Melanocanthon vulturnus Edmonds, 2023

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 : 18-20

4. Melanocanthon vulturnus Edmonds , new species

Fig. 15–16 , 43–50

Type material. Holotype, male. Florida State Collection of Arthropods, Gainesville , Florida.

Type locality. Florida: Alachua Co. , near Gainesville Regional Airport ( GNV).

Diagnosis. Head: Evenly covered with coarse granulation ( Fig. 50 ); anterior portion usually lacking an array of larger, prominent punctures, which, if present, number fewer than 5. Pronotum: Densely covered by distinct granulation ( Fig. 43–44 ), granules elongate on disk, becoming more rounded peripherally, rarely accompanied by sparse punctures. Elytra: Interstriae bearing generally uniformly distributed, coarse granulation ( Fig. 46–47 ). Pygidium : Evenly, rather densely covered with coarse granules. Venter: Granulation seldom extending to venter, and then very weak with vestiges confined to anterior portion of metaventrite and 6 th abdominal ventrite. Legs: Metatarsus ( Fig. 45 ) slender, basitarsus usually longer than second tarsomere, length of apical tarsomere (excluding claws) greater than combined lengths of tarsomeres 3–4. Parameres: apical margins only weakly separated at middle, lower apical lobes small, rounded knobs ( Fig. 48–49 ). General: Black, head and pronotum often with dull, metallic green undertone ( Fig. 43 ). Length: 6–10 mm. Geographic distribution: Southern South Carolina and Georgia, Florida peninsula and Big Pine Key ( Fig. 15–16 ). Specimens examined: 231.

Notes on holotype and allotype: Holotype male; length 9.5 mm; aedeagus ( Fig. 48–49 ) removed and pointed; head and pronotum dull, metallic green; bears two labels, printed in black on white paper—(1) FLORIDA: Alachua Co. /nr Gainesville / Airport 14-vii-83/ M.C. Thomas / pitfall trap yeast; (2) Melanocanthon vulturnus Edmonds 2023 HOLOTYPE. Allotype female; length 9.0 mm, head and pronotum dull metallic green; bears two labels, printed in black on white paper—(1) same as holotype; (2) Melanocanthon vulturnus Edmonds 2023 PARATYPE [printed in blue]/ ALLOTYPE [handwritten in red]. Holotype and allotype are intact and very good condition with negligible wear and soiling, drawn from topotypic series of 13 individuals with same label data as holotype . Holotype and allotype are deposited in the Florida State Collection of Arthropods , Gainesville, Florida .

Distribution of remaining paratypes (by collection and number of specimens). Institutional collections: American Museum of Natural History [5]; California Academy of Sciences [3]; Canadian Museum of Nature [9]; Carnegie Museum of Natural History [8]; Clemson University Arthropod Collection [2]; Cornell University Insect Collection [2]; Enns Entomology Museum, University of Missouri [1]; Field Museum of Natural History [4]; Florida State Collection of Arthropods [128]; Georgia Museum of Natural History, University of Georgia [4]; Mississippi Entomological Museum [1]; Snow Entomological Collections, University of Kansas [22]; Texas A&M University Insect Collection [20]; University of Central Florida Collection of Arthropods [3]; University of Nebraska State Museum [5]. Private collections: Paul K. Lago, University, Mississippi [1]; Edward G. Riley, College Station, Texas [6]; Kyle E. Schnepp, Gainesville, Florida [5].

Etymology. Latin adjective vulturnus (masculine), meaning southeast (southeastern or southeasterly) in reference to distribution restricted to far southeastern United States.

