Agrilus langei Obenberger, 1935

Hansen, Jason A., Basham, Joshua P. & Nalepa, Christine A., 2021, New adult host records for three Buprestidae (Coleoptera) rarely encountered in the United States and significant extension of the known geographic range of Agrilus pilosicollis Fisher, Insecta Mundi 2021 (869), pp. 1-6 : 2-3

Agrilus langei Obenberger, 1935

TEXAS: Cameron Co., nr. Sabal Palm Sanctuary, 25.859757, −97.424329, 4–5.xi.2018 (2), 14.x.2019 (3) on Abutilon trisulcatum , coll. J.A. Hansen. New adult host record.

Though not uncommon in the more tropical habitat of Mexico, A. langei is rarely encountered in the United States. A single male specimen in the TAMU collection labeled from “Tex” was found by Westcott and Noguera (1995) to be incorrectly identified as A. cavifrons Waterhouse. Still , no mention of its occurrence in the U.S. is seen in current catalogs ( Nelson et al. 2008; Bellamy 2008). The vague label data and lack of any additional specimens are likely reasons for its exclusion from the published North American buprestid fauna. A chance image of A. langei from Hidalgo Co., Texas was submitted to the popular website bugguide.net, which appeared to confirm its presence in the U.S. ( Zurovec 2012). Though the specimen was not collected or vouchered, the images were of sufficient quality for Richard L. Westcott to confirm the identity of the beetle.

The specimens reported here were collected by hand or with sweep net over a two-year period just north of Sabal Palm Sanctuary along the border wall in Cameron Co., Texas. All specimens were collected while resting on leaves of Abutilon trisulcatum (Jacq.) Urb. The first specimen collected was a female resting on the leaf of an isolated, knee-high Abutilon plant. The following day a large patch of mature A. trisulcatum was found not far from where the original specimen was collected in a vacant lot between the border wall and an adjacent neighborhood. Upon further investigation, a male specimen was seen flying among the plants and subsequently collected ( Fig. 1a–e ). Despite an exhaustive search of the area, no other specimens were found. Considering the time of year, it was likely peak flight time had passed several weeks earlier. The following year the author returned to the same location on 14.x.2019 and collected three additional specimens, despite most of the plants having been bulldozed as the nearby neighborhood expanded.

The collection of five specimens in south Texas over a two-year period (2018–2019), along with the image posted on bugguide.net and the vaguely labeled TAMU specimen, confirm the presence of A. langei in the United States, specifically in the two southernmost Texas counties of Cameron and Hidalgo. Albutilon trisulcatum is known to occur from Nicaragua north to Hidalgo and Cameron counties in the United States ( Fryxell 1983). It was one of several native plants used to manage invasive grasses as part of a 15-year revegetation program in the Lower Rio Grande Valley ( Best 2009). Several other species of Abutilon occur in the United States, but no records of A. langei exist north of the two southmost counties, suggesting A. langei may prefer specific Abutilon species or simply is not suited to a more northerly environment. It remains to be shown if A. langei is associated with A. trisulcatum exclusively; seven other species of Abutilon occur in south Texas. Further investigation may show a more diverse host range within the plant genus, as is common with many Agrilus species. No larval activity could be found in the stems or roots of several plants inspected by the first author. Given the low number of adults in the area, it is possible larvae would be hard to locate, despite the fact its late instar larvae would undoubtedly rival those of A. planipennis Fairmaire (emerald ash borer) in size.

eral view. d) Dorsal view of aedeagus. e) Frons.

Given the limited distribution of A. langei in the United States and the dearth of individuals observed in south Texas, it is reasonable to have concern about the elimination of habitat where A. langei is known to occur along the southern border. Abutilon trisulcatum was found in small patches by the author in multiple locations in Hidalgo and Cameron counties, but A. langei was observed only near Sabal Palm Sanctuary. As development continues to occur on land surrounding the few existing protected areas across the Lower Rio Grande Valley, the importance of preserving the shrinking habitat for native wildlife to thrive has become ever more pronounced.

In the United States, A. langei somewhat resembles A. cavifrons in size and general mottling, but the latter is only known from Arizona and is readily distinguished by its more robust form and rounded elytral tips.

Figures

Figure 1. Agrilus langei Obenberger ♂. a) Dorsal view. b) Ventral view. c) Lat-