Mideopsis Neuman, 1880

Pešić, Vladimir, Cook, David, Gerecke, Reinhard & Smit, Harry, 2013, The water mite family Mideopsidae (Acari: Hydrachnidia): a contribution to the diversity in the Afrotropical region and taxonomic changes above species level, Zootaxa 3720 (1), pp. 1-75 : 7-8

Genus Mideopsis Neuman, 1880

Type species: Mideopsis orbicularis (Müller, 1776)

Diagnosis: Surface of dorsal shield varying from plain to various development of ornamentation and ridges; posterior suture lines of Cx-IV poorly developed and not closely surrounding genital field; coxae not forming a medial suture line; a short ridge extending anterolaterally from area of middle of Cx-III (a relatively long, pronounced ridge usually extending anterolaterally to edge of ventral shield); Cxgl-2 usually located well anterior to genital field; either condyles or small extensions of Cx-IV associated with openings for insertion of IV-L; three pairs of Ac; Ac flanked by a setae- bearing sclerites which typically are fused with ventral shield but not fused in some species; typically the glandularia with the long associated setae at posterior end of ventral shield lacking the associated glands, but in one species with one pair of glands (both pairs of glands present); swimming setae present; palp not uncate; palpal morphology variable, P-4 with two small setae near middle which lie either directly on surface or on variously developed tubercles; with the exception of the genital field area no sexual dimorphism of idiosoma, legs or palp (males of the South American species group with extensive patches of small setae flanking genital field).

Remarks: Most probably the species from South America represent a distinct genus characterized by extensive setal patches in the genital field area of males. For the time being we keep these species in the present concept of Mideopsis , waiting until both sexes are known of a number of species described by Lundblad and K. Viets from females only.

Distribution: Disjunct. One group of species are Holarctic with a few species extending into Costa Rica in the New World and another group confined to South America.

Genus Neoxystonotus Lundblad, 1927 , nov. stat.

Type species: Xystonotus torrei Marshall, 1927

Diagnosis: Dorsal shield with varying degrees of ridge development; posterior margins of Cx-IV poorly developed; coxae well separated medially; short ridges extending anterolaterally from region of third coxae; Cxgl- 2 located anterolateral to genital field; small condyles present on openings for insertion of IV-L; three pairs of Ac, with only two to five pairs of setae flanking gonopore; two pairs of glandularia with long associated setae at posterior end of ventral shield with both pairs of glands present; swimming setae present; palp not uncate; P-4 with a well developed, interiorly directed projection bearing two small setae similar to Xystonotus ; males exhibit sexual dimorphism; often in the shape of the idiosoma, and in the lengthening and curvature of IV-L-5 and the tendency for glandularia of the dorsal shield to shift posteriorly, often ending with three pairs of glandularia in a small group at extreme posterior end of dorsal shield.

Remarks: Closely related to other South American genera, but the unusual sexual dimorphism listed above will easily distinguish this genus from all other genera.

Distribution: Mostly neotropical but with one described species extending into central USA.

Genus Octomideopsis K. Viets, 1931 , nov. stat.

Type species: Mideopsis minuta Soar, 1910 .

Diagnosis: Both the original description and illustrations of this taxon are very inadequate and unfortunately the type, and only specimen cannot be located. However, two important characteristics were listed: four pairs of Ac and the legs without swimming setae. Also, Soar had done considerable work on British Arrenurus and, if the palp had been uncate, it almost certainly would have been mentioned in the description.

Remarks: If the characters listed in the original description are correct, and we are assuming they are, this taxon deserves full generic ranking. However, its status will remain somewhat tentative until additional specimens are collected.

Distribution: Known only from the type locality (Lake Tanganyika in East Africa).