Digitonthophagus gazella (Fabricius)

Edmonds, W. D., 2018, The dung beetle fauna of the Big Bend region of Texas (Coleoptera: Scarabaeidae: Scarabaeinae), Insecta Mundi 642, pp. 1-30 : 15-16

Digitonthophagus gazella (Fabricius)

Fig. 54–59

Diagnosis. Elytra yellow to mottled yellowish brown; pronotum blackish-brown except for continuous yellow band following lateral and posterior borders. Length 6–8 mm. Male ( Fig. 54–55 ) – Head of larger individuals with pair of widely spaced, vertical, slightly curved, acute horns set just inside eyes; carina separating frons and clypeus bowed anteriorly; pronotum with narrow, bilobate central tumosity near anterior margin; protibia ( Fig. 56 ) tridentate, slender and rather strongly curved medially, inner apical angle extended as digit-like spur projecting beyond spur ( Fig. 59B , arrow). Female ( Fig. 57–58 ) – Head with strongly elevated ridge extending between eyes; carina separating frons and clypeus bowed anteriorly; pronotum with wide, bilobate prominence; protibia tridentate, wider, only slightly curved medially, inner apical angle simple, not digitiform ( Fig. 59A ). This species was re-described by Génier and Moretto (2017) and the correct usage of the species epithet ‘gazella’ was considered by Génier and Davis (2017).

Big Bend collection sites (altitudinal range: 1010–1850 m).

Brewster Co.: [1] ~ 17 km W Alpine ( Paisano Baptist Encampment ), 30°17′37″N 103°47′35″W, 1550 m (Jul) ; [2] * Big Bend National Park , North Rosillos Mountains Preserve, 29°28′48″N 103°11′16″W, 1010 m (Jul) .

Jeff Davis Co.: [1] 8 km SE Fort Davis (via TX 118), Chihuahuan Desert Research Institute ( Quarry Unit ), 30°32′06″N 103°50′37″W, 1480 m (Aug) ; [2] Davis Mountains State Park , 30°35′43″N 103°56′05″W, 1540 m (Jun, Aug) ; [3] Davis Mountains Preserve, 31°41′40″N 104°07′30″W, 1850 m (Jul–Aug) ; [4] 8 km SE Fort Davis (via TX 118 ), Chihuahuan Desert Research Institute ( Visitor Center area), 30°32′32″N 103°50′11″W, 1555 m (Aug) .

Presidio Co.: [1] ~ 6.5 km W Marfa (Hip-O Ranch ), 30°21′54″N 104° 7′12″W, 1530 m (Aug–Sep) ; [2] ~ 30 km SSE Marfa (along FM 169 ), Humphreys Ranch , 30°02′30″N 104°01′00″W, 1285 m (Jul) ; [3] 27 kmSSE Marfa (along FM 169 ), 30°08′42″N 104°02′13″W, 1335 m (Jun) ; [4] 60 kmSSE Marfa (along FM 169 ), Casa Piedra, 29°44′07″N 104°03′03″W, 1055 m (Sep) ; [5] ~ 1 km E Marfa (along FM 1112 ), 30°18′56″N 104° 00′08″W, 1490 m (Aug) ; [6] ~ 16 km W Valentine ( Miller Ranch , near headquarters), 30°33°30″N 104°38′44″W, 1350 m (Jul–Aug) ; [7] 12 kmNE Ruidosa (via Chinati Hot Springs road), Chinati Hot Springs, 30°02′17″N 104°36′02″W, 1090 m (Aug) ; [8] ~ 13 km E Marfa (via US 90/67), 30°16′07″N 103°48′44″W, 1565 m (Jul) ; [9] 20–26 km SSE Marfa (multiple sites along FM 169 ), 1355–1415 m (Jun– Jul) ; [10] ~ 3 km N Marfa (along TX 17 ), 30°20′27″N 104°01′7″W, 1500 m (Jul) ; [11] 37 km SSW Marfa (along FM 2810 ), 1630 m (Jun) ; [12] Pinto Canyon Ranch (~ 58 km SSW Marfa on FM 2810 ), 30°01′18″N 104°27′42″W (headquarters area), 1475 m (Aug) .

Collection method(s). a) baited pitfall trap (human feces); b) direct capture (cow dung; horse dung); c) UV and incandescent light trap.

Surface activity. Nocturnal.

Habitat. Generally distributed throughout the region in all habitats, although more common in open pasturelands and desert scrub.

Comments. The generic name derives from the finger-like projection of the tibial apex of the male ( Fig. 56, 59B ). Digitonthophagus gazella was originally placed in Onthophagus , where it is often still found in the literature. Recent molecular studies ( Breeschoten et al. 2016), however, show Digitonthophagus to be somewhat distantly related to Onthophagus . The scientific literature on this species, especially in the context of the livestock industry, is extensive.

Figures

Figures 49–59. Onthophagus and Digitonthophagus. 49) O. knausi, dorsal view, male. 50) Same, dorsal view, female. 51) Same oblique frontal view, female. 52) Same, prolegs (A, male; B) female). 53) Same, pronotal sculpturing. 54) D. gazella, dorsal view, male. 55) Same, partial oblique frontal view of forebody. 56) Same, proleg, male. 57) Same, oblique frontal view of female forebody. 58) Same, dorsal view, female. 59) Same, apex of protibia and protarsus (A, female; B, male [arrow marks apical tibial “digit”]).