Acmaeodera opacula LeConte 1858: 69

Hansen, Jason A. & Westcott, Richard L., 2023, A new synonym of Acmaeodera opacula LeConte, 1858 (Coleoptera: Buprestidae) and lectotype designations for Acmaeodera amabilis Horn, 1878 and Acmaeodera disjuncta Fall, 1899, Insecta Mundi 2023 (984), pp. 1-4 : 2-3

Acmaeodera opacula LeConte 1858: 69 .

Acmaeodera disjuncta Fall 1899: 9 . New synonymy.

The holotype of A. opacula shares several characters with A. disjuncta that lead us to consider the two species conspecific. The most significant of these characters involves the lateral elytral intervals. The first lateral interval is more inflated basally, the second more convex about the middle and the third most convex at the apical third of the elytra. In most specimens this pattern gives the specimen a rather robust appearance, but the convexity of the intervals can vary as demonstrated by specimens of A. opacula from Fabens, Texas [NSCH] and several other specimens across NM and AZ [FSCA], which show reduced convexity of the lateral intervals similar to the holotype.

The dorsal markings of A. opacula can also be highly variable and it is instructive to consider common patterns here in regard to their taxonomic value. For instance, the lateral elytral stripe of A. opacula is almost always broken or nearly so at some point along the basal third of the elytra ( Fig. 1b, d ; Horn 1878, fig. 2). In addition, the two apical bands are always marked with red, though sometimes only laterally. The lateral yellow stripe of the pronotum is broad and reaches four-fifths of the pronotal length. It is not uncommon for some specimens of A. opacula to exhibit a lighter shade of red on the apical elytral bands. Such is the case with the holotype, on which red is very faintly marked. It is possible the color was faint to begin with; however, more likely it faded with the passage of time or was muted by prolonged storage in fluid, presumably alcohol, before being pinned ( Fall 1899). This may have caused the specimen to become distorted, especially if it was teneral when collected, such that the elytra are not fused apically ( Fig. 1a ). Regardless, the characters of the holotype are within the range of phenotypic variation seen among specimens that were placed under A. disjuncta ; i.e., lateral elytral stripe broken, both apical bands marked with red (albeit faintly), and broad pronotal stripe on each side. This further supports synonymy of the two species.

Another important factor to consider is habitat. Acmaeodera opacula was described from “El Paso” (Texas), which is in the Chihuahuan Desert Ecoregion. Acmaeodera opacula was not listed from Texas under its synonym in the world catalog or the most current North American catalog ( Bellamy 2008; Nelson et al. 2008) but has been commonly collected as far east as the Pecos River Bridge in Val Verde Co., Texas by the first author and was recorded from the Chisos Mountains by Chamberlain ( Chamberlin 1926). The distribution of A. opacula mirrors that of its only known larval host, Fouquieria splendens Engelm. (Fouquieriaceae) in Texas ( Westcott 1991, as A. fisheri Cazier ). This plant host has historically been widespread in El Paso, but its occurrence has undoubtedly diminished due to development over the past century and a half.

Acmaeodera opacula can exhibit a similar appearance to species within what we are calling the flavomarginata species group (i.e., A. amabilis , A. chiricahuae Barr, 1972 , A. flavomarginata (Gray, 1832) , A. jubata Barr, 1992 , A. reflexa Barr, 1992 ), though it does not appear closely related to them. Acmaeodera opacula can be separated from those species by the increased convexity of the first three lateral intervals of the elytra, which usually give it a more robust appearance, and the more coarsely punctate elytra ( Horn 1878; Fall 1899). Species within the flavomarginata group, with the exception of A. flavomarginata , appear to occur only at higher elevations, in environments far different from where A. opacula occurs.

The following represents a new Mexican state record for A. opacula : NUEVO LEÓN, Hwy. 85, 1 mi N Río Salado, C. R. Ward, 17-X-70 [ UCDC] ; 5 mi W Doctor Arroyo , 4-VII-74, Clark, Murray, Ashe & Schaffner [ FSCA] ; 16 mi N La Gloria , 19-IX-75, J. Powell & J. Chemsak [ FSCA] ; 18 mi W Monterrey , 3950′, 15-X-57 [ OSAC] ; same except 15 mi W, 3250′ [OSAC]; 9 mi. west Iturbide , 3-VII-1974, Clark, Murry, Ashe, Schaffner [ TAMU] .

Figures

Figure 1. Acmaeodera spp.a) A. opacula (holotype), dorsal. b) Same, lateral. c) A. disjuncta (lectotype), dorsal. d) Same, lateral. e) A. amabilis (lectotype), dorsal. f) Same, lateral. Each image in scale, scale line = 1 mm.