Tropicus nigrellus, King & Lago, 2012

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 : 9

Elytra, pronotum and head uniformly black ( Fig. 29 ); ventral surface of male genitalia with a depression containing a dark, y-shaped suture ( Fig. 52b ). Rare southeastern species .............. ........................................................................................................ 19. Tropicus nigrellus n. sp.

4(2).

— Mesothoracic coxal lines absent ........................................................................................................ 5 Mesothoracic coxal lines present ( Fig. 6 ) ...................................................................................... 12 5(4).

—

Elytra dark brown or reddish brown and similar in hue to the pronotum; pronotum without pale markings (as in Fig. 17 ) ................................................................................................................. 6

Elytra dominated by undefined pale markings and lighter in color than pronotal disc; pronotum often with pale margins (as in Fig. 11, 12 ) .................................................................................. 9

6(5).

—

Male genitalia with anterior edge of dorsal plate strongly notched ( Fig. 8 ); parameres narrow conspicuously near base, causing outer anterior edge to curve ( Fig. 36, 39 ) .......................... 7

Male genitalia with anterior edge of dorsal plate not strongly notched ( Fig. 35 ); parameres narrow at an even rate throughout length, outer anterior edges relatively straight ( Fig. 35 , compare to Fig. 36 ) .............................................................................................................................................. 8

7(6).

Figures

Figures 26-29. Habiti of small southeastern species. 26) Tropicus pusillus. This level of color variation can be seen in either sex. 27) Head of Tropicus pusillus. 28) Heterocerus selanderi. 29) Tropicus nigrellus, holotype male and allotype female. 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 4-7. Morphological structures. 4) Right antenna of Heterocerus pallidus. Borders of the eleven antennomeres are difficult to distinguish due to pubescence and have been highlighted. 5a) Hypermandibulate male of Heterocerus intermuralis. 5b) Female (generally similar to “normal” males). 6) Venter of Augyles auromicans exhibiting some taxonomically important structures. 7) Dorsal aspect of Heterocerus sandersoni exhibiting conspicuous longitudinal striations on the elytra. Scale line = 1mm.

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 8-10. Male genitalia of Heterocerus spp. 8) H.pallidus exhibiting some of the characters which are important in identifying members of this genus. 8a) Ventral and 8b) dorsal aspect. Apices of genitalia face downward. 9) Heterocerus collaris, ventral. 10) Heterocerus stankerus, ventral.

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.