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in addition to three previously described species, remained mostly unrecognized by subsequent workers. The genus was reduced to four species, including a single new one, and four subspecies by Neu.. mann (1911). H. ae tium was used as a "'catchall" name by most persons until the Iggls. During the early twentieth century, British workers in Africa, depending on Nuttall and Warburton
at Cambridge for identification of their collections, developed
a group of names that are herein referred to those in contemporary usage after having studied the Nuttall collection in British Museum (Natural History).
Between 1919 a.nd 1950, Schulze and a few of his students
and followers seized upon the apparently unlimited opportunities for providing dozens of species names for variants in this genus. Scarcely a single one of the some eighty species and subspecies proposed by Schulze and colleagues has withstood the test of comparison with reared progeny from a single female tick. After having studied parts of Schulze's collection, now housed in Rocky Mountain Laboratory, one can understand, from the small series and poor labelling, how misconceptions regarding species identity developed among persons eager to tag each variation with a spe_ cies name. Schulze even went so far as to name the progeny of
a single female as different species (H. delpyi Schulze and
Gossel, 1936) (Delpy 1946A).
RENT REVISIONAL AND SUPPCBTING STUDIES
During the last twenty years a certain amount of cosmos has begun to evolve from this nomenclatorial chaos, although it is obvious that additional modifications in species concepts and names are yet to come. The careful, tedious, and time-consuming pioneer work of Delpy, who secured specimens from many areas where hyalommas occur and reared the progeny from single females, enabled him to determine the range of variation within a single species and to show that characters proposed for many so-called species were due merely to nmltiformity of appearance within a few species. In a few instances, however, Delpy in. cluded species that we now know to be distinct genetic entities worthy of species rank.
Shortly afterwards, Adler and Feldman.Muhsam commenced rear. ing Palestinian species in the same manner as Delpy. They corroborated Delpy's species definitions but not his species names.
In their 1948 paper these authors povided a potash clearing method for females by which they established constant species characters for the unmated female genital aperture. elpy expanded this finding to mated females, thus making it of greater value for identification of field_co1lected material. Neverthe. less, some questionable specimens inevitably crop up in routine collections.
Unfortunately, as stated above, Delpy and Adler and Feldman. Muhsam arrived at different conclusions regarding which name from the scores available should be applied to individual species. Recently Feldman.Muhsam (1954), after study of Koch's (1844) type specimens for several species in the genus, has corroborated some of Delpy‘s earlier decisions and poposed a few changes. Although Koch's material is badly damaged and its labels have been inexcusably tampered with, these studies probably represent the final word on these species; therefore this teminology is accepted with certain reservations as noted in the appropriate places.
Delpy's chief morphological and taxonomic contributions to H alomma have been his notes on the genus (l936,l946A), descrip_ tIon of H. schulzei (l937A), description of the imatue stages of H. dramedarii (I937B), generic revision by expeimental methods (19170 and I919‘, es ciall the latter), and a synoptic list and discussion (l949B), s des studies on bovine theilerosis and tick transmission (1937c,191.6B,191.'7A,19z.9c and 1950). Adler and Feldman_Muhsam presented their chief overall findings in their 1948 paper; subsequent reports by the latter author are listed in the bibliography.
Whenever possible, Delpy's (l949B) synonym has been followed in the present work. Some changes have been necessary, however, on the basis of the kind of proof that Delpy himself advocated: rearing of progeny from single, known females. A few other changes have been necessary due to Feldman_Muhsam's study of Koch's t s. It is impossible to dcide whether Delpy or Pomerantzev (1950 should be followed for the synonymy of certain Russian species. Pomerantzev's ideas, whenever they differ, have been included as notes under the names indicated by Delpy.
It has been attempted herein to indicate present and previous nomenclatorial concepts of these species as clearly as possible, especially for experimental workers and reviewers. Non_taxonomists, who consider themselves “practical workers“, will undoubtedly be annoyed by the remaining confusion. The end is now in sight, and within a very few years will undoubtedly be reached. A little more patience will be rewarded by better understanding of what has been an especially difficult complex of variable species in previously poorly explored parts of the world.
