Boreocanthon melanus ( Robinson, 1948 )

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 : 58-60

Boreocanthon melanus ( Robinson, 1948) , restored generic combination.

Fig. 45 , 110–119

Canthon melanus Robinson 1948: 88 .

Boreocanthon melanus (Robinson) (new combination per Halffter 1958: 209).

Canthon (Boreocanthon) melanus Robinson (new combination per Howden 1966: 727).

Boreocanthon melanus Robinson , restored generic combination.

Type. Syntype (sex undetermined). National Museum of Natural History, Washington, D.C. Not examined.

Type locality: Arizona, base of Pinal Mts.

Diagnosis. Head: Clypeus ( Fig. 112 ) lightly roughened, weakly glistening anteriorly; bearing four strong marginal teeth; posteriorly, along with remainder of head, densely alutaceous, conspicuously punctate. Paraocular notch small, setting off small, angulate corner of paraocular area. Labio-gular fimbria ( Fig. 117 ) curved posteriorly, followed medially by V-shaped field of coarse, setose punctures. Prothorax: Pronotum evenly punctate on shagreen background ( Fig. 110, 118 ); anterolateral angles at most only very weakly upturned, posteromedian angle not noticeably impressed. Circumnotal ridge smooth, not serrate posteriorly. Hypomeral carina usually present, curving laterad to point one-eighth to one-fourth distance to outer margin (as in Fig. 108 ). Pterothorax: Mesoventrite smooth; metaventrite evenly, sharply punctate. Elytra: Striae ( Fig. 115 ) lacking carinulate margins. Interstriae densely alutaceous, weakly microspotted; anterior ends of interstriae 2 and 3 weakly swollen ( Fig.110– 111, 118 ), interstriae 3 and 5 with minute, acute tubercle in middle of anterior margin. Subhumeral (8 th) stria carinulate, usually strongly so ( Fig. 115 ); epipleural (9 th) stria effaced. Legs: Protibia evenly dilated, inner margin not offset; apical spur sexually dimorphic, apically acute in female ( Fig. 116a ), bifurcate in male ( Fig. 116b ). Hind femora lacking anterior row of longer setae, distal end bearing several conspicuous setae. Abdomen: Pygidium ( Fig. 119 ) weakly punctured, apex sometimes distinctly more convex and shinier than remainder of surface. Sixth ventrite punctate medially; other ventrites smooth. Genital capsule: Laterally compressed distal portion of parameres shortened, truncate (“snub nosed”), almost right-angled ( Fig. 113 ); ventral apical angles in form of rounded knobs ( Fig. 114 ). General: Black, sometimes with green or blue highlights. Length: 4.0 – 6.5 mm. Geographic distribution ( Fig. 45 ): Southern Arizona and northern Sonora, Mexico. Ecogeographic environment ( Fig. 2 ): Deserts and Xeric Shrublands biome (Sonoran Desert ecoregion). Specimens examined: 645.

Collection localities.

MEXICO — CHIHUAHUA: Mpio. Janos ● Colonia Dublán ● 45 mi N Casas Grandes. SONORA: Mpio. Alamos ● Alamos [Feb]; Mpio. Altar ● Llano Blanco [Jul]; Mpio. Agua Prieta ● 10 mi SE Agua Prieta [Sep] ● 15 mi SW Agua Prieta [Aug]; Mpio. Hermosillo ● Hermosillo [Sep]; Mpio. Naco ● Naco, 5000 ft [Aug]; Mpio. Santa Ana ● 6 mi S Benjamin Hill [Aug] ● 4mi, 17 mi S Santa Ana [Aug].

