1 12 
H. WOMERSLEY 
Grossia onychia n. sp. (figs. 2 A-E). 
Description of Larva. — Size large, length (engorged) 1500^; width 1300^. Shape like a small pea. 
Colour in life ? Scutum as figured, large, triangular, with apex pointing forwards ; AM setae absent, AL 
setae behind the midlength; PL near the posterior corners; sensillae in between AL and PL, very long 
and moderately thick, with short adpressed barbs or ciliations on distal half; AL and PL setae long, thick 
and shortly ciliated or barbed. Eyes 2+2, on ocular shield, and nearer to lateral body margins than to 
scutum. Chelicerae as figured, with a few fine teeth distally on inner (dorsal) edge, and fine teeth all the 
length of outer edge. Galeal setae short and simple. Palpi as figured, tibiae with curved short bifurcate 
claw; setae on femur and genu, thick and shortly ciliated; setae on tibia and tarsus not ascertainable. 
Dorsal setae thick and shortly cihated, arising from small platelets, 26 in number, arranged 6. 6. 6. 6. 2. from 
156^. long anteriorly to 195^ long posteriorly. Ventrally, a pair of short setae anteriorly on maxillae, 
a pair of short set setae on coxae I, and one seta on each of coxae II and III, a pair of short apparently 
simple setae between coxae III and thereafter 4 setae, followed by five setae on each side of anus; these 
ventral setae gradually lengthening and apparently nude. The anus is furnished with two pairs of setae. 
Legs all 7-segmented, I 540[x long, II 540^, III 6oo;j.; tarsi I and II without any dorsal rod-like seta, 
III without any long nude seta; all tarsi furnished with a single strong claw, on each side of which is a 
shorter spathulate seta. 
The Standard Data for the type are : 
AW 100.0, PW 156.0, SB 73.0, ASB 143.0, PSB 20.0, SD 163.0, A-P 55.0. 
AL 1 12.0, PL 84.0, Sens. 168.0. 
Loc. and Host. — A single specimen attached to an adult Trombidiid ( Chyzeria austraiiense Hirst) 
from the Ottwav Ranges, Victoria, 1951 (G. F. Gross). 
Genus Mackerrasiella nov 
Shape globose, with leg I 7-segmented, II and III 6-segmented, tarsal claws single, no 
empodium. Scutum ill defined, overlapped with longitudinal striations, with no AM, 2 AL 
and 2 PL and two small additional setae at posterior end; sensillae filamentous. Eyes 2+2, 
widely separated and posterior the smaller. Chelicerae hook-like. 
Type Mackerrasiella globus n. sp. 
Remarks . — In the segmentation of the legs this new genus may be placed in the subfamily 
Apoloniinae of the Leeuwenhoekiidae, which already contains rather a heterogeneous collection 
of genera. In the absence of AM scutal setae, and the slight posterior prolongation of the 
scutum and the additional two small posterior setae it might equally well be placed in the 
Gahrliepiinae of the Trombiculidae. The presence of single tarsal claws, however, also allies 
it with the Apoloniinae. Altogether its true relation is obscure and will remain so until it becomes 
possible to correlate the larvae with nymphs or adults. 
This genus is dedicated to Mrs. J. M. Mackerras, Parasitologist, Queensland Institute of 
Medical Research. 
Mackerrasiella globus n. sp. (figs. 3 A-I). 
Description of Larvae. — Shape globose, when mounted and compressed perfectly round. Length of 
idiosoma (engorged) 845^, width 84501. Scutum small, margins ill defined, and overlapped by longi- 
tudinally striated cuticle; no AM setae present, anterior margin between AL lightly concave; sensillae 
filamentous, apparently nude and bases close to AL, wide apart, SB being only a little less than distance 
between AL; PL still nearer together; scutum posteriorly behind PL with two short fine additional setae, 
iiul long: scutal setae apparently nude. Eyes large, 2+2, widely separated and posterior the smaller, 
anterior in line with SB, and posterior about in line with PL, posterior eye with strongly refringent centre. 
Mandibles large, with the chelicerae hook-like and non-serrate. Galeal setae ? Palpi as figured, tibial 
claw bifurcate; setae on femur and genu relatively short with short indistinct barbs, on tibia all 3 setae 
nude, tarsus rather long and cylindrical, with a long strong apical seta, and no sensory rod, as figured. 
Dorsal setae sparse and apparently nude; two humeral setae 450. long, then a row of four 5 1 [jt long, followed 
by submedial 207. long, then four of which the laterals are 45[r long and the submedials 20 g, then two 
submedials 20 g long, and apically two more 20 [jl long. Ventrally: apparently no setae on maxillae, one 
short setae on the tip of the evanescent coxae I, none on coxae II and one short seta towards apex of coxae 
III ; no setae between any coxae; a pair of short 20 p. setae in front of anus; anus itself on a small triangular 
shield and carrying two small setae; behind anus 8 small setae. No true spiracles between gnathosoma 
and coxae I apparent. Legs relatively short, I 7-segmented, Hand III 6-segmented; leg I 240^ long, 
II I95 k u long, III 208 [i., long; tarsal claws only one, and no empodium present; setae of specialised nature 
on legs as follows : 1, 2 genulae and 1 micro-genuala, 2 tibialae and 1 microtibiala, 1 tarsala and 1 microtarsala ; 
II, one tarsala only; III with two femoralae, one whip-like mastigenuala ; no sensory rod on any tarsi. 
STUD. INST. MED. RES. 
