Copris arizonensis Schaeffer 1906

Copris arizonensis Schaeffer

Fig. 64–69

Diagnosis. Black, surface lustrous, sides of body more-or-less parallel. Length 13–22 mm. Male (Fig. 64–66) – Head of large individuals bearing posteriorly curved horn, tip of which approaches bifurcated median process of pronotum; flanks of pronotum each with large, acute, forward-directed, blade-like process separated from apically bifurcated median process by broad, declivitous concavity (in smaller individuals horn and processes progressively attenuated, Fig. 65). Female Fig. 67–69) – Head with short, erect horn, apex widened, scoop-like; pronotum convex except for pair of blunt tubercles, one on each side near anterior angle and separated by thick transverse ridge. Matthews (1961) provides a full re-description of this species.

Big Bend collection sites (altitudinal range: 1375–1800 m).

Brewster Co.: [1] Alpine, Sul Ross State University campus, 30°22′04″N 103°38′52″W, 1375 m; [2] * Big Bend National Park, Basin area, 29°16′04″N 103°17′39″W, 1660 m (May); [3] * Alpine, Sunny Glen, 30°22′41″N 103°45′06″W, 1445 m (Jun).

Jeff Davis Co.: [1] * Davis Mountains State Park, 30°35′43″N 103°56′5″W, 1540 m (Jun, Aug); [2] * Davis Mountains Resort, 30°37′30″N 104°05′30″W, 1800 m (Jun–Aug).

Collection method(s). a) UV light trap; b) *direct capture beneath nests of Neotoma.

Surface activity. Nocturnal.

Habitat. Montane, juniper-pinyon woodlands and arroyos in association with the wood rat, Neotoma albigula (and possibly also N. mexicana Baird).

Comments. This is by far the rarest dung beetle in the Big Bend. All examined specimens from the region were collected at lights. Copris arizonensis is also known from various locations in the mountains of southeastern Arizona and adjacent areas of southwestern New Mexico and northern Chihuahua, Mexico [Matthews 1961; McCleve and Kohlmann 2005; Warner 1990].) Figure 64 depicts a specimen from southeastern Arizona (Dragoon Mts., Cochise Co.) exhibiting maximum expression of male armament, which I have not observed in Big Bend specimens (Fig. 65). The occurrence of C. arizonensis in scattered higher mountainous areas of northern Chihuahua and the desert southwest is doubtless the result of shrinking and vertical isolation of suitable, high-elevation habitat during post-Pleistocene desertification of the region.