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IXODES PTERODROMAE Arthur

Ixodes pterodromae Arthur, 1960, pp. 217-23, figs. 55-62b.

The male and larva are unknown.

Female

Diagnosis

Scutum suboval, emargination very shallow; basis capituli with large, rounded, raised, and posterolaterally directed cornua, porose areas large, covering most of basis, auriculae strong; palpi clavate, article 1 large with a conspicuous, internal, anteriorly directed horn-like process and a distinct mesodorsal spur; hypostome dentition mainly 4/4, becoming 3/3 and 2/2 basally; anal grooves wide open posteriorly; coxae I-III with internal spurs, those on coxae II and III small, pointed, all coxae with external spurs; trochanters with strong dorsal and ventral spurs.

Description

Body.-Unfed Specimens 2.3 by I.5 mm, engorged specimens to 10.8 by 8.2 mm; marginal groove well defined, disappearing on engorgement; with scattered, short, pale hairs.

Capitulum.- Length 0.58-0.64 min; basis dorsally 0.46-0.58 mm wide, posterior margin almost straight, slightly elevated, posterolateral margins curved; cornua prominent, dark, rounded, and somewhat elevated, slightly longer than their greatest width, directed post erolaterally; porose areas large, subcircular or broadly oval, almost contiguous with posterior margin and extending towards base of palpi; the interval narrow and depressed; basis ventrally rounded posteriorly, auriculae strong, as large, heavy spurs with almost straight lateral margins; palpal article I large with a prominent, internal, anteriorly directed, horn-like process, directed dorsally apically, and with a distinct mesodorsal spur, articles 2 and 3 with faint sutural line, clavate, about 0.30-0.35 mm in length.

Hypostome spatulate and broadly rounded apically, dentition with minute teeth apically, mainly -1/4 and 3/3, becoming 2/2 and sometimes also 1/1 basally.

Scutum.- Suboval, longer than wide, I.10-I.32 mm by 0.86-I.01 mm, widest just anterior to mid-length, median field convex, lateral fields flat, anterolateral margins straight or slightly sinuous, posterolateral margins convex, posterior angle broadly rounded; no lateral carinae; punctations mainly fine, moderate in number and scattered, a few relatively, coarse and shallow with some confluency sometimes most numerous near the margins; cervical groove, broad becoming shallow and divergent posteriorly, but not quite attaining the: posterolateral margins; emargination almost lacking; scapulae shallow and rounded.

Genital aperture.- At level of coxa III.

Genital grooves.- Divergent and practically straight.

Anal grooves.- Broadly rounded anteriorly, slightly convergent posteriorly.

Spiracular plate.- Subcircular or broadly oval, the longer axis transverse, about 0 . 31-0 . 36 mm in length; macula anterior and a little dorsal to centre.

Legs.- Relatively strong and of moderate length; coxae convex, smooth, with some long hair, coxa I with a broad, blunt internal spur, internal spurs on coxae II and III small, pointed, all coxae with prominent external spurs, that on coxa I relatively large and heavy; trochanters with strong ventral and dorsal spurs; tarsi slender, tapering gradually, tarsus I 0.72-0.80 mm in length, tarsus IV 0.68-0.78 mm in length.

Nymph

Diagnosis

As in female, cornua strong and elevated.

Description

Body.- Partly engorged and engorged specimens 2.7-3.2 mm by I.9-2.4 mm; some small, pale, scattered hairs.

Capitulum .-Length 0.30-0.35 mm ; basis dorsally 0.25-0.28 mm wide, shape as in female, surface smooth, but occasionally with some scattered punctations in region of porose areas, cornua strong and divergent: basis ventrally rounded posteriorly, auriculae prominent; palpi as in female articles 2 and 3 about 0.19 mm in length.

Hypostome about 0.21 mm in length, broadly rounded apically, some minute teeth apically, dentition mainly 3/3 becoming 2/3 basally.

Scutum.- Longer than wide, suboval, 0.60 by 0·50 mm, and widest just anterior to midlength; punctations mainly laterally where they tend to show some confluency cervical grooves, emargination, and scapulae as in female.

Anal grooves.-As in female.

Spiracular plate.-Broadly oval to subcircular, about 0.24 mm along greater axis.

Legs.-As in female.

Hosts and Distribution

The Australian record is based on 2 females and 5 oo from Diomedea exulans. De Witt I., Tas., 10.viii.1916. 8 females and 7 oo from "penguin", Macquarie I., were also available.

The species was described by Arthur (1960) from females from Pterodroma brevirostris and P. mollis, Marion I, Indian Ocean.

Comments

Considerable confusion has existed in the determination of the species I. auritulus Neumann, 1904, and I. percavatus Neumann. 1906. Zumpt (1952), from an examination of females and nymphs from the type locality, concluded that I. percavatus was identical with I. auritulus, and Arthur (1953), from a comparison of the types of both species, supported Zumpt's decision. Later. however. Arthur (1960), from a further study of the types and of other material, concluded that there existed a percavatus group with a well-defined mesodorsal spur on palpal article I. and an auritulus group in which this palpal spur was absent. Four species were placed in the former group, namely I. percavatus and three new species, I. cornuae, I. zumpti, and I. pterodromae. These four species are very similar but have been distinguished by Arthur (1960) mainly on the form of the porose areas, cornua, and coxal armature.

The female specimens described as I. pterodromae by the present author were originally identified as I. auritulus. When Arthur's paper (1960) appeared they were submitted to him for identification and were determined as I. pterodromae. The specimens agree substantially with his description of this species. A description of the nymph is published for the first time.

Reference

Roberts FHS (1960): A systematic study of the Australian species of the genus Ixodes (Acarina: Ixodidae). Australian Journal of Zoology 8:392-485.

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