Collection localities. UNITED STATES — FLORIDA: Alachua Co. • County Road 17B [Apr] • Gainesville [Feb, Apr–Oct] • 5mi W Hawthorn • Newmans Lake [Apr] • 9.5 mi N Alachua, Santa Fe River Ranch, Beef Unit [Oct] • 3.5 mi NE Gainesville [Jul] • 4 mi N High Springs [Mar] • High Springs, Oelfke Dairy • Co. Rd. 178, 0.4 mi S junction Co. Rd. 38 [Apr] • Archer [Apr]; • 2.5 mi SW Archer [Jul] • San Felasco Hammock [Jul]; Baker Co. • Glen St. Mary [Apr–May, Sep] • Trail Ridge; Citrus Co. • Inverness [Apr]; Clay Co. • 2 mi NE Gold Head Branch State Park [May]; Columbia Co. (no data); Dixie Co. • Old Town [May, Jul] • 4 mi N Old Town [May] • 10 mi N Old Town [Jul] • Suwannee [Jun]; Franklin Co. • St. Vincents Island [Jul]; Gilchrist Co. • 5 mi NNW Newberry, Watson Dairy [Apr, Oct]; Hernando Co. • Withalacoochee State Forest, Goat Road [May]; Highlands Co. • Archbold Biological Station, Lake Placid [Apr]; Hillsborough Co. • Lutz [Apr]; Jefferson Co. • Monticello [Aug] • Lamont [Jul]; Lafayette Co. • 5 mi E Mayo [May]; Lake Co. • Leesburg [May] • Tavares [Jan]; Lee Co. • Hwy. 41, 3.4 mi NW Koreshan [Apr]; Levy Co. • Cedar Key • 3.8 mi S Archer { Alachua Co. } [Mar, Jun]; Marion Co. • Ocala [Jul] • 14.3 mi E Ocala [Mar] • Romeo [Apr]; Monroe Co. • Big Pine Key, Key Deer Refuge, Watson Hammock [May–Jun, Aug]; Orange Co. • Orlando, Central Florida University campus [Jul] • Wekiwa Springs State Park [Apr, Aug]; Osceloa Co. • Disney Wilderness Preserve, 19 mi SE Kissimmee, 28.07° N 81.26° W [Jun]; Palm Beach Co. • Jupiter [Apr]; Putnam Co. • Red Water Lake [Jun]; Sarasota Co. • Sarasota [Apr]; Suwannee Co. • Suwannee Springs [Jul]; Taylor Co. • Blue Springs Lake [Jun]. GEORGIA: Charlton Co. • Okefenokee Swamp [Jul–Sep]; Clinch Co. • Fargo [Sep]; Early Co. (no data); Glynn Co. • Brunswick [Jun–Jul]; Johnson Co. • 0.5 mi E Kite [Oct]; Liberty Co. • Fort Stewart [Jun]; Lowndes Co. (no data); McIntosh Co. • Harris Neck National Wildlife Refuge [Aug]; Thomas Co. (no data); Tift Co. (no data). SOUTH CAROLINA: Aiken Co. • Savannah River Site [Jun].

Comments. Woodruff (1973) treated this new species as M. granulifer , with some reservation (p. 45): “I have seen only a few specimens from Texas (type locality), and they seem to differ slightly from those from Florida. Further study of additional material will be necessary to determine if the two disjunct populations are distinct.” I have no reservation about regarding these Florida populations as a separate, but closely related species to M. granulifer , but the structural differences between the two are as much in degree as in substance. The pronotal granulation of M. vulturnus is equally dense but finer in texture than of its Texas relative. They lack the generous array of conspicuously large clypeal punctures characteristic of M. granulifer , or at most present only very few. The shape of the lower apical lobes of the parameres of M. vulturnus never approaches the robust, spoon shape characteristic of M. granulifer . Moreover, while the head and pronotum of the new species are often have a dark metallic green undertone, M. granulifer is always dull black. At first glance, distinctly green specimens resemble Boreocanthon depressipennis , and occasional specimens in collections are so labeled. Differences in metatarsal structure are ordinarily distinct on close examination, but they can also be subtle. By far the most distinctive feature of M. vulturnus is its southeastern US distribution far from that of M. granulifer , roughly 1000 miles due west in Texas.

