Acoma westcotti, Warner, 2011

Warner, William B., 2011, Four new species of Acoma Casey, with a key to species in the genus (Coleoptera: Scarabaeidae: Melolonthinae), Insecta Mundi 2011 (172), pp. 1-17 : 2-3

Acoma westcotti new species

Figures 2-5

Type Material. Holotype ( UNAM): “ MEX, Baja Calif. Sur, 10 km SE Mulegé , dunes, 18-VI-1993, Westcott & Equihua.”

Paratypes (22 males): same as holotype (3); “ Mex : Baja Calif. Sur, 5.7 mi. SE Mulege, vii-7-1979, Andrews, Hardy, & Giuliani; collected at blacklight” (12) ; same except “ cereal bowl pit trap ” (2) ; “ Mexico: Baja California Sur, 6 km S. Mulege, 18 November 1981, W.E. Steiner ” (2) ; “ Baja California, 4 mi. S Mulege , 18-ix-1991, Robert Gordon” (3) .

Paratypes are deposited at CASC, CSCA, FSCA, CMNC, RLWE, USNM, WBWC.

Diagnosis. Castaneous; shiny, head and pronotum unusually smooth for genus, glabrous except for margins, elytral disc hairy; antennae 9-segmented with 3-segmented club, club segments slightly shorter than length of other segments combined; anterior tibia distinctly bidentate.

Description. Holotype male, length: 5.8 mm, width: 2.7 mm.

BODY medium brown, elongate, moderately convex. HEAD including clypeus unusually smooth and shiny for genus, sparsely finely punctulate, punctures mostly separated by 3-5 times their own diameters, more dense on either side of subtriangular mostly impunctate area extending from base of head to half way to frontoclypeal junction; supraorbital areas narrowly subcarinately overhanging eyes, this narrow shelf becoming obsolete at base of ocular canthus. Clypeus subsemicircular, apex slightly flattened in dorsal view, free margins strongly reflexed, reflection weakly emarginate at clypeal apex. Ocular canthus short, about one-sixth of eye width, densely setose, setae twice or more as long as canthus. PRONOTUM slightly less than half as long as elytron; disc glabrous, moderately convex, finely sparsely punctate similar to head; posterior and lateral margins with bead fine, anterior marginal bead wide and flat, the margin rather strongly concave from angle to angle; posterior margin very weakly convex; posterior angles rounded, lateral margins parallel in posterior two-thirds, narrowing in anterior onethird; anterior angles drawn anteriorly, very narrowly rounded at apices; anterior marginal setae about one-third pronotal length, lateral marginal setae nearly one-half length of pronotum, posterior marginal setae about one-third or less as long as anterior marginal setae. SCUTELLUM small, parabolic, about one-third as wide as elytron, rather densely setigerously punctulate in basal half. ELYTRON slightly less than three times as long as pronotum, surface shagreened, subrugosely punctate, punctures sparse on disc, more dense on declivity, setigerous; striae evident on disc, obsolescent basally, laterally, and in apical fourth. PYGIDIUM parabolic, moderately punctate, punctures shallow, setigerous ( Fig. 5 ). LEGS: Anterior tibia bidentate, emargination between middle and apical teeth deep, middle tooth strong, arising basal to insertion of tibial spur ( Fig. 4 ). GENITALIA: paramera with apex weakly deflexed, ventrobasal emargination moderate.

Variation. Length: 4.7 – 5.9 mm, width: 1.9 – 2.8 mm. Clypeal shape varies from semicircular to subtrapezoidal, with the apical emargination varying from obsolete to subdistinct; minor variation in surface sculpture; color varies from honey brown to dark brown.

Etymology. I am pleased to name this new species for Rick Westcott, Salem, Oregon, expert on the Buprestidae , who has a great talent for collecting rare Scarabaeoidea, and who collected part of the type series.

Remarks. Acoma westcotti apparently occupies an isolated position within the genus based on the distinctive pronotal and tibial shapes. It is easily recognized by the strongly bidentate anterior tibia ( Fig. 4 ) and smooth head ( Fig. 2 and 3 ), both characters being very unusual for the genus. (The head of Acoma glabrata Cazier , a species with a relatively smooth head compared to most Acoma , is shown in Fig. 1 for comparison.) The anterior tibial shape is very similar to that of the unrelated but sympatric Chaunocolus cornutus Saylor , and may represent a parallelism.

Figures

Figure 1-5. Acoma spp. 1) Acoma glabrata Cazier, head and pronotum. 2-5) Acoma westcotti Warner: 2) Head and pronotum, 3) Dorsal habitus. 4) Left anterior tibia. 5) Pygidium.