Boreocanthon puncticollis ( LeConte, 1866 )

Edmonds, W. D., 2022, Taxonomic review of the North American dung beetle genus Boreocanthon Halffter, 1958 (Coleoptera: Scarabaeidae: Scarabaeinae: Deltochilini), Insecta Mundi 2022 (952), pp. 1-65 : 33-38

Boreocanthon puncticollis ( LeConte, 1866) , restored generic combination

Fig. 54–63

Canthon puncticollis LeConte 1866: 381 .

Boreocanthon puncticollis (LeConte) (new combination per Halffter 1958: 210).

Canthon (Boreocanthon) puncticollis LeConte (new combination per Howden 1966: 727).

Boreocanthon puncticollis (LeConte) , restored generic combination.

Canthon nyctelius Bates 1887: 31 (new synonymy per Schaeffer 1915: 50).

Canthon mixtus Robinson 1948: 91 , new synonymy.

Type material. 1) Canthon puncticollis LeConte : syntype, female. Museum of Comparative Zoology, Harvard University, MCZ-ENT 00003698. Examined by photograph (https://mczbase.mcz.harvard.edu/guid/ MCZ:Ent:3698). 2) Canthon nyctelius Bates : Syntype (sex undetermined). The Natural History Museum, London. Not examined. 3) Canthon mixtus Robinson : Holotype, male. National Museum of Natural History, Washington, D.C. Not examined.

Type localities. 1) Canthon puncticollis LeConte : Cape San Lucas, Lower California [ Mexico]; 2) Canthon nyctelius Bates : Santa Clara (Chihuahua) , Chihuahua City, Durango City (Durango); 3) Canthon mixtus Robinson : Marfa, Texas.

Diagnosis. Head: Clypeus ( Fig. 55, 62 ) finely roughened, weakly shiny; remainder of head surface distinctly punctate on shagreen background with very weak microspotting. Sexdentate, clypeal teeth prominent, rounded apically, median pair separated by broadly rounded emargination, paraocular notch large, nearly right-angled, anterior angle of paraocular area obtusely dentate. Labio-gular fimbria broadly V-shaped, constricted apically and reaching about one-third length of gula. Prothorax: Pronotum ( Fig. 59, 61 ) boldly, conspicuously punctate, punctures shallow, evenly distributed over entire surface shagreen, microspotting conspicuous. Anterior angles of pronotum only very slightly reflexed; postero-median angle depressed as dark, triangular declivity adjacent anterior ends of first elytral interstriae ( Fig. 55, 59 ). Hypomeral carina absent. Pterothorax: Mesoventrite smooth, sometimes with few coarse, median punctures. Metaventrite shiny, evenly covered by small, sharp, evenly dispersed punctures. Elytra: Interstriae ( Fig. 59, 61 ) alutaceous, microspotting dense, punctures absent. Striae bold, with crisp, sharply defined edges, especially anteriorly. Anterior ends of 2 nd and 3 rd interstriae swollen, those of 1 st depressed, forming with the adjacent depression of the pronotum a rimless median “crater” or fossa ( Fig. 55, 59 ). Subhumeral (8 th) stria carinulate, usually strongly so; epipleural (9 th) stria almost always distinct apically, occasionally weakly carinulate. Legs: Inner margin of protibia gently curved, not offset. Protibial teeth sexually dimorphic, apically acute in female, bifurcate in male. Metafemora lacking conspicuous anterior row of long setae. Abdomen: Pygidium weakly punctured on shagreen background, microspotting weak, apex sometimes more convex and shinier than rest of surface. Sixth ventrite with small median field of coarse punctures, remaining ventrites smooth, impunctate. Genital capsule: Compressed distal portion of parameres ( Fig. 58 ) triangular, lower apical angles bearing lateral, ear-like flanges ( Fig. 56–57 ). General: Black, usually with strong blue highlights, very rarely with green highlights. Length: 4.0 – 6.5 mm. Geographic distribution ( Fig. 63 ): Southern Baja Peninsula and Central Mexico from the Transverse Volcanic Axis to far western Texas and southern Arizona. Ecogeographic environment ( Fig. 2 ): Desert and Xeric Shrublands biome. Specimens examined: 833.

Collection localities.

