Studies on Southeast Asian Haemaphysalis Ticks (Ixodoidea, Ixodidae). H. (alloceraea) vietnamensis sp. n., the First Structurally Primitive Haemaphysalid Recorded from Southern Asia

Abstract

Structurally primitive haemaphysalids of Eurasia have been found only in temperate, northern areas. In spite of this contemporary distribution pattern, it has been postulated that the genus Haemaphysalis probably originated in tropical Southeast Asia, where numerous more structurally advanced haemaphysalid species now occur. We therefore consider it of outstanding phylogenetic and biological interest to report the discovery of two female specimens of a highly distinctive species, Haemaphysalis (Alloceraea) vietnamensis sp. n., possibly the most structurally primitive of all described species in this genus, from vegetation in the temperate or subtropical highlands of Vietnam. Structurally primitive forms comprise approximately 10% of the total number of species now known in the genus Haemaphysalis. Ecologically and geographically, all except one of the described species of this archaic morphological pattern are confined to temperate zones of North America [H. (Aboimisalis) chordeilis (Packard)] and Eurasia. The single exception in a tropical clime has been H. (Sharifiella) theilerae Hoogstraal of Madagascar. Low temperatures and slow reproductive rates appear to be partially responsible for preservation of the primitive prototype or possibly for survival of certain species that have changed slightly if at all since the genus originated (see Hammer, 1965). We have postulated that Haemaphysalis ticks arose with reptiles in the late Paleozoic or early Mesozoic in warm, humid forests of tropical southeast Asia. Here, owing to severe competition from numerous more recent forms, structurally primitive haemaphysalids have become extinct (Hoogstraal, 1965). Received for publication 1 March 1966. *From Research Project MR005.09-1402.3, Bureau of Medicine and Surgery, Department of the Navy, Washington, D. C. The opinions and assertions contained herein are the private ones of the authors and are not to be construed as official or as reflecting the views of the Department of the Navy or of the naval service at large. t Department of Medical Zoology, U. S. Naval Medical Research Unit Number Three, Cairo, Egypt, UAR. t Bernice P. Bishop Museum, Honolulu, Hawaii. This report represents partial results of fieldwork and research supported by the U. S. Army Medical Research and Development Command, Research Grant DA-MEDDH-60-1, and NIH, Grant AI 01723, to Bernice P. Bishop Museum. Thus, it is especially interesting to report at this time the presence of a species, possibly the most structurally primitive of all contemporary haemaphysalids, from temperate or subtropical highlands of Vietnam. Only two female specimens are available. Until more is known about the ecology, life cycle, host relationships, and morphology of the male and immature stages of this species, we hesitate to attempt to evaluate its role as an indicator of phylogenetic associations and history of Haemaphysalis ticks. Investigation of the potential of this species as a reservoir of pathogens is exceptionally desirable. Haemaphysalis (Alloceraea) vietnamensis sp. n. The Vietnam Primitive Haemaphysalid