HYALOMA DISTRIBUTION IN AFRICA
Two species, H. truncatum and_H. rufi s, are common in drier areas throughout the '_"""sthiepian Faunal l'l'e'g'I£en (Figure 1). Two others, H. albiparmatum and_§. impressum, are restricted to equa. torial regions of Africa; these four species appear to have e. volved in Africa from Near Eastern stock. Only H. rufi s ex. tends beyond the confines of the Efihio ian Region. Two other species H. detritum and H. marginatum range into North Africa from the Near East and have tenuous, scattered footholds in the transitional zones just south of the great deserts along the northern periphery of the Ethiopian Region. Another Near Eastern species, H. impeltatum, appears to be extending its range a little more aggressive y into East and West Africa. The last species known from continental Africa, H. turanicum, has established it. self in the South African Karroo after Having been introduced on
sheep from the Near or Middle East.
In East Africa, the arid lowlands along the Red Sea and the Indian Ocean carry a number of Near Eastern and North African species southwards into the Somalilands and parts of Kenya towards and even slightly south of the equator. For instance, H. dromedarii is known from the coastal lowlands of Kenya (Walker, unpu5Iished) and H. impgltatum occurs in scattered foci in Kenya and Tanganyika.
There is little question that other species do exist in nature but their identity can be established only by breeding experiments. The presence of a possibly undescribed species similar to H. drome_
darii)in the French Somaliland fauna has also been noted (Hoogstraal
Note the following incorrect Ethiopian Region records:
H. mar inatum (= H. savi ') reported by Rousselot (1948)
from I)'renc rice, was not subsequently confirmed (Rousselot 1953B .
g. detritum reported from French Cameroons (Rageau 1951) was subsequentIy (I953) assigned to Li. truncatum (= Q. transiens) by the same author.
References to “ii. savi n i" from Portugese Guinea (Tendeiro 1949.195-20) actually appIy go 11. truncatum.
In northern and central fizdan, eight species are established though seldom in a continuous range. Of these, only four are com. men. In most Near Eastern and North African areas about the same proportion of common and rare species occur. Yet with even so few species among which to choose the student frequently encounters difficulty in positive identification of all material in most large collections. Some specimens are so variable and intermediate that they defy assignment to a definite species. Unfortunately, previous workers have not provided pertinent details over extremes of variation among species that they have reared. Attempts to properly identify Sudan material for this report have necessitated so much study of material from other parts of the world that pub. lication has been long delayed.
With regard to the paucity of specimens of some species col. lected in northern &1dan, it should be emphasized, from our experience with vertebrate and invertebrate animals in arid and semiarid areas of Africa, Arabia, and the Near East, that not infrequently small relict populations of animals are found in. explicably surviving in barely marginal habitats. This appears to be true of LI. detritum, §. marginatum, g. truncatum, and E. impressum in northern S1_1dan.
The northcentral areas of the Sudan, by reason of their proximity and similarity to the Mediterranean subregion and their tenuous routes of entry from Arabia, West Africa, and via
the Nile, are inhabited by more species of H alomma ticks than apparently any other area of the Ethiopian Faun§I Region. The fact that some of these species appear to be represented in the Sudan only by small populations, either as a result of chance introduction or as survival or relicts, has been noted above.
The Asiatic species that do not reach the Sudan are H. hussaini of India (page 520), H. schulzei, an Iranian camfil par. asite that reaches the Sinai PEninsEIa Between Asia and Africa (page 525), H. ae tium, the tortoise parasite that extends from southern Rus§ia westward through much of the Mediterranean basin (page 51A), and H. turanicum of southern Russia and Iran that has been introduced Into the South African Karroo (page 528). As stated above, the original center of distribution of hyalommas appears to have been in southern Russia or Iran.
Delpy and Adler and Feldman.Muhsam have provided few de. tails about the geographical source and range of species that they treat, and there is still considerable question in the minds of specialists and reviewers as to the distribution of H alomma species. This section has therefore been given special attention in the following text. Synonyms, listed by country of origin of specimen material whenever it can be determined, are based on Delpy's (l949B) lists, which give every evidence of being carefully and judiciously assembled. These references do not include the entire literature, except I trust for Africa, but are furnished for what they are worth in elucidating the distribution of Hyalomma species and indicating the major stu. dies of each species in different parts of the world.
Biological data for H alomma ticks derive chiefly from veterinarians‘ observations on those infesting doestic animals and on laboratory experiments. From field work and from a few other sources we have gained a somewhat different impression of H alomma biology, especially relating to host preferences of tte Immature stages. In this respect, special attention is called to the HOSTS and BIOLOGY sections in the following text, especially for Q. excavatum. The natural life cycle of Hyalomma