Dicaelus (Dicaelus) purpuratus purpuratus Bonelli 1813

Dicaelus purpuratus purpuratus Bonelli
Dicaelus purpuratus Bonelli, 1813:447; [type a female for which no locality is indicated]. — Dejean, 1826:385. — Le Conte, 1853:388. — Chapuis and Candeze, 1853:375.— Zimmerman, 1868:246; (1868).— Horn, 1880:51-52; (1880).— Dimmock and Knab, 1904:21-30, pis. 1-2.
Dicaelus violaceus Bonelli, 1813:447. Type locality: Carolina; (specimen collected by Bosc.).— Dejean, 1831.— Le Conte, 1848 : 424.— Laferte, 1851: 276.— Le Conte, 1853.— Horn, 1880.
Dicaelus chalybeus Dejean, 1826:385. Type locality: Louisiana. — Dejean, 1831.— Le Conte, 1848.— Laferte, 1851 : 276.— Le Conte, 1853.— Horn, 1880.
Dicaelus cyaneus Dejean, 1831:686. Type locality: Amer. sept.; (type specimen received from M. Le Conte). — Le Conte, 1848:425. — Laferte, 1851: 276.— Le Conte, 1853.— Horn, 1880.
Dicaelus confusus Le Conte, 1848:424; [type specimen a female from "Georgia"; in Le Conte Coll. no. 5711].— Le Conte, 1853.— Horn, 1880.
Dicaelus iricolor Le Conte, 1848 : 426 ; [type specimen a male, collected at St. Louis Mo.; in Le Conte Coll. no. 5712].— Le Conte, 1853.— Horn, 1880.
The western limits of distribution of D. p. purpuratus seem to be formed principally by the Mississippi Valley, but I have seen a single specimen from " Texas " and one labelled " Mo." Otherwise all specimens which I have examined are from localities east of the Mississippi River. To the north this subspecies ranges into southern Michigan, north to Berrien County, is known to occur along the southern shore of Lake Erie, but is known from New York State, only from Long Island and Staten Island in the east, and extends northward to " Mass.", presumably close to the Atlantic Coast. Southward, the range of D. p. purpuratus contacts that of D. p. quadratus along the eastern Gulf Coast.
Synonymical Notes. — The synonyms of D. purpuratus are all based upon specimens which differ from one another only in color, a character which seems to vary individually and not geographically. I feel, therefore, that the synonomy presented by Horn in 1880, and which is reproduced above, is correct.
Variation.— The following features vary intra-subspecifically : color, pronotal sculpture, pronotal shape, punctation of abdominal sternite 6, and size.
Total length — males, 20.6-25.0 mm. (22.8 mm.); females, 20.724.7 mm. (23.2 mm.). Maximum width — males, 9.0-10.5 mm. (9.5 mm) ; females, 9.3-11.1 mm. (10.0 mm.). Samples of specimens from the Gulf Coast average larger than those from further north. On the whole, the color of the dorsal surface of this subspecies is a rich dark purple varying to bright violaceous, metallic blue, and in the elytra in a few specimens to a dull metallic green. This latter condition is exhibited by the following specimens : one female, Wayne County, and one female, Berrien Co., Mich.; one male, Lafayette, Ind. ; one male, Tippecanoe Co., Ind. ; one female, Chicago, and one male from Oregon, 111. A single female from Mobile has an entirely black dorsal surface.
Pronotal sculpture varies approximately with size, large specimens with the dorsal surface rather strongly rugose, smaller specimens, especially from the northeast, with the pronotal surface only rugulose and with the median portion of the disc approximately smooth. The conformation of the lateral margins of the pronotum varies from approximately parallel, through narrowly arcuate, to broadly arcuate ; from slightly incurved anteriorly to strongly incurved posteriorly ; from more or less straight, to slightly sinuate. A majority of specimens from the northern part of the range (90 percent) have a moderately convex disc, but a few specimens have the disc flattened medially. Specimens with the convex disc usually have small to moderate sized discal impressions which do not interrupt the curvature of the disc laterally. Specimens exhibiting a more flattened disc also have more extensive impressions which either may or may not interrupt the lateral declivity. All seven specimens of this subspecies which I have seen from Mobile, Alabama have the latter type of pronotum, in which the lateral declivity is shallowly interrupted by the posterior extension of the lateral discal impressions. (See table 38 for a detailed analysis of variability of the diagnostic features in the Mobile, Alabama specimens).
Elytral intervals 3 and 5 are slightly more convex in a few specimens from localities scattered throughout the range of this subspecies.
Females usually have relatively more accessory punctures on the 6th abdominal sternite than the males, and, further, more females from the more eastern localities have relatively more punctures than individuals from the more westerly localities. More specimens, both males and females, from the North Central States completely lack accessory setae, and their punctures, than specimens from east coast localities. Presence or absence of accessory punctures and their relative abundance seems to vary continuously in an east-west direction. Further, since absence of the accessory setigerous punctures seems to be a characteristic of D. p. splendidus, those specimens which have purple elytra but lack the accessory punctures may be thought of as intergrades between splendidus and typical purpuratus.
Biology. — Dr. A. B. Champlain has informed me that he has observed specimens of this subspecies feeding on snails. Dimmock and Knab (1904:30) have published a description of the habits and life history of Dicaelus purpuratus and report having observed an adult feeding on the snail Tropidopsis tridentata Say.
Distribution.— I have seen one hundred eighteen males and eightyseven females collected in the following states.
Southern and western peripheral localities — Alabama : Mobile County, Mobile. Texas : " Texas." Illinois : Knox County ; Galesburg. Wisconsin : Chippewa County ; Stanley. Additional states — Connecticut. District of Columbia. Georgia. Indiana. Kentucky. Louisiana. Maryland. Massachusetts. Michigan. Mississippi. New Jersey. New York. North Carolina. Ohio. Pennsylvania. South Carolina. Tennessee. Virginia. West Virginia.