1908.] AUSTRALIAN FOSSORIAL WASPS. 507 



Nysson (Acanthosthethus) spiniger, sp. n. 

 $ . Olypeus depressed to the apex, and broadly but sliallowly 

 emai-ginate anteriorly, clothed with very short silvery pubescence. 

 Antennfe inserted a little further from each other than from the 

 eyes ; the three apical joints of the flagellum much thickened, the 

 apical joint twice as long as the second, which is longer than 

 the third. Eyes separated from each other at the base of the 

 elypeus by a distance equal to about two-fifths of the length of 

 the antenna?, strongly divergent towards the vertex, but not 

 emarginate ; the posterior ocelli half as far again from the eyes 

 as from each other. Head strongly and very closely punctured ; 

 an indistinct, very short, longitudinal carina between the 

 antennae ; the front and pronotum with very short and sparse 

 white pubescence. Thorax punctured-rugose ; the pronotum 

 short, gradually sloped, the anterior angles prominent ; the meso- 

 pleura? strongly and closely, the mesosternum feebly and sparsely 

 punctured. Scutellum subrectangular, very little broader than 

 long. Median segment very short, in the middle only about 

 half as long as the scutellum ; the posterior angles strongly 

 produced, ending in an acute spine directed outwards and back- 

 wards, the enclosed space with convergent lateral carinas and 

 marked with about six longitudinal cai-ina? ; vertically truncate 

 posteriorly, with several longitudinal carinte on the surface of 

 the truncation ; the sides of the segment finely and sparsely 

 punctured, the dorsal surface outside the enclosed area clothed 

 with silvery pubescence. Abdomen closely punctured ; the first 

 segment longer than the second, subtruncate at the base, and 

 more strongly punctured than the second segment ; the pygidial 

 area granulate, subtriangular, and narrowly truncate at the apex. 

 The first ventral segment with a veiy strong median carina and 

 a long spine on each side at the apical angles ; the second 

 segment much longer than the first and strongly punctured. 

 Posterior tibiae almost unarmed, slightly emarginate near the 

 apex. 



Black ; the mandibles, the basal third of the antenna?, the 

 tegulfe, the legs, the basal segment of the abdomen, the apical 

 margin of the remaining segments obscurely, and the sides and 

 ventral surface of the pygidium, dark ferruginous ; a short, 

 obscure, transverse band on the sides of the first and second 

 abdominal segments yellow. Wings hyaline, nervures black. 



The second cubital cell is almost petiolate, the first recurrent 

 nervure is received by the first cubital cell at about one-fifth from 

 the apex, the second close to the apex, almost interstitial with 

 the first transverse cubital nervure. The anal cell of the hind 

 wing is short. 



cj . As in the female, but without the spine at the angles of 

 the first ventral segment, and the apical segment is widely 

 emarginate at the apex. 



Length 5 mm. 



Hab. Mackay, Queensland (Turner) ; October. 



