Pachybrachis kentuckyensis Riley and Barney

Riley, Edward G. & Barney, Robert J., 2015, Definition And Revision Of The Viduatus Species- Group Of North American Pachybrachis Chevrolat (Coleoptera: Chrysomelidae: Cryptocephalinae), The Coleopterists Bulletin 69 (1), pp. 25-59 : 42-46

7. Pachybrachis kentuckyensis Riley and Barney , new species ( Figs. 17 , 21 ; Map 4)

Pachybrachys viduatus: Fall 1915: 464 , 486 (misidentification, partim).

Pachybrachis viduatus: Balsbaugh and Hays 1972: 38 (misidentification, partim).

Holotype. Male ( Fig. 17 ), labeled “KY: Hardin Co. / Eastview Barrens SNP / 37.603476 -86.047614 / 9 Jun 2009 front / R. J. Barney [printed, black on white] // [circular blue disc signifying dissection by RJB] // HOLOTYPE / Pachybrachis / kentuckyensis / Riley & Barney [printed, black on red].” Deposited in MCZ. The specimen is point-mounted and dissected, with abdomen and genitalia affixed to the point. It is in excellent condition with all appendages intact. There is one female paratype with collecting data identical to those of the holotype, and other paratypes are from the same location but differing in details.

Paratypes. 26♂♂, 24♀♀ (Appendix 4).

Description. Male: As described for P. bloxham , except length 2.40–2.79 mm (mean = 2.59 mm, n = 10); width across humeri 1.27–1.56 mm (mean = 1.42 mm, n = 10); L/ W 1.78 –1.94 (mean = 1.84, n = 10). Head: Width 0.86– 1.07 mm (mean = 0.95 mm, n = 10); eyes widely separated, IOD 0.39–0.48 mm (mean = 0.43 mm, n = 10); IOD/HW 0.42–0.50 (mean = 0.46, n = 10). Pronotum: Length 0.78–1.03 mm (mean = 0.88, n = 10), width 1.12–1.33 mm (mean = 1.23 mm,

Map 4. Distribution of Pachybrachis species based on specimens examined. P. picturatus (circles); P. kentuckyensis

(diamonds).

n = 10), PL/PW 0.68–0.77 (mean = 0.71 mm, n = 10). Elytra: Lateral vitta weaker, often interrupted, leaving detached, or partially detached, incurved apical spot. Pygidium: Black with lower half occupied by 2 large, confluent, yellow spots. Genitalia: Median lobe in en-face view with shaft widest subapically, side margins broadly, very feebly emarginate behind apicolateral curvature ( Fig. 21 ); orificial space with side straight, following marginal contour of shaft; length of postorificial space moderate, twice as long as narrowest marginal space; lateral basal endophallic plates wellpigmented, median plate lightly pigmented, strap-like basally. En-face outline with apicolateral margin broadly and evenly rounded, oblique to terminus, very shallowly emarginate before terminus, defining indistinct, broadly triangular nodule. Beard consisting of moderately conspicuous apicolateral wisp on each side; setae of wisp dense, grouped in trans- verse patch, graded in length, longest setae subbasal in serial position, curved mesad. Ventral surface flat, unmodified, apicolateral marginal area thickened; distal profile of low continuous curve, emarginate before terminus.

Female. As described for P. bloxham , except length 2.87–3.05 mm (mean = 2.99 mm, n = 10); width across humeri 1.51–1.78 mm (mean = 1.67 mm, n = 10); head width 1.01–1.17 mm (mean = 1.09 mm, n = 10); interocular distance 0.46– 0.55 mm (mean = 0.52 mm, n = 10); IOD/HW 0.42–0.51 (mean = 0.48, n = 10).

Etymology. This species is named for the state where it was first discovered and where most of the known specimens originated.

