Ataenius nocturnus (Nomura)

Ataenius nocturnus (Nomura)

Saprosites nocturnus Nomura, 1943:77.

Ataenius gracilis.—Nakane, 1961:26 [not Melsheimer, 1844: 137].

Ataenius nocturnus.—Cartwright and Gordon, 1971:271.

DESCRIPTION.—Length 2.8 to 3.6 mm; width 1.0 to 1.3 mm. Moderately shining, piceous, legs and sometimes anterior margins of head and pronotum reddish, elongate, parallel, only weakly convex. Antennae testaceous. Head convex, clypeal margin very finely reflexed, rounded each side of broad, shallow, median emargination, sides very weakly arcuate to right-angled genae; surface shining and slightly uneven close to median emargination, elsewhere with close, elongate punctures united in lines except at middle of occipital area where the somewhat larger punctures are round in shape, punctures dense everywhere, separated by less than their diameters. Pronotum nearly quadrate, averaging about 1.1 mm wide, 0.8 mm long; base and sides finely margined, without marginal setae, anterior angles rounded, posterior angles very broadly rounded; surface closely punctate, the punctures generally moderate in size, a little finer near lateral and anterior margins, a trifle larger and shallower near lateral foveae, midline distinct and deeper over basal half, the punctures here practically uniting in a narrow row. Elytra averaging about 2.0 mm long and 1.2 mm wide, humeri finely dentate, striae deep, finely crenate-punctate intervals convex with median row of minute punctures, minutely alutaceous along inner edge, sutural interval flat with row of close, fine punctures, lateral intervals not noticeably different. Mesosternum broadly carinate between the coxae. Metasternum smooth and shining on disc, midline strong and deep, punctures moderately coarse and close anteriorly, much finer posteriorly, scabriculate at sides. Metasternal triangle deep, sharply defined anteriorly, finely alutaceous within. Abdonimal sterna finely fluted along anterior margin, surface with scattered, fine to very moderate, evenly spaced punctures generally separated by one or two diameters, suture in front of 5th sternum unusually and noticeably deep. Pygidium with deep basal line, disc and apical area very finely, closely punctate. Anterior femora with perimarginal groove, surface with scattered, coarse, shallow punctures separated by one diameter or less. Middle femora shining; scattered, very fine punctures, posterior marginal line short, one-third length of femur. Posterior femora similiar but with marginal line still shorter. Hind tibia without accessory spine, fringe of nine short, close setae, tarsus shorter than tibia, first tarsal segment one-fourth longer than long spur, equal to following three segments combined. The male pygidium is longer and the 5th abdominal sternum is shorter than in the female. The male 5th sternum also tips inward anteriorly.

NEOTYPE MALE (present designation).—Male, USNM No. 71443. Original holotype and type series were destroyed during World War II.

TYPE-LOCALITY.—Saipan. The neotype bears the following data: “Saipan I., Marianas, As Mahetog area, 1:I;45. Col. & Pres. by Henry S. Dybas. Lot 449.”

SPECIMENS EXAMINED.—175+.

DATES COLLECTED.—March 8 to December 14.

DISTRIBUTION (Figure 19).—Arizona: Arlington, Arivaca, Buckeye, Cochise County, Colossal Cave Park (Pima County), Douglas, Fort Yuma, Gila Valley, Globe, Graham Mts., Granite Reef Dam, Hot Springs, Madera Canyon (Santa Rita Mts.), Patagonia, Phoenix, Portal, Riverside, Roosevelt Lake, Sabino Canyon (Santa Catalina Mts.), Safford, Tortolita Mts. (Cottonwood Canyon), Willcox, Playa, Yuma. California: Berkeley, Colorado Desert, Fresno, Holtville, Kaweah, Kern County, Los Angeles, San Bernardino, Sonoma County, Three Rivers, Visalia, Willows, Yuma. New Mexico: Albuquerque. Texas: Big Bend National Park, Lajitas, Limpia Creek Canyon (Davis Mts.).