Microrhopala excavata
Creators: name: Eiseman, Charles S.
name: Feldman, Tracy S.
name: Palmer, Michael W.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Chrysomelidae
Microrhopala
Microrhopala excavata

description: Microrhopala excavata (Olivier)
(Figs. 11, 53–56, 135–136)
Reared specimens. COLORADO: Fremont Co., Bear Creek, Forest Rd. 101, off of 49 Rd, 7.vii.2015, em. by 19.vii–2.viii.2015, C.S. Eiseman, ex Solidago, # CSE1718 (6 adults, MLBM); MAINE: Hancock Co., Gouldsboro, Chicken Mill Pond Rd., 2.viii.2019, em. 2–14.viii.2019, C.S. Eiseman & K. Fowler, ex Euthamia graminifolia, # CSE5746 (2 adults, MLBM); MASSACHUSETTS: Franklin Co., Northfield, 276 Old Wendell Rd., 25.vii.2017, em. 12.viii.2017, C.S. Eiseman, ex Solidago rugosa, # CSE4112 (1 adult, ZFMK); 4.viii.2017, em. 4.ix.2017, # CSE4223 (2 adults, ZFMK); Middlesex Co., Townsend, 42.699173, -71.664734, 20.vii.2017, em. 7.viii.2017, C.S. Eiseman, ex Doellingeria umbellata, # CSE4089 (2 adults, ZFMK).
Collected specimen. MASSACHUSETTS: Worcester Co., Gardner, Old Matthews Rd (42.597124, -71.965425), 14.vi.2017, C.S. Eiseman, on Doellingeria umbellata, # CSE3819 (1 adult, ZFMK).
Hosts. * Asteraceae: Doellingeria umbellata (Mill.) Nees, Euthamia graminifolia (L.) Nutt., Solidago sp. (subsect. Triplinerviae), S. rugosa Mill. Ours are the first definite rearing records for Microrhopala excavata; Grant (1969) found adults in association with an empty leaf mine on Heterotheca villosa (Pursh) Shinners in British Columbia. All other previous host records for this species appear to refer only to caught adults; these include Doellingeria umbellata, Helianthus L., H. strumosus L., Rudbeckia missouriensis Engelm. ex C.L. Boynton & Beadle, Solidago sp., S. drummondii Torr. & A. Gray, S. petiolaris Aiton, S. ulmifolia Muhl. ex Willd., and Symphyotrichum praealtum (Poir.) G.L. Nesom (Asteraceae) (Douglass 1929; Walker 1936; Riley & Enns 1979; Clark 1983; Ford & Cavey 1985; Clark et al. 2004). Helianthus annuus L. has been listed as a host for this beetle based on Hilgendorf & Goeden (1981), but their record is based on Walker (1936), who did not specify which of his observations involved H. annuus rather than other Helianthus spp. We have found a possible M. excavata mine on Solidago odora Aiton in North Carolina (BG 1681380).
Biology. The egg is invariably laid singly on the lower leaf surface and at the leaf margin, and covered with dark brown to blackish excrement (Fig. 11). An adult was found in Massachusetts on 14 June in association with three such eggs. The mine is full-depth, with the frass mostly in long, dark strands that are densest in a roughly circular area adjacent to the egg that ultimately becomes a blisterlike swelling where pupation takes place (Figs. 53–56). This does not always form a solid black spot as in the mine of Microrhopala xerene (Newman). Our Colorado material belongs to the subspecies M. excavata cyanea (Say) and was reared from leaves of basal rosettes of an undetermined three-nerved Solidago species (Figs. 53, 134). Each mine was formed at the leaf apex but was otherwise consistent with mines of the nominate subspecies; the lower leaf surface was not photographed, so we cannot confirm the egg location, but the circular concentration of frass was adjacent to the leaf margin in each case, suggesting the egg placement is the same in this subspecies.
Parasitoid. Conura odontotae (Howard) (Chalcididae) was reared from a mine of M. excavata on Solidago rugosa (CSE4142, UFES).
Notes. Our six barcoded specimens, all from Massachusetts, constitute the BIN BOLD:ADP0789. Its nearest neighbor, differing by 4.17%, is BIN BOLD:ABA6340, which comprises four Ontario specimens of M. excavata. Unfortunately our specimens of M. excavata cyanea from Colorado were not barcoded.
description: Published as part of Eiseman, Charles S., Feldman, Tracy S. & Palmer, Michael W., 2024, New larval host records, parasitoid records, and DNA barcoding data for North American leaf-mining leaf beetles (Coleoptera: Chrysomeloidea), pp. 1-60 in Zootaxa 5549 (1) on page 20, DOI: 10.11646/zootaxa.5549.1.1, http://zenodo.org/record/14387856