Explanation of Names
Author of genus is
Fabricius, 1775. Possibly related to Latin (from Greek?)
scarus, a type of fish, the
Mediterranean Parrotfish, Sparasoma cretensis (prominent jaws, like the beetle?). Alternatively, possibly related to Latin
scariosus, meaning, in botany, dry and membranous
(2), (Internet searches). Blatchley
(3) says that
Scarites is from Latin, meaning scratched, but the words for "scratched" have an "f" (or ph in the Greek equivalents). One more possible root is Greek,
scari(s), meaning "a little worm"
(2)Identification
The two most widespread members, Scarites subterraneus and S. vicinus, are shiny black ground beetles with large mandibles, head with two large depressions, elytra grooved and separated from a smooth pronotum by a narrow "waist" (peduncle). Besides differences in antennomere shape as noted in the taxonomic key below, these two species can usually be distinguished by size: most subterraneus body length < 21 mm and elytron < 10 mm compared to most vicinus body length > 21 mm and elytron > 10 mm. Elytron length is the more reliable separator. Earlier reported distinctions based on various external morphologies (protibial denticles, mandibles, body proportions) are unstable and therefore unreliable. Assessment of antennomere shape is unfortunately not reliable in most BugGuide photographs which usually do not capture the required perpendicular viewing angle of the broad faces of the antennomeres. An oblique angle will make the antennomeres appear artificially more elongated.
Determining sex
Distinguishing sex externally in Scarites is difficult as the protarsi appear the same in both sexes. Lindroth (1961) observed that in S. subterraneus the females show four setae-bearing punctures equally spaced along posterior border of last sternite while in males the two median punctures are somewhat more widely spaced. More reliable sex separators follow.
Naturally exposed apical portions of the genitalia in females (a symmetrical pair of small dark styli) and in males (a single median lobe bearing to the left) are rarely observed in specimens of Scarites. However, it is possible to quickly determine the sex by gently probing for the more superficial genital sternites (ventral) and genital tergites (dorsal) located in the apical openings of relaxed abdomens. The female genital sternite is a plate split symmetrically down the middle with the adjacent apices right angled. The female genital tergite is thick and darkly scleritized. The male genital sternite is asymmetrically split with well-rounded apices (left most rounded) and with the left plate somewhat overlapping beneath the right plate. The male genital tergite is thin and pale.
Other ground beetle genera show similar sexual differences in apically exposed genitalia, genital sternite, and genital tergite.
KEY TO NORTH AMERICAN (NORTH OF MEXICO) SPECIES OF SCARITES
The following is a key after Bousquet & Skelley (2010) and Nichols (1986) with consolidations/modifications by Peter W. Messer (page version 2011.I.8). This provisonal taxonomy of North American Scarites awaits refinement from future morphological scrutiny and DNA sequence analysis. Currently the most challenging species separation is between S. quadriceps and recently resurrected S. vicinus in the quadriceps group. Abbreviations: ABL = apparent body length (mandible tip to elytron apex); LE = elytron length; LMs/LMc = ratio of metasternum length to metacoxa length through same line as defined by Bousquet.
1. Antennomeres 8–10 longer than wide (length/width of 10th antennomere = 1.1–1.3) with segments 5–7 usually more elongated (filiform). ABL at least 21 mm (LE at least 10 mm) with small variants in regions west of Mississippi River ==> 2 [quadriceps group]
– Antennomeres 8–10 wider than long or subquadrate (length/width of 10th antennomere = 0.8–1.0), without obvious further elongation of segments 5–7 (moniliform). ABL < 21 mm (LE < 10 mm) ==> 3 [subterraneus group]
–– QUADRICEPS GROUP ––
2. Metasternum visibly same length compared to that of metacoxa (LMs/LMc = 0.98–1.02). Common and widespread throughout North America, replacing many northern specimens previously labeled "S. quadriceps" ==> S. vicinus Chaudoir [synonym is possibly S. substriatus]
– Metasternum proportionally longer compared to metacoxa (LMs / LMc = 1.10–1.30). No other reliable external discriminator known. Uncommon in north-central USA with somewhat increasing occurrences southward and eastward from Kansas to the Atlantic and Gulf Coast states ==> S. quadriceps Chaudoir [S. lissopterus sensu Nichols (1986), considered a synonym by Bousquet & Skelly (2010), is a small variant (LE < 13.0 mm) occurring mainly west of the Mississippi River with elytra often with striae less impressed (laterally) and intervals flat.]
