Acoma chihuahuaensis Evans & Smith, 2020

Evans, Arthur V. & Smith, Andrew B. T., 2020, On the tribal classification of the Nearctic Melolonthinae (Coleoptera: Scarabaeidae), with descriptions of new species of Acoma Casey, 1889, Zootaxa 4748 (1), pp. 51-77 : 56-58

Acoma chihuahuaensis Evans & Smith , new species

Figs. 5–10

urn:lsid:zoobank.org:act:BD4FB72A-5BD1-4671-886A-C0E05D1BE391

Type material. Holotype male ( CASC Type 19747), labeled “ MEXICO: Chihuahua / 7.1 mi. W Concho / VII-23- 1982 / Fred G. Andrews / coll. blacklight // Dr. Alan R. Hardy / Donation to the / California Academy / of Sciences // CASENT / 8424526 // HOLOTYPE / Acoma / chihuahuaensis / Evans & Smith, 2019”.

Paratypes, (9 males): same data as holotype, except with CASC database numbers CASENT 8424527– 8424535 .

Paratypes are deposited in AVEC (1 paratype; CASENT 8424534), CASC (6 paratypes; CASENT 8424527– 8424532), CMNC (1 paratype; CASENT 8424535), UNAM (1 paratype; CASENT 8424533) .

Diagnosis. Brown dorsally; anterior clypeal margin emarginate medially; antennae composed of 10 antennomeres, antennomeres 8–10 lamellate; protibia distinctly tridentate; elytra with disc glabrous and scattered setae along margins.

Description. Holotype male ( Figs. 5–10 ), length: 6.9 mm, width: 2.6 mm. BODY elongate, moderately convex, and uniformly brown dorsally, underside and appendages slightly lighter. HEAD ( Fig. 8 ) rugosely punctate; supraorbital carinae becoming obsolete at base of clypeus. Clypeus subtrapezoidal with margins strongly reflexed, lateral margins arcuate basally, becoming straight before broadly concave anterior margin flanked by prominent obtuse angles. Ocular canthus slightly less than one-third of eye length in lateral view, with scattered pale setae each not quite as long as canthus. PRONOTUM slightly wider than long, broadest at middle, and less than half length of elytron; disc convex, glabrous, shiny, sparsely punctate with punctures separated by four or more of their diameters, with a narrow longitudinal impunctate line medially; margins with distinct bead, anterior margin bisinuate between obtuse anterior angles, with marginal bead relatively broad and raised; anterolateral margins straight, converging anteriorly, posterolateral margins slightly converging posteriorly with posterolateral angles broadly rounded. SCUTELLUM small, parabolic, about one-fifth basal width of elytron, finely and setigerously punctate basally, and glabrous and becoming impunctate apically. ELYTRON convex, with disc shiny, glabrous, and distinctly punctostriate with deep punctures separated by 1.5–3.0 X their diameters, punctures becoming confused at apical declivity; margins setigerous, setae on lateral margins becoming shorter apically. LEGS with tridentate protibia moderately emarginate between apical and middle teeth, and shallowly emarginate between middle and basal teeth. PYGIDIUM parabolic, shiny, finely shagreened, with scattered setigerous punctures, setae long. GENITALIA with parameres symmetrical, slender and slightly sinuate when viewed laterally, with membranous flange extending to apical fifth, and about as long as phallobasis ( Figs. 9–10 ).

Variation. Length: 5.9–6.9 mm, width: 2.2–2.6 mm. Color varies from light brown to brown, occasionally with elytra lighter, while the head and pronotum are slightly darker. Clypeus varies from subtrapezoidal to nearly parabolic with narrowly to broadly concave anterior margin flanked by prominent angles or not.

Etymology. This species is named after the Mexican state of Chihuahua, where the type series was collected.

Remarks. Acoma glabrata Cazier, 1953 , A. nonglabrata new species, and A. chihuahuaensis new species all have antennae with 10 antennomeres, of which 8–10 form the lamellate club. Acoma chihuahuaensis new species is readily distinguished among these species by its darker color, distinct elytral punctostriae with deep punctures, more rounded and less pronounced protibial teeth, and its occurrence in mainland Mexico.

Figures

FIGURES 5–10. Acoma chihuahuaensis Evans & Smith, new species, male holotype. 5, Dorsal habitus; 6, oblique habitus; 7, ventral habitus; 8, head; 9, dorsal parameres; 10, lateral genitalia.