132 
J. R. AUDY 
The sensory rods (solenidia) of tarsi I and II have been named spurs by Wharton, but 
Womersley has objected to this use of a term which has special meaning in entomology. 
Furthermore, the stout blunt character which distinguishes the tarsal spurs may also be shared 
by the distal tibiala. It is suggested therefore that the sensory rods of the tarsi may be called 
tarsalae, and the microspurs microtarsalae, thus bringing the nomenclature into line with that 
of the corresponding setae on the other segments. 
Some species or groups tend to have heavily barbed leg-setae, among which nude setae 
are particularly significant. Other species or groups, e.g. the indica- group (p. 154), have 
leg-setae on which barbs are generally poorly developed: the presence of nude setae among 
these is usually of much less significance, and these setae should not be freely compared with 
similar nude setae in other groups. The presence of ordinary leg-setae of different lengths, i.e. 
long setae and short setae, is however of taxonomic importance, not only at the subgeneric level 
(as with Neotrombicula , p. 143) but at the specific level (the long nude or almost nude setae of 
Eusch. audyi , for example). A third point about these ordinary leg setae also concerns all the 
setae of the body and palps, and that is that there is no full agreement among acarologists on the 
proper description of the various types of barbs or other processes which clothe these setae. 
Descriptions such as branched , barbed , plumose , ciliated , pectinate , trifid , are not used with the 
same meanings by different workers. The exact description of the setae on body, palps, and 
legs is however of considerable taxonomic importance and it is proposed in a later ‘paper to 
illustrate and describe terms which have been agreed upon by those taxonomists concerned. 
Apart from inter-specific differences, various combinations of characters, especially in the 
setation of leg III, have distinct subgeneric and even generic importance. The lengths of the 
tarsi (including the pretarsus and the bases of the claws so that measurements can be made 
accurately) and of the sensory rods (tarsalae, spurs) on the tarsi are being recorded for the 
Malaysian material for later assessment but it is not yet known if this is worth while. The 
following characters are recorded roughly in the order of what appears to be their importance. 
All legs: lengths in relation to thickness (as it is both tedious and inaccurate to attempt to measure 
legs which are considerably bent, the tarsi might perhaps be taken to represent the legs); plumosity or 
nudity, and relative lengths, of the leg setae generally; occasionally, claws and empodium deserve comment. 
Leg III: all specialised setae, especially the whip-like setae. The latter appear to be of two distinct 
kinds : true solenidia, like the femoralae and genualae, which are unusually long and whip-like, generally 
curved, showing the hollow refractile appearance and often the striae of the shorter setae; and long nude 
setae which resemble the ordinary non-specialised setae. The latter are usually straight and outstanding, 
so that the description whip-like is not very apt; similar setae may carry traces of ciliations or barbs near 
the base, others may carry a few barbs but have a long free tip (cf. T. flagellifera, tuhana). The terms 
mastitarsala, mastitibiala, etc. are retained for the latter type of seta, while the former type is described as 
whip-like tibialae, genualae, etc. (Audy, 1952): Wharton, in correspondence, states that this is the correct 
usage of his terms, while he also refers to the short (not whip-like) nude setae as, e.g., “ a short mastitibiala”. 
Leg I: The position of the microtarsala in relation to the base of the tarsala; the general shape and 
size of the sensory setae (these may be short, stout, slender, long, pointed or blunt ; the distal tibiala on leg I 
or II may be blunt while the proximal seta is pointed and more slender). The relative lengths of the 
microsetae (the microtibiala and microgenuala may at times be very long) ; in addition, the microsetae may 
occasionally be modified, as in the hook-like microtarsala of T. harrisoni. Occasionally the presence of 
long nude, plumose, or pectinate setae, sometimes mastisetae, on the femur; occasionally, the length of the 
parasubterminala relative to the subterminala. 
Leg II: position of microtarsala relative to base of tarsala; whether the tibialae are in tandem or not. 
In general, an attempt has been made in all descriptions to refer measurements to 
comparisons with other features which will be before the observer on the same part of the 
specimen, so that setae may be compared with the lengths of segments, or, for example, the 
microsetae or parasubterminala with their associated sensory setae. In illustrating the leg 
setae, it is probably best to concentrate effort on the shapes and positions of the sensory setae, 
and to show only the bases of the other setae together with a few examples to illustrate the type 
STUD. INST. MED. RES. 
