Date of Award

12-1982

Degree Type

Thesis

Degree Name

Doctor of Philosophy (PhD)

Department

Biology

Supervisor

Professor D.M. Davies

Abstract

The relationship among simuliid species in the genus Hellichiella from Europe and North America was studied on the basis of their salivary gland chromosomes, morphology and ecology. The banding pattern of polytene chromosomes of eight species was examined and compared with that of H. congareenarum defined by Dunbar (1967) as the standard. Species studied for the first time are H. rendalense (from Norway), H. latipes (subexcisum syn. from Britain) and H. saccai (from Italy) and the undescribed "Opinaga" (from Quebec) and "near dogieli" (from Norway). H. congareenarum, H. anatinum and H. innocens were restudied. These species were found to differ from the standard by a minimum of one and maximum of three fixed inversions. It is concluded that the sibling distinction between congareenarum and congareenarum 'b' proposed by Dunbar (1967) is not valid and that H. anatinum differs from standard by only one inversion.

The genus Hellichiella Riv.&Card. is redefined and distinguished from Eusimulium annulum group sensu stricto. Described for the first time are the larva, pupa and male of both H. rendalense and H. near dogieli and the pupa of H. fallisi. The close relationship of these species is confirmed both chromosomally and morphologically.

The immature stages of H. rendalense s.l. were discovered in shallow seepages with water current 1-30 cm/sec and temperature 10°-16°C in sloping sedge-Sphagnum bogs. This habitat is the source of larvae of these simuliids and the origin of first order streams which are secondarily colonized by these and other bog species. The occurrence of related species in similar habitats in the Nearctic and Palaearctic regions establishes that sloping Sphagnum bogs, primarily in the Boreal region, are the main source of Hellichiella species. Thus species of this taxon, some of which are known vectors of Leucocytozoon, are linked ecologically with Anopheline mosquitoes and Ceratopogonid flies. The theory is proposed that the breeding habitat of these vectors of haematozoa is the unifying factor in the epizootiology of Haemosporidia.

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