DIAPERINI NORTH OF MEXICO — TRIPLEHORN 413 



Description. — Short, broadly oval, moderately convex, brownish 

 black to black, often with purplish cast, dull in lustre. Head evenly 

 arcuate in front, anterior margin reddish, flattened or feebly convex 

 between eyes, epistomal suture well defined, surface uniformly 

 coarsely and densely punctured; eyes small, widely separated both 

 above and below, convex, broadly and deeply emarginate anteriorly, 

 dorsal anterior margin deeply set in head, sharply elevated behind; 

 separated ventrally by a distance subequal to about two (1.8-2.6) 

 times the longer axis of one eye; mouthparts light reddish brown, 

 terminal segment of maxillary palpus broadly triangular with distal 

 angle prolonged; antennae uniformly pale reddish brown from base 

 to apex. Pronotum twice as broad as long, strongly narrowed from 

 base to apex, sides strongly arcuate, narrowly margined, bead fine 

 and slightly reflected, basal angles rectangular, apical angles broadly 

 rounded, disc finely but distinctly punctured, lateral punctures 

 larger, subequal to those of head. Elytra convex, sides strongly 

 rounded, narrowly margined with distinct bead, striae feebly or 

 not at all impressed, finely and closely punctured, intervals flat to 

 rather strongly convex, impunctate, rarely with a few minute, widely 

 scattered punctures. Prosternal process variable, usually hori- 

 zontal with apex promineht, sometimes feebly convex or convex 

 with apex secondarily reflected, margined between coxae. Ventral 

 surface of pronotum concave, usually coarsely and densely punc- 

 tured, sometimes smooth, edges very thin ; metasternum with coarse, 

 widely spaced punctures; abdominal sternites coarsely and densely 

 punctured, each with at least a faint lateral depression, always 

 especially pronounced on fourth sternite; entire ventral surface 

 including epipleiu-a reddish brown, except apical sternite which is 

 often black. Male aedeagus with apical sclerite flat, blade like, 

 about one-fifth longer than basal sclerite; a strong constriction be- 

 tween apical and basal sclerites (pi. 5, figs. 40, 41). Measurements: 

 length 3.5-5.8 mm.; width 2.0-3.4 mm. 



Remarks. — This is probably the most frequently encountered and 

 abundant species of Platydema inhabiting eastern North America, 

 excluding the New England states and the northern parts of Alinne- 

 sota, Wisconsin, and Michigan. It is difficult to characterize because 

 there is nothing particularly distinctive about it. Its salient features, 

 consisting of a broadly oval form, dull and velvety dorsal surface, 

 coarsely and densely punctured head and pronotum, and uniformly 

 pale antennae, separate it from its congeners, with the possible 

 exceptions of P. ruficolle and P. wandae. Characters which will sep- 

 arate it from these two are discussed separately under each of the 

 latter. In collections it is frequently confused with both P. nigratum 

 and P. jlavipes, but these readily may be distinguished by means of 



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