Boreocanthon integricollis ( Schaeffer, 1915 )

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 : 38-40

Boreocanthon integricollis ( Schaeffer, 1915) , restored generic combination

Fig. 63–71

Canthon puncticollis var. integricollis Schaeffer 1915: 50 .

Canthon integricollis Schaeffer (new status per Robinson 1948: 90).

Boreocanthon integricollis (Schaeffer) (new combination per Halffter 1958: 210).

Canthon (Boreocanthon) integricollis Schaeffer (new combination per Howden 1966: 727).

Boreocanthon integricollis (Schaeffer) , restored generic combination.

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

Type localities. Hidalgo and Brownsville , Texas; Santa Rita Mountains , Arizona (see Comments below).

Diagnosis. Head: Margin strongly sexdentate ( Fig. 66 ), anterior one-half of clypeus rugose and moderately shiny; remainder of head surface flat, with fine, shallow punctures on dense shagreen. Paraocular notch strong, setting off angulate, anteriorly-directed, toothlike angle of paraocular area. Middle clypeal teeth narrowly rounded apically, separated by rounded, V-shaped emargination; lateral teeth strong, rounded apically. Labio-gular fimbria ( Fig. 69 ) gently curved posteriorly, often interrupted medially by coarse punctures. Prothorax: Pronotum ( Fig. 65, 71 ) covered by dense shagreen, punctured, punctures scattered, somewhat larger, deeper than those on head, microspots numerous; anterior angles weakly, narrowly reflexed; posteromedian angle at most only slightly impressed. Hypomeral carina vestigial. Pterothorax: Mesoventrite ( Fig. 70 ) densely, coarsely punctured. Metaventrite ( Fig. 70 ) with widely spaced, small punctures on dense shagreen. Elytra: Interstriae ( Fig. 64, 67, 71 ) with dense shagreen and numerous microspots; anterior ends of 2 nd and 3 rd usually only weakly raised, 1 st interstriae depressed. Striae well delineated, with sharp, carinulate lateral margins, especially anteriorly. Subhumeral (8 th) stria sharply carinate basally; epipleural (9 th) stria almost always visible at least posteriorly. Legs: Inner margin of protibia straight or only very gently curved; protibial spur sexually dimorphic, apex acute in female, bifurcate in male. Metafemora lacking row of long setae along anterior surface; ventral surface punctured, with few short setae. Abdomen: Pygidium weakly punctate, with dense shagreen; apex weakly tumid, shinier than base. Sixth ventrite punctured; remaining ventrites with dense shagreen, lacking distinct punctures. Genital capsule: Compressed apical portion of parameres narrowly triangular ( Fig. 68b ); lower apical angles in form of elongate flanges ( Fig. 68a ). General: Black, dull, sometimes with weak blue highlights. Length: 4.0 – 5.5 mm. Geographic distribution: Endemic to south Texas and adjacent Mexico along the Rio Grande ( Fig. 63 ). Ecogeographic environment: Xeric Shrublands and Tropical Grassland biomes (Western Gulf coastal grasslands, Tamaulipan mezquital and Tamaulipan matorral ecoregions). Specimens examined: 55.

Collection localities.

MEXICO — NUEVO LEON: Mpio. San Nicolás de los Garza ● San Nicolás de los Garza [Sep].

UNITED STATES — TEXAS: Bastrop Co. ● Bastrop [Apr] ● 6 mi N Bastrop, Camp Swift [Nov]; Cameron Co. ● 7.4 mi ENE jct. hwys 48 & 511 [Aug] ● Laguna Atascosa National Wildlife Refuge [Oct]; Dimmit Co. ● Chaparral Wildlife Management Area [Mar-May]; Duval Co. ● 2.2 mi W Freer [Sep] ● 5 mi S Realitos [Mar]; Frio Co. ● US Hwy. 57, 20.6 mi W route I-35 [Apr]; Hidalgo Co. ● Santa Ana National Wildlife Refuge [Oct] ● Las Palomas Wildlife Management Area (Penitas Unit) [Apr]; ● Bentsen-Rio Grande Valley State Park [May]; Jim Wells Co. ● Ben Bolt [Jun]; Lee Co. ● Fedor [May]; Kleberg Co. ● Kingsville [Sep]; La Salle Co. ● Chaparral Wildlife Management Area, 8 mi W Artesia Wells [Oct]; Live Oak Co. ● 8 and 12 mi S George West [May]; McMullen Co. ● 20 mi N Freer (Duval Co.) [Oct]; Starr Co. ● 6 mi S La Gloria [Jun] ● Falcon Woodlands, Falcon Dam [Apr] ● Falcon State Park, 26°35.22 ʹ N 99°08.82 ʹ W, 270 ft [Oct]; Uvalde Co. ● 7 mi W Uvalde [Jun]; Webb Co. ● 16 mi NW Freer [Aug].

Comments. Schaeffer (1915) included specimens from the Santa Rita Mountains ( Santa Cruz Co. , Arizona) in his type series of “ var. integricollis ”, which he distinguished from B. puncticollis by its lack of a mid-dorsal depression at the base of the elytra. I have not seen these specimens, but I suspect that they are assignable to Boreocanthon melanus , which occurs along with “good” B. puncticollis in the Santa Rita Mountains region. In any case, future designation of a lectotype from Schaeffer’s syntypic series is in order to fix the species name to the concept of Boreocanthon integricollis presented here. I have seen two specimens from Hidalgo, Texas, from the Charles Schaeffer Collection currently housed at the California Academy of Science, which are definitely B. integricollis as defined here and possible syntypes.

I regard B. integricollis and B. puncticollis (q.v.) as sister species The former can be confused with B. probus , with which it can occur in scattered localities in southern Texas. Both have the head margin strongly sexdentate and an often shiny anterior portion of the clypeus, but they are clearly distinguished by pronotal and mesoventrite sculpturing and shape of the apical angles of the parameres. I have seen but one specimen from Mexico, from the environs of the city Monterrey about 125 miles south of Laredo, Texas; I would expect it to occur throughout northern Nuevo Leon and adjacent Tamaulipas. The biology of this species is essentially unknown. I have one rather tantalizing record of its capture in Cameron County , Texas, in a Berlese funnel at a pack rat nest.

Figures

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

Figures 64–71. Boreocanthon integricollis (Schaeffer). 64) Habitus, dorsal view. 65) Habitus, anterodorsal view. 66) Dorsal view of head. 67) Dorsal view of mid-body. 68) Genital capsule. a) Lateral view. b) Apices of parameres. 69) Ventral view of labium and gula. 70) Ventral view meso- and metaventrites. 71) Dorsolateral view of pronotum and elytron.