
An INTERESTING anp PRIMITIVE NEW GENUS of 
LAELAPTIDAE (ACARINA) rrom AUSTRALIA 
Anp NEW GUINEA 
By H. WOMERSLEY, A.L.S., F.R.E.S., Exromotocisr, SouTH AusrraniAN Musrum, 
In 1988, Triigiirdh (Entom. Tidskft, Hft. 3.4, p. 123) published his important 
paper ‘Further Contributions towards the Comparative Morphology and Classi- 
fieation of the Mesostigmuta.’’ In this paper he stressed the importance of the 
ventral shields of this group of Acarina, especially in the female sex, as affording 
valuable evidence of the relationship of the various genera, 
Tn his view the four pairs of setae found on the jugular, sternal and meta- 
sternal shields indicate the coxal plates of the four pairs of legs. (It is generally 
accepted that the sternal shield in the Acarina is really formed by the fasion of 
eoxal plates and that a true sternal shield does not oceur). Generally in the 
Mesostigmata the sternal shield carries 2, 3 or 4 pairs of setae, mostly 3 pairs, 
the fourth pair often being found on the pair of small metasternal shields, as in 
Porgamasus and Maerocheles, 
Tn front of the sternal shield frequently oecur 1 or 2 pairs of small shields, 
generally termed the jugular shields, one pair of which (posterior if 2 are pre- 
sent) often bear a pair ofsetac. If these carry asetathey areregarded by Trégardh 
as representing the coxal plates of leg 1 and then it is found that the sternal shield 
hears only 2, or if the metasternal plates are fused with it, 3 pairs of setae. if 
the anterior pair of small plates do not bear setae, (hey are then considered as hay- 
ing nothing to do with leg 1, and are termed ‘‘pre-endopodal shields’? hy Txi- 
eiirdh, Tn these eases the true coxal plates of lez 1 are frsed with the sternal 
shield and their pair of setae ave found thereon. 
The new genus, with two species described in this paper, furnishes further 
evidence of Triwirdh’s views, in that the sternal shield is longitudinally divided 
down the middle, each half carrying 3 setae with the corresponding pores. Each 
half therefore bears the setae corresponding to the coxal plates of legs [to TL. The 
metasternal shields are wanting but are represented by the setae and their corre- 
sponding pores, 
Tt appears evident, then, that the new genus, Sezsswralaclaps is more primitive 
than any genus of the Mesostigmata or Laclaptidae so far known in that coalescence 
of the coxal plates m the medial line has not taken place. 
Famiry LAELAPTIDAE. 
Genus SctssuRALABLAPS nov, 
Deseription. Hypoaspis-like. Lightly chitinizied with moderately long to 
short fine dorsal setae. Female with sternal shield divided longitudinally, ventral 
ghield fused with genital, widely separated from anal. Pre-endopodal shields pre- 
sent or absent. Meta-sternal shields only vepresented by seta and pore. Dorsal 
shield entire, not entirely covering body. Male with sternal, genito-ventral aud 
shields coalesced. Legs without strong spines or processes. Mandible with pro- 
eess on movable finger of chelicerae, 
Ty pe Scissuralaelaps novagquined sp.M. 
