Tribe 8. Tychini 



The Tychini are delineated by the following combination of characters: 

 (1) the neotropical species have eleven-segmented antennae which are never 

 geniculate, and are always widely separated at their bases. This particular 

 character tends to make neotropical tychines unfamiliar in habitus to the 

 student of nearctic Tychini, since such genera as Tychus, Cylindrarctus and 

 their North American and European allies have the antennae approximate at 

 base, the head correspondingly narrowed into more or less of an antennal 

 tubercle, and therefore imparting to the whole animal a distinctive facies. 

 The neotropical tychines, on the other hand, never have the antennae close 

 together upon a common median antennal tubercle and hence the head has a 

 broad, unfamiliar outline approaching Batrisini in many genera; (2) Mentum 

 normal, never expanded to cover the mouth and mouth-parts; (3) Abdomen 

 with five visible tergites. The first tergite is margined each side by an external 

 and an internal carina and the second and third tergites are also usually 

 margined each side by at least a single, short carina. This pattern holds for 

 all neotropical genera with the exception of one genus, Dalmophysis, which 

 has no marginal carinae on the first tergite or any succeeding tergites and is 

 wholly marginless. Some genera have the lateral margins well-developed 

 {Iniocyphus, Dalnwdes, Dalmomima, Batriphysis) although narrow and vari- 

 ously foiTned. Other genera (Buris) have the margin indistinct, limited to the 

 base of the first tergite; (4) Abdomen with the first stemite as long or much 

 longer than the posterior coxae and always continuously visible from side to 

 side. Females always with six sternites. Males with six stemites in all but 

 three neotropical genera. These latter {Buris, Dalmoburis, Dalmophysis) 

 have seven sternites in the male sex. Dalmophysis has a small, transversely 

 triangular seventh sternite; Buris and Dalmoburis have the seventh stemite 

 relatively large and longitudinally divided into a right and a left plate. It 

 should be added that in a few genera only a single sex is known, thus Iniocyphus 

 and Batriphysis are known only from males, and Bythinophysis from the female 

 sex alone; (5) Posterior coxae have their mesial faces globular; (6) Femora 

 obliquely articulated with their trochanters, so that coxa and femur, of the 

 intermediate legs at least, are close together; (7) Three-segmented tarsi with 

 the first tarsomere very small, and the last two relatively very long, the distal 

 tarsomere bearing either a single large claw, or a large claw and an accessory 

 bristle-like claw. 



In contrast to Batrisini, neotropical Tychini are represented by a relatively 

 large number of genera, but few species. Thus, there are fourteen genera and 

 only thirty spcies. The neotropical genera may be artificially separated as fol- 

 lows : 



(260) 



