Gyascutus (s. str.) castaneus (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 : 2270-2271

3. Gyascutus (s. str.) castaneus (Helfer) , comb. nov.

(®gures 4, 17, 35, 48)

Hippomelas insularis castanea Helfer, 1953: 36 .

Hippomelas (Gyascutus) castanea Barr, 1970: 4 ; Linsley and Ross, 1977: 274.

Diagnosis. In colour, coppery-black below and on head, black on pronotum, chestnut-brown on elytra; males average 16 mm long, females 17.6 mm; antennae reaching to just beyond posterior third in female; smooth areas of pronotum prominently raised; elytral costae evident; male genitalia elongate slender, slightly swollen at base, slightly narrowed apically (®gure 35).

Redescription, holotype male. Helfer (1953) mentions several characters to distinguish G. castaneus from G. insularis ; however, with larger numbers of G. insularis available for comparison, it was found that the only reliable external feature that identi®es G. castaneus is the chestnut-brown colour of the elytra. The male genitalia are more robust than in G. insularis (®gure 35). Length, 16.5 mm; width, 6.0 mm.

Redescription, allotype female. DiOEers from male as follows: slightly more robust; antennae shorter, reaching barely past middle when laid alongside; protibia without teeth; apex of last visible abdominal sternum crenulate. Length, 17.6 mm; width, 6.9 mm.

Type locality: Mexico, Baja California Norte: Angel de la Guardia Island, Pond Island Bay , Gulf of California .

Type material. The holotype lof Hippomelas insularis castanea Helfer (CASC) is labelled as follows: Pond Isd Bay Gulf Calif. Jun. 30 1921 (p)/Angel de la Guardia Isd (p)/ex Larrea Mexicana (p)/ E. P. VanDuzee Collector (p)/(red label) HOLOTYPE Hippomelas insularis Ssp. castanea Helfer (p)/ California Academy of Sciences Type No. (p) 8114 (h)/PLESIOTYPE Gyascutus castanea, Nelson lGenit. (h).

Variation. There is little variation in the two males and one female in the type series, the only specimens known. The paratype male is 15.5 mm long and 5.8 mm wide.

Distribution (®gure 48). Known only from the type locality.

Biology. The three specimens in the type series were collected on Larrea tridentata [mexicana] (Sesse & Moc. ex DC.) Cov. as reported in Linsley and Ross (1977). Adults were collected 30 June and 1 July .

Comparisons. This species is most similar to G. insularis (Helfer) , but diOEers primarily in its distinctive chestnut-brown elytra, and the male genitalia are less slender. The other characteristics used by Helfer (1953) to separate these two are not reliable diOEerences.