Fig. 13:56. Ancyronyx variegatus, adult (Garman, 1912). 



Phanocerus clavicornis Sharp 1882; fig. 18; 2-3 

 mm.; brown; Texas, Mexico, Central America. 



— Antennae not clubbed; pronotum without sub lateral 

 sulcus; each elytron with an accessory stria near 

 suture below the scutellum; length 6-7 mm.; black; 

 western Lara LeConte 1852 



3. Coxae very widely separated and of about the same 

 size, located more on the side of body than on the 

 nearly flat venter; metacoxae almost globular; posterior 

 margin of prosternal process almost as wide as head 



4 



— Coxae less widely separated, especially the procoxae; 

 metacoxae distinctly larger and transverse; posterior 

 margin of prosternal process less than 1/2 the width 

 of the head 5 



4. Pronotum with 2 oblique, transverse depressions at 

 anterior 3rd, without sublateral carinae; antennae 

 filiform, with 11 segments, not clubbed; tibia without 

 patches of tomentum; elytra without sublateral carinae 

 (fig. 13:56) Ancyronyx Erichson 1847 



Ancyronyx variegatus (Germar) 1824; 2.3-2.6 mm.; 

 black, maculate; eastern U.S. 



— Pronotum without transverse depressions, but with 

 basal sublateral carinae; antennae 7-segmented, last 

 segment enlarged; elytra with tomentum extending up 

 to sublateral carinae; tarsi with 1 or 2 patches of 

 tomentum Macronychus Miiller 1806 



Macronychus glabratus Say 1825; 2.8-3.4 mm.; 

 black; eastern U.S. 



5. Posterior lateral corner of 4th or middle of lateral 

 margin of 5th abdominal sternites not produced into a 

 prominent upturned tooth; half of epipleura of elytra 

 usually uniformly and narrowly tapered to fine point, 

 (fig. 13:53a, e) 6 



— Posterior lateral corner of 4th or middle of lateral 

 margin of 5th abdominal segment produced into a 

 prominent tooth, which is bent upward to clasp epi- 

 pleura (less conspicuously bent in Zaitzevia which 

 has 8-segmented antennae); epipleura slightly to con- 

 spicuously widened to receive tooth, usually bluntly 

 narrowing to apex posterior to tooth (fig. 13:536,0"). . 13 



6. Epipleura extending to apex of elytra (fig. 13:53a); 

 protibia without a patch of tomentum 7 



— Epipleura usually ending near base or middle of 5th 

 abdominal segment (fig. 13:53e); protibia with a patch 

 of tomentum on anterior side 8 



7. First medial elytral stria short, about 1/6 the length 

 of 2nd (fig. 13:52<7); granules of head and legs elongate 



Ordobrevia Sanderson 1953 



Ordobrevia nubifera (Fall) 1901; 2.2-2.4 mm.; 

 black, maculate; California to Washington, in 

 foothill streams 



361 

 Leech and Chandler: Coleoptera 



— First elytral stria as long a.s 2nd; granulen of head 

 and legs round (fig. 13:53c); mostly eastern with 1 

 species from Nevada Stenelmis Dufour 1836 



Stenelmis calida Chandler 1949; 3-3.4 mm.; brown, 

 gray pile; Nevada, in warm springs 



8. Pronotum smooth, without sublateral carina; maxillary 

 palpi 3- or 4-segmented 9 



— Pronotum with sublateral carina extending from base 

 to or nearly to anterior edge (fig. 13:5 \e)\ maxillary 

 palpi 3-segmented 10 



9. Three-segmented maxillary palpi; larger species, 

 length 3-4 mm.; markings, if present, transverse; 

 western Narpus Casey 1893 



— Four-segmented maxillary palpi; smaller species 

 2-3.3 mm. long; markings, if present, longitudinal 

 (fig. 13:52a); U.S Dubiraphia Sanderson 1954 



10. Size larger, 2.5-2.6 mm. long; prosternum projecting 

 under head; epipleura extending to middle of 5th 

 abdominal segment Rhizelmis Chandler 1954 



Rhizelmis nigra Chandler 1954; 2.5 mm.; black; 

 California in shaded streams at 2,000 to 5,000 feet 



— Size smaller, 1.8-2.2 mm. long; prosternum not pro- 

 jecting under head; epipleura ending at base of 5th 

 abdominal segment 11 



11. Pronotum with sides parallel basally, strongly con- 

 vergent anteriorly (fig. 13:51e), lateral margins densely 

 punctured, nearly obliterating short, lateral branch of 

 the carinae running to posterior margin; anteriorly the 

 area between margin and carinae depressed; elytra 



broad, very convex or dome-shaped 



Ampumixis Sanderson 1954 



Ampumixis dispar (Fall) 1925; 1.8-2.2 mm.; black, 



elytra black to red; California, Oregon; in rapid 



clear steams, up to 6,000 feet 



— r Sides of pronotum not parallel, converging anteriorly 



from base, anterior marginal area not depressed, elytra 



less convex 12 



12. Pronotum with shallow, transverse, basal impression 

 connecting the 'carinae, sides nearly straight, carinae 

 gradually less distinct anteriorly to apical 4th, not 

 forked posteriorly, marginal area densely punctate; 

 spindle-shaped species Atractelmis Chandler 1954 



Atractelmis wawona Chandler 1954; 2 mm.; black, 

 elytra with humeral and subapical maculae; rare 

 in rapid streams, 2,000 to 5,000 feet elevation in 

 California 



— Sides of pronotum convex, carinae with posterior lateral 

 branch reaching posterior margin, marginal area not 

 so densely punctate, without transverse impression; 



sides of elytra more parallel (fig. 13:54c) 



Cleptelmis Sanderson 1954 



13. Fourth abdominal sternite with prominent tooth on 

 posterior angle, 5th abdominal segment not clasping 

 epipleura (fig. 13:536) 14 



— Fifth abdominal sternite with basal half of lateral margin 

 strongly clasping epipleura, middle of segment with a 

 prominent tooth which is bent vertically to fit into 

 widened area of epipleura (fig. 13:530") 19 



14. Antennae with 8 segments, last segment enlarged 

 (fig. 13:54^); pronotum with median, longitudinal 

 groove , elytra with 3 sublateral carinae 



Zaitzevia Champion 1923 



Zaitzevia parvula Horn 1870, fig. 30; 2 mm.; black, 

 with rufous to black elytra; western U.S. and 

 Canada; in streams up to 6,000 feet in California 



— Antennae 10- or 1 1-segmented; posterior lateral corners 

 of 4th abdominal sternite with prominent tooth sharply 

 bent upward to clasp the epipleura 15 



15. Pronotum with steplike sublateral carinae extending 

 from base to anterior margin (fig. 13:52A); elytra with 

 3 sublateral carinae; size small, 1.4 mm. long 



Limnius Erichson 1847 



Limnius latiusculus (LeConte) 1866, 1.4 mm.; 

 black; eastern U.S. 



— Pronotum with sublateral carinae short or absent, 

 elytra without sublateral carinae 16 



