Heterocerus longilobulus (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 : 16-17

3. Heterocerus longilobulus (Pacheco)

New Combination

( Fig. 15 , 36 , 56 )

Neoheterocerus longilobulus Pacheco 1964: 74 .

Description. Length 3.5-6.0 mm. Pronotal disc and much of elytra dark brown. Elytra trifasciate, basal series of pale markings usually with a distinct lateral lunate marking and an ovoid medial spot; striae weak or absent. Pronotal disc same color as elytra. Post-metathoracic coxal and post-mesothoracic coxal lines absent. Male genitalia ( Fig. 36 ) of the typical Heterocerus type, parameres triangular, constricted towards apices; dorsal plate of aedeagus depressed on the right anterior edge. Hypermandibulate males common.

Diagnosis. Heterocerus longilobulus is similar in appearance to H. gnatho , and H. fatuus . The lunate outer marking of the basal series on the elytra is quite distinctive. This species, however, can be positively identified only through inspection of the male genitalia. The constricted tips of the parameres ( Fig. 36 ) easily distinguish this species from all other southeastern species.

Notes. This species is most often collected along large rivers, including the Mississippi, Pascagoula, Chickasawhay and Big Black rivers in Mississippi, and the Conecuh, Big Flat and Little rivers in Alabama. A few specimens were taken along smaller creeks. On one occasion, three specimens were collected along a tiny, unnamed stream, 1.5 miles north of Dixon, Neshoba County, Mississippi. The habitat was deciduous forest up to the stream edge and did not appear promising for heterocerids.

Distribution. Heterocerus longilobulus occurs from Iowa east through Illinois and Pennsylvania, south to Mississippi, Alabama and northern Georgia ( Fig. 56 ). Specimens examined. 105 (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 54-57. Distribution by county in the United States. 54) Heterocerus pallidus. 55) Heterocerus gnatho. 56) Heterocerus longilobulus. 57) Heterocerus insolens.