MEXICO — AGUASCALIENTES: Mpio. Aguascalientes ● 15 mi E Aguascalientes. BAJA CALIFORNIA: Mpio. Ensenada ● 4.3 mi W El Rosario [Sep]. BAJA CALIFORNIA SUR: Mpio. Los Cabos ● 5 mi N Cabo San Lucas [Oct] ● Santiago ● San José del Cabo ● 11 km N Santa Anita [Aug] ● 20 km NW Cabo San Lucas, 120 m [Sep] ● 22 km NW Cabo San Lucas, 23°01.538 ʹ N 110°04.895 ʹ W, 30 m [Jul] ● 4.3 mi SW Miraflores ● Miraflores [Jul]; Mpio. Mulejé ● San Venancio [Oct] ● Santa Rosalia ; Mpio. La Paz ● 2.5 mi SE La Huerta, 2200 ft [Oct] ● 9.5 mi S San Pedro [Sep] ● 3 mi N San Pedro [Jul] ● La Paz [Oct] ● 8 mi SE La Paz, 1000 ft [Oct] ● 17 mi S La Paz [Sep] ● 15 mi W La Paz ● 11 mi S Todos Santos, Playa Los Cerritos [Sep] ● 2 mi W El Triunfo, 1900 ft [Oct] ● 3 mi S El Triunfo [Aug-Sep] ● 11.8 mi N El Triunfo [Sep] ● 0.5 mi NW El Triunfo, 1800 ft [Oct] ● 7 mi W El Triunfo, 1500 ft [Oct] ● Sierra de la Laguna , 3 mi W Cuadaño [Sep] ● Sierra de la Laguna , 5 mi S San Antonio [Sep] ● Sierra de la Laguna , 27 km W Hwy 1 on Ramal a Las Naranjas, 23°14 ʹ 12 ʺ N 109°57 ʹ 15 ʺ W, 2450 ft [Jul-Aug] ● 3.5 mi W Los Barriles, 500 ft [Dec]; Mpio. Loreto ● Canipolé [Oct]. CHIHUAHUA: Mpio. Chihuahua ● 12 km N Chihuahua [Aug]; Mpio. Janos ● 45 mi NW Casas Grandes [Aug]. COAHUILA: Mpio. Castaños ● 1 mi NE Junction Hwy 53 and Baján Rd.; Mpio. Ocampo ● 35.5 mi W Ocampo, Laguna La Leche Flats, 27°17.0 ʹ N 102°53.6 ʹ W ● Sierra El Carmen (Maderas del Carmen), 28°59 ʹ 54 ʺ N 102°36 ʹ 42 ʺ W, 2310 m. [Jul] ● Boquillas del Carmen [Jul]; Mpio. Saltillo ● 6 km E Saltillo [Jul]. DISTRITO FEDERAL: ● Tepeyac [Aug]. DURANGO: Mpio. Cuencamé ● Hwy 49, 20 km SE Cuencamé; Mpio. Durango ● Tapías, 6400 ft [Jun]; Mpio. Lerdo ● La Loma, 4100 ft [Aug]; Mpio. Mapimí ● Reserva de la Biósfera Mapimí [Jun, Sep]; Mpio. Ocampo ● 173 mi N Durango [Aug]; Mpio. Saucillo ● Estación Conchos [Jun]. HIDALGO: Mpio. Jacala de Ledezma ● 7 mi N Jacala [Jul]; Mpio. Zimapán ● Zimapán [Jun]. OAXACA: Mpio. Santiago Chazumba ● San Sebastián Frontera [Jul]. PUEBLA: Mpio. Tepeyahaulco ● Alchichica [Jun]. SAN LUIS POTOSÍ: Mpio. Guadalcázar ● 19.6 mi N Huizache [Jul]; Mpio. Matehuala ● Matehuala [Jul]. SONORA: Mpio. Naco ● Naco, 5000 ft [Aug]. ZACATECAS: Mpio. Villa de Cos ● Tropic of Cancer marker, Hwy 54 (Zacatecas – Saltillo), ~ 23°26 ʹ 12 ʺ N 102°12 ʹ 05 ʺ W, 1958 m [Jul].

