Tribe 7. Batrisini 



The Batrisini, in contrast with the neotropical Brachyglutini, are gen- 

 erically impoverished. The tribe at present contains eight neotropical genera 

 which have in common (1) antennae distantly inserted on the head, never 

 subcontiguously articulated on a common, median antennal tubercle. (2) 

 Mentum normal, never expanded to cover the mouth and mouth-parts. (3) 

 First stemite very small, nearly hidden between the posterior coxae and 

 median apical margin of metasternum but not invisible as in the Brachy- 

 glutini. (4) Lateral abdominal margins absent or represented by one, or at 

 most two, carinae; never wide and strongly formed. (5) Trochanters of inter- 

 mediate legs always obliquely articulated on the femora so that each femur 

 and coxa are close together. (6) Posterior coxae with their mesial ends form- 

 ing a subtriangular articulating area for the posterior legs. (7) Tarsi three- 

 segmented, with the first segment minute and the last two segments relatively 

 much longer and elongate-cylindrical to elongate-obconical, the distal segment 

 bearing apically two very unequally developed tarsal claws. 



The Batrisini are in reality a very highly specialized tribe. Subfamily 

 status could be advocated for them without too much diflSculty. Numerically 

 the tribe is only exceeded by the Brachyglutini in species from the viewpoint of 

 the world fauna. Raffray (1908) finds the batrisines to be best developed in 

 the Indo-Malayan region, poorly represented in Africa, New Zealand, Aus- 

 tralia, and Madagascar. From an Indo-Malayan center they appear to have 

 spread chiefly north into the Palarctic and Nearctic areas, chiefly by means 

 of the great genus Batrisodes and its allies, and from these two northern realms 

 to have penetrated into the African region and into the Neotropical region. 



The Batrisini are approached in their carinoid abdominal margin by a few 

 genera of Brachyglutini and some Metopiini, and by the Metopiini in the 

 construction of the first stemite and tarsal claws. 



Many batrisines are synoeketes of the ant society, especially within the 

 genus Batrisodes, where they eat the eggs and larvae of the host while more 

 or less tolerated by the host workers. The palarctic synoeketes have been dis- 

 cussed by Donisthorpe (1927) and the nearctic synoeketes in Batrisodes have 

 been cited with their host ants by Blatchley (1910), Fall (1912), Holmquist 

 (1928), Mann (1911), Park (1929, 1932, 1935a, 1935b), Schwarz (1890, 1896), 

 and by Wickham (1894, 1896, 1898, 1900). Food, habits, and ecological re- 

 lations within the ant nest have been reported less abundantly (Park, 1929, 

 1932, 1935b). Virtually nothing is known of the neotropical inquilines among 

 the Batrisini. 



In general the majority of the Batrisini is free-living, inhabiting the floor 

 stratum of forests, in moist leaf and log mold. Here they are strictly pre- 

 daceous, feeding on mold mites (Oribatidae) or even attacking larger injured 



(214) 



