Heterocerus angustatus Chevrolat, 1864

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 : 22

8. Heterocerus angustatus Chevrolat

( Fig. 17 , 35 , 61 )

Heterocerus angustatus Chevrolat 1864: 407 .

Neoheterocerus angustatus (Chevrolat) : Pacheco 1964: 80.

Description. Length 4.5 - 5.5 mm. Reddish brown. Elytra trifasciate; striae weakly indicated ( Fig. 17 ). Post-metathoracic coxal and post-mesothoracic coxal lines absent. Male genitalia ( Fig. 35 ) of the typical Heterocerus type; phallobase constricted to 80% of its greatest width anteriorly, then expanded slightly; median plate with faint brown ovate sclerites on either side anteriorly, median plate tapering anteriorly to a distinct point; dorsal plate ovoid, posterior edge truncate, neither end deeply notched; medial edges of parameres slightly divergent. Hypermandibulate males unknown.

Diagnosis. Heterocerus angustatus is most similar to H. fatuus and H. sandersoni . Heterocerus angustatus and H. fatuus usually exhibit elytral striae that are much less distinct than those of H. sandersoni . Heterocerus angustatus usually has more extensive and paler elytral markings than H. fatuus ; however, the male genitalia are the most reliable means of separating the three species. The simple (not notched), ovoid dorsal plate and the pointed medial plate distinguish this species from all other southeastern Heteroceridae .

Notes. This species is known from a variety of habitats and appears to be most common in coastal areas in the Southeast. Within the region, it is most abundant in Florida, from which the great majority of specimens were seen. In fact, of the three species of Heterocerus occurring in that state, H. angustatus is by far the most abundant.

Distribution. Heterocerus angustatus is widely distributed throughout the Caribbean and occurs north through most of the southeastern United States ( Fig. 61 ), with two county records from Ohio. Pacheco (1964) reported localities from New York and Massachusetts, but no specimens from that far north were seen during this study.

Specimens examined. 1085 (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.