Pachybrachis spumarius Suffrian, 1852

Barney, Robert J., 2017, Definition and Revision of the Spumarius Species-Group of North American Pachybrachis Chevrolat (Coleoptera: Chrysomelidae: Cryptocephalinae), The Coleopterists Bulletin 71 (3), pp. 449-460 : 451-456

Pachybrachis spumarius Suffrian, 1852 ( Fig. 1 )

Pachybrachys spumarius Suffrian 1852: 179 . Blatchley 1910: 1132 (regional species list), 1924: 51 (regional species list); Hughes 1944: 131 (regional species list); Wilcox 1954: 391 (regional species list).

Pachybrachys roboris Fall 1915: 420 . Knaus 1916 –1917: 262 (regional species list); Dozier 1922: 117 (regional species list); Blatchley 1924: 51 (regional species list); Hughes 1944: 131 (regional species list); Wilcox 1954: 391 (regional species list).

Pachybrachys obfuscatus Fall 1915: 416 . New synonymy.

Pachybrachis spumarius: Fattig 1948: 10 (regional species list); Downie and Arnett 1996: 1319 (regional species list); Kirk 1970: 86 (regional species list); Balsbaugh and Hays 1972: 34 (regional species list); Wilcox 1979: 5 (plant associations); Barney 1984: 141 (regional species list); Riley et al. 2003: 163 (catalogue); Clark et al. 2004: 161 (plant associations); Ciegler 2007: 181 (taxonomy, plant associations); Barney et al. 2011: 10 (regional species list), 2013: 134, habitus 17 (taxonomy).

Pachybrachis roboris: Fattig 1948: 10 (regional species list); Kirk 1969: 89 (regional species list); Kirk 1970: 86 (regional species list); Balsbaugh and Hays 1972: 34 (regional species list).

Pachybrachis obfuscatus: Fattig 1948: 9 (regional species list); Downie and Arnett 1996: 1318 (catalogue); Riley et al. 2003: 161 (catalogue); Clark et al. 2004: 160 (plant associations); Ciegler 2007: 180 (taxonomy, plant association).

Type Material. A male specimen of P. spumarius , recently discovered in the Natural History Museum in London among some previously unrecognized type material of Suffrian and labeled “ E. Coll. / Chev. t [printed, white paper with black outline] // 67 56 // 13 [printed, tan paper] // carbonarius? / Dj Cat amer b / Poey [hand-inked, green paper] // Spumarius Suffr. / 179-23 / Carolina D Poey 5159 [hand-inked, green paper] // LECTOTYPE / Pachybrachys / spumarius Suffrian 1852 // desig. R. J. Barney, 2017 [printed black on red paper]”, was examined, photographed, dissected, and is herein designated as a lectotype ( Fig. 1 ). Suffrian (1852) cited P. spumarius as “Brought from Carolina D. Schaum , but also in Mr. Chevrolat’ s available collection without specifying the discovery site as North American Beetles” (Google Translate 2016).

An examination of Suffrian material labeled as “ spumarius ” from the MNHUB revealed two females from “ Carolina ” designated by the MNHUB as syntypes. The first specimen was labeled “24078 [printed, white paper] // spumarius / Suffr.* / Carolina [printed, green paper] // SYNTYPUS / Pachybrachis / spumarius Suffrian, 1852 / labeled by MNHUB 2013 [printed, red paper]”. The second specimen has no locality label .

Fall (2015) mentioned examining a female specimen, which he described as “supposedly a type or cotype – from the Suffrian collection”, that was numbered “30490” and did not bear a locality label. He made no mention of the specimens referenced above.

Fall’ s male P. roboris holotype, labeled “ C. A. Frost / Malden / 7/15 [hand-inked] Mass. [printed, white paper] // 6 // TYPE [printed] / roboris [handinked, white paper] // H. C. FALL / COLLECTION [printed, white paper] // M. C. Z. / Type [printed] / 24977 [hand-written, red paper]”, was examined, photographed, and dissected ( Fig. 2 ) .

There are three [266 1♀] specimens in the MCZ- FALL collection from the same collecting event as the holotype. Two males are labeled “ C. A. Frost / Malden / 7/15 [hand-inked] Mass. // 6 // H. C. FALL / COLLECTION // [circular blue disc signifying dissection by RJB]”, and one female is labeled “ C. A. Frost / Malden / VII-15 [hand-inked] Mass. // ♀ // H. C. FALL / COLLECTION” .

