Melanocanthon granulifer ( Schmidt, 1920 )

Edmonds, W. D., 2023, Taxonomic review of the North American dung beetle genus Melanocanthon Halffter, 1958 (Coleoptera: Scarabaeidae: Scarabaeinae: Deltochilini), Insecta Mundi 2023 (14), pp. 1-28 : 10-13

2. Melanocanthon granulifer ( Schmidt, 1920)

Fig. 3–8 , 15 , 17 , 27–33

Canthon granulifer Schmidt 1920: 126 .

Melanocanthon granulifer (Schmidt) (new combination per Halffter 1958: 211).

Type material. Syntype male (labeled “Typus”, SMNH 9678 E92) and syntype female (labeled “Type/ Allotypus ”, SMNH 9678 93), Swedish Museum of Natural History, Stockholm. Examined by proxy (see Comments below). Syntype male (labeled “ Syntypus ”, DEI Müncheberg Col – 07658), Senckenberg Deutsches Entomologisches Institut, Müncheberg, Germany. Examined by photograph in Vaz-de-Mello and Cupello (2018).

Type locality. Texas.

Diagnosis. Head: Dorsum boldly granulate on shagreen background ( Fig. 27 ) with interspersed, very small punctures; granules rounded, numerous, evenly distributed, rarely sparse; shiny microspots lacking. Clypeus bearing loose, transverse array of 5–15 conspicuous, large, flat punctures just behind clypeal teeth ( Fig. 27 ). Pronotum: Completely, evenly covered by prominent granules on shagreen background ( Fig. 28–29 ), sometimes with (50×) minute, interspersed punctures on sides and anterior angles; granules elongated on disk, becoming more rounded laterally. Elytra: Completely, usually evenly and densely covered by round granules on shagreen background with occasional micropunctures ( Fig. 28 ); granules arranged in poorly organized, longitudinal rows, generally uniform in size and density over surface. Pygidium : Evenly, coarsely granulate. Venter: Granulation weaker than on dorsum, extending to pteropleura, lateral portions of metaventrite and abdominal sternites ( Fig. 30 ); central portion of metaventrite completely, evenly and conspicuously punctured, usually lacking distinct granulation except for weakly rugose area behind mesosternite. Legs: Metatarsus ( Fig. 33 ) wide, lengths of tarsomeres 1–4 about equal to width at apex; length of apical tarsomere (excluding claws) about equal to combined lengths of tarsomeres 3–4. Parameres: Ventral apical lobes flattened, ovoid (spoon-shaped) tabs ( Fig. 32 ); apical margins usually strongly curved outward at middle, creating wide, oval gap. General: Length 5.5–10 mm. Geographic distribution: Central Texas ( Fig. 15 , 17 ). Specimens examined: 303.

Collection localities. UNITED STATES — TEXAS: Bexar Co. • San Antonio, 29.48708, −98.69572 [May] ; Blanco Co. • Pedernales State Park , 30.33° N 98.25° W [Oct] ; Briscoe Co. • Quitaque [Jun] ; Brown Co. • 6.6 mi km SE Brownwood, Camp Bowie National Guard, 31.628° N 98.906° W [Jun – Jul] ; Comal Co. • Bulverde [Apr] • Landa Park [Nov] ; Crockett Co. • Ozona [Jun] ; Dickens Co. • White River Reservoir [May – Jun] ; Hays Co. • 6

mi NW Dripping Springs, 30°13.589′ N 98° 11.096′ W, 30°13.554′ N 98° 11.039′ W, 1340 ft [Jun]; Kendall Co. • Boerne [Apr] • Sisterdale [Jul] • Cave Without a Name [Jul] ; Kerr Co. • Kerrville [May] ; Kimble Co. • I-10 at N. Llano River , 4.2 mi NW Junction [Jun] ; • Junction , Texas Tech University Center [Apr–May] • 2 mi S Junction [May] ; McColloch Co. • 2 mi SE Brady [Sep] ; Menard Co. • 30 mi W Menard [Jul] ; Parker Co. • Dennis ; Pecos Co. • 5 mi W Sheffield [Jun] ; Real Co. • 27 mi N Leakey [Oct] ; Runnels Co. • 4 mi N Ballinger [Jun] ; Sutton Co. • Sonora [Oct] ; Terrell Co. • 15 mi S Sheffield , Oasis Ranch, 30.4665° N 101.8008° W ; Tom Green Co. • Christoval [Jun] ; Travis Co. • Austin, 30.312° N 97.808° W [May, Oct] ; Uvalde Co. (no data) [May] ; Val Verde Co. • 23.6 mi N Comstock [Jun] • Devils River Preserve, Texas Nature Conservancy, Dolan Falls [Feb, Apr–Jun] .

Comments. Vaz de Mello and Cupello (2018) recorded three syntypes of Schmidt’s species, one in Munich and two in Stockholm. Mattias Forshage of the Swedish Museum of Natural History has very kindly compared photographs provided by me with the two Schmidt syntypes under his care; thanks to his efforts, I am confident that the name M. granulifer is used here in the exact sense of its describer.

This species has previously been cited from Florida ( Robinson 1948; Woodruff 1973; Gordon and Cartwright 1974; Kaufman and Wood 2012). These references likely refer to the new species, Melanocanthon vulturnus , described below.

The distribution of M. granulifer is evidently largely restricted to the oak-juniper scrub habitat common to the Edwards Plateau of central Texas. This area is sometimes recognized as the Balconian Biotic Province, one of the principal bioregions of the state ( Smith and Buechner 1947; Blair 1950). The granulation characteristic of this species varies little in texture and density. I have noted only one instance (in a population from Dickens Co.) of pronotal sculpturing with distinct punctures in addition to granules.

Biological data on the habits of M. granulifer are scarce. The few records I have include cattle and human dung as well as one instance of attraction to dead land snails in Bexar Co. It is the only species of the genus lacking any record of association with fungi.

Figures

Figure 15. Approximate distributions of species of Melanocanthon.

Figures 1–8. Generic features of Melanocanthon. 1) M. bispinatus (Robinson) habitus in vivo, New Hanover County, North Carolina. 2) M. nigricornis, habitus in vivo, Lake County, Illinois. 3) M. granulifer (Schmidt), right protibia-tarsus of male. 4) Same, frontal view middle portion clypeus (square encloses area magnified in Figure 5). 5) Same, spiniform clypeal process. 6) Same, shape of clypeal process modified by wear. 7) Same, lateral view of portion of head and prothorax. 8) Same, ventral view of head (arrow indicates labio-gular fimbria).

Figures 16–19. Distributions of Melanocanthon species. 16) By-county distributions of M. vulturnus and M. punctaticollis. 17) Same, M. granulifer and M. nigricornis. 18) Same, M. bispinatus. 19) Central United States, rectangle demarcates area of potential sympatry between M. bispinatus and M. nigricornis (see text for explanation).

Figures 27–33. Melanocanthon granulifer (Schmidt). 27) Dorsal view of head. 28) Dorsal view of left elytron. 29) Dorsal view of pronotum. 30) Lateral view of midbody. 31) Lateral view of parameres. 32) Apical view of parameres. 33) Lateral view of metatarsus.