Remarks. The viduatus species-group characters, together with the heavy median elytral vittae, and the distinctive male genitalia distinguish the species. Externally, this species is inseparable from some members of the viduatus complex ( P. bloxham , P. chester , and P. viduatus ), but it may be separated from P. picturatus by having heavy black maculation and dense, coarse dorsal punctation. Males of P. kentuckyensis are distinguished from other members of the viduatus complex by not having their genitalia with the ventral surface inflated, the curvature in profile being minimal and flat subapically before the base of the nodule. We have been unable to find definitive external characters to distinguish females. The lateral elytral vitta is usually incomplete in this species ( Fig. 17 ). Two males from Mobile, Alabama in the Fall Collection were identified as P. viduatus by Fall (1915).

Distribution. This species ranges from the Gulf States (Alabama, Mississippi, and Florida) north to Kentucky, Ohio, and West Virginia (Map 4).

Biological Notes. According to the Kentucky State Nature Preserves Commission, the type locality, Eastview Barrens State Nature Preserve, is a fire-maintained grassland and open woodland. Five adults collected from this location did not feed on any of seven species of Fabaceae offered under laboratory conditions (Barney and Hall 2011). One specimen was taken on Hypericum dolabriforme Vent. at Raymond Athey Barrens State Nature Preserve in Kentucky. Like the other vittate species of the viduatus complex, this species is not common in collections.

Specimens Examined. See Appendix 4.

8. Pachybrachis picturatus ( Germar, 1824) ( Figs. 3 , 7 ; Map 4)

Cryptocephalus picturatus Germar 1824: 560 (original description); Melsheimer 1853: 128 (catalogue).

Pachybrachys picturatus: Suffrian 1852: 209 (taxonomy, partim?). Gemminger and Harold 1874: 3356 (catalogue); LeConte 1880: 209 (catalogue); Henshaw 1885: 107 (catalogue) [as valid species, with P. m-nigrum Melsheimer as synonym]; Clavareau 1913: 103 (catalogue); Fall 1915: 463, 486 (taxonomy, catalogue); Leng 1920: 290 (catalogue).

Pachybrachis picturatus: Wilcox 1975: 31 (catalogue); Riley et al. 2003: 162 (catalogue); Ciegler 2007: 181 (taxonomy).

Type Material. Status unknown, probably not extant. Germar’ s (1824) brief original account does not indicate the number of specimens nor an explicit source for specimens. He gave North America as the geographical origin of his species. Suffrian (1852) appears to have interpreted the species broadly, considering Melsheimer’ s P. m-nigrum a synonym, citing localities of Kentucky and Pennsylvania (the Kentucky record is cited as from the Germar collection). Fall (1915) did not see Germar material, and he had a mere five specimens that he assigned to this species, accepting those as the best match for Germar’ s short original description.

Germar’ s collection, including his types, was sold after his death and went to two different collections: MNHUB and the Senckenberg Deutsches Entomologisches Institut (Horn and Kahle 1935). The curators in charge of those collections were unable to confirm the existence of authentic Germar material for P. picturatus . In the present study, we perpetuate Fall’ s concept for the species .