There are four P. roboris paratypes [266 2♀♀] in USNM. One male is labeled “PlummersI / 15.6.05 [hand-inked] Md [printed, white paper] // EASchwarz / Collector [printed, white paper] // roboris Fall [handinked] / Fall 1915 Revis [printed,white paper] // U.S. N. M. / Paratype [printed, red paper] // [circular blue disc signifying dissection by RJB]”. One female is labeled “Plummer’ sI / 3. VI.02 [hand-inked] Md [printed, white paper] // RPCarrie / Collector [printed, white paper] // Pachybrachys / atomarius Melsh [hand-inked on folded white paper] // roboris Fall [hand-inked] / Fall 1915 Revis [printed, white paper] // U.S. N. M. / Paratype [printed, red paper]”. One male and one female are labeled “Meridian / 12.7 [hand-inked] Miss [printed, white paper] // Collection / H.Soltau [printed, white paper] // roboris Fall [hand-inked] / Fall 1915 Revis [printed, white paper] // U.S. N. M. / Paratype [printed, red paper]”.

There is one female in the MCZ-FALL collection from the same collecting event as the only P. spumarius specimen cited in Fall (1915). It is labeled, “TumblingGapAla / June 3-8’11 / H. P. Löding // ♀ // H. C. FALL / COLLECTION” .

Fall’ s male P. obfuscatus holotype, reportedly from the Van Dyke Collection and labeled “ Black Mts. / N. C. [printed, white paper] // 6 // TYPE [printed] / obfusca - / tus [hand-written, white paper] // H. C. FALL / COLLECTION [printed, white paper] // M. C. Z. / Type [printed] / 24958 [hand-written, red paper]”, was examined, photographed, and dissected ( Fig. 3 ) .

Redescription. Male. Yellow, with brown, reddish brown, or rust-colored punctures, with standard maculae diffuse, often dark brown or fuscous; L = 1.75–2.45 mm (mean = 2.02 mm, n = 31); W = 0.98–1.35 mm (mean = 1.11 mm, n = 31); L / W = 1.72–1.93 (mean = 1.82, n = 31). Head: Slightly wider than thoracic apex, HW = 0.64–0.92 mm (mean = 0.77 mm, n = 31); eyes moderately separated, IOD = 0.17–0.30 mm (mean = 0.22 mm, n = 31); IOD /HW = 0.24–0.33 (mean = 0.29, n = 31); face yellow with brown, W-shaped macula connecting vertex and base of antennae and extending to base of upper lobe of eyes; punctation dense; antennae brown, not reaching distal elytral declivity. Pronotum: Yellow, with M-shaped marking broadly diffuse,leaving small, scattered,slightly convex, yellow spots; scattered punctation extending to lateral margins; PL = 0.60–0.83 mm (mean = 0.69 mm, n = 31); PW = 0.85–1.06 mm (mean = 0.95 mm, n = 31); PL / PW = 0.67–0.89 (mean = 0.72, n = 31). Elytra: Punctation dense, confused; lateral striae mostly distinct; 1 or 2 discal costae defined by punctures; marginal interspace mostly impunctate. Pygidium: Brown, with 2 oval, yellow maculae. Venter: Brown, upper sides of last ventrite yellow. Legs: Brown with standard yellow spots. Genitalia: Median lobe in en-face view widest at base, narrowing to gently rounded ALM with a prominent nodule ( Fig. 2F ), varying to circular orificial space formed by midpoint constriction ( Fig. 1F ); lateral basal plates moderately sclerotized. In lateral view, ventral surface well-inflated at base, forming tube-like median lobe that narrows sharply to terminus; ventral keel absent. Setal beard short and fine at apicolateral angle (244 males from 33 states and provinces were dissected) .

Female. As in male, except L = 2.01–2.63 mm (mean = 2.33 mm, n = 30), W = 1.11–1.50 mm (mean = 1.31 mm, n = 30), HW = 0.76–1.00 mm (mean = 0.88 mm, n = 30), IOD = 0.19– 0.38 mm (mean = 0.29 mm, n = 30), IOD/HW = 0.24–0.40 (mean = 0.33, n = 30).

