20 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 121 



for spadix, but study of the types of abdominalis reveals it is an un- 

 familiar species which apparently does not occur in North America. 



3. Melanotus decumanus (Erichson) 



Figures 4/-/i, M; Plate 16 



Cratonychus decumanus Erichson, 1842, p. 104. — LeConte, 1853, p. 474. 

 Melanotus decumanus. — Candfeze, 1860, p. 341. — Blatchley, 1910, p. 749. — 



Thomas, 1941, p. 258.— Severin, 1949, p. 15.— Fattig, 1951, p. 20. 

 Cratonychus cuneatus LeConte, 1853, p. 473. 

 Melanotus cuneatus. — Thomas, 1941, p. 258. 

 Cratonychxis incertus LeConte, 1853, p. 474. 

 Melanotus canadensis Candfeze, 1860, p. 342. — Blatchley, 1910, p. 751. — Thomas, 



1941, p. 258.— Dietrich, 1945, p. 55. 



Male. — Large species, body color dark reddish brown, covered 

 with yellowish hairs evenly distributed over body. 



Head: Front coarsely punctate, most punctures hexagonal shaped, 

 distance between punctures less than half puncture diameter, sm-face 

 with broad depression anteriorly, margin strongly jutting and forming 

 noticeable shelf above clypeus; parantennal fovea very shallow, 

 usually teardrop shaped. Mandible without pit; palpi reddish to 

 yellowish brown. Antenna about exceeds tip of hind angle by IK 

 segments, erect male hairs dense and easUy observed, average ratio 

 of segments 2:3:4 varies from 5:10:20 to 5:8:19, segments 4 and 

 following longer and more slender than similis. 



Pronotum wider than long, ratio of width/length =1.2, a little 

 flattened dorsally, punctures about same size as those on front, at 

 center separated by distance equal to punctiu-e diameter or less, little 

 more dense on sides and front, oval in shape except those on anterior 

 angles hexagonal shaped as on front; hind angles divergent, with 

 single, strong, black carina, and often a second smaller one; sides 

 divergent and nearly straight to about two-thirds distance from base, 

 rather sharply angled before concavity in front of hind angles. 



Elytron and venter of metathorax and abdomen as in similis. 

 Genitalia as figiu-ed, paramere straight or with gently sloping sides 

 basad of apical blade, blade with 8 hairs. 



Elytron: 11.2 ±0.6 mm (10.0-12.4). 33 spec. 



Female. — Similar to male. Larger, antenna little shorter. Gen- 

 italia as figm-ed; bursa completely devoid of spines or sometimes with 

 patch of 5-8 small spines (like those of similis) on either side of 

 bursa near base. 



Elytron: 12.2 ±0.8 mm (10.0-14.1). 47 spec. 



Types. — Holotype of decumanus: Female, "Amer. Sept." (ZM). 

 Only specimen in type series. 



