Heterocerus texanus (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 : 26

14. Heterocerus texanus (Pacheco)

New Combination

( Fig. 24 , 46 , 67 )

Peditatus texanus Pacheco 1964: 122 .

Description. Length 2.9 - 3.5 mm. Brown or reddish-brown. Elytra trifasciate, with two distinct basal spots ( Fig. 24 ); surface relatively shiny; striae absent. Post-metathoracic coxal lines absent, post-mesothoracic coxal lines present. Male genitalia ( Fig. 46 ) of the H. undatus type; slightly more than two times longer than its greatest width; body of phallobase dominated by median plate; anterior half of median plate gradually expanded anteriorly, anterior edge with a rounded central lobe and dorsal spinelike projections laterally; lateral arms of phallobase greatly reduced and projecting from notches between central lobe and lateral projections on the anterior edge of the median plate; dorsal plate with a bilobed projection on its anterior edge that extends beyond the parameres; parameres membranous, small, bilobed and extending from beneath the rounded central lobe of the median plate. Hypermandibulate males unknown.

Diagnosis. This species is most similar to H. schwarzi and H. tenuis , two less common southeastern species. The elytral surface of H. texanus is smoother and has wider pale yellow markings in comparison to the other two species. Male genitalia should, however, be used to separate the three, unless a side-byside comparison with identified material is possible. Heterocerus texanus lacks the long dorsally curved spines seen on the lateral projections of the median plate that are present in H. schwarzi and H. tenuis (compare Fig. 46 and 47 ). The latter two species also have a conspicuous plate on the ventral side of the anterior tip of the genitalia.

Notes. Heterocerus texanus is relatively common throughout Mississippi and Alabama. In the study area, this species is commonly collected from the banks of the Mississippi River and nearby oxbow lakes. It has also been collected from coastal areas, and occasionally from ponds, swamps and small streams. On two notable occasions, specimens were collected in relatively large numbers from the banks of the Mississippi River, along with large series of H. pallidus . Molecular data suggests that these two species are close relatives, although their general morphology would suggest otherwise.

Distribution. Heterocerus texanus occurs from southern Texas north to Iowa and east to the coast of the Carolinas and south to Florida ( Fig. 67 ).

Specimens examined. 212 (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.

Figure 66-72. Distribution by county in the United States. 66) Heterocerus undatus. 67) Heterocerus texanus. 68) Heterocerus schwarzi. 69) Heterocerus tenuis. 70) Augyles auromicans. 71) Tropicus pusillus. 72) Tropicus nigrellus.