Boreocanthon forreri ( Bates, 1887 )

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 : 56-58

Boreocanthon forreri ( Bates, 1887) , restored generic combination

Fig. 45 , 102–109

Canthon forreri Bates 1887: 31 .

Boreocanthon forreri (Bates) (new combination per Halffter 1961: 234).

Canthon (Boreocanthon) forreri Bates (new combination per Howden 1966: 727).

Boreocanthon forreri Bates , restored generic combination.

Type material. Syntype (sex undetermined), The Natural History Museum London. Examined by photograph courtesy of Fernando Vaz-de-Mello.

Type locality. Mexico, Presidio (see Comments below)

Diagnosis. Head: Clypeus ( Fig. 106 ) lightly roughened, weakly glistening anteriorly; bearing four marginal teeth; posteriorly, along with remainder of head, densely alutaceous, conspicuously punctate. Paraocular notch slight, setting off small, angulate corner of paraocular area ( Fig. 106 ). Labio-gular fimbria curved posteriorly, interrupted medially by short V-shaped extension bearing coarse, setose punctures (as in Fig. 117 ). Prothorax: Pronotum ( Fig. 102–103, 105 ) rather boldly, evenly punctate on weakly alutaceous background; anterolateral angles at most only very weakly upturned, posteromedian angle not noticeably impressed. Circumnotal ridge smooth, not serrate posteriorly. Hypomeral carina ( Fig. 108 ) usually present, curving laterad to point one-eighth to one-fourth distance to outer margin. Pterothorax: Mesoventrite smooth; metaventrite evenly, sharply punctate. Elytra: Striae ( Fig. 107, 109 ) lacking crisp margins ( Fig. 107 ). Umbone distinctly shinier than disk (Fig, 109). Interstriae densely alutaceous, weakly microspotted; anterior ends of interstriae 2 and 3 not swollen, interstriae 3 and 5 with minute, acute tubercle in middle of anterior margin. Subhumeral (8 th) stria carinulate basally, usually strongly so ( Fig. 109 ); epipleural (9 th) stria often visible, occasionally carinulate. Legs: Protibia ( Fig. 104 ) evenly dilated, inner margin not offset; apical spur sexually dimorphic, apex acute in female, bifurcate in male. Hind femora lacking anterior row of longer setae, distal end bearing several conspicuous setae. Abdomen: Pygidium weakly punctured (as in Fig. 119 ), apex sometimes distinctly more convex and shinier than remainder of surface. Sixth ventrite punctate medially; other sternites smooth, impunctate. Genital capsule: Laterally compressed distal portion of parameres shortened, truncate (“snub nosed”), almost right-angled (as in Fig. 113 ); ventral apical angles in form of rounded knob (as in Fig. 114 ). General: Pronotum dark, shiny green, yellow-green or coppery, elytra and pygidium darker than pronotum with less pronounced color. Length: 4.5 – 6.0 mm. Geographic distribution ( Fig. 45 ): NW coast of Mexico from Sonora to Nayarit. Ecogeographic environment: Tropical and Subtropical Dry Broadleaf Forests biome (Sonoran-Sinaloan Subtropical Dry Forest and Sinaloan Dry Forest ecoregions). Specimens examined: 88.

Collection localities.

MEXICO — NAYARIT: Mpio. Del Nayar ● Jesus Maria [Jun-Jul] . SINALOA: Mpio. Culiacan ● Altata [JulAug] 14 mi N Culiacan [Aug] ; Mpio. Salvador Alvarado ● 11mi S Guamúchil [Aug] ; Mpio. San Ignacio ● Rio Piaxtla , 1 mi W Hwy 15 . SONORA: Mpio. Alamos ● Alamos [Jul-Aug] ● 2 mi E Alamos ● La Aduana [Sep] ; Mpio. Etchojoa ● Rio Mayo [Aug] ; Mpio. Huatabampo ● 53 mi S Navojoa [Jul] ; Mpio. Navojoa ● Bacabachi [Sept] ● Tesopaco [Sep] ● 5 mi E Navojoa [Aug] ● 3 mi N Navojoa [Aug] ; Mpio. Santa Ana ● 6 mi S Benjamin Hill [Aug] ● 11 mi S Benjamin Hill [Sep] ; Mpio. Ures ● 30 mi E Ures, 2700 ft [Aug] .

Comments. The stated type locality of B. forreri is “ Mexico, Presidio,” which Selander and Vaurie (1962) identified as either the river, Rio Presidio, or the small village of Presidio east of Mazatlán, Sinaloa. Bates’ specimens were collected in “N.W. Mexico ” by Alphonse Forrer, one of the collectors who supplied material for the production of Biologia Centrali-Americana ( Godman 1915). Besides work on the mainland, Forrer also collected on Islas Tres Marias, offshore from the small port of San Blas, Nayarit, which, like Mazatlán, could have been a point of embarkation to the islands. This port is close to another possible candidate for type locality, Presidio de los Reyes, a small town in Ruíz Municipality, Nayarit, about 65 km to the northeast. For present purposes, the choice remains moot as both “Presidios” are clearly within the range of forreri as considered here.

I regard this species as sister to B. melanus . Except for color, they are very similar and apparently overlap along the far northern coast of Sonora. Specimens assignable to both species occur in the area of Alamos, Sonora, begging the question of conspecificity, but I have not seen enough material from southern Sonora that I would want to resolve the question. Whether regarded as distinct species or not, the twosome comprises a distinct taxonomic entity.

I know nothing about the biology of B. forreri other than one record on fox excrement and another at blacklight.

Figures

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

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 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.