Page images
PDF
EPUB

Infrequent hosts of adults are monitor lizards (Varanus spp.) (Robinson 1926, Tendeiro 1951D, and Sudan record above), Agama lizard (Loveridge 1929, Bequaert 1930A), python (Bedford 1932B), hedgehog (Robinson 1926), man (Schwetz 1927C), and one specimen from a domestic goat (Theiler, unpublished).

Nymphs and Larvae

Immature stages infest tortoises and also Varanus lizards, birds, and hares. Guineapigs may be used for laboratory rearing. Owing to the paucity of field records for immature stages it is impossible to determine their host preference in nature. It is unusual to find a tick that normally feeds on warm blooded animals in the immature stages and on cold blooded animals in the adult stages; the reverse is usually true. Yet Theiler (correspondence) has nymphs from South African hares and from a turkey on a farm where the mountain tortoise is also common. Further field study of this matter is indicated but, as A. nuttalli appears to be curiously localized and seldom abundant, the success of such investigation will depend on local factors. Note that in Equa toria Province, single nymphs were found on each of two species of Varanus lizards, on an oribi (antelope), and on a francolin partridge, but none were taken from the many tortoises examined.

Various literature records for "iguana" lizard, a non-African reptile, should be "leguan" or monitor lizard (Varanus spp.). Alexander (1931) was unable to induce adults to feed on laboratory animals.

See also BIOLOGY below.

BIOLOGY

Santos Dias (1950A) reared this species using guineapigs and tortoises as hosts. He subsequently reparted (1955B) that the life cycle is a three-host type. A maximum of 22,891 eggs from a single female were noted with the claim that this is the greatest number of eggs yet observed in any of the Ixodoidea. The minimum period for completion of the life cycle is estimated at 134 to 151 days, the maximum period 217 to 296 days. This paper

is illustrated with photographs of both sexes feeding from the interstices of the host's shields. Our Torit adults, however, were taken in the host's axillae (during a native big-game hunt and stored in a hunter's ear, plugged with mud, for three hours until our lost vials could be recovered).

DISEASE RELATIONS

Experimental attempts to transmit heartwater (Rickettsia ruminantium) of cattle by this tick species have failed.

It is claimed that specimens have been found infected with Q fever (Coxiella burnetii) in Portugese Guinea.

As with the Aponomma parasites of lizards and snakes, it is of interest to conjecture that the small reptile-amblyomma may be a vector of the hemogregarines of tortoises.

REMARKS

Misshapen specimens have been reported (Santos Dias 1949B, 1950A,1955A).

Amblyomma werneri werneri Schulze, 1932 (A), described from Kinixys b. belliana (see Werner 1924) from Talodi, Kordofan, Sudan, appears to be a synonym of A. nuttalli. Following Schulze's practice of applying species names to any variant, he distin guished a single specimen as different from A. nuttalli for the following reasons: the dark marking not blackish brown, but light red brown on a light reddish brown background; darker markings bounded with a coppery color (in A. nuttalli dark yellow brown without copper borders); median stripes more irregular than in A. nuttalli and broadened at the ends; lateral groove sharply defined against the scutum, in A. nuttalli irregular; and ventral median muscleplate smaller.

All characters proposed to separate A. werneri from A. nuttalli fall well within the normal range of variation due to age, nutrition, or methods of preservation. In long series of any Amblyomma species,

some specimens vary in roundness, flatness, development of the ventral muscleplate, and sharpness of the lateral groove. Com parison of many specimens of this genus preserved in alcohol with those preserved as dry specimens shows that those preserved in alcohol frequently develop a coppery sheen due to chemical change. Theiler has made similar observations in this respect. The obscu rity of the color pattern and its overlay with a basic color in some specimens in any extensive collection of amblyommas from even a single host is taken for granted by most students. Using the above mentioned criteria, proposed by Schulze, large collec tions of A. variegatum and A. lepidum from single herds of cattle have been examined. It has been found that each collection contains no less than four "species"" and up to seven "species".

Comparison of Sudan specimens with others from various parts of Africa and of the type specimens of A. nuttalli in British Museum (Natural History) reveals no significant differences to obtain between any of them.

It is for these reasons that it has been proposed (Hoogstraal 1954B) to consider A. werneri werneri Schulze, 1932 (A), as a synonym of A. nuttalli Dönitz, 1909.

It is also of some interest to consider the status of A. werneri poematium Schulze, 1932, described on the basis of two males from a young rhinoceros, at the Amsterdam zoological gardens, from East Africa. This subspecies was distinguished by a wonderful metallic, copper, partly greenish gloss (with) brown elements of the conscutum bordered in copper, in one of the two specimens, but in the other "the structure producing the metallic coloration was in greatest part destroyed, only in a few places did the greenish coppery sheen show up". The size of these specimens was also larger than that of the subspecies werneri.

I have seen a male specimen taken from a Somali tortoise #17691, Rocky Mountain Laboratory, Hamilton, determined as A. werneri by Dr. E. Stella). This tick answers the description of A. w. poematium but has a somewhat rugo se scutum suggestive of injury during molting or during an immature stage. The specimen resembles a teneral individual, i.e. one that has been preserved shortly after molting while still bloated and before the colors are fast.

The

Santos Dias (1954G) opines that (1) A. poematium is a sepa rate species, (2) A. schlottkei Schulze, 1932, might be a synonym, and (3) A. faiai Santos Dias, 1951, definitely is a synonym. specificity of A. poematium is hardly convincing on the basis of descriptions and illustrations, though there is a possibility that comparison of specimens may provide yet unmentioned clues to separate this morphologically from A. nuttalli. Breeding experiments are also indicated.

IDENTIFICATION

A. nuttalli is similar to A. marmoreum in characters mentioned under that species, except for the following: Males: Size is smaller, always less than 6.0 mm. long. Pale ornamentation of the scutum is somewhat variable, but all specimens are like the one illustrated in that the dark areas are less extensive and more broadly separated from each other by light areas than they are in A. marmoreum.

Females: This sex is also smaller than that of A. marmoreum (body approximately 7.0 mm. long, 5.5 mm. wide; scutum about 3.2 mm. long, 3.3 mm. wide); the central pale scutal ornamentation tapers to a narrow point posteriorly and is therefore very distinctive.

[graphic][subsumed][merged small][merged small][graphic][merged small][merged small]

Figures 80 and 81, d, dorsal and ventral views
Figures 82 and 83, q, dorsal and ventral views

AMBLYOMMA POMPOSUM

specimen from Belgian Congo

Q specimen from the Sudan

PLATE XXVIII

- 240

« PreviousContinue »