Heterocerus collaris Kiesenwetter, 1851

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 : 24-25

12. Heterocerus collaris Kiesenwetter

( Fig. 25 , 46 , 65 )

Heterocerus collaris Kiesenwetter 1851: 292 .

Dampfius collaris (Kiesenwetter) : Pacheco 1964: 115.

Description. Length 3.0 - 4.2 mm. Brown or reddish-brown. Elytra vaguely trifasciate, limits of pale markings enlarged and sometimes poorly defined ( Fig. 25 ); elytral striae weakly indicated. Post-metathoracic coxal lines absent, post-mesothoracic coxal lines present. Male genitalia ( Fig. 46 ) of the H. undatus type; approximately three times longer than wide; phallobase dominated by the median plate, posterior third of median plate with parallel sides, slightly broadened in middle third; anterior third gradually constricted to approximately one sixth of its greatest width and curved dorsally; lateral arms of phallobase curved outwardly and produced dorsally in lateral view; dorsal plate twice as wide anteriorly, about 50% greatest width of the phallobase and 50% the length of the body of the phallobase; parameres membranous, arising from beneath median plate at its anterior point of articulation with the lateral arms, parameres lobed and extended laterally on either side of the downwardly curved median plate; the majority of the anterior end of median plate and parameres extend beyond the anterior tip of the lateral arms. Hypermandibulate males unknown.

Diagnosis. Heterocerus collaris is similar in size and appearance to H. undatus , although the pale elytral markings of H. collaris are generally more pronounced. However, the coloration in both species is variable, and only characters of the male genitalia can irrefutably separate the two. The constricted anterior one-third of the median plate and its sharp dorsal curvature distinguish this species from all other North American Heterocerus .

Notes. This species inhabits shoreline tunnels in sandbars throughout the eastern U.S. It shares this habitat with the pygmy mole crickets ( Tridactylidae ), Ellipes gurneyi Gunther and Neotridactylus apicialis Say. Egg guarding behavior displayed by the female beetles has apparently evolved in response to egg predation by the crickets ( Folkerts 1989).

Distribution. Heterocerus collaris has been recorded from every state in the eastern U.S., except Florida. In the Midwest it is known from Iowa, Oklahoma and Texas. Records are especially common between the Ohio and Illinois rivers north of their junction with the Mississippi River. This species was previously unknown from Mississippi, although it has been recorded from Alabama and Louisiana ( Miller 1996). During this study, specimens were collected from an oxbow off the Tallahatchie River (N 34 o 01.484, W - 90 o 08.460'), as well as from the banks of the Mississippi River in Bolivar County, Mississippi ( Fig. 65 ).

Specimens examined. 46 (See Appendix).

Figures

Figures 21-25. Habiti of Heterocerus species of intermediate size with post-mesocoxal lines. 21) H. schwarzi. 22) H. tenuis. 23) H. undatus. 24) H. texanus. 25) H. collaris. Scale line = 1mm.

Figures 45-53. Male genitalia of southeastern species. The ventral view is shown unless otherwise stated. 45-50) Heterocerus species in the undulatus group. 45) H. undatus. 46) H. collaris. 47) H. texanus; left - ventral view, right - lateral view. 48) H. schwarzi; left - ventral view, right - lateral view. 49) H. tenuis. 50) H. selanderi. 51-53) Augyles and Tropicus species. Figures 52-53 are at roughly 2x relative scale of prior genitalia. 51) Augyles auromicans. 52) Tropicus nigrellus; left - dorsal view, center - ventral view, right - lateral view. 53) Tropicus pusillus; left - dorsal view, right - ventral view.

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.