The range of M. vulturnus is overlapped by those of M. punctaticollis and M. bispinatus . From the former species it is reliably separated by head and pronotal sculpturing. In reference to M. bispinatus, Woodruff (1973) observed in his diagnosis of “ granulifer ” (p. 45): “.. this species [ vulturnus ] is … often difficult to separate from bispinatus without comparative material. In general, everywhere the granules are more dense and with greater relief … Punctures of head and pronotum, although perhaps no less numerous, [are] not as noticeable because of the density of the granules.” To Woodruff ’s observation I add the obvious difference in the form of the lower apical lobes of the parameres (cf. Fig. 49 , 56 ) and that M. vulturnus often presents a rather strong green color on the head and pronotum. The distributional picture of these three closely related species begs the question of habitat, behavioral and life cycle attributes that might promote their co-existence at a local scale.

Robinson’s (1948) reference to M. granulifer from Romeo (Marion Co.), Florida (cited by Gordon and Cartwright 1974), probably refers to M. vulturnus . Kaufman and Wood (2012) referenced M. vulturnus (also cited as M. granulifer ) among the uncommon members of the very diverse cattle pasture fauna in Alachua County , Florida. Fincher (1975) reported this species (also as M. granulifer ) on Blackbeard Island, McIntosh County, Georgia, where the much commoner M. bispinatus outnumbered it 30:1. Miller’s (1954) report of M. granulifer in Ware Co., Georgia, is undoubtedly also referable to M. vulturnus . Label data I have indicate its attraction to human, cattle, snake, and pig dung, snake carrion (decomposed cottonmouth, Agkistrodon piscivorus [Lacépède]), fungi and rotting fruit.

Peck and Howden (1985) were first to report M. vulturnus on Big Pine Key, although they listed it as M. bispinatus . A voucher specimen collected by Peck in the collection of the Canadian Museum of Nature confirms its new identity. I have also seen specimens collected on Big Pine Key by Kyle Schnepp and by Ed and Tom Riley. I have no records of M. bispinatus south of the Florida flatwoods ecoregions (i.e., roughly south of Highlands County). As suggested by Peck and Howden, the Big Pine population is a relic enclave isolated from the mainland during the post-glacial rise in sea level that formed the Florida Key archipelago within the last 10,000 years. Before that time, the archipelago was a corridor of land continuous with the peninsula ( Neill 1957). Once isolation of the keys was underway, and the terrain of the southern tip of the peninsula became permeated by waterways and lakes, intervening populations became extinct, and a previously continuous range of M. vulturnus became the naturally disjunct one it is today, a disjunction also seen in many other organisms ( Neill 1957). The known Florida Keys scarabaeine fauna includes ten species, all of which also occur on mainland Florida ( Woodruff 1973; Peck and Howden 1985). As reported by Peck and Howden, of these ten, Pseudocanthon perplexus (LeConte) occupied the most islands (11 of 19 sampled keys). Of the 19 keys sampled, Big Pine Key had the most diverse fauna (8 of 10 species known from the keys). Of the eight scarabaeine species known from Big Pine Key, Melanocanthon vulturnus was the only one confined to that island.

Figures

Figure 15. Approximate distributions of species of Melanocanthon.

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 43–50. Melanocanthon vulturnus, new species. 43) Dorsal view of pronotum. 44) Same, augmented to emphasize granulation. 45) Lateral view of metatarsus. 46) Dorsal view of left elytron. 47) Dorsal view of interstriae 1–6. 48) Lateral view of aedeagus. 49) Apical view of parameres. 50) Frontal view of head.

Figures 51–58. Melanocanthon bispinatus (Robinson).51) Dorsal view of head.52) Dorsal view of pronotum. 53) Dorsal view pronotal disk. 54) Dorsal view of left elytron. 55) Lateral view of metatarsus. 56) Oblique lateral view parameres. 57) Apical view of parameres (arrow indicates oval gap). 58) Lateral view parameres.