NEOTROPICAL PLATYRHACID MILLIPEDS — HOFFMAN 21 



known species. The angulation of the telopodite contrasted in couplet 

 3 is much more pronounced than might be suggested by the illustra- 

 tions. 



Genus Platyrhacus Koch 



Platyrhacus Koch, 1847, p. 58.— Hoffman, 1953a, p. 300; 1953b, p. 252; 1956, p. 46. 

 Barydesmus Cook, 1896b, p. 53 (ortliotype: Barydesmus herri Cook), New- 

 synonymy. 

 Barydesmus was very briefly diagnosed in the body of a synoptic 

 key to American platyrhacoid genera, and the type species was not 

 illustrated. The generic name therefore fell into disrepute and has 

 remained a nomen inquirendum down to the present time. Fortu- 

 nately, the original type specimen of Barydesmus kerri is located in 

 the U.S. National Museum collection, and has been available for 

 restudy. I am of the opinion that this type specunen belongs to the 

 large genus of South American species that seems to include the type 

 species of Platyrhacus; however, it is still not possible to state definitely 

 that B. kerri is absolutely congeneric with P. scaber Koch. 



Platyrhacus kerri (Cook), new combination 



Figure la, b 

 Barydesmus kerri Cook, 1896b, p. 53. 



Holotype, male, USNM 2380, Ecuador (further details of locahty 

 and collector not indicated) . 



Remarks : I do not at this time venture a specific diagnosis for 

 P. kerri since the characters of most of the known platyrhacids are as 

 good as unknown. The type specimen is in good condition though 

 discolored and perhaps somewhat telescoped from strong alcohol. 

 It is about 89 mm. in length and 19 mm. in greatest width. The 

 antennae are 11.6 mm. long. The second segment is wider than the 

 collum and slightly wider than the third segment. The coUum is 

 nearly smooth, without anterior marginal tubercules or a postmarginal 

 transverse groove. The tergites are smooth or at most finely coria- 

 ceous, with fine low tubercules evident upon drying. Lateral margins 

 of paranota dentate with three to five subacute projections. On the 

 caudalmost segments, the caudolateral apex of the paranota is drawn 

 out into a short, acute, incurved point. 



The gonopods, in situ, cross each other at about the midlength of 

 the telopodite. The coxites are rather elongate, with three long 

 macrosetae on the dorsal side, and with other vestiture lacking. From 

 the mesial aspect, the telopodite is very slightly arcuate, cm'ving 

 somewhat cephalomesiad over the coxa. The solenomerite is short, 

 slender, and a little sinuate; the tibiotarsus has a flattened lamina 

 and is drawn out mto an acute tip, with only the narrow dimension 

 visible mesially. 



