317 



Leech and Chandler: Coleoptera 



21. Dorsal surface pale flavotestaceous; 2nd segment 

 of front tarsus not outstandingly dilated, only slightly 

 wider than 3rd; broadly oval species; southern California 

 (=males of) fraternus (LeConte) 1852 



— Dorsum brownish-yellow to brownish-ferrugineous; 

 2nd segment of front tarsus of male dilated, nearly 

 1/2 again as wide as 3rd; elongate-oval species; north- 

 west Pacific Coast 



(in part) obscureplagiatus (Fall) 1919 



Key to the California Species of Hydroporus 10 



Adults 



l.Hind margin of metacoxal processes conjointly dis- 

 tinctly sinuate, somewhat depressed at median line 

 and there angulate and sloping to meet first visible 11 

 abdominal sternite; hind coxal process glabrous. Hind — 

 trochanters usually elongate, their apices nearly 

 halfway from hind angles of hind coxal processes to 

 apices of femora. Mostly small, dorsally glabrous, 

 reddish or brownish species 2 



— Hind margin of metacoxal processes truncate or some- 

 what rounded, if distinctly angulate medially then 

 median line not depressed and sloping to meet 1st 12 

 sternite; hind coxal processes usually hairy. Hind 

 trochanters shorter and stouter, clearly less than 1/2 

 length of distance from hind coxal processes to apices 



of femora. Mostly larger species, piceous in color, 

 with an obvious elytral vestiture 11 — 



2. Hind coxal lines narrowly separated, curving strongly 13 

 outward in apical half; hind trochanters shorter, not 

 reaching halfway from hind coxal processes to apices 



of femora; pronotal side margins broad, about as wide — 

 as a median antennal segment; form narrower, size 

 small, 3 mm. or less in length; median lobe of male 14 

 genitalia simple apically 3 



— Hind coxal lines more widely separated, curved slightly 

 outward near apices; hind trochanters longer, pronotal 

 side margins narrower than a median antennal segment; 

 body form broader, size various; median lobe of male — 

 genitalia bifid apically 5 



3. Size smaller, 2.1-2.4 mm. long; form elongate -oval, 

 more convex, elytra notably coarsely punctate; Men- 

 docino County bidessoides Leech 1941 



— Size larger, 2.5-3 mm.; form more broadly oval, flatter, 

 elytra finely punctate 4 15, 



4. Slightly larger species, 3 mm. long; front tarsal claws 

 of male nearly twice as large as those of middle tarsi; 

 southern California barbarae Fall 1932 



— Slightly smaller species, 2.5-2.8 mm.; front tarsal 

 claws of male like those of middle tarsi; California, 

 southern Oregon terminalis Sharp 1882 



5. Area between metacoxal lines nearly flat, smooth, 

 with at most a few tiny punctures; apex of last abdom- — 

 inal sternite of female produced, lobate; California 



(a complex of species centering around 



rossi Leech 1941) 16, 



— Area between metacoxal lines clearly though irregu- 

 larly punctured, often somewhat inflated; last abdom- 

 inal sternite of female evenly rounded at apex 6 



6. Form broader, more convex; ventral punctation coarse. 

 The undersurface shining, polished, without slightest 

 trace of alutaceous sculpture between punctures. 

