Morphology and cytology study of Foleyella agamae complex (Nematoda: Filarinae) infecting the agamid lizard Agama agama in Nigeria.

Three cytotypes of Foleyella agamae were isolated from naturally infected wild-caught Agama agama in Nigeria. Cytotype A (2n = 8) has a body length/oesophageal length ratio (L/O) of 87.6 +/- 14.2 in female worms and a large somatic size (length, 63.8 +/- 12.7 mm in female worms and 25.5 +/- 3.4 mm in males). Cytotype B (2n = 6) has an L/O of 43.4 +/- 6.6 in females and a small to average somatic size (length, 36.7 +/- 11.9 mm in females and 19.5 +/- 2.3 mm in males). Cytotype C (2n = 4) has an L/O of 23.8 +/- 8.2 in female worms and a small somatic size (length, 18.8 +/- 3.8 mm in females and 14.1 +/- 3.0 mm in males). No cytotype with odd numbers of chromosomes was observed. Comparisons with similar types of speciation in medically important filarial parasites were drawn. Introgressive hydridisation in the speciation of filarial parasites is postulated.