Gyascutus (s. str.) paci

Nelson, G. H., 2000, A revision of the subtribe Hippomelanina, part II: Gyascutus (Gyascutus) LeConte (Coleoptera: Buprestidae), Journal of Natural History 34 (12), pp. 2251-2292 : 2273-2275

5. Gyascutus (s. str.) paci ®cus (Chamberlin), comb. nov.

(®gures 7, 18, 49) Hippomelas paci W ca Chamberlin, 1938: 446; Nelson, 1962: 56; Barr, 1970: 4; Linsley and Ross, 1977: 276; Westcott, 1991: 77.

Diagnosis. Colour black with copper tint; males average 16.9 mm long, females 17.5 mm; width between eyes 1.1 Ö width of eye when viewed from above; antennae reaching second third of pronotum when laid alongside in male and female; pronotum as wide at middle as at posterior margin; pronotal disc a mixture of small raised areas and densely punctate intervals; elytra without costae; male genitalia elongate slender, sides subparallel, slightly sinuate.

Redescription, holotype male. Head width between eyes 1.1 Ö width of eye in dorsal view; front ¯at (concave between antennae) with mixture of numerous smooth raised areas and course punctures, more densely, ®nely punctate on vertex; short, grey-white pubescence sparse on most of surface but more dense along inner margin of eyes; clypeal margin shallowly, arcuately emarginate; antennae short, reaching second third of pronotum when laid alongside, serrate from antennomere 4, narrowing slightly apicalward, antennomere 11 weakly notched at outer angle (®gure 18).

Pronotal width 1.6 Ö length, widest just before posterior margin; laterally carinate in posterior third; lateral margins subparallel behind, then weakly arcuately converging to narrowest at anterior angles; anterior margin broadly weakly lobed at middle; posterior margin distinctly bisinuate, median lobe arcuately emarginate before scutellum; disc convex, transversely impressed behind anterior margin and before posterior margin, especially two-thirds to lateral margin; surface densely coarsely punctate with numerous irregular, smooth, raised areas, pubescence not apparent. Scutellum small, depressed, transverse.

Elytra as wide as pronotum at base; lateral margins subparallel in anterior twothirds, weakly converging in posterior one-half with several small teeth apically, apex weakly arcuately emarginate; disc transversely convex, surface ®nely irregularly sculptured, transversely strigate toward base, striae weakly indicated in apical third; pubescence short, sparse, recumbent, grey-white but most apparent apically and laterally.

Ventrally, moderately densely punctate including legs, with recumbent, greywhite pubescence laterally on metasternum and abdomen; prosternum with anterior margin slightly lobed laterally; disc with midline depression anterior to procoxal cavities; prosternal process subāttened with coarse punctures and deeply sulcate lateral margins; metasternum with strong midline sulcus; protrochanter with faint tooth; protibia weakly arcuate, slightly dilated apicalward with several small teeth on inner margin; meso- and metatibia slender and straight; metatarsomere 1 equal in length to 2 1 3, longer than 5; abdominal sterna 2±4 with slight depressions laterally; last visible sternum triangular, apex truncate with subapical crest. Length, 9.9 mm; width, 3.3 mm.

Male genitalia ( Nelson and Bellamy, 1996, ®gure 80).

Redescription, allotype female. DiOEers from male as follows: more robust; last antennomere more distinctly notched; protibia straight, more slender and not widened apicalward. Length, 12.3 mm, width, 4.5 mm.

Type locality: California, Fresno Co., Rolinda .

Type material. The holotype lof Hippomelas paci W ca Chamberlin (CASC) is labelled as follows: Rolinda Fresno Co. Cal. VI-12-27 (h)/From Coll. of W. J. Chamberlin (p)/Type (p) Hippomelas paci ®ca l(h) W. J. Chamberlin (p).

Variation. The 16 males and 15 females examined revealed that there is only slight variation in the rather uniform black colour with some showing a more brassy tint. The lateral margin of the pronotum is occasionally widest just before the middle. One specimen ( CASC) from the Gulf of California , Bahia San Pedro, that might represent a variant of this species has a more copper hue and slightly more robust male genitalia. Males vary from 9.9 to 19.5 mm long (mean5 16.9 mm, n 5 16) and 3.3±7.1 mm wide (mean5 6.0 mm, n 5 16); females from 12.3 to 20.9 mm long (mean 5 17.5 mm, n 5 15) and 4.5±8.0 mm wide (mean5 6.5 mm, n 5 15).

Distribution (®gure 49). This species appears to be largely con®ned to the great central valley of California. It has been collected at Mendota and Rolinda in Fresno Co., and near Kettleman City and Kettleman Hills in Kings Co. One female (RLWE) from Mexico, Sonora, Yavaros is possibly this species, but is not included on the distribution map.

Biology. Westcott (1991) recorded it reared from Suaeda fruticosa (L.) Forsk. Most adults have been collected on Atriplex polycarpa (Torr.) Wats. (previously recorded by Nelson, 1962, and Linsley and Ross, 1977), but one was collected on Allenrolfea occidentalis (Wats.) Kunz. All of these plants are in the family Chenopodiaceae . Chamberlin (1938) recorded it from`sagebrush’ (possibly a misidenti®cation of an Atriplex ). Adults have been collected from mid-June to August.

Comparisons. This distinctive species appears most similar to the more diminutive species in Baja California: G. granulatus (Van Dyke) and G. paragranulatu s Nelson. From G. granulatus it diOEers in being larger, the distance between the eyes (dorsal view) is much narrower, the sculpture of the dorsal surface is more dense, and the male genitalia are much narrower. From G. paragranulatu s it diOEers in being larger, the sculpture of the dorsal surface is more dense, and the male genitalia are diOEerently shaped.