The Animal Parasites of Man

by Harold Benjamin Fantham; Max Braun; J. W. W. Stephens; Fred. V. Theobald

[In many species moulting takes place off the host, but in I. bovis, now known as Rhipicephalus annulatus, Say (the carrier of Texas fever), moulting takes place on the host, and in many other species also.[337] Some species of ticks leave their host on its death (as the dog tick, Hæmaphysalis leachi), but others die with the host (bont tick, Amblyomma hebræum).

[Two species are of special importance, namely Ornithodorus moubata, Murray, which may infect human beings with the spirillum of African tick fever, and Dermatocentor reticulatus var. occidentalis, which is said to be the carrier of Rocky Mountain spotted fever.

Classification of Ixodidæ.

[The ticks, or Ixodidæ, are divided into two groups, known as (1) Argantinæ, (2) Ixodinæ. The Argantinæ are told from the Ixodinæ by the absence of dorsal or ventral shields in both sexes, and also by the rostrum being placed beneath the cephalothorax, which covers it over: except in the larval stage, in which it is subterminal, and in the pupal, when it partly projects. Legs nearly equal in length. The sexual orifice is situated between the two first pairs of legs. The males usually smaller than the females.

[The Ixodinæ have the legs unequal, of six segments with two false segments, making them look as if composed of eight segments. The rostrum is terminal and never hidden beneath the body. The sexual orifice is situated between the bases of the first three pairs of legs. In the males the orifice is obsolete or very rudimentary, sexual intercourse being effected by the rostrum. The males are smaller than the females. The shield in the females never covers so much as one-half of the body even when fasting, also in the larvæ and nymphs; but in the males, which do not distend, the shield covers the body entirely, or all but a narrow margin. The Ixodinæ are divided into two groups: (i) the Ixodæ, and (ii) the Rhipicephalæ. The former have a long proboscis reaching nearly to the end of the palpi or even a little longer than the palpi. The palpi are longer than broad. The Rhipicephalæ have short palpi, nearly or quite as broad as long, more or less conical or subtriangular. They were called Conipalpi by Canestrini.

Synopsis of Genera.

[A. Argantinæ: Rostrum concealed in adult, partly exposed in larvæ and nymphs. No dorsal and ventral shields.
	Body flat with thin edges, finely shagreened and punctate Argas.
	Body with numerous small round granules and with thick sides	Ornithodorus.
[B. Ixodinæ: Rostrum terminal. Body with dorsal shield over some part of it.
I.	Rostrum and palpi longer than broad (Ixodæ).
α.	A groove around anus in front.
	Palpi caniculated in both sexes	Ixodes.
	Palpi claviform, not caniculated in the male; legs very long	Eschatocephalus.
	Palpi claviform, not caniculated in the male; anal groove absent in the female	Ceratixodes.
β.	A groove around the anus behind.
	No eyes; adanal shields	Aponomma.
	Eyes present.
	Males with no adanal shields	Amblyomma.
	Males with adanal shields	Hyalomma.
II.	Labium and palpi short; palpi not, or very little, longer than broad (Rhipicephalæ).
α.	No eyes.
	Rostrum rectangular; no ventral shields in the male	Hæmaphysalis.
β.	Eyes present.
	No adanal shields, but usually with greatly developed coxæ on fourth pair of legs. Capitulum quadrangular	Dermacentor.
	Capitulum hexagonal	Rhipicentor.
	Adanal shields in male. Stigmata comma-shaped	Rhipicephalus.
	Stigmata oval or round; legs normal	Boophilus.
	Segments of legs expanded	Margaropus.
[The genus Ceratixodes of Neumann, 1902, occurs on birds.
[The genus Eschatocephalus of Frauenfeld, 1853, of which seven species are known, is mostly parasitic on bats, and is found in holes, caves, and church towers.
[The genus Aponomma of Neumann, 1899, is exotic, and almost entirely confined to snakes and saurians.
[The following are synonyms of the different genera:—
	Argas, Latreille, 1796 (Rhynchoprion, Hermann, 1804).
	Ixodes, Latreille, 1795 (Acarus, Linnæus, 1758; Cynorhæstes, Hermann, 1804; Crotonus, Dumeril, 1822).
	Ceratixodes, Neumann, 1902 (Ixodes, Cambridge, 1879; Hyalomma, Cambridge, 1879).
	Eschatocephalus, Frauenfeld, 1853 (Sarconyssus, Kolenati, 1857).
	Amblyomma, Koch, 1844 (Ixodes, Latreille, 1795).
	Hæmaphysalis, Koch, 1844 (Rhipistoma, Koch, 1844; Gonixodes, Dugès, 1888; Opitodon, Canestrini, 1897).
	Rhipicephalus, Koch, 1844 (Acarus, Linnæus, 1758; Ixodes, Latreille, 1795; Phanloixodes, Berlese, 1889; Boophilus, Curtice, 1890).
	Dermacentor, Koch, 1844 (Ixodes, Latreille, 1795; Pseudixodes, Haller, 1882).—F. V. T.]

Genus. Ixodes, Latreille.

Ixodes reduvius, L., 1758.[338]

Syn.: Acarus reduvius and ricinus, L.; Ixodes ricinus, Latreille, 1806.