126 J. R. AUDY 
characters are listed below together with references to pages where they are discussed or 
illustrated. 
1. Variation in the extension of the scutum to exclude or include setae. — A reduction of the 
scutum, leaving the PL setae isolated, is encountered in Tecomatlana , Trisetica, and Sauriscus 
(of which Sauriscus at least, and perhaps Trisetica , may not be congeneric with Tecomatlana; 
p. 149). Anomalaspis; Speleocola(P); As cos chong astia (p. 155), Pseudoschongastia (p. 155); 
Apolonia, Womersia (p. 165). This character is discussed by Womersley (1953, this Study 
p. 120). Extension of the scutum to include some of the dorsal setae is especially developed 
in the Gahrliepiinae (Walchiinae), but it is also encountered in the following, either with 
inclusion of dorsal setae or reduplication of the PLs : Novotrombicula (p. 149), Heaslipia (p. 149), 
and Mackerrasiella Worn. 1953 :(p. 114) 
2. Scutal submergence and cuticular encroachment. — A number of unrelated species show 
some encroachment of the cuticle onto the scutum, or even a partial submergence of the 
scutum, e.g. Eusch. rectangulare (Womersley 1952:186), T. dimolinae Audy 1952 : 139, and 
Speleocola tardaridae Lipovsky 1952:132. The submergence of the scutum is more complete 
and regular, and in several species apparently of a different nature, in the heterogeneous 
genus Neo schongastia , and this requires further investigation (see comments, pp. 133, 156). 
3. Division of the femora of legs II and III. — This has been accepted by many authorities 
as the chief character which distinguishes the Gahrliepiinae from the Trombiculinae. The 
division of the femur is a false articulation, sometimes evident only on the ventral aspect of the 
femur, and in some species (. Pseudoschongastia ) the division may be difficult to detect in one or 
other of the legs — although as Brennan (1952) has pointed out, there is no doubt about the 
division on careful examination. 
A species of great taxonomic interest in this connexion is Schongastia oudemansi , the larva 
of which is distinctive and clearly not congeneric with the other species of Schongastia s. str. 
(p. 150). It should therefore be taken out and either accommodated in Euschongastia s. lat. or 
given a new genus or subgenus, the genus or subgenus Schongastia s. str. being redefined 
accordingly. Fuller (1952) has, we think rightly, placed this species in new genus, Walchiella , 
which however automatically falls in the Gahrliepiinae as at present defined. Both Walchiella 
and the genus Pseudoschongastia have therefore been placed in the Gahrliepiinae by Wharton & 
Fuller (1952). But the Gahrliepiines form a notably consistent group in both larval and 
postlarval stages, while oudemansi is a typical Trombiculine in all larval and postlarval 
characters except the division of the femora in the larva. Furthermore, some 21 species, of 
which 2 are described in this Study (p. 84), have now been found which show characters 
intimately relating oudemansi to similar forms without cheliceral teeth but with divided 
femora, and to others with undivided femora, including E. lacunosa (Gater). The nymphs of 
4 of these forms are available and they share so many characters with the Trombiculinae and 
differ on so many diagnostic points from the twelve described gahrliepiinae nymphs, that the 
affinities of the oudemansi-g roup would appear to lie with the Trombiculinae and near to the 
lacunosa-g roup. For this reason, we here treat Walchiella as a subgenus of Euschongastia , 
probably related to the sister lacunosa- group. 
The only reason for suspecting that the oudemansi-gyowp is intermediate, linking the 
Trombiculinae with the Gahrliepiinae, lies in the division of the femora, and oudemansi in 
fact fits more uncomfortably into the Gahrliepiinae on general characters than it ever did in the 
genus Schongastia s. str. from which it has rightly been rescued. The division of the femora 
appear to have been independently acquired. Once this character in the legs is not given 
prime subfamilial importance, the genus Pseudoschongastia also can be seen as being more 
properly trombiculine ; but this genus is different from the oudemansi-g roup in general characters 
STUD. INST. MED. RES. 
