Nilotonia Thor, 1905

Goldschmidt, Tom, 2008, Taxonomical, ecological and zoogeographical studies on anisitsiellid water mites (Acari: Hydrachnidia: Anisitsiellidae Koenike, 1910) from Madagascar, Zootaxa 1954 (1), pp. 1-120 : 8

Nilotonia Thor, 1905

Diagnosis (modified after Cook 1974, Gerecke 1992, Goldschmidt 2004b, Panesar 2004): Dorsum bearing two small post-ocular platelets and one larger postero-medial plate (from relatively small platelets to large plates, sometimes even fused); secondary sclerotization of venter absent to extensive, especially at caudal margin of Cx-IV and post-genital sclerite (in some species secondary sclerotization of Cx-IV fused with postgenital sclerite, forming ventral shield); coxae in four groups, Cx-I and Cx-II medially separated or fused, suture between Cx-III and Cx-IV variable; leg-IV-6 without claws, with terminal peg-like setae and none, one or several larger sub-terminal setae; well developed terminal claws on leg-I to leg-III without, with single or with several clawlets; palp typical for the family.

Remarks: The diagnosis of the genus Nilotonia still remains very broad, including a wide variety of characters and the number and separation of subgenera is unclear. Lundblad (1952) separated the African species of Nilotonia mainly by the completeness or incompleteness of the suture between Cx-III and Cx-IV in the subgenera Neodartia and Dartiella ; meanwhile both have been synonymised with Nilotonia s. str. (K. Viets 1956; Cook 1974). Cook (1974) as well as K.O. Viets (1987) separate five subgenera within Nilotonia , mainly by means of the number of terminal/sub-terminal setae on leg-IV-6, sexual dimorphism on leg-II-5, presence/ absence of swimming hairs and degree of secondary sclerotization. Following K.O. Viets (1987), all African species (except of one species in the subgenus Dartia ) belong to the principle subgenus Nilotonia s. str.. In a redefinition and re-organisation of the subgenera of Nilotonia, Panesar (2004) separated seven (partly different) subgenera also including size and arrangement of the acetabula as well as length relations of the medial coxal suture of Cx-I and the genital field into taxonomic diagnosis. He shifted most African species to the subgenera Dartiella and Manotonia. As the type species of the genus — Nilotonia loricata ( Nordenskiöld, 1905) — possess true swimming hairs, only two species from Africa and two from India are included in Nilotonia s. str. ( Panesar 2004). Until additional information (larval descriptions, morphology of genital skeleton, morphology of all legs in all species, molecular data) on most species are available, I am following the present subgeneric classification by Panesar (2004). However, as the separation of the subgenera is still relatively weak, often based upon very few characteristics and with many exceptions, in the following remarks to the new species the differences to similar species in other subgenera (and sometimes even similar genera) are also discussed. With regard to the new material of Nilotonia (especially the subgenera Telotaolana and Cookonia ) from Madagascar, Mamersonia (K. Viets, 1954) — classified as an independent genus by Goldschmidt (2004b), regarded as a subgenus of Nilotonia by Panesar (2004) — again has to be considered as a subgenus within Nilotonia .