Phanaeus texensis Edmonds, 1994

Edmonds, W. D., 2018, The dung beetle fauna of the Big Bend region of Texas (Coleoptera: Scarabaeidae: Scarabaeinae), Insecta Mundi 642, pp. 1-30 : 14

Phanaeus texensis Edmonds

Fig. 70–73

Diagnosis. Black, often with blue-violet highlights; upper surface dull. Length 12–22 mm. Male ( Fig. 70–72 ) – Head of large individuals bearing long horn curved posteriorly over the pronotum; pronotum roughened by irregular granular sculpturing, strongly flattened, with salient, laterally curved posterior angles; in smaller males head horn shorter and triangular area of pronotum reduced in size and prominence. Female ( Fig. 73 ) – Head with anteriorly bowed ridge between and in front of eyes; pronotum granulate, convex, with transverse, weakly bowed ridge near anterior margin. Elytral interstriae flat, densely roughened. Edmonds (1994) provides a formal description of this species (as P. triangularis texensis ; raised to species status in Edmonds and Zidek 2012).

Big Bend collection sites (altitudinal range: 1325–1850 m).

Jeff Davis Co: [1] Davis Mountains Preserve , 31°41′40″N 104°07′30″W, 1850 m (Jul–Aug) ; [2] Davis Mountains Preserve (Madera Canyon Unit), 1845 m (Sep) ; [3] 16 km S Fort Davis (along TX 17 ), 30°27′48″N 103°58′59″W, 1600 m (Aug) ; [4] 8 km 8 km SE Fort Davis (via TX 118 ), Chihuahuan Desert Research Institute (Quarry Unit), 30°32′06″N 103°50′37″W, 1480 m (Sep) ; [5] ~ 16 km NE Valentine, Muerto Springs Ranch (Muerto Springs), 30°40′50″N 104°20′22″W, 1555 m (Jul) .

Presidio Co.: [1] 37 km SSW Marfa (along FM 2810, Petan Ranch – Cherry Hills sector), 30°07′35″N 104°19′24″W, 1630 m (Jun) ; [2] 20–26 km SSE Marfa (along FM 169 ), 1355–1415 m (Jun) ; [3] 27 km SSE Marfa (along FM 169 ), 30°08′42″N 104°02′13″W, 1325 m (Jul) ; [4] ~ 16 km W Valentine ( Miller Ranch , near headquarters), 30°33°30″N 104°38′44″W, 1350 m (Jul–Aug) ; [5] Miller Ranch (~ 16 km W Valentine), 30°32′50″N 104°39′40″W (Camp Holland) 1410 m (Aug) ; [6] 3 km NE Marfa (along FM 1112 ), Marfa Golf Course, 30°19′40″N 103°59′41″W, 1470 m (Jul, Sep) .

Collection method(s). a) baited pitfall trap (human feces); b) direct capture (cowdung; pronghorn dung; horse dung; *deer carcass).

Surface activity. Diurnal.

Habitat. Montane woodlands and grasslands throughout the Big Bend area.

Comments. Phanaeus texensis is not common in the Big Bend, but it is widespread there. It is a burrowing species that searches for food (usually dung) on the surface that, once located, is buried by bits in tunnels underneath or to the side of its find. Often the only sign that it is present is a small mound of soil pushed to the surface during excavation of the tunnel. Because it passes most of its adult life underground, this species is, in spite of its size and conspicuousness, largely unknown to ranchers, hunters and others who frequent pasturelands in the area. While it prefers montane habitats, it can be found in other grassland and scrub habitats as well, but usually above 1380 m. Big Bend specimens of this species are always darkly colored, but scarce individuals can occasionally assume metallic green/coppery coloration in eastern parts of the state. In 1994, I considered P. texensis (as P. triangularis texensis ) essentially absent from the Big Bend, an error corrected here. A peripheral record in Pecos Co. about 32 km northwest of Marathon on U.S. Hwy 385 (Brewster Co.), reports P. texensis from a deer carcass.

While P. texensis occurs throughout much of the western two-thirds of the state, including the Big Bend, another species occurs at the periphery of the Trans-Pecos and could be regarded as an incipient (or perhaps previous) member of the Big Bend fauna. This second Phanaeus is P. difformis LeConte ( Fig. 74–75 ), which is broadly distributed in the south-central United States and has penetrated western areas into the northern limit of the Trans-Pecos via river drainage systems into southeastern New Mexico and eastern Colorado ( Edmonds 1994). A few isolated specimens have been collected in the Hueco Mountains east of El Paso ( Schoenly 1983) as well as in Guadalupe Mountains National Park and near Malaga, New Mexico (personal records). Another common Phanaeus , P. vindex MacLeay , occurs widely in the Texas plains, New Mexico and Arizona; I agree with Bill Warner (pers. comm.) that its apparent absence from the Trans-Pecos is surprising.

Figures

Figures 70–75. Phanaeus. 70) P. texensis, dorsal view, large male. 71) Same, oblique anterolateral view. 72) Same, dorsal view, small male. 73) Same, dorsal view, female. 74) P. difformis, dorsal view, male. 75) Same, female.