Anomalohimalaya lama, New Genus and New Species (Ixodoidea: Ixodidae), a Tick Parasitizing Rodents, Shrews, and Hares in the Tibetan Highland of Nepal1

Abstract

ANOMALOHIMALAYA lama, new genus and new species, is described from adults, nymphs, and larvae. This parasite was taken in 3 localities in the Tibetan alpine desert biotope at 12,500 feet altitude in Mustang District of Nepal, first during winter from rodents trapped in snow-covered runways, and later in spring. Hosts were voles, Alticola sp.; field mice, Apodemus sp.; shrews, Sorex sp.; and a woolly hare, Lepus oiostolus subsp. This parasite appears to have evolved from protorhipicephaline stock but to have developed structurally and biologically along a unique line differing significantly from Rhipicephalus and related genera. Thus a new generic category is proposed. Exceptional biological adaptations have been combined with arrested development or progressive degeneration through successive developmental stages of certain characteristic rhipicephaline structures and with hypertrophy of palpal segment 1. The larva is rhipicephalid-like and possesses eyes, but unlike in Rhipicephalus, eyes are lost in the nymph and adult. The male basis capituli resembles that of certain nymphal Rhipicephalus . Lack of both adanal and accessory shields on a crinkly, membranous male ventral integument is unique among rhipicephalid-related genera. The male is exceptionally large in comparison to the female. The adult leg segments distad of the coxae are like those of the nymph rather than the adult Rhipicephalus . The female palpi, as in nymphs, are elongate (short and compact in female Rhipicephalus ). The remarkably hypertrophied adult palpal segment 1 is more or less similar to that of adult and/or immature stages of certain Ixodes species, most of which parasitize small burrowing mammals or marine birds. No adult Rhipicephalus possess an equally hypertrophied palpal segment 1 though a vestige of this adaptation occurs in the nymph of a few species. The palpal structure is discussed. The hypertrophied segment 1 functions are possibly to prevent the elongate hypostome of the relatively large tick from penetrating unfavorably deeply into the small-size host and to permit formation of a large cement cone around the hypostome, thus preventing easy dislodging from the small host of the large, otherwise superficially attached tick. The collecting region, north of the Himalayas, differs ecologically and zoogeographically from the rest of Nepal. Characteristic tick parasites of domestic animals in this highland area are Dermacentor everestianus Hirst and Hyalomma marginatum turanicum Pomerantzev. The former species is recorded from only 1 locality in Nepal outside of Mustang District, the latter is unknown elsewhere in Nepal.