UNITED STATES — ARIZONA: Apache Co. ● White Mountains, Diamond Creek [Aug]; Cochise Co. ● 10 mi N Portal [Sep] ● 2 mi NE Portal [Jul] ● 4 mi NNW Portal, 31°58 ʹ N 109°09 ʹ W, 4600 ft ● 13 mi W Gleeson [Aug] ● Dragoon Mountains, Cochise Stronghold [Jul] ● Dos Cabezas [Aug] ● Palominas [Aug] ● Guadalupe Canyon [Jul] ● Douglas [Jul] ● 15 mi E Douglas [Aug] ● Turkey Creek Canyon, Chiricahua Mountains, 31.8657° N 109.4125° W, 1642 m [Jul] ● San Simon [Aug]; Graham Co. ● 12 mi S Safford [May]; Mojave Co. ● 17 mi S Wikieup [Aug]; Pima Co. ● Tucson [Sep] ● Saguaro National Park (West) [Aug] ● Green Valley [Sep] ● 18 mi S Tucson [Jul]; Santa Cruz Co. ● Nogales [Aug] ● Santa Rita Mts [Aug]; Yavapai Co. ● 4 mi N Clarkdale [Jul]. CALIFORNIA: San Bernadino Co., New York Mountains [Aug]. NEW MEXICO: Catron Co. ● 5 mi NW Reserve [Jul]; Doña Ana Co. ● La Jornada Experimental Range, 15 mi N Las Cruces [Jul-Sep] ● 6 km NW Mesilla Dam ● Las Cruces [Jul-Aug] ● 1 mi SE Afton Pump Station [Jul] ● 10 mi NE Las Cruces, 32.490206 -106.781367, 4523 ft; Grant Co. ● Silver City ● 8 mi E Silver City [Jul]; Hidalgo Co. ● 1 mi N Rodeo [Jul] ● 5 mi N Rodeo [Aug] ● 13 mi NE Rodeo [Jul] ● 1 mi S Rodeo; Luna Co. ● Deming [Jul-Aug] ● 6 mi NW Columbus [Jul]; Otero Co. White Sands National Park, Lake Lucero [Aug] ● Lake Holloman Camp, 32.811° N 106.121° W, 1230 m; Quay Co. ● 1.1 mi N Tucumcari, 4100 ft [Aug]; Sandoval Co. ● 4 km NE Sandia, Sandia Pueblo, 35.224547 -106.529917 [Jul]; Sierra Co. ● Elephant Butte [Oct] ● Eagles Point, Elephant Butte Reservoir [Aug]. TEXAS: Brewster Co. ● ~ 17 km W Alpine (Paisano Baptist Encampment), 30°17 ʹ 37 ʺ N 103°47 ʹ 35 ʺ W, 1550 m (Jul) ● Chisos Mountains [Jul] ● 15 mi S Marathon [Jun] ● 20 mi E Marathon, 30°12 ʹ 04 ʺ N 102°54 ʹ 47 ʺ W [Jun] ● Boquillas [Jul] ● Tornillo Creek at Hwy 227, Big Bend National Park [Jul] ● Elephant Butte Wildlife Management Area, 26 mi S Alpine [Apr] ● Big Bend National Park, Buttrill Springs [Jul]; Culberson Co. ● 17 mi E Van Horn [Jul, Sep] ● 4 mi E Kent [Jun]; Dickens Co. ● 2 mi E Dickens [May]; Ector Co. ● Odessa, 31.884°N 102.32°W [Jul]; El Paso Co. ● 18.5 mi E El Paso, Hueco Mts. [Sep]; Howard Co. ● Big Spring; Hudspeth Co. ● 8 mi W Sierra Blanca , 31.21° N 105.49° W, 1390 m [Aug]; Jeff Davis Co. ● Ft. Davis [Jul] ● 16 km S Fort Davis (along TX 17), 