Heterocerus selanderi (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 : 23-24

10. Heterocerus selanderi (Pacheco)

New Combination

( Fig. 28 , 50 , 63 )

Efflagitatus selanderi Pacheco 1969: 37 .

Description. Length 2.6 - 2.8 mm. Orange-brown. Elytra trifasciate, markings faint, darker than the rest of the elytral surface; striae vaguely indicated ( Fig. 28 ). Post-metathoracic coxal lines absent, postmesothoracic coxal lines feebly marked. Male genitalia ( Fig. 50 ) of the typical Heterocerus type, although its overall shape is unusual among North American species; genitalia about 2.5 times longer than wide; anterior end of phallobase rounded and slightly enlarged; median plate expanded anteriorly to the width of the entire phallobase, its anterior end fused to, and indistinguishable from, the rounded anterior end of the phallobase; parameres small, hornlike and pointed, proximate at their base and diverging apically. Hypermandibulate males unknown.

Diagnosis. The small size and coloration of this beetle allows it to be easily separated from all other southeastern species except Tropicus pusillus and H. texanus . The orange-brown elytra and indistinct elytral markings make it easy to confuse H. selanderi with T. pusillus without the aid of a microscope. The difference in elytral pattern, however, is obvious under magnification, with Tropicus pusillus having one common macula and H. selanderi being trifasciate. The rounded anterior edge of the phallobase and horn-like parameres distinguish this from H. texanus and all other North American heterocerids.

Notes. This species emerges near the beginning of the rainy season in Florida, usually in May or June (Mark Deyrup, Archbold Biological Station, pers. comm.), but apparently ceases to fly soon thereafter. A trip to the Archbold Biological Station in early July, 2005, failed to yield any specimens.

Pacheco (1969) believed that this enigmatic species was the only North American representative of the South American genus Efflagitatus Pacheco. Molecular data collected as part of this study strongly support this species as a member of the predominantly North American undatus group, implying that Efflagitatus Pacheco is polyphyletic. This species was weakly supported as a sister species to H. tenuis , another predominantly Floridian species with genitalia that are quite different from this species.

Distribution. This species has been collected primarily in Florida and extreme southern Georgia, although one specimen of H. selanderi has been collected in southern Mississippi ( Fig. 63 ). Although the latter is a female, the identification (W.V. Miller) appears to be correct. It was attracted to a UV light on the sandy bank of the Buffalo River in Wilkinson County (Buffalo River at Highway 61, 24 June 1982, Paul K. Lago).

Specimens examined. 36 (See Appendix).

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 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.