Dorsal view of Isobactrus uniscutatus, from Bartsch & Smit (2006).

Belongs within: Halacaridae.

Isobactrus is a cosmopolitan genus of marine halacarid mites with the ventral armature reduced and not forming a solid shield, and a club-like seta in front of the lateral disti-dorsal seta on tarsi I and II (Newell 1947).

Characters (from Newell 1947): Genital opening of female ventral in position, not guarded by opercula and surrounded by only three pairs of setae. Adults more heavily armoured than nymphs; all dorsal and ventral plates separate. Ventral plates greatly reduced, not forming a solid shield. Femur I greatly swollen, less than 1.5 times as long as high. Tarsi I and II each with a single club-like seta in front of lateral disti-dorsal seta. Two claws on all tarsi.

<==Isobactrus Newell 1947AB07
    |--I. microdensAB07
    `--+--I. macquariensis Newell 1984AB07, L90
       `--+--I. magnus (Lohmann 1907)AB07, N47 [=Rhombognathus magnusN47]
          `--+--I. calderensisAB07
             `--+--+--I. obesusAB07
                |  `--+--I. luxtoniAB07
                |     `--+--I. asperAB07
                |        `--+--I. ponapensisAB07
                |           `--+--I. australiensisAB07
                |              `--I. pacificusAB07
                `--+--I. peregrinusAB07
                   `--+--+--I. gryposetusAB07
                      |  |--+--I. hamatusAB07
                      |  |  `--I. levis (Viets 1927)AB07, N47 [=Rhombognathus levisN47]
                      |  `--+--I. hartmanniAB07
                      |     `--+--I. dentatusAB07
                      |        |--I. latistriatusAB07
                      |        `--I. tuberculatusAB07
                      `--+--I. ponticusAB07
                         `--+--I. rugosusAB07
                            `--+--I. uniscutatusAB07
                               `--+--I. cryptorhynchus (Trouessart 1901)AB07, N47 [=Rhombognathus cryptorhynchusN47]
                                  `--+--I. ungulatusAB07
                                     `--+--*I. setosus (Lohmann 1889)N47, AB07, N47 [=Aletes setosusN47, Rhombognathus setosusN47]
                                        |--I. hutchinsoni Newell 1947AB07, N47
                                        `--I. pulchellusAB07

*Type species of generic name indicated


[AB07] Abé, H., & I. Bartsch. 2007. Historical biogeography of the halacarid mite genus Isobactrus (Prostigmata, Halacaridae). In: Morales-Malacara, J. B., V. M. Behan-Pelletier, E. Ueckermann, T. M. Pérez, E. G. Estrada-Venegas & M. Badii (eds) Acarology XI: Proceedings of the International Congress pp. 119–126. Instituto de Biología and Faculdad de Ciencias, Universidad Nacional Autónoma de México, Sociedad Latinoamericana de Acarología: México.

[L90] Luxton, M. 1990. The marine littoral mites of the New Zealand region. Journal of the Royal Society of New Zealand 20 (4): 367–418.

[N47] Newell, I. M. 1947. A systematic and ecological study of the Halacaridae of eastern North America. Bulletin of the Bingham Oceanographic Collection 10 (3): 1–232.

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