A Review of the Nilothauma pictipenne Group And a Description of Four New Afrotropical Species of Nilothauma Kieffer, 1921 (Diptera: Chironomidae: Chironominae)

ABSTRACT

A revised generic diagnosis of the genus Nilothauma Kieffer, 1921a, is given. Four new Afrotropical species, N. loba sp. n., N. tricaudata sp. n., N. flabella sp. n., and N. insolita sp. n., are described as male imagines. N. pictipenne Kieffer, 1921a is redescribed as male and female imagines. Two Neotropical species (N. aleta Roback,1960 and N. Buena Roback, 1960) are regarded as nominal dubia and placed in Paratendipes. A key to male imagines of the Nilothauma pictipenne group is given and the phylogenetic relationships of the Nilothauma group of genera {Nilothauma, Neelamia Saponins, 1986 and Paranilothauma Soponis, 1986), of the different species groups of Nilothauma, and of the Nilothauma pictipenne group are discussed. The genus Paratendipes Kieffer, apparently forms the sister group of a group consisting of the genera Paranilothauma, Neelamia and Nilothauma. Within Nilothauma, four species groups are recognized with the babiyi group forming the sister group of the remaining groups. The bicorne group apparently forms the sister group of the mirabile and the pictipenne groups combined. Paratendipes is cosmopolitan. The Neotropical group of genera (Neelamia and Paranilothauma) appear to have split off very early with the fragmentation of Pangaea. The species of Nilothauma treated here fall into four species group of Megagaeic lineages and are confined to the Holarctic, Sino-Indian, Afrotropical and Australian zoogeographical regions for freshwater fauna. The babiyi group is made up of 2 Afrotropical, 1 Holarctic and 1 Sino-Indian species. N. babiyi (Rempel, 1937) and N. japonicum Niitsuma, 1985, limited to North America (Holarctic region) and Japan (Sino-Indian region) apparently are sister species. The N. babiyi group apparently first speciated with the fragmentation of Megagaea. In the bicorne xii group, N. bicorne (Townes, 1945) and N. brayi (Goetghebuer, 1921) occur in the Holarctic region. However, N. brayi has also been described from Japan in the SinoIndian zoogeographical region. This group is also of a Megagaeic lineage with some dispersal probably haven taken place. The mirabile group consisting of N. mirabile (Townes, 1945) and N. hibaratertia Sasa, 1993, present in North America and Japan respectively is distributed in the Holarctic and East Asian regions. The pictipenne group is made up of 2 species (N. nojirimaculata Sasa, 1991, and N. hibaraquarta Sasa, 1993) from the Sino-Indian region and 5 species (N. pictipenne, N. loba, N. tricaudata, N. flabella and N. insolita) from the Afrotropical region. The phyletic interrelationship of the Nilothauma group of genera suggests the early splitting of their common ancestor into the Neotropical group (namely Neelamia and Paranilothauma) and the Megagaeic lineage group during the fragmentation of the super-continent Pangaea. The Megagaeic lineage group is made up of Nilothauma species with further fragmentation and possible dispersal into the Holarctic, SinoIndia, Afrotropical and Australian regions. The distributions and ecologies of the different species of the genus are outlined.