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Art. XXIV.—A Species of Ixodes parasitic on the Grey Duck.
[Read before the Philosophical Institute of Canterbury, 4th November, 1903.]
Plate X.
In May, 1903, Mr. W. W. Smith, of Ashburton, sent me some specimens of a “tick” found-on a specimen of the grey duck (Anas superciliosa.), with the request that I would examine them, and describe them, if necessary.
The specimens forwarded appear to belong to the genus Ixodes, Latreille, of which five species have been already described as parasitic on various New Zealand birds. Of these three were described by the late W. M. Maskell—viz., I. eudyptidis, from a penguin;** I. apteridis, parasitic on the North Island kiwi (Apteryx mantelli)†;† and I. aptericola, found on the South Island kiwi (Apteryx australis‡).‡ Mr. T. W. Kirk has described one species, I. maskellii, obtained from young specimens of the pencilled albatros, and has also recorded the fact that he found on a large gull a tick exactly similar to the one from the crested penguin described by Mr. Maskell§. § A fifth species has been more recently described by M. Neumann in a paper which I have had no opportunity of consulting∥.∥ I have been unable to identify my specimens with any of the others described from New Zealand, and have therefore ventured to describe them as new. I do so, however, with considerable hesitation, as I have not specially studied the group. I hope, however, that the description and figures given below will be sufficient for future identification. In the general shape and markings on the body the species here described seems to rather closely resemble Ixodes maskellii, T. W. Kirk, but in the absence of figures of that species I have not ventured to refer my specimens to his species.
Female.—Body broadly elliptical, slightly constricted at the sides; cephalic shield lighter in colour than rest of body, very small, oval, narrowing in front, only partially visible in dorsal view. On dorsal surface two shallow grooves or markings extend backwards and outwards from the cephalic shield, and lead to two irregular depressions situated about one-third the length of the body from the anterior end; from these depressions extend two well-marked lateral grooves, curving slightly inwards and reaching nearly
[Footnote] * Trans. N. Z. Inst., xvii., p. 19.
[Footnote] †L.c., xxix., p. 291.
[Footnote] ‡L.c., xxix., p. 29.
[Footnote] §L.c., xix., p. 65.
[Footnote] ∥ Mem. Soc. Zool. France, 1899, p. 132.
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to the posterior end of the body. An indistinct median groove runs forward from the posterior extremity of the body and gradually disappears before reaching as far forward as the depressions. Whole dorsal surface free from hairs, but marked with very fine parallel striæ, which anteriorly are concentric with the margins of the cephalic shield, but soon become transverse. On the ventral surface two grooves arise at the bases of the legs and run backwards, at first nearly parallel, but afterwards curving slightly outwards, and not reaching so far as the posterio-lateral margins of the body. Posteriorly is a median groove extending from the posterior margin for nearly one-third the length of the body; it is well-defined anteriorly, but becomes shallower and less distinct posteriorly.
Rostrum and palpi short, scarcely visible in dorsal view; rostrum cylindrical, straight, proximal two - thirds smooth above, distal third provided with numerous recurved hooks; on the under-surface these hooks extend along two-thirds of the length and proximally become arranged in four rows, the teeth of the inner row smaller than those of the outer. Palpi straight, not extending beyond the end of the rostrum, only the two terminal joints distinct; penultimate joint nearly twice as long as the terminal, slightly narrowed at the base; terminal joint rounded at the end, and with an oval marking on the under-surface; both joints with a few fine scattered hairs. Legs with the last two joints indistinctly separated, the last bearing two strongly curved claws arising from a small pad.
Male.—Smaller specimens (length, 3 mm.; breadth, 1–5 mm.), which are presumably males, are similar in most respects to the females, but have the cephalic shield darker in colour and the grooves on the dorsal and ventral surfaces less well marked, and bear a few very fine hairs sparsely scattered over the body.
The colour of the animals when alive was, according to Mr. Smith, “females dull-green, males brownish-green.”
Type specimens have been deposited in the Canterbury Museum.
I have to thank Miss E. G. Freeman, of the Christchurch School of Art, for drawing for me figures 1 and 2, representing the dorsal and ventral surfaces of the female.
Description of Plate X.
Ixodes anatis, Chilton. ?.
| Fig. 1. |
Dorsal view of female, × about 4 times. |
| " 2. |
Ventral view of the same, × about 4 times. |
| " 3. |
Rostrum, Been from above, × about 60 times. |
| " 4. |
Rostrum, seen from below, × about 60 times. |
| " 5. |
Fourth leg, × about 30 times. |
| " 6. |
End of same, more highly magnified. |