2 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 123 



In this study T. cruentipennis Lacordaire and T. maderi Delkeskamp 

 have been removed from Triplax as now described and have been 

 referred to Haematochiton Gorham. Triplax valdiviana Philippi has 

 been declared incertae sedis because of the inconspicuous small 

 pronotal angle pores, the lack of a brush on the maxillary palpal 

 terminal segments, and the extremely elongate appearance (length to 

 width ratio: 2.5 to 1). Triplax azureipennis has been declared 

 incertae sedis, while T. bicolor is declared Triplax{1) bicolor Guerin. 

 The present author has been unable to locate the types of these two 

 forms. 



The exact relation of the following genera, listed as Neotropical 

 Triplacinae by Blackwelder (1945), to the Neotropical species of 

 Triplax is not known: Pselaphacus Percheron; Megischyrus Crotch, 

 Ischyrus Lacordaire, Oocyanus Hope, Callischyrus Crotch, Mycomystes 

 Gorham, Mycophthorus Lacordaire, Pseudolybas Gorham, Lybas 

 Lacordaire, Lybanodes Gorham, Mycolybas Crotch, and Neoxestus 

 Crotch. It is felt, however, that the closest related genera to the 

 Neotropical species of Triplax are Paratritoma Gorham, Tritoma 

 Fabricius, Haematochiton Gorham, and Mycotretus Lacordaire. 

 Species of Haematochiton Gorham are recognized easily by their 

 weakly widened, semicircular maxillary palpal terminal segments, 

 by their inconspicuous, small pronotal angle pores, and by a body 

 shape similar to Triplax. 



Neotropical Triplax species are separated easily from Paratritoma 

 by the pronotal angle pores. In Paratritoma the pores are small and 

 inconspicuous, while in Triplax they are large and distinctly umbili- 

 cate. In other characters, such as the length to width ratio of the 

 body, shape of the pronotum, development of the postmandibular 

 lobes, and width of the terminal segments of the maxillary palpi with 

 distinct apical brush, few significant differences have been found. 

 Thus, at present, Paratritoma is considered the most closely related 

 of the Neotropical genera to Triplax. 



The one Neotropical Tritoma specimen examined, that of T. 

 dorsalis Gorham, can scarcely be confused with Triplax. Its broadly 

 oval body, long prosternal lines, and maxillary palpal terminal seg- 

 ments without apical brush are all non-Triplax characters. 



The taxonomic results of this study are that three specific names 

 have been placed in new synonymy and three new species are described. 

 Four species previously placed in Triplax are referred to Haema- 

 tochiton Gorham or are declared incertae sedis. One species is, 

 at present, of uncertain taxonomic position, while another species is 

 moved from Paratritoma Gorham to Triplax. Twelve species are 

 listed as Neotropical members of the genus Triplax. 