Redescription. Male: Length 2.57–2.77 mm (mean = mm, n = 10); width across humeri 1.39–1.51 mm (mean = 1.45 mm, n = 10); L/ W 1.76 –1.94 (mean = 1.84, n = 10). Head: As wide as thoracic apex, width 0.94–1.04 mm (mean = 0.98 mm, n = 10); eyes widely separated, IOD 0.37–0.43 mm (mean = 0.40 mm, n = 10); IOD/HW 0.38–0.43 (mean = 0.40, n = 10); face mostly yellow with black, inverted Y-shaped macula connecting vertex and base of antennae, punctation dense in black areas, more sparsely placed in pale areas; antenna black, basal antennomeres partially yellowish, extending to elytral declivity. Pronotum: Length 0.90–1.01 mm (mean = 0.94, n = 10), width 1.21–1.33 mm (mean = 1.25 mm, n = 10), anterior width slightly less than basal width, lateral margin arcuate basally, from there to anterior angle straight to vaguely emarginate; PL/PW 0.72–0.81 (mean = 0.75, n = 10); punctation fine and sparse, more widely spaced than that on elytra, M-shaped macula narrow, complete or partially interrupted; surface between punctures moderately shiny; scutellum yellow with black tip. Elytra: Each elytron with suture very narrowly and narrow median vitta black; median vitta usually not reaching declivity; lateral vitta not developed, reduced to small black spot on humeral umbone and rarely dark smudge before declivity; punctation confused in basosutural area, weak stria evident laterally and apically on declivity, lightly impressed; costae not evident; surface areas between punctation moderately shining. Pygidium: Finely punctate, almost entirely yellow. Venter: Mostly yellow to brownish with median areas blackish, last ventrite almost entirely yellow. Legs: Yellow except dorsal margin of profemur brownish. Genitalia: Median lobe in en-face view of near equal width throughout, side margins of shaft little tapered behind apicolateral curvature ( Fig. 3 ); postorificial length short, about as long as narrowest marginal space; lateral basal plates broad and well-pigmented, median plate lightly pigmented, narrow basally, strap-like and gradually narrowed distally. En-face outline with apicolateral margin broadly and evenly rounded; distal en-face outline oblique to terminus, very shallowly emarginate before terminus, defining indistinct, broadly triangular nodule. Beard consisting of moderately conspicuous apicolateral wisp; setae of wisp sparse, grouped in transverse patch, graded in length, longest setae subbasal in serial position, curved mesad. Ventral surface with sharply defined, short keel, strongly arched, positioned subapically within in membranous field, basal slope steeply inclined, distal slope gradually inclined to base of nodule.

Female. As in male, except length 2.81–3.29 mm (mean = 3.02 mm, n = 10); width across humeri 1.49–1.85 mm (mean = 1.65 mm, n = 10); head width 1.03–1.23 mm (mean = 1.12 mm, n = 10); interocular distance 0.46–0.55 mm (mean = 0.51 mm, n = 10); IOD/HW 0.42–0.48 (mean = 0.46, n = 10); antenna short, only attaining elytral mid-length; M-shaped macula on pronotum usually broken into five separate spots.

Remarks. This is a distinctive species with a combination of unique characters isolating it from the other members of the viduatus complex. The microsculpture and punctation of the dorsal surfaces are less strongly developed than in the other species, and the dark markings everywhere on the body are less developed. The broad membranous field that surrounds the keel on the ventral surface of the male genitalia is also unique to this species.

Early misapplications of this species’ name in the American literature stem from Suffrian (1852), who cited Melsheimer’ s m-nigrum as synonymous. Fall (1915) noted the discrepancy between his specimens having a black, M-shaped marking on the pronotum versus the pronotum with six spots as recorded by Germar. We have seen females where the black, M-shaped mark on the pronotum is broken into five spots, but we are not aware of any vittate cryptocephaline in eastern North America with a six-spotted pronotum.

Distribution. The few specimens seen by Fall (1915) were from North Carolina. As now known, its distribution is still restricted, being found in the coastal regions of North Carolina, South Carolina, and Georgia (Map 4). The basis for the records from New Jersey and Pennsylvania listed by Riley et al. (2003) are certainly misidentifications.

Biological Notes. Fall (1915) considered this distinctive species to be among the most uncommon of the eastern North American Pachybrachis . In his analysis of P. picturatus , he states “This is one of our rarest species, and thus far only five specimens have been seen by me. It is probably quite restricted in range.” There are no previously known plant associations for this species (Clark et. al 2004); however, adults are now known to have a clear association with Atlantic St. John’ s-wort, Hypericum tenuifolium Pursh. Our recent collecting experience has shown that this species can sometimes be abundant on this plant. It was encountered once in high numbers where this plant was growing on a swale between sand ridges (Emanuel County, Georgia). Beetles were numerous enough that, when the Hypericum plants were disturbed, one would sometimes see beetles take flight and alight on individual plants. Sporadic specimens were also encountered on this plant in a long-leaf pine savanna-pocosin transitional area and along disturbed roadsides.