Remarks. The recent rediscovery of a previously unrecognized or undatabased male specimen of P. spumarius from Chevrolat’ s collection, believed to have been purchased by Hamlet Clark and later acquired by BMNH (M. Geiser, personal communication, August 2016), permits the naming of a lectotype. The large, folded green-paper label is believed to be hand-written by Chevrolat, with the line “179-23” representing the page and number of Suffrian’ s (1852) description.

Fall (1915) did not list any specimens under P. spumarius , except “provisionally” a male from Tumbling [sic] Gap, Alabama collected by Loding. The MCZ-FALL collection holds a pair of specimens (16 1♀) with identical locality labels, “TumblinGapAla [sic] / June 3-8’11 / H.P.Löding // H. C. FALL / COLLECTION”. However, the male was identified as “ P. spumarius Suffr. ” [hand-inked, white paper with red-lined border], while the female was sorted as P. roboris .

Dissections of 244 male specimens previously identified as P. roboris or P. obfuscatus revealed them to have a tube-like median lobe with a distinct nodule. Initially, there appeared to be two versions: an almost parallel-sided version ( P. roboris holotype, Fig. 2F ) and a circular-constricted version ( P. obfuscatus holotype, Fig. 3F ). However, specimens in the MCZ-FALL unit trays of P. roboris and P. obfuscatus had varying degrees of variation between these versions, often from the same location or collecting event. Therefore, even after conducting over 200 dissections, I could not in good conscience separate the specimens into two species. Only series with dissected males have been listed in the Specimens Examined section in Appendix I.

Balsbaugh and Hays (1972) synonymized P. roboris under P. spumarius based upon their examination of specimens in the Loding collection, paying attention to variability of punctation near the pronotal margins. However, there is no evidence they had personally examined the types of either species.

Fall (1915) described P. obfuscatus as nearly identical with P. atomarius , and then remarked that it may be very difficult to separate darker examples of P. obfuscatus from P. roboris , to which he considered it “very closely allied.” Males of P. atomarius are distinguishable from other eastern USA species of Pachybrachis by their yellow face and protruding black pygidium.

A historical review of specimens within this species-group reveals that until Fall (1915), few if any specimens in collections were identified as P. spumarius , as most Coleopterists were not sure what P. spumarius was. Fall created P. roboris to fill this void, and until Balsbaugh and Hays (1972), many specimens in collections were identified as P. roboris . After the name P. roboris was synonymized under P. spumarius in 1972, practically all specimens were identified as P. spumarius . In 1915, Fall also created P. obfuscatus , but the species concept was rarely attributed to any specimens I have examined.

Distribution. Pachybrachis spumarius has been found in virtually every state east of the 100 th

Map 1. Distribution of Pachybrachis spumarius based upon specimens examined.

meridian, from Maine to Florida (Map 1). New state records are confirmed for Delaware, Louisiana, Michigan, Minnesota, and Tennessee.

Biological Notes. I have collected multiple large series of P. spumarius on Rhus copallinum L. ( Anacardiaceae ) in Illinois, Kentucky, North Carolina , and West Virginia. Clark et al. (2004) reported a MSc thesis associating P. obfuscatus with Cercis canadensis L. ( Fabaceae ) in Ohio, but this cannot be confirmed. Label data indicate specimens collected on Rhus sp. in Indiana and North Carolina , Ceanothus sp. (Rhamnaceae) in Massachusetts and North Carolina , Quercus sp. (Fagaceae) in New Jersey, and Eriogonum allenii S. Watson (Polygonaceae) in Virginia shale barrens. Clark et al. (2004) reported many citations with many plant associations for P. spumarius . Label data indicate some specimens were collected via Malaise and Lindgren traps.

Specimens Examined. See Appendix I.

Figures

Fig. 1. Pachybrachis spumarius, lectotype. A) Dorsal habitus, B) Lateral habitus, C) Face, D) Pygidium, E) Median lobe of aedeagus, lateral view, F) Median lobe of aedeagus, en-face view.

Fig. 2. Pachybrachis roboris, holotype. A) Dorsal habitus, B) Lateral habitus, C) Face, D) Pygidium, E) Median lobe of aedeagus, lateral view, F) Median lobe of aedeagus, en-face view.

Fig. 3. Pachybrachis obfuscatus, holotype. A) Dorsal habitus, B) Lateral habitus, C) Face, D) Pygidium, E) Median lobe of aedeagus, lateral view, F) Median lobe of aedeagus, en-face view.