Agrilus impexus Horn

Hespenheide, Henry A., 2007, The identity of Agrilus impexus Horn, a new species, and taxonomic notes and records for other Agrilus Curtis species (Coleoptera: Buprestidae), Zootaxa 1617 (1), pp. 57-66 : 58-59

Agrilus impexus Horn

( Fig. 1 )

Agrilus impexus Horn, 1891: 327–328 ; Fisher 1928: 262–265.

Male: Relatively robust, subcylindrical, head and pronotum dark metallic green, front black on both sides of midline, pronotum with reddish-coppery reflections on disc, elytra coppery red, more golden at apices, beneath and legs brighter yellow-green; setae pale and recumbent, short, sparse and relatively inconspicuous throughout, except denser on front and sides of pronotum, and dense and conspicuous in three patches on elytra – in basal depressions and in more elongate spots along suture at 1/3 and 2/3 – on dorsal portions of abdominal ventrites, in spots on lateral portions of ventrites 3–5, in narrow line at middle of ventrites 1–2, on outer ½ of posterior coxae, in upper posterior corners of metasternum and epimeron, setae dense and semierect on prosternum and continuing along midline of anterior ½ of metasternum.

Head with front shallowly but distinctly depressed along midline, surface rugose, more coarsely so above middle; epistoma 1/3 width of distance between inner margins of eyes between antennal insertions, shallowly emarginate below, eyes oval, slightly emarginate on inner margins; antennae serrate from segment 5, segments 5–11 rounded-triangular.

Pronotum subequal to elytra at posterior margin, with sides shallowly rounded outward, widest near middle; marginal and submarginal carinae undulate, separated and subparallel for entire length when viewed from side; from above anterior margin regularly shallowly rounded; basal margin slightly emarginate at middle of each elytron, nearly transverse before scutellum; disk moderately convex, with distinct depression along midline and oblique depressions along lateral margins; prehumeral carinae strong, nearly straight,1/3 length of pronotum; surface coarsely transversely rugose; two tiny pores along basal margin just medial to prehumeral carinae. Scutellum pentagonal with transverse ridge.

Elytra subequal in width at humeri and beyond middle, lateral margins shallowly emarginate between, apices narrowly, separately rounded, minutely toothed; disk convex each elytron with narrow oblique depression at base and broader, shallower one along suture for apical 4/5; surface transversely imbricate-punctate.

Prosternum with sides of prosternal process slightly narrowing between coxae, truncate and emarginate at apex, prosternal lobe nearly transverse. Posterior coxae with posterior margin shallowly, regularly emarginate, upper angles obtusely rounded. Abdomen with suture nearly obsolete between ventrites 1 and 2, narrowly depressed along midline of ventrites 1–2. Legs with first metatarsal segment equal in length to next two combined, tarsal claws similar on all feet, cleft with short inner tooth. Genitalia as in Fig. 1 .

Female: As male except coloration reddish coppery throughout, more golden beneath; setae on prosternum and along midline of metasternum sparse and appressed; abdominal ventrites 1–2 convex, without medial depression or line of setae.

Specimens examined. Colorado, Colo.Spr. , 6000–7000ft, 15– 30.06.1896, H.F. Wickham ( USNM) . Iowa, County 5, 16.07.1936 ( USNM) . Kansas, [without locality] ( USNM) , Madison , M.C. V [anDuzee].coll. ( CASC) , Onaga, Crevecoeur ( USNM) , Onaga , 08.07.1901 ( SGWC), VI/24 , Wickham Coll. ( USNM) , Snow , Coll Hubbard & Schwarz ( USNM) , Topeka, 03 Aug ( USNM) ; Meade Co., 30.06.1986, G.A. Salsbury, sweep rangeland ( TCMC) ; Riley Co., Jun, Popenoe ( USNM) , Riley Co., July 13, 14, 17, Popenoe ( SGWC) , Riley Co., July 19, G.A. Dean ( SGWC) . Minnesota, Ft. Snelling, 28.06.1923, high prairie assn. ( USNM) . Missouri: Camden Co., Ha Ha Tonka State Park, Lodge Glade, 7.06.2001, D.G. LeDoux & F.Lloyd ( TCMC) ; Nebraska, J.B. Smith “#1 C. T.” ( USNM) . New Mexico: Jemez Springs , 18. VI.1947, B.E. White, on Chrysothamnus sp. ( CASC) . Oklahoma: Paroner (?), 14.07.1932, A.E.P. ( SGWC) . Wyoming, Sundance , 31.07.1935 ( USNM) , Crook Co., 08.07.1938 ( USNM) .

Hosts. Adults have been collected on Chrysothamnus (Asteraceae) in New Mexico. Species of Chrysothamnus are the adult and presumed larval hosts of at least three other Agrilus : A. duncani Knull , col- lected commonly on C. nauseosus (Pall.) Britton at Portal, Arizona; A. pubifrons Fisher , collected on C. viscidiflorus (Hook.) Nutt. by W.F. Barr in Idaho; and A. walsinghami Crotch.

Discussion. The geographic distribution of A. impexus appears to coincide roughly with the Great Plains. In his description Horn (1891) listed specimens from both Arkansas and Nebraska. Fisher (1928) also listed specimens from Mississippi which I have not seen. The species has not been collected frequently, with only three specimens in the last 60 years known to me. As noted in the introduction, the name has been misapplied to the much more common and widespread species associated with woody legumes treated below; this practice dates from Fisher’s (1928) inclusion under A. impexus of two specimens from Arizona, reared from “Palo Verde,” that are the following species. Agrilus impexus is interesting for its weak sexual color dimorphism. In the series from New Mexico males are usually more or less greenish on the head, pronotum, and beneath, with a distinctly black front, and reddish-coppery on the elytra, whereas females are usually reddish-coppery throughout, although more golden beneath. Agrilus impexus is significantly larger than the following species - males measure 6.2–7.7 mm long (mean = 7.00 mm for 16 specimens), and females measure 6.7–8.0 mm long (mean = 7.31 mm for 22 specimens).

Figures

FIGURES 1–5. 1–3, Genitalia of male Agrilus: 1. A. impexus (New Mexico, Jemez Springs, CASC); 2. A. paraimpexus (Holotype); 3. A. addendus (Texas, Rocksprings, CHAH), scale bar indicates 1.0 mm; 4–5, Agrilus funestus Chevrolat: 4. dorsal habitus and lateral habitus (Texas specimen), scale bar indicates 2.0 mm; 5. genitalia of male (specimen from Mexico, Chiapas, 2 mi NNW Pueblo Nuevo, LLU Biol. Sta., 12.07.1965, G.H. Nelson, FSCA), scale bar indicates 1.0 mm.