UNITED STATES — ARIZONA: Cochise Co. ● Dragoon [Aug] ● 12 mi NE Douglas [Aug] ● Palominas [Aug] ● Tombstone [Aug] ● 6 mi E Tombstone [Aug] ● Texas Pass (hwy I-10) [Aug] ● 1 mi E Douglas [Aug] ● Apache , 5000 ft [Aug] ● Douglas [Jul-Aug] ● 12 mi E Douglas [Aug] ● 28 mi E Douglas, Guadalupe Canyon [Jul, Sep] ● Sierra Vista [Aug] ● Sunsites [Jul] ● 5 mi SW Portal, Southwest Research Station [Jul, Sep] ● Willcox Dry Lake [Jul-Sep] ● San Pedro Riparian National Conservation Area [Oct] ● Coronado National Forest, Parker Canyon, 4800 ft [Sep] ● Courtland [Jul] ● Gleeson [Jul] ● Chiricahua Mountains, El Dorado, 5600 ft [Aug]; Gila Co. ● Globe [May]; Graham Co. ● Gila Valley /Safford [Aug]; Maricopa Co. ● Seven Springs Camp [Jun] ● El Dorado [Jul]; Pima Co. ● Hwy 89, 1 mi W Continental [Sep] ● 11 mi E Continental [Sep] ● 2 mi N Continental, 932 m, 31°50 ʹ 19 ʺ N 110°56 ʹ 56 ʺ W [May] ● Tumacacori [Aug] ● Rio Rico [Jul] ● Santa Rita Mountains, Madera Canyon , 16 km SE Green Valley, 4454 ft [Aug] ● Arivaca [Sep] ● Proctor Ranch, Madera Canyon [Jul] ● Green Valley [SepOct] ● Jct. Hwy 86 and 386, entrance to Kitt Peak National Observatory [Sep] ● Hwy 286, 8 mi S. Three Points [Aug] ● Tucson [Aug-Sep]; Santa Cruz Co. ● Pajarito Mountains, Peña Blanca Canyon [Aug] ● Amado [Jul] ● 7 mi E Sonoita [Aug] ● 2.5 mi E Lochiel [Sep] ● Peña Blanca Lake [Jul] ● Duquesne Road, 2 mi E jct. Hwy 82 [Aug] ● 4 mi N Nogales [Jul] ● 10 mi NE Nogales [Jul] ● Nogales [Aug-Sep] ● Patagonia [Aug-Sep] ● 10 mi W Patagonia ● Box Canyon , Santa Rita Mts. [Aug]; Yavapai Co. ● Yarnell [Sep] ● 20 mi W Prescott [Aug].

Comments. Boreocanthon melanus is a common species south of the Colorado Plateau in southern Arizona, where it is sympatric with B. puncticollis and, less frequently, B. simplex . Its range extends to southern Sonora, where it apparently contacts its sister species, B. forreri (q.v.). There is a specimen in the Snow Entomological Collection (University of Kansas) labeled “S. Fe Canon [sic] 7000ft Aug 1880 (Snow)” presumably from F. H. Snow’s trip to area in the summer of 1880; it is not referenced in Snow’s report on the trip ( Snow 1880). It, like a similar record for B. simplex (q.v.), I regard as a labeling error.

Label data record Boreocanthon melanus from human and cattle excrement. William Warner (pers. comm.) has collected it at blacklight and in flight intercept traps.

Figures

Figure 45. Approximate distributions of Boreocanthon melanus (Robinson), B. forreri (Bates) and B. ateuchiceps (Bates).

Figures 110–119. Boreocanthon melanus (Robinson). 110) Habitus, dorsal view. 111) Habitus, oblique dorsolateral view. 112) Dorsal view of head. 113) Lateral view of genital capsule. 114) Apical view of parameres. 115) Dorsolateral view of lateral striae. 116) Apex of protibia and tarsus. a) Female. b) Male. 117) Ventral view of submentum and gula. 118) Dorsal view of pronotum and elytra. 119) Posterior view of pygidium.

Figures 102–109. Boreocanthon forreri (Bates). 102) Habitus, dorsal view. 103) Anterolateral view of forebody. 104) Anterior view right male tibia. 105) Dorsolateral view of pronotum. 106) Dorsal view of head. 107) Laterodorsal view of pronotum and elytra.108) Ventral view of right hypomeron (arrow indicates hypomeral carina). 109) Lateral view of humeral region.

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).