Haemaphysalis (Dermaphysalis) nesomys subgen. et sp. n. (Ixodoidea, Ixodidae), a Leathery Parasite of Nesomys rufus Peters (Rodentia) in Madagascar

Abstract

Haemaphysalis (Dermaphysalis) nesomys subgen. et sp. n. is described from a single male from Nesomys rufus Peters (Rodentia, Nesomyinae) from a virgin forest of mountainous eastern Madagascar. Remarkable for leathery argasidlike integument, shagreened pseudoscutum and leg segments, continuous lateral suture, knoblike denticles on the hypostome, lack of ventral spur on palpal segment 3, and apical position of palpal segment 4, H. (D.) nesomys also has several other features that are unusual for members of this genus. This species has apparently branched from the haemaphysalid subgenus Rhipistoma Koch, which has proliferated in several forms on the few carnivores and numerous insectivores of this island, and appears to be adapted to rodents, which form an unusually small and uncommon component in the Madagascar mammalian fauna. Haemaphysalis (Dermaphysalis) nesomys subgen. et sp. n., is the only haemaphysalid species known to have leathery, argasidlike scutal integument, a definite, shagreened pseudoscutum, shagreened leg segments, a continuous lateral suture, and knoblike denticles on the hypostome. The absence of cornua, elongate basis capituli, obsolete ventral spur on palpal segment 3, apical position of palpal segment 4, and reduction of spurs on all appendages are unusual features in this genus. In spite of attempts to obtain more material of this unique species, only a single male has thus far been collected. Within the past 20 years, short-term efforts by several collectors in Madagascar have revealed the presence of a large endemic tick fauna, especially rich in Haemaphysalis species, on this island. The Received for publication 13 April 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 Head, Department of Medical Zoology, United States Naval Medical Research Unit Number Three, Cairo, Egypt, UAR. + Chef du Service d'Entomologie et Protozoologie, Laboratoire Central de l'Elevage, Institut d' Elevage et de Medecine Veterinaire des Pays Tropicaux, Tananarive, Madagascar. ? Entomologiste Medical, Institut Pasteur, Paris, France. new species described here is the first Malagasy haemaphysalid to be associated with rodents, which comprise an unusually small component in the mammalian fauna of this island (see Hoogstraal, 1953, p. 100-103) and are usually localized and few in numbers. The new subgenus described here probably represents a highly specialized, rodent-adapted branch from the haemaphysalid subgenus Rhipistoma Koch (see Hoogstraal, Kohls, and Trapido, 1965), species of which are more or less common parasites of the numerous insectivores and few carnivores of Madagascar. It is exceptionally desirable to learn more about the female, nymph, and larva and the biology and host-parasite relationships of this remarkable tick. Subgenus Dermaphysalis subgen. n.