30°27 ʹ 48 ʺ N 103°58 ʹ 59 ʺ W, 1600 m [Aug] ● Valentine [Jul] ● 13 mi E Valentine [Aug] ● ~ 16 km NE Valentine, Muerto Springs Ranch (Muerto Springs, near headquarters), 30°40 ʹ 28 ʺ N 104°24 ʹ 07 ʺ W, 1475 m [Jul] ● 8 km SE Fort Davis (via TX 118), Chihuahuan Desert Research Institute (Visitor Center area), 30°32 ʹ 32 ʺ N 103°50 ʹ 11 ʺ W, 1555 m [Aug] ● Chihuahuan Desert Research Institute (Quarry Unit), 30°32 ʹ 06 ʺ N 103°50 ʹ 37 ʺ W, 1480 m [Aug–Sep]; Pecos Co. ● 25 mi W Fort Stockton [Jul]; Motley Co. (no data) [May]; Presidio Co. ● C.E. Miller Ranch (~ 16 km W Valentine), 30°32 ʹ 50 ʺ N 104°39 ʹ 40 ʺ W (Camp Holland) 1410 m (Aug) ● ~ 16 km W Valentine (Miller Ranch, near headquarters), 30°33°30 ʺ N 104°38 ʹ 44 ʺ W, 1350 m [Jul–Aug] ● ~ 6.5 km W Marfa (Hip-O Ranch), 30°21 ʹ 54 ʺ N 104° 7 ʹ 12 ʺ W, 1530 m [Aug–Sep] ● Pinto Canyon Ranch (~ 58 km SSW Marfa on FM 2810), 30°01 ʹ 18 ʺ N 104°27 ʹ 42 ʺ W (headquarters area), 1475 m [Aug] ● Dalquest Research Site, 29°33 ʹ 30 ʺ N 103°47 ʹ 30 ʺ, 1010 m [Sep]; ● 37 km SSW Marfa (along FM 2810, Petan Ranch – Cherry Hills sector), 30°07 ʹ 35 ʺ N 104°19 ʹ 24 ʺ W, 1630 m [Jun] ● 20–26 km SSE Marfa (along FM 169), 1355–1415 m [Jun] ● 3 km NE Marfa (along FM 1112), Marfa Golf Course, 30°19 ʹ 40 ʺ N 103°59 ʹ 41 ʺ W, 1470 m [Jul, Sep] ● ~ 30 km SSE Marfa (along FM 169), Humphreys Ranch, 30°02 ʹ 30 ʺ N 104°01 ʹ 00 ʺ W, 1285 m [Jul] ● ~ 8km W La Viuda Peak, 29°42 ʹ 30 ʺ N 103°54 ʹ 30 ʺ, 1200 m [Sep] ● ~ 19 km E Marfa (via US 90/67), 30°16 ʹ 07 ʺ N 103°48 ʹ 44 ʺ W, 1565 m [Jul] ● ~ 3 km N Marfa (along TX 17), 30°20 ʹ 27 ʺ N 104°01 ʹ 7 ʺ W, 1500 m [Jul] ● near Plata ( FM 169/Alamito Creek bridge) Kennedy Ranch (headquarters), 29°52 ʹ 16 ʺ N 103°59 ʹ 28 ʺ W, 1200 m [Jun] ● Pinto Canyon Ranch (~ 65 km SSW Marfa on FM 2810), 29°59 ʹ 54 ʺ N 104°30 ʹ 48 ʺ W (Pinto Canyon Creek), 1460 m [Aug] ● 7 mi N Presidio [Oct] ● Big Bend Ranch State Park, La Cuesta Campground, 29.298° N 103.954° W [Aug] ● FM 170 (River Road) jct. Casa Piedra Rd., 8 mi NW Redford ● 2.5 mi S Shafter [Jun]; Terrell Co. ● Sheffield [Jun] ● ~ 15 mi W Sanderson, Hwy 90 at Longfellow Draw, 30°09.7 ʹ N 102°38.2 ʹ W, 3380 ft [Apr] ● Oasis Ranch, Independence Creek, 15 mi S Sheffield, 595 m, 30.4665° N 101.8008° W [May]; Tom Green Co. ● 12.8 km N San Angelo [Oct]; Ward Co. ● 1 mi SE Barstow [Jul].

