Heterocerus sandersoni (Pacheco)

King, Jonas G. & Lago, Paul K., 2012, The variegated mud-loving beetles (Coleoptera: Heteroceridae) of Mississippi and Alabama, with discussion and keys to the species occurring in the southeastern United States, Insecta Mundi 2012 (275), pp. 1-53 : 20

6. Heterocerus sandersoni (Pacheco)

New Combination

( Fig. 16 , 39 , 59 )

Neoheterocerus sandersoni Pacheco 1964: 75 .

Description. Length 4.5 - 5.5 mm. Red to dark brownish-red. Elytra trifasciate; pale markings usually broken into separate spots; striae prominent ( Fig. 16 ). Apical angles of pronotum pale. Post-metathoracic coxal and post-mesothoracic coxal lines absent. Male genitalia ( Fig. 39 ) of the typical Heterocerus type; anterior fifth of phallobase slightly constricted to 90% of its greatest width, then widened slightly; median plate with dark ovate sclerites on either side anteriorly; dorsal plate of phallobase elongated on its right anterior edge; parameres curved ventrally, medial edges diverge slightly in ventral view. Hypermandibulate males unknown.

Diagnosis. Heterocerus sandersoni is similar in appearance to H. fatuus and previous workers have often confused the two species. It is also similar in appearance to H. angustatus , with which it shares a small crescent of its range (northern Alabama and possibly eastern Tennessee). The presence of prominent elytral striae usually can be used to distinguish this species from both H. fatuus and H. angustatus . Strial definition varies, however, and unless a side-by-side comparison with identified specimens can be made, male genitalia are the most reliable means of separating these species.

Notes. This species may be encountered in a wide range of habitats. It is almost always present in light trap samples taken along the Mississippi River or oxbow lakes near the river. Ponds and flood control reservoirs also yielded specimens. This is one of the few species that frequently is captured in light traps placed considerable distances away from aquatic habitats.

Distribution. Heterocerus sandersoni is known from southeastern Canada and the eastern U.S. west to the Mississippi and Missouri Rivers, but is not known from the Carolinas south to Florida ( Fig. 59 ).

Specimens examined. 516 (See Appendix).

Figures

Figures 11-17. Habiti of large Heterocerus species lacking post-mesocoxal lines. 11) H. pallidus (male is hypermandibulate). 12) H.intermuralis (male is hypermandibulate). 13) H.fatuus. 14) H. gnatho. 15) H.longilobulus. 16) H. sandersoni. 17) H. angustatus.Scale line = 1mm.

Figures 32-44. Male genitalia of southeastern Heterocerus species. The ventral view is shown unless otherwise stated. 32-39) Species that lack post-mesocoxal lines. 32) H. fatuus. 33) H. glicki. 34) H. intermuralis. 35) H. angustatus; left - ventral view, right - dorsal view. 36) H. longilobulus. 37) H. pallidus; left - ventral view, right - dorsal view. 38) H. gnatho; left - ventral view, right - dorsal view. 39) H. sandersoni; left - ventral view, center - dorsal view, left - lateral view. 40-44) Species with post-mesocoxal lines. 40) H. sinuosus; left - dorsal view, right - ventral aspect. 41) H. mollinus. 42) H. insolens; left - dorsal view, right - ventral aspect. 43) H. parrotus. 44) H. brunneus.

Figures 58-65. Distribution by county in the United States. 58) Heterocerus fatuus. 59) Heterocerus sandersoni. 60) Heterocerus intermuralis. 61) Heterocerus angustatus. 62) Heterocerus mollinus. 63) Heterocerus selanderi.64) Distribution of Heterocerus sinuosis by county in Mississippi. 65) Distribution of Heterocerus collaris by county in the United States.