoicated with the names Alycidae Canestrini & Fazago, 1877 and Pachygnathidae Kramer, 1877 (Acari). Memorie della Società Entomologica Italiana 78 (2): 533–540.) (rather than the BIMICHAELIIDAE of some recent authors). Additionally, Lordalycus Grandjean (LORDALYCIDAE) is a junior synonym of Hybalicus Berlese, the latter of which was designated by Theron as the type genus for his family Hybalicidae (Theron 1974Theron 1974:
Theron PD. 1974. Hybalicidae, a new family of endeostigmatic mites (Acari: Trombidiformes). Acarologia 16: 397–412.). The species of Hybalicus described in that work are referable instead to the oft-misspelled endeostigmaticendeostigmatic:
adjectival form of Endeostigmata. 
genus Oehserchestes Jacot (OEHSERCHESTIDAE) (Kethley 1977). Finally, the enarthronote oribatid family PEDICULOCHELIDAE often has been misplaced in the Endeostigmata.