Speciation and development in the genus Lagochilascaris

Abstract

The habitat of patients with L. minor infection in Trinidad, Tobago and Surinam is described. Three species of Lagochilascaris are redescribed and compared. A new species from Felis concolor is described and a synopsis, with a key to the genus is provided.The development of L. minor is described from eggs and larval stages obtained from neck lesions of patients. The developmental pattern through third- and fourth-stage larvae was found to conform closely to that of other ascaridoid species, but the tail of the second-stage larva showed a unique conformation.The earliest stage of development found in human lesions was the third stage, the smallest larva being 1·8 mm in length. The third moult was observed at about 5 mm and the fourth moult at 8 mm. Adult worms were observed with a minimum length of 5 mm in the male and 6 mm in the female. Eggs were present in some females of 8 mm length.The observations are discussed in relation to previous concepts concerning the affinities, host specificity and evolution of this group of nematodes.The writer takes pleasure in acknowledging the considerable help he received in this work from several colleagues and friends: Professor J. J. C. Buckley for sending specimens of L. minor and L. buckleyi from the Department of Helminthology, London School of Hygiene and Tropical Medicine; Drs A. G. Chabaud and Marie-Claude Durette from the Museum national d'Histoire naturelle, Paris for sending specimens of L. major; Dr P. Araujo from the Universidade de São Paulo, Faculdade de Farm´cia e Bioquímica for sending specimens of L. minor; Dr J. F. Teixeira de Freitas of the Instituto Oswaldo Cruz, Rio de Janeiro for sending specimens of L. turgida; Drs M. D. Little and P. C. Beaver from the Department of Tropical Medicine, Tulane University New Orleans, for sending specimens of L. minor and notes on their observations relating to L. minor. Grateful acknowledgement is also due to Dr O. H. Siung of the Ministry of Health, Port of Spain, Trinidad, and Dr Cox, Chief Medical Officer, Tobago, Dr A. H. Jonkers and his colleagues at the Trinidad Regional Virus Laboratory, and to His Excellency Dr B. F. J. Oostburg, Minister of Health of Surinam, for their considerable help and co-operation which enabled the writer to observe patients and examine specimens in Trinidad and Surinam. The able technical assistance of Miss Mary Cremin, Mrs A. McKeown and Mrs A. Green is gratefully acknowledged. Financial assistance for this study was provided under grants from the Australian Research Grants Committee, the U.S. Dept. of Health, Education and Welfare no. A. 107023–02, and the University of Queensland Research Grant.