150 
J. R. AUDY 
Remarks. — Novotrombicula and Heaslipia have a major character (additional posterior 
scutal setae) in common but this has clearly developed independently. The anterior part of 
the scutum of Novotrombicula resembles that of T. rara and T. thori , common on skinks, in 
the placing of the sensillary bases ; this and the absence of a mastitarsala are probably of generic 
importance. 
Genus Ipotrombicula Womersley 1952 
Type. — Trombicula elegans Worn. 1942:173, Rec. S. Aust. Mus., 7, 169-181. Adults only; sea-shore, 
Australia. 
Diagnosis. — Monotypic, adults only: as described by Womersley 1952:323, Rec. S. Aust. Mus., 10, 
1 - 435 - 
b. — Schongastia group of genera — expanded sensillae 
Genus Schongastia Oudemans, 1910 
Type. — Thrombidium vandersandei Ouds., 1905:216, Ent. Ber ., Amst., 1, 216-218. From man, rats, 
birds in eastern Indonesia, New Guinea, Solomon Is. 
Diagnosis (restricted). — Trombiculines whose larvae have 7-segmented legs; shield-like scutum with 
markedly convex posterior margin, 5 scutal setae, sensillary bases fairly close together, and globose sensillae; 
a series of teeth on the chelicers (which are usually long), and a nude seta or mastitarsala on tarsus of leg III 
( ? ? may not always be present) ; apparently restricted to the Old World tropics and sub-tropics ; primarily 
parasitic on reptiles and often on birds, sometimes extending to mammals and including two important 
scrub-itch mites. Nymphs and Adults (known from 2 or 3 species : schuffneri , vieta, maldiviensis) without 
eyes, with the sensillary area about as wide as long, roughly triangular with apex directed backwards, SB 
relatively fairly wide (ASL/SB ratio 2); tectum rounded; sensillae nude or lightly barbed; precoxal plates 
present on coxae I. Not recorded from the New World. 
Remarks. — This genus has been “ defined ” on a key-character (toothed chelicers) instead 
of being based on relationships with the genotype. What appears to be a good natural group of 
(larval) generic status has thus been confused by the inclusion of outsiders. It seems best to 
restrict the genus as rediagnosed above to the clear group-characters of the vandersandei 
species-group, viz., the triad, scutal shape, toothed chelicers, and mastitarsala III, added to the 
general host-preference for birds and reptiles. The general appearance of the scutum closely 
resembles that of the lanius-growp (new subgenus Helenicula below). Dr Lawrence (in 
correspondence) describes a mastitarsala III near the base of the joint, clearly visible in his 
S. platysoairi , S. pseudocordyli and S. scincicola, but he could not see this in the other species 
(see fists below). Varma (in litt.) is describing a new Schongastia from near Calcutta: it has 
the typical almost-pentagonal scutum and the mastitarsala. 
There is no doubt that a large number of ill-sorted chiggers are related to Schongastia 
and Womersley has made this a major genus sensu lato. The writer feels that this group is 
well characterised in the larvae and is not the best choice as the typical subgenus of a 
heterogeneous group which is almost certainly destined to be split up into several genera in 
spite of apparent similarities between the post-larval stages. He therefore prefers to recognise 
Schongastia sensu stricto and Euschongastia sensu lato, the latter including a heterogeneous 
collection and corresponding to the other heterogeneous genera Trombicula sensu lato, 
Gahrliepia sensu lato. 
Three species at least (excluding Lawrence’s species ? without mastitarsala^, noted above, 
which require close study) are not congeneric. Schongastia oudemansi Gater is quite distinct 
on a number of characters and while approving of Fuller’s action in placing it in a new (and at 
the time monotypic) genus, Walchiella , it is unfortunate that this particular name was chosen 
because for reasons already discussed we cannot attach sufficient importance to the number of 
leg-segments to include this species in the Gahrliepiinae : it affinities are clearly with 
Euschongastia (see p. 153 below). 
Womersley’s species bidentata , of which Mr Womersley has kindly sent us a specimen, is 
very distinctive and not congeneric : it must be accommodated in Euschongastia despite the blunt 
STUD. INST. MED. RES. 