Comments. Boreocanthon puncticollis is a common species in arid central Mexico and the southwestern United States as well the southern portion of the Baja Peninsula. It is sister species to B. integricollis (q.v.), with which it shares apically flanged parameres, strong (“crisp”) dorsal sculpturing, and tumid 2 nd and 3 rd elytral striae. The apical flanges of the parameres vary somewhat in shape ( Fig. 56–57 ), but the variation is subtle and appears continuous and taxonomically insignificant.

Besides its presence in the southern portion of the Baja California Peninsula, this species is widely distributed across the arid highlands (Altiplano) of Mexico between the Sierra Madre cordilleras flanking it on the east and west, from which it ranges into Arizona, New Mexico and the western portion of Texas. Whether or not the Baja California Sur distribution of B. puncticollis is truly disjunct from its distribution on the mainland remains an open question. My inclination is that it is, indeed, isolated as shown in Figure 63 . The northern portion of the Sonoran Desert (i.e., the Yuma Desert portion of the Sonoran Desert) appears to produce a collective void in the distribution of the genus. (See biogeographical comments in the Introduction.) In their analysis of dung beetle ecology in Mexican arid zones, Halffter et al. (2012) pointed out that “… only few species … range across the expansive arid zones [of Mexico]. These species are widely distributed and co-occur in the dry habitats of the northern Mexican Altiplano and southwest of the United States … Canthon (Boreocanthon) puncticollis is distributed in the desert zones of Baja California, Arizona and Chihuahua, arid zones of the Mexican Altiplano (even near Barranca de Metztitlán [Hidalgo], with a southern limit in Tehuacán [Puebla-Oaxaca].” I have seen several specimens of B. puncticollis from the Tehuacán–Cuicatlán desert region of Puebla / Oaxaca, Mexico, and suspect that this region marks the southernmost point of its distribution. I have seen a single specimen labeled Puente de Ixtla, Morelos, but its presence there needs confirmation.

Blume’s (1972) reference to B. puncticollis in Kerr and Bexar counties, Texas, is likely incorrect and should probably read B. integricollis . As far as I know, B. puncticollis does not occur as far east as the Edwards Plateau of central Texas. This species is commonly collected along with B. praticola throughout the Texas–New Mexico – Arizona portion of its range. As with most other congeners, this species is poorly known biologically. Edmonds (2016) reported it to be diurnal and a generalist feeder (cattle, human, and equine feces) inhabiting grassland and open scrub habitats in the Big Bend region of west Texas; M. J. Paulsen (pers, comm.) reported collecting it from burrows (probably a species of ground squirrel) in Hudspeth County, Texas. Lobo (1996) collected specimens in low numbers from cattle dung in various desert habitats at Mapimí Biosphere Reserve in northern Durango, Mexico, where the dung beetle fauna was overwhelmingly dominated by two introduced scarabaeines, Digitonthophagus gazella (Fabricius) an Euoniticellus intermedius (Reiche) (see Edmonds 2018).

LeConte’s (1866) original description of Canthon puncticollis was based on two specimens from “Cape San Lucas, Lower California.” The description is somewhat ambiguous in several respects, but the photographs of the syntype I have examined clearly show the salient features used here to diagnose this common species. Bates (1887) distinguished his species, Canthon nyctelius , from B. puncticollis by its having a “… remarkable depression at the base of the thorax and elytra, and the corresponding elevation of the second and third elytral interstices at their base.” Schaeffer (1915), in his argument supporting their synonymy, pointed out that B. puncticollis also shares this feature and noted that it was not clearly mentioned by LeConte (1866) in his description. Bates (1887) did not consider B. puncticollis in his work and probably did not have specimens on hand to compare with his species, prompting him to rely on LeConte’s description for comparison. In addition to the syntype cited above, there is another probable syntype also present in the LeConte Collection at the Museum of Comparative Zoology, Harvard University (Crystal Maier, pers. comm), and the two specimens are almost certainly LeConte’s original type series.

Robinson (1948) based his description of Canthon mixtus on three specimens. I was not able to examine the holotype, which resides in the USNM collection in Washington, D.C. However, I have examined the paratype referenced by Robinson from the Casselberry Collection, now deposited in the collection of the American Museum of Natural History. It lies well within the taxonomic limits I adopt here for B. puncticollis , which I here regard as senior synonym. My references ( Edmonds 2018) to Canthon mixtus in western Texas should now be taken as B. puncticollis .

Figures

Figure 63. Approximate distributions of Boreocanthon puncticollis (LeConte) and B. integricollis (Schaeffer).

Figures 54–62. Boreocanthon puncticollis (LeConte). 54) Habitus, dorsal view. 55) Habitus, frontal view. 56–57) Apical views of parameres. 58) Lateral view of genital capsule. 59) Dorsal view of mid-body (note triangular, posteromedian depression of pronotum and swelling of interstriae). 60) Ventral view of submentum and gula. 61) Oblique dorsal view of pronotum and elytron. 62) Comparison of unworn (above) and heavily worn (below) head margin (dorsal views).

Figures 1–2. 1) Approximate corporate distribution of the genus Boreocanthon. 2) Generalized depiction of vegetation biomes of the United States (Biome key in box; See Materials and Methods for explanation).