Taxonomy, distribution and chromosomal analysis of the Egyptian diving beetles (Coleoptera: Dytiscidae & Noteridae)

Abstract

A comprehensive taxonomic account of families Noteridae and Dytiscidae, with references to their African and Egyptian distribution and chromosomal analysis of some species are presented. All together, 68 species grouped in 30 genera and 17 tribes are recognized. Of which three tribes (Noterini, Aciliini & Dytiscini), four genera (Synchortus, Bidessus, Rhantaticus & Dytiscus) and eight species (Synchortus imbricatus, Hyphydrus cycloides, Hyphydrus maculatus, Hygrotus pallidulus, Bidessus ovoideus, Hydaticus bivittatus, Rhantaticus congestus & Dytiscus circumflewxus) are new records, in addition to one new species to the world fauna (Copelatus n. sp.). Keys are given to the families, sub-families, tribes, genera and species based on morphological characters of the adults, as well as a picture- key. Most keys and diagnostic characters of each species are illustrated by camera lucida and scanning electron micrographs. Distributional records that have been gathered from my own data, private collections, museums and literature are presented as a catalogue of provincial records (for Egyptian localities) and as individual distribution maps (for African and Egyptian localities). Several species known previously from only a few localities in Egypt, have been shown to have much wider distribution in the country. Nebrioporus insignis, Nebrioporus lanceolatus and Nebrioporus walkeri together with Scarodytes halensis recorded from Africa for the first time. The results presented in the chromosomal analysis part represent the first karyological data on African diving beetles. Karyotype and sex chromosome systems are listed and described for one species of family Noteridae (Synchortus imbricatus) and nine species of family Dytiscidae (Hydrovatus cuspidatus, Hydroporus humilis, Nebrioporus insignis, Nebrioporus walkeri, Nebrioporus lanceolatus, Agabus biguttatus, Colymbetes piceus, Eretes sticticus and Hydaticus decorus. Nine of the investigated species are new record to cytology. Synchortus imbricatus (family: Noteridae, tribe: Noterin) has been found to have a multiple sex chromosome system which is X+XY in the male and XXX2X in the female, as in Noterus. The cytogenetic picture of the world-wide species Eretes sticticus (family: Dytiscidae) has been confirmed to be 2n = 43(21+ XO).