–– SUBTERRANEUS GROUP ––
3. Setigerous puncture present on proximal elytral interval #3. Elytral striae impunctate. Metasternum proportionally more elongate (LMs / LMc = 1.10–1.40). Membranous wings fully developed. Widely distributed in the United States and also in southern Ontario ==> S. subterraneus Fabricius [synonyms include S. texanus (small Texan variant with weakly impressed striae), S. californicus (CA), and S. patruelis (FL, GA)]
– Setigerous puncture on proximal elytral interval #3 absent (or present in some S. ocalensis). Metasternum proportionally shorter (LMs/LMc = 0.75–1.03). Membranous wings reduced. Range only LA to FL in North America ==> 4
4. Eyes flat, head width at level of eyes smaller than at level of temples. Pustules at base of elytra more expanded, reaching level of humeral carina apex between intervals 2–4. Elytral interval 7 markedly convex, more or less cariniform, in basal third. Elytral striae impunctate. Known only from sandy soil in Levy Co, FL ==> S. stenops Bousquet & Skelley
– Eyes slightly to moderately convex, head width at level of eyes subequal or greater than width at level of temples. Pustules at base of elytra less expanded, distinctly not reaching level of humeral carina apex between intervals 2–4. Elytral interval #7 slightly convex or flat in basal third ==> 5
5. Elytral striae very finely impressed, vanishing at apex, striae with punctulae. Elytra very shiny (disc without microsculpture). Metasternum proportionally more elongate (LMs / LMc = 0.98–1.03). Eyes more convex, head width at level of eyes greater than width at level of temples. Larger body size (usually LE > 7.5 mm). Occurs on sea beaches of FL and LA Gulf Coast ==> S. marinus Nichols
– Elytra with striae well impressed without punctulae, with distinct microsculpture. Metasternum proportionally shorter (LMs/LMc = 0.76–0.84). Eyes less convex, head width at level of eyes subequal to width at level of temples. Small body size (elytron < 7.5 mm). Known only from peninsular FL (inland and coastal) ==> S. ocalensis Nichols
The six valid North American species of Scarites including synonyms:
S. marinus Nichols, 1986
S. ocalensis Nichols, 1986
S. quadriceps Chaudoir, 1843: p729 [syn. S. lissopterus Chaudoir, 1880: p93]
S. stenops Bousquet & Skelley, 2010
S. subterraneus Fabricius, 1775 [syn. S. californicus LeConte, S. patruelis LeConte, S. texanus Chaudoir, 1880: p94]
S. vicinus Chaudoir, 1843 [?syn. S. substriatus Haldeman]
Literature cited.
Chaudoir, M. de. 1843. Bulletin de la Société impériale des naturalistes de Moscou 23.
Chaudoir, M. de. 1880. Annales de la Societe Entomologique de Belgique 23: 5-130.
Lindroth, C.H. 1961. Opuscula Entomologica, Supplementum 20.
Nichols, S.W. 1986. Proc. Entomol. Soc. Wash 88(2): 257-264.
Bousquet, Y., and P.E. Skelley. 2010. The Coleopterists Bulletin 64(1): 45-49.
Range
Ontario and most of United States except northwestern states. Also represented in Mexico, Cuba, Eurasia, India, Madagascar, others?
For historical taxonomic interest, below are the seven species names and their associated ranges as they appeared in a catalogue by Bousquet & Larochelle (1993):
S. lissopterus - KS, NM, OK, TX
S. marinus - FL to LA
S. ocalensis - FL only
S. patruelis - GA, FL
S. quadriceps - eastern US plus Ontario: NJ to FL to TX to SD to ON
S. subterraneus - Ontario and most of US except northwestern states
