Heterocerus insolens Miller, 1994

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 : 18

4. Heterocerus insolens Miller

( Fig. 18 , 42 , 57 )

Heterocerus insolens Miller 1994:16 .

Description. Length 4.5 - 5.5 mm. Chestnut brown. Apical angles of pronotum usually pale. Elytra dark brown and distinctly trifaciate with relatively large medial and distal pale markings, and small broken pale basal marks; striae absent ( Fig. 18 ). Post-metathoracic coxal lines absent; post-mesothoracic coxal lines prominent. Male genitalia ( Fig. 42 ) of the typical Heterocerus type, phallobase constricted to its narrowest point at anterior third and then slightly broadened towards outer edges of parameres; medial edges of parameres approximately 30 o divergent; dorsal plate ovoid, with no constrictions. Hypermandibulate males rare.

Diagnosis. The presence of post-mesothoracic coxal lines and distinctive elytral coloration distinguishes this species from all other southeastern species except H. mollinus , the most common North American Heterocerus . In most specimens of H. insolens , the two distal pale marks on the elytra are much more extensive than is typical of H. mollinus (compare Fig. 18 and 20 ). Some males of H. insolens are reported to have a small lateral projection on the mandibles, which are absent on H. mollinus ( Miller 1994) , but we have not observed this character. The abruptly constricted anterior end of the phallobase and the divergent parameres immediately distinguish H. insolens from H. mollinus , in which the phallobase slowly tapers anteriorly and the internal edges of the parameres only slightly diverge (compare Fig. 41 and 42 ). Another southeastern species with post-mesothoracic coxal lines, H. sinuosus , has the pronotum consistently darker than the head and elytra, which immediately distinguishes it from H. insolens . The external features and genital morphology of this species are also similar to those of H. brunneus , a western species with several dubious southeastern records (see Pacheco 1964). Characters of the male genitalia must be used to separate these two species (see couplet 19).

Notes. During this project, H. insolens was collected on two occasions. In both instances the beetles were taken from cypress-dominated overflow areas along the Tallahatchie and Yazoo rivers. Previously collected H. insolens came from a variety of habitats, including small streams above the fall line in northern Alabama.

Several of Miller’s paratypes were found to be misidentified specimens of H. mollinus . Genitalia had not been extracted from these paratypes.

Distribution. Heterocerus insolens has been collected in four different physiographic regions above the fall line in northern Alabama and it is also common throughout the Alluvial and Coastal plains of Mississippi and Alabama ( Fig. 57 ). Miller (1994) provided single records from Louisiana and Illinois. Since this distribution indicates adaptation to a variety of habitats, and because the species was described fairly recently, it is probable that H. insolens has a much wider distribution than is currently known.

Specimens examined. 98 (See Appendix).

Figures

Figures 18-20. Habiti of large Heterocerus species with post-mesocoxal lines. 18) H. insolens. 19) H. sinuosus. 20) H. mollinus. Specimens 20a and 20c are hypermandibulate. 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.