Specimens Examined. See Appendix 6.

9. Pachybrachis viduatus (F., 1801) ( Figs. 18 , 22 ; Map 3)

Cryptocephalus viduatus Fabricius 1801: 49 (original description); Olivier 1808: 808, pl. 5, fig. 75 (taxonomy); Zimsen 1964: 123 (type).

Pachybrachys viduatus: Suffrian 1852: 155 (taxonomy, partim?); Gemminger and Harold 1874: 3357 (catalogue); Henshaw 1885: 107 (catalogue) [listed as valid species, with P. albescens Suffrian as synonym]; Bowditch 1908: 217 (identification comments); Clavareau 1913: 108 (catalogue); Fall 1915: 464, 486 (taxonomy, catalogue, partim); Leng 1920: 290 (catalogue); Wilcox 1954: 393 (taxonomy).

Pachybrachis viduatus: Melsheimer 1853: 127 (catalogue); Balsbaugh and Hays 1972: 38 (taxonomy, partim); Wilcox 1975: 32 (catalogue); Riley et al. 2003: 165 (catalogue); Clark et al. 2004: 162 (plant associations); Ciegler 2007: 183 (taxonomy, partim).

Type Material. Neotype, here designated. Fabricius (1801) gave the source for his species as “Carolina. Mus. D. Bosc.” The American Chrysomelidae in the collection of Louis Augustin Guillaume Bosc housed in the Muséum National d’ Histoire Naturelle, Paris were studied by Doris Blake during visits in 1925 and 1950. Later, she reported her detailed notes ( Blake 1952) but made no mention of the species now belonging in Pachybrachis . Blake found the Bosc chrysomelids to be in good condition, considering their age, mentioning in passing that those that were not in good condition “probably … had long since been discarded.” Fall (1915) made no mention of Fabrician material, and specimens of P. viduatus were not documented by Zimsen (1964). Olivier (1808) provided an excellent figure for P. viduatus that was almost certainly based on Bosc material.

Following Blake’ s account, we conclude that the original P. viduatus material from the Bosc collection is no longer extant. To fix the application of this early name, consistent with the descriptive remarks of Fabricius and Olivier, Olivier’ s figure, and the majority of the specimens representing Fall’ s concept, we herein designate a neotype. The geographic source for the Bosc material is the area about Charleston, South Carolina ( Blake 1952). Our only male specimen from South Carolina is herein designated as neotype. It is labeled, “Yemasee, S.C. / June 14, 1954 / R. L. Fischer [printed, black on white] // [circular blue disc signifying dissection by RJB] // Michigan State Univ / A. J. Cook Arthropod / Research Collection / Loan# 2009-05 [printed, red and black on white] // NEOTYPE / Cryptocephalus / viduatus Fabricius 1801 / design. Riley & Barney [printed, black on red].” This specimen is in good condition with all appendages intact and has been dissected, with the median lobe and abdomen glued to the specimen’ s card point. Deposited in MSUC.

Redescription. Male: As described for P. bloxham , except length 2.89–3.29 mm (mean = 2.99 mm, n = 10); width across humeri 1.52–1.86 mm (mean = 1.66 mm, n = 10); L/ W 1.50 –1.89 (mean = 1.79, n = 10). Head: Width 1.02–1.14 mm (mean = 1.10 mm, n = 10); eyes widely separated, IOD 0.43–0.51 mm (mean = 0.48 mm, n = 10); IOD/HW 0.38–0.48 (mean = 0.44, n = 10). Pronotum: Length 0.99–1.18 mm (mean = 1.07, n = 10), width 1.32–1.64 mm (mean = 1.46 mm, n = 10); PL/PW 1.27–1.43 (mean = 1.36, n = 10). Elytra: Lateral vitta weak, often short and interrupted, with detached, or partially detached, incurved apical spot, or broken into 3 irregular spots. Genitalia: Median lobe in en-face view with shaft widest subapically, side margins broadly, feebly emarginate behind apicolateral angle ( Fig. 22 ); postorificial length moderate, ca. 2–3 times as long as narrowest marginal spaces are wide; lateral basal plates well-pigmented; median basal plate weakly pigmented, broad at base and narrowed apically. En-face outline with apicolateral margin abruptly rounded; distal en-face outline nearly transverse to base of nodule, broadly, shallowly emarginate, defining broad, triangular nodule. Beard consisting of conspicuous apicolateral wisp on each side; setae of wisp dense, grouped in transverse patch, long, abruptly graded to short on both ends of patch, curved mesad. Ventral surface moderately inflated, with distinct keel; keel strongly arched, extending from near base to mid-length, basal and distal inclines equally precipitous, distal incline continuous to base of nodule.

