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rarely serrated or with teeth; wide host range but mostly on mammals. Nymphs and Adults similar to 
those of Schongastia but with eyes and precoxal plates absent or completely fused to form a sternum, in 
species so far examined. 
Remarks. — As discussed in a footnote by Womersley (1952:170) and reaffirmed in a paper 
to be published (Womersley and Audy, 1955) Euschongastia has priority over Ascoschongastia 
and the former should be extended to include all those chiggers which have been included in 
Schongastia (. Ascoschongastia ) by Womersley {loc. cit.). Womersley’s intention in this matter 
is quite clear (private communication), and evidently the amendment of his monograph proved 
impracticable. 
The writer believes that Schongastia sensu stricto discussed above is a valid genus. The 
assortment of chiggers included by Womersley in his subgenus Ascoschongastia (amended to 
Euschongastia ) are therefore here treated as a genus, Euschongastia sensu lato. 
As noted below, however, the type (E. sciuricola ) belongs to a species-group which has 
hitherto been distinguished by the accessory apical prongs to the palpal claws. Although 
the number of prongs on the claws is by itself a variable character of doubtful significance, this 
species-group appears to be distinctive in other ways and the writer doubts if such species as 
E. lacunosa (Gater) and E. indica (Hirst) will ultimately prove to be congeneric with it. Usage 
however dictates that Euschongastia should for the time being taken as the temporary repository. 
As with Trombicula it appears to the writer that the proper procedure here is to attempt to 
define the type subgenus fairly strictly, and to recognise as many distinct species-groups and 
possible subgenera as may be necessary. A number of species will for a time inevitably remain 
unallocated to a group within the genus. As a step in the stabilisation of these affiliated groups, a 
new subgenus is here raised to accommodate the well-knit lanius-mutabilis- group. It will 
probably be helpful to raise another subgenus for the indica- group also, but this would at 
present be premature, because the indica-g roup might prove to be congeneric v/ith Doloisia. 
Subgenus Euschongastia Ewing, 1938 
Type. — ( Euschongastia americana Ewing, 1938: 293, J. Wash. Acad. Sci ., 28, 288-295, synonym) = 
Schongastia sciuricola Ewing, 1925:261, Amer. J. trop. Med., 5, 251-265. On American rodents. 
Diagnosis. — Larvae with a characteristic shaped scutum, generally broader than long, with PW 
appreciably wider than AW and the posterior margin medially convex ; palpal claws variable but generally 
with several small apical accessory prongs, 4-6 in number (these may vary in number even on both sides of 
the same specimen, and may be obscured by the main axis of the claw); so far not recovered from the 
Asiatic-Pacific area. 
Remarks. — It might be a mistake to insist on the regular presence of the apical prongs on 
the palpal claws in the diagnosis of this subgenus. Certain African species appear to be related, 
but have 3-pronged claws. These are aethomyia , otomyia , and two species very near to 
these sent to the writer by Dr. Lawrence: the latter species have a mastitibiala and a mastitarsala 
III, both very fine and tapering, but the writer has been unable to compare them with any of 
the described species. 
Subgenus Helenicula nov. 
Type. — Neoschongastia lanius Rad., 1946:261, Proc. Zool. Soc. Lond., 116, 247-265. From a bird and 
rats, Indo-Burma border. 
Diagnosis. — Larval Euschongastia with shield-shaped scuta with convex posterior margins (cf. 
Schongastia s.s., but emarginate in signata ) and sensillary bases very close together (ca. 15^, or considerably 
less than twice the diameter of the bases, apart), globose sensillae, with basal stem ; generally with multisetose 
coxae III (i-setose in signata)', without mastitarsala III. Several species appear to be widely distributed 
and there is evidence suggesting that larvae of this subgenus are seasonal, appearing in relatively cold dry 
seasons. Nymphs & Adults (based on 4 species) with the general characters of Euschongastia but with 
thickened and well-barbed shafts to the sensillae, a relatively narrow sensillary area (ASL/SB ratio 
2. 3-2. 8). The posterior dorsal setae in mutabilis and signata have a long terminal setule. Not recorded 
from the New World. 
STUD. INST. MED. RES. 
