Onthophagus browni Howden and Cartwright

Edmonds, W. D., 2018, The dung beetle fauna of the Big Bend region of Texas (Coleoptera: Scarabaeidae: Scarabaeinae), Insecta Mundi 642, pp. 1-30 : 10

Onthophagus browni Howden and Cartwright

Fig. 41–43

Diagnosis. Dorsum black, occasionally showing weak greenish reflections; legs coffee brown. Length 5–7.5 mm. Pronotum evenly but not densely covered by small shining granules, each with associated short seta, on field of extremely fine shagreening (as in Fig. 48 ); elytral interstriae with two longitudinal rows of small, setose granules on field of fine shagreening; pygidium evenly punctate, punctures setose. Front legs similar in the two sexes. Male ( Fig. 41–42 ) – Head lacking horns, bearing two transverse carinae; clypeus slightly upturned medially. Pronotum with large, flattened, apically widened, emarginate process extending over posterior portion of head (reduced in small individuals). Female ( Fig. 43 ) – Head bearing two simple, transverse carinae; clypeal margin not upturned. Pronotum convex except for low, transverse ridge rising above anterior margin. Complete formal description given by Howden and Cartwright (1963).

Big Bend collection sites (altitudinal range: 725–1785 m).

Presidio Co.: [1] C.E. Miller Ranch (~ 16 km W Valentine), 30°32′50″N 104°39′40″W (Camp Holland) 1410 m (Aug) ; [2] ~ 16 km W Valentine ( Miller Ranch , near headquarters), 30°33°30″N 104°38′44″W, 1350 m (Jul–Aug) ; [3] ~ 6 km W Marfa (Hip-O Ranch ), 30°21′54″N 104° 7′12″W, 1530 m (Aug–Sep) ; [4] Fort Leaton , 29°32′31″N 104°19′28″W, 770 m (Jun) ; [5] ~ 40km E Redford via Hwy 170, Grassy Banks Rest Area, 725 m, ~ 29°17′01″N 103°53′12″W (nd) .

Jeff Davis Co.: [1] ~ 16 km NE Valentine, Muerto Springs Ranch ( Muerto Springs ), 30°40′50″N 104°20′22″W, 1555 m (Jul) ; [2] Davis Mountains Preserve , 31°37′42″N 104°05′01″W, 1785 m (May) .

Collection method(s). a) baited pitfall trap (human feces); (b) incandescent light trap; (c) flight intercept trap; (d) *soil beneath wood rat nest.

Surface activity. Nocturnal.

Habitat. All zones in association with wood rats ( Neotoma ).

Comments. This species is closely related to O. velutinus ; and while males and larger females are easily distinguished, small or worn females can be difficult to identify if not associated with larger specimens or conspecific males. While they are attracted to human feces, they are collected in significantly larger numbers from soil beneath the living area of wood rat nests ( Halffter and Matthews 1966; Howden and Cartwright 1963). Onthophagus browni is also common in southeastern Arizona, where it was apparently referred to as O. hecate by Dajoz (1994). Bill Warner (pers. comm.) reports that O. browni and O. velutinus are separated by altitude/habitat in southeastern Arizona, the former species higher in the mountains and the latter at lower elevations in the flats and bajadas, a distribution pattern paralleled by Copris arizonensis and C. macclevei .

Figures

Figures 36–48. Onthophagus. 36) O. brevifrons, dorsal view, male. 37) Same, oblique frontal view. 38) Same, dorsal view of forebody, female. 39) Same, prolegs (A, female; B, male. 40) Same, pronotal sculpturing. 41) O. browni, dorsal view, male. 42) Same, oblique frontal view. 43) Same, oblique frontal view, female. 44) O. velutinus, dorsal view, male. 45) Same, oblique frontal view. 46) Same, dorsal view of female forebody. 47) Same, oblique frontal view. 48) Same, pronotal sculpturing.