Female. As described for P. bloxham , except length 3.63 mm (n = 1); width across humeri 2.07 mm (n = 1); head width 1.28 mm (n = 1); interocular distance 0.65 mm (n = 1); IOD/HW 0.50 (n = 1); lateral elytral vitta with partially detached apical macula or broken into separate spots.

Remarks. Pachybrachis viduatus is separated from P. picturatus by its heavy black maculation and distinct, coarse dorsal punctation, but it is externally inseparable from other members of the viduatus complex ( P. bloxham , P. chester , and P. kentuckyensis ). Males are distinguished by their genitalia, but we have been unable to find definitive characters to distinguish females. In P. viduatus , the ventral surface of the median lobe is moderately inflated, with a distinct, strongly arched keel extending most the length of the shaft and steeply inclined both basally and distally.

Fall (1915) reported this species from some additional localities, but these are now known to have been based on other species of the viduatus complex or were based only on females whose identity cannot be firmly established (see Appendix 11). As pointed out by Bowditch (1908) and reiterated by Fall (1915), P. viduatus was long confused with the common and widespread Pachybrachis bivittatus (Say) . This stems from Suffrian’ s treatment of P. viduatus (1852) , where Say’ s species was treated as a synonym of the Fabrician species. This error was perpetuated by LeConte (1880), which taken together explains early reports in the American literature of P. viduatus from outside the geographic range documented here.

Distribution. Pachybrachis viduatus is found in the coastal states from North Carolina to Texas, with one record from Tennessee (Coffee County) (Map 3).

Biological Notes. Previously, there were no definitive plant associations for this species ( Clark et al. 2004); however, our recent collecting has confirmed H. tenuifolium as a plant association. The beetle was collected at two localities in North Carolina in association with this plant but found only in very small numbers. These localities are best described as a long-leaf pine savanna-pocosin transition and a disturbed roadside. Specimens were swept from this plant, together with a few specimens of P. picturatus . Like the other vittate species of the viduatus species-group, this species is uncommon in collections.

Specimens Examined. See Appendix 9.

Figures

Figs. 15–18. Pachybrachis species, dorsal and lateral habitus, face and pygidium. 15) P. bloxham, holotype;

Figs. 19–22. Pachybrachis species, median lobe, en-face and lateral views. 19) P. bloxham, holotype; 20) P. chester, holotype; 21) P. kentuckyensis; 22) P. viduatus.

Figs. 1–3. 1) Pachybrachis median lobe (diagrammatic), lateral view, BC = basal constriction, BP = basal piece, K = keel, OS = orificial space, POL = postorificial length; PRL = preorificial length, S = shaft, TG = tegmin, W = wisp; 2) Pachybrachis median lobe (diagrammatic), en-face view, ALM = apicolateral margin, BF = basal lateral fold, DEO = distal en-face outline, LBP = lateral basal plate, MBP = median basal plate, N = nodule, T = terminus; 3) Pachybrachis picturatus, median lobe, en-face and lateral views.

Figs. 4–7. Pachybrachis species, dorsal and lateral habitus, face, and pygidium. 4) P. m-nigrum, lectotype;