Gyascutus (s. str.) insularis (Helfer) Nelson, 2000

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 : 2269-2270

2. Gyascutus (s. str.) insularis (Helfer) , comb. nov.

(®gures 5, 16, 36, 48)

Hippomelas insularis Helfer, 1953: 34 ; Barr, 1970: 4; Linsley and Ross, 1977: 275.

Diagnosis. Black with brassy tint to copper in colour; males average 16.9 mm long, females 19.3 mm; antennae usually reaching posterior angle of pronotum when laid alongside in male, to just beyond middle in female; smooth areas of pronotum usually prominently elevated; elytra usually with evident costae; male genitalia elongate, weakly swollen at base, slender apically (®gure 36).

Redescription, holotype male. Width of head between eyes 1.4 Ö width of eye in dorsal view; front of head ¯at, depressed between antennae; surface ®nely, densely punctate with longitudinal smooth raised areas in midline and paralleling eyes; supra-antenna l ridges connected by carina that is separated from shallowly emarginate clypeal margin by ®nely punctate area; clothed by short, semi-erect, white, hairlike setae; antennae reaching to near posterior angles of pronotum when laid alongside, serrate from antennomeres 4±11, each ¯attened, subtruncate on outer border, and 11 with distinct notch at outer angle (®gure 16a).

Pronotal width 1.6 Ö length, widest at posterior margin; laterally carinate in posterior half; lateral margin slightly ¯aired near posterior margin, subparallel to just before middle, then converging to narrowest at anterior margin; anterior margin with slight arcuate lobe; posterior margin with broad slightly emarginate median lobe; disc convex, slightly transversely impressed just behind anterior margin, ¯attened posteriorly at middle and strongly depressed midway to lateral margin; surface coarsely punctate with smooth raised areas predominent except anteriorly and toward lateral margins; clothed by sparse, inconspicuous, short, semi-recumbent, white, hair-like setae. Scutellum transverse, impunctate, glabrous with large puncture anteriorly in midline.

Elytra slightly wider than pronotum at base; lateral margins gradually converging apically, more strongly in posterior half with several teeth near bidentate, emarginate apices; disc transversely convex with four prominent discal costae, ®rst and second complete, third to apical fourth, fourth to near apex; punctate areas of numerous small punctures, punctate areas with few inconspicuous, short, semi-recumbent, white, hair-like setae and pulverulent.

Ventrally, ®nely, densely punctate, less so medially, moderately clothed by semirecumbent, white setae; anterior margin of prosternum slightly lobed laterally, prosternal process ¯at with irregular punctures medially and sulcate along lateral margin; metasternum with midline sulcus; protrochanter with evident tooth; protibia weakly arcuate, slender with several small teeth on inner margin toward apex; meso- and metatibia slender, straight; metatarsomere 1 subequal in length to 2 1 3, longer than 5; last visible abdominal sternum roundly truncate apically with posterolateral angles dentate, and with weak subapical crest. Length, 17.1 mm; width, 6.6 mm.

Male genitalia (®gure 36).

Redescription, allotype female. DiOEers from male as follows: slightly more robust; antennae shorter, reaching to middle of pronotum when laid alongside; antennomeres of serrate portion more triangular, 11 with smaller apical notch (®gure 16b); protibia without teeth; metatarsomere 1 longer than 2 1 3, longer than 5; last visible abdominal sternum more elongate triangular, apex with median rounded lobe. Length, 19.7 mm; width, 7.5 mm.

Type locality: Mexico, Baja California Sur: Isla de San Marcos, Gulf of California .

Type material. The holotype lof Hippomelas insularis Helfer (CASC) is labelled as follows: San Marcus [sic] I. Gulf Calif. June 19, 1921 (p)/on Larrea mexicana (p)/E. P. VanDuzee Collector (p)/(red label) HOLOTYPE Hippomelas insularis Helfer (h)/ California Academy of Sciences Type No. (p) 8113 (h).

Variation. The 244 males and 61 females examined revealed that some of the specimens collected on mainland Baja California lack the elytral costae evident on the type series, and the series from Sonora, Desemboque have the elytral costae weakly developed. In colour, many from Desemboque are more coppery than the type series and among those from mainland Baja California are some with brassygreen punctate areas. The males vary from 12.0 to 21.0 mm long (mean5 16.9 mm, n 5 50) and 4.2±8.3 mm wide (mean5 6.2 mm, n 5 50); females from 14.3 to 23.3 mm long (mean 5 19.3 mm, n 5 50) and 5.3±9.6 mm wide (mean 5 7.4 mm, n 5 50). The male genitalia are more slender in some specimens .

Distribution (®gure 48). In Baja California Sur besides the type locality of San Marcos Island, it has been taken at San Bruno, and in Baja California Norte, it has been collected 5 km N of and on the beach near Bahia de Los Angeles, and 1 km N Rancho Progresso, vicinity of km marker 115. A long series was collected in Sonora at Desemboque on the eastern margin of the Gulf of California.

Biology. Larval hosts are unknown. Little is known of adult habits. Several from mainland Baja California are labelled as from Larrea tridentata (Sesse & Moc. ex DC.) Cov., as are part of the type series (Linsley and Ross, 1977), and a pair on Prosopis glandulosa (L. Benson) M. C. Jtn. Adults have been collected from the middle of June to late August.

Comparisons. This species is most similar to some forms of G. planicosta (LeC.), but it can usually be distinguished by its male genitalia that are more slender at the base; and in typical forms the elytral costae are more distinct.