Pachybrachis confederatus Fall, 1915

Barney, Robert J., 2018, Definition and Revision of the Atomarius Species-Group of North American Pachybrachis Chevrolat (Coleoptera: Chrysomelidae: Cryptocephalinae), Including Descriptions of Nine New Species, The Coleopterists Bulletin 72 (1), pp. 9-74 : 39-40

17. Pachybrachis confederatus Fall, 1915 ( Figs. 17 , 22F , Map 3A)

Pachybrachys confederatus Fall 1915: 387 . Wilcox 1954: 390 (taxonomy).

Pachybrachis confederatus: Fattig 1948: 9 (regional species list); Downie and Arnett 1996: 1317 (catalogue); Riley et al. 2003: 156 (catalogue); Clark et al. 2004: 156 (plant associations); Ciegler 2007: 178 (taxonomy, plant association).

Pachybrachys tybeensis Fall 1915: 388 . New synonymy.

Pachybrachis tybeensis: Fattig 1948: 9 (regional species list); Balsbaugh and Hays 1972: 32 (taxonomy); Riley et al. 2003: 164 (catalogue); Ciegler 2007: 182 (taxonomy, plant association).

Type Material. Fall’ s male type of P. confederatus , herein designated as lectotype and labeled “N. Y. // 6 // Collection / J. B. Smith [printed, white paper] // TYPE [printed, white paper] / confederatus [hand-inked, white paper] // Type 24925 [hand-inked, red paper] // H. C. FALL / COLLECTION // LECTOTYPE 24925 / Pachybrachys / confederatus Fall 1915 / R. J. Barney 2017 [printed, red paper]”, was examined, photographed, and dissected ( Fig. 17 ) .

Fall’ s male type of P. tybeensis , herein designated as lectotype and labeled “Tybee Is / VII – 2 [hand-inked] Ga [printed, white paper] // 6 // TYPE [printed, white paper] / tybeensis [handinked, white paper] // Coll. by / H.A. Wenzel [printed, white paper] // H.C. FALL / COL- LECTION [printed, white paper] // M. C. Z. / Type [printed] / 24983 [hand-inked, red paper] // LECTOTYPE 24983 / Pachybrachys / tybeensis Fall 1915 / R. J. Barney 2017 [printed, red paper]”, was examined, photographed, and dissected ( Fig. 22F ) .

Redescription. Male. Yellow, with rufous to fuscous punctures, standard maculae diffuse, often dark brown or fuscous; L = 1.84–2.21 mm (mean = 2.00 mm, n = 9); W = 0.97–1.19 mm (mean = 1.05 mm, n = 9); L/W = 1.82–2.00 (mean = 1.90, n = 9). Head: Slightly wider than thoracic apex, HW = 0.61–0.78 mm (mean = 0.69 mm, n = 9); eyes narrowly separated, IOD = 0.10–0.18 mm (mean = 0.14 mm, n = 9); IOD/HW = 0.17–0.24 (mean = 0.20, n = 9); face yellow with brown to black, W-shaped macula connecting the vertex and bases of antennae and up to base of upper lobe of eyes, punctation dense, antennae brown, reaching elytral declivity. Pronotum: Yellow, M-shaped macula dark brown to black, broadly diffuse; incomplete punctation to lateral margins; PL = 0.57– 0.76 mm (mean = 0.65 mm, n = 9); PW = 0.80–1.04 mm (mean = 0.89 mm, n = 9); PL/ PW = 0.69–0.77 (mean = 0.73, n = 9). Elytra: Yellow, with rufous to fuscous punctures, confused in baso-sutural region; standard maculae diffuse, often dark brown or fuscous; striae distinctly impressed, subhumeral striae dislocated. Pygidium: Dark brown to black, with 2 oval, yellow maculae. Venter: Dark brown to black, upper sides of last ventrite yellow. Legs: Dark brown to black, with standard yellow spots. Genitalia: Median lobe in en-face view with large, oval OS within parallel-sided shaft, with reduced PRL. Thickened sides gently narrow to extended POL deflexed at near 90° angle at ALM, thereby creating a triangular, arrowheadshaped area with a gently rounded terminus and 2 posteriorly projecting denticles or protuberances ( Fig. 17G ). EFW = 0.21–0.25 mm (mean = 0.23 mm, n = 9); AAM = 0.08–0.15 mm (mean = 0.11 mm, n = 9); AAL = 0.09–0.15 mm (mean = 0.13 mm, n = 9); AAW = 0.09–0.13 mm (mean = 0.11 mm, n = 9); AAL/AAW = 0.88–1.36 (mean = 1.11, n = 9). Ten males from five states were dissected.

Female. As in male, except L = 1.97–2.29 mm (mean = 2.13 mm, n = 10); W = 1.05–1.31 mm (mean = 1.16 mm, n = 10); L/W = 1.75– 1.89 (mean = 1.84, n = 10); HW = 0.68–0.78 mm (mean = 0.75 mm, n = 10); IOD = 0.15–0.25 mm (mean = 0.18 mm, n = 10); IOD/HW = 0.22– 0.31 (mean = 0.24, n = 10).

Remarks. Historically, few if any specimens were identified in collections as P. confederatus or P. tybeensis . Fall (1915) believed P. confederatus to be closely allied to P. relictus and P. tybeensis . While these three species are virtually indistinguishable externally, comparison of the aedeagal median lobe of the lectotypes reveals P. confederatus and P. tybeensis to be identical, and distinctly different from P. relictus .

After examining 70,000 specimens of Pachybrachis , I found less than five specimens identified as P. tybeensis , but none could be confirmed via dissection. In an attempt to locate additional specimens, I visited Tybee Island on 3 June 2016. Tybee is a barrier island of only 6.0 km 2 (2.3 mi 2), and I literally searched the entire island looking for specimens of P. tybeensis but was unsuccessful.

Distribution. This species is sparsely distributed across the eastern USA (Map 3A). New state records are confirmed for two states: Florida and Indiana.

Biological Notes. Labels documented specimens collected from beating Quercus sp. in Florida and in a pine barren in New York. A Malaise trap was reported as a collection method on a label .

Specimens Examined. See Appendix 17.

Figures

Fig. 17. Pachybrachis confederatus, 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, G) Median lobe of aedeagus, dorsal view.

Fig. 22. Pachybrachis species types, dorsal habitus. A) P. infaustus (female lectotype), B) P. atomus (female paralectotype), C) P. vestigialis (male lectotype), D) P. luctuosus (possible male syntype), E) P. carolinensis (male lectotype), F) P. tybeensis (male lectotype).