 Sides of first 3 abdominal sternites as coarsely punc- 

 tate as sides of metasternum, more so than metacoxal — 

 plates; next 2 sternites less coarsely but very densely- 

 punctate; last sternite with a broad, heavily punctate 

 transverse groove. Length 3.2-3.5 mm.; southern 

 California, north to Sequoia National Park 



latebrosus LeConte 1852 



— Form narrower and less convex, undersurface with at 17, 

 least in part an alutaceous sculpture on metacoxal 

 plates or abdominal sternites; punctation finer and 

 generally sparser 7 — 



7. Elytra nearly or quite uniform in color, varying, how- 

 ever, from yellowish-testaceous to dark brown or 



castaneous 8 



Elytra conspicuously and rather abruptly paler at 



base, coast of central and northern California 



palliatus Horn 1 883 



. Size large, 4 mm. long; elytra finely punctate; San 



Francisco Bay region hardyi Sharp 1882 



Size smaller, never as long as 4 mm., rarely more 

 than 3.5 mm 9 



. Larger species, 3.0-3.5 mm. long; California 



vilia LeConte 1 852 



Smaller species, 2.4-2.8 mm. long 10 



.Strongly flattened, more nearly parallel-sided; usually 

 rufous beneath, with clearly defined alutaceous sculp- 

 ture; southwest U.S belfragei Sharp 1882 



Rather broadly subovate, evidently convex; piceous- 

 brown beneath, with scarcely detectable alutaceous 

 sculpture; southern California. . barbarenais Wallis 1933 



. Size larger, 3.5-6.5 mm. long 12 



Size smaller, rarely as much as 3.5 mm. long. Form 

 narrowly oblong-oval, color black to brownish, elytra 

 usually with a few small yellowish spots near humeri 

 and in apical 3rd; elytral surface alutaceous, punc- 

 tures not obscured by pubescence; last 4 abdominal 

 sternites sparsely, very finely punctate; Pacific Coast 

 occidentalis Sharp 1882 



. Size very large, more than 6 mm. long; elytra densely 

 pubescent, punctation very fine; abdominal sternites 

 densely, nearly uniformly punctate. Second segment 

 of front tarsi of male wider than 1st, claws elongate, 



slender, equal; Pacific Coast fortis LeConte 1852 



Size smaller, not more than 5.2 mm. long 13 



. Hind coxal plates with coarse, shallow punctures, 

 like those on sides of metasternum and 1st few abdom- 

 inal sternites 15 



Hind coxal plates impunctate, or at most with small 

 deep punctures 14 



. Hind coxal plates impunctate; last abdominal sternite 

 densely punctate. Antennae less stout, intermediate 

 segments about twice as long as broad; antennae 



fuscous, paler at base; western U.S 



axillaris LeConte 1853 



Hind coxal plates with sparse, small, deep punctures. 

 Last sternite rather sparsely punctate. Antennae 

 relatively stout, intermediate segments much less 

 than twice as long as broad; antennae and legs almost 



black throughout; Sierra of California 



funestus Fall 1923 



, Lateral margins of elytra, as viewed from the side, 

 rather strongly arcuately ascending at base. Sides 

 of pronotum and elytra, in dorsal view, less continuous 

 in outline than usual. Lateral marginal bead of prono- 

 tum very narrow, low, its inner edge indefinite towards 

 base; hind margins of pronotum almost straight from 

 hind angles to scutellar lobe. Elytra of female duller, 



more finely punctate than that of male 16 



Lateral margins of elytra much less strongly ascending 

 at base; sides of pronotum and elytra with nearly 

 continuous outline, in dorsal view 17 



, Form more robust and less depressed. Hind angles 

 of pronotum more broadly rounded, sides arcuate, 

 discontinuity of outline with elytra more apparent. 

 Second protarsal segment of male asymmetric, more 

 produced on inner (anterior) side of mid-line than on 

 outer; 3rd segment more nearly parallel-sided. Typically 

 a species of ponds and lakes; south central British 

 Columbia to Sierra of California. . .tademus Leech 1949 

 Form less robust, more depressed. Hind angles of 

 pronotum more nearly rectangular, sides straighter. 

 Second protarsal segment of male symmetric; 3rd seg- 

 ment not appreciably parallel-sided. A species of 

 streams and rivers; Alaska to northern coast of Cali- 

 fornia mannerheimi J. Balfour-Browne 1944 



, Larger species, 4.5-5.3 mm. long. Elytra of male 



shining, of female dull; Pacific Coast 



subpubescens LeConte 1852 



Smaller species, 3.7-4.3 mm. long. Elytra shining in 

 both sexes 18 



