329 

 Leech and Chandler: Coleoptera 



the front femora, shape of the elytral apices, and 

 size of the insect are important. In Gyretes size and 

 form, width of the lateral band of vestiture, and form 

 of the outer apical elytral angle are of most use. 



Key to the Nearetic Genera of Gyrlnidae 

 Adults 



1. Dorsum glabrous; last abdominal segment rounded, 

 sternite without a median longitudinal line of hairs; 

 scute Hum visible or not 2 



— Sides of pronotum and elytra pubescent; last abdominal 

 segment elongate, conical, sternite with a median 

 of golden hairs; scutellum not visible (fig. 13:22c). 

 ORECTOCHILINAE Gyretes Brulle 1835 



2. Scutellum visible; elytral striae punctate, suture 

 margined; smaller and more convex species, 3 to 8 

 mm. long (fig. 13:22*). GYRININAE 



Gyrinua (Geoffroy in) Muller 1764 



— Scutellum not visible; elytral striae not punctate, 

 suture not margined; larger and flatter species, 9 to 



16 mm. long (fig. 13:22o). ENHYDRINAE 



Dineutus MacLeay 1825 



Key to Nearetic Genera of Gyrlnidae 



Larvae 



l.Head subcircular with collum narrow and distinct; 

 mandible falcate without retinaculum (fig. 13:21a). 

 ENHYDRINAE Dineutus MacLeay 1825 



— Head elongate (fig. 13:21&), with collum about as wide 

 as rest of head and not distinct; mandible with ret- 

 inaculum 2 



2. Nasale without teeth. ORECTOCHILINAE 



• Gyretes Brulle 1 835 



— Nasale with 2 to 4 teeth in a transverse row. GYRI- 

 NINAE Gyrinus (Geoffroy in) Muller 1764 



Key to the California Species of Gyrinus 



Adults 



1. Under surface, except legs but including hypomera 

 and epipleura, testaceous to ferrugineous (subgenus 

 Gyrinus) 2 



— Under surface, except legs, entirely metallic black, 



Fig. 13:23. Gyrinus sp., lateral view of adult head showing 

 divided eyes (Leech, original). 



Fig. 13:24. Gyrinus, male genitalia, a, bifarius; b, plicifer; 

 c, consobr/'nus; d, affinis; e, pleural/ s; f, parcus; g, picipes 

 (Fall, 1922). 



or sides of ventral segments rarely dull rufous, epi- 

 pleura often testaceous or rufous (subgenus Oreo gyrinus) 

 4 



2. Elytra minutely punctulate and very finely alutaceous, 

 more noticeably so in female; median lobe of aedeagus 

 of male very like that of G. bifarius Fall (fig. 13:24a), 

 constricted at apical third, thence flat, narrow, nearly 

 parallel-sided, tip rounded; British Columbia to Cali- 

 fornia, New Mexico punctellus Ochs 1949 



— Elytra highly polished, either not at all alutaceous 

 or punctulate, or only visibly so under high power . 3 



3. Outer apical angle of elytra with an inflated plica 

 across angle close to margin, margin thereby depressed 

 in this area; color beneath nearly uniform, surface 

 without trace of microsculpture in either sex; median 

 lobe of aedeagus of male (fig. 13:246) very narrow, 

 parallel-sided; British Columbia to Baja California, 

 Colorado to Texas plicifer LeConte 1852 



— Outer apical angle of elytra without an inflated fold 

 across angle; under surface normally darker medially 

 than along margins; median lobe of aedeagus (fiR. 

 13:24c) much broader, at least 1/3 as wide as a lateral 

 lobe; California to British Columbia, Utah 



consobrinus LeConte 1852 



4. Under surface metallic black, hypomera and epipleura 

 testaceous or ferrugineous; larger species, 5.5 to 7 

 mm. long 5 



— Under surface entirely metallic black, or virtually so, 

 epipleura normally showing no more than an obscure 

 rufous tint in certain lights; smaller species, 4.25 

 to 6 mm. long 6 



5. Elytra in both sexes thickly covered with very fine, 

 short, oblique striolae; median lobe of aedeagus 

 (fig. 13:24a") very slender in about apical third, thence 

 gradually widened to base, carinate medially, flattened 

 apically; northern North America, California 



affinis Aube 1838 



— Elytra in both sexes micropunctulate and minutely 

 alutaceous; median lobe of aedeagus (fig. 13:24e) 

 gradually decreasing in width from base to narrowly 

 rounded tip, dorsally carinate in more than apical 

 half; California to Colorado, British Columbia and 

 Alberta pleuralis Fall 1922 



6. Form strongly convex, nearly symmetrically arched 

 in profile; pronotum strongly bi-impressed on each 

 side, anterior impressions usually joined across disc, 

 sides and lateral margin finely wrinkled; 11th elytral 

 striae strictly marginal, lateral striae slightly canalicu- 

 late basally; elytra of males shining, of females 

 dulled by a sculpture of rounded meshes, except near 

 suture and across base; male genitalia similar to that 

 of typical parcus (fig. 13:24/); San Diego, Orange 

 counties parcus calif omicus Ochs 1949 



— Form only moderately convex, greatest convexity 



