Female, CNC, UNITED STATES. Holotype locality: Archbold Biological Station, Highlands County, Florida, USA.

First label: U.S.A. FL: Highlands Co./Archbold Biol. Sta./1-8.vi.1987, D. B. Wahl/CNC489773.

1♀, 8 ♂ (CNC) from the same locality than holotype. Voucher codes: CNCHYM 01662, CNCHYM 01663, CNCHYM 01665, CNC483424, CNC489814, CNC654633–CNC654636. Collecting dates: 1–29.vi.1987 and 18–24.viii.1987, some specimens collected with Malaise trap and others with flight interception traps.

Microgaster archboldensis and M. syntopic are very distinct and unique among all known species of Microgaster from North America because of its color pattern, body size, and flagellomeres with three rows of placodes. The latter is the most important feature, as it had not been recorded from any known Nearctic species until now, and it was rather considered to characterize the different but related genus Hygroplitis (e.g., Mason 1981). However, M. archboldensis and M. syntopic clearly belong to Microgaster as they both have pectinated tarsal claws, pleated hypopygium, apical tarsomeres not enlarged, and body not partially depressed (whereas Hygroplitis has simple tarsal claws, inflexible hypopygium, apical tarsomeres enlarged and body partially depressed). Besides morphology, available DNA barcodes clearly place these new species within Microgaster and not Hygroplitis. Microgaster archboldensis can in turn be separated from M. syntopic because of different color of front and mid legs, part of propodeum, scutellar disc and metanotum (compare Figs 4A, C, F versus Figs 5A, C, E); longer ovipositor sheaths, body length and fore wing length; and some additional minor differences in mesopleuron sculpture, and number of costulae in scutoscutellar sulcus. From a molecular perspective (DNA barcoding), the two species differ in 27 base pairs (bp), which amounts to a rather significant difference of more than 4.5% bp (the available sequences for M. archboldensis represent almost complete barcodes with 626–627 bp, but the available sequences for M. syntopic are shorter at only 422–593 bp).

Female. Head and mesosoma mostly black (except for reddish-orange spots on posterior half of propodeum, posterior margin of scutellar disc and central part of metanotum); metasoma with T1–3 reddish-orange, T4+ orange-yellow, hypopygium mostly yellow to yellow-white; front legs entirely dark brown to black; mid legs almost entirely dark brown to black (except for coxa, trochanter and trochantellus, which are partially orange and partially dark brown); hind legs mostly orange (except for posterior 0.3 of metatibia, metatibial spurs and metatarsus which are dark brown to black); wings strongly infumated, pterostigma and veins dark brown to black. Flagellomere with three rows of placodes. Scutoscutellar sulcus with 5–6 costulae. Hypopygium pleated. Tarsal claws pectinate. Body measurements (mm). Body L: 5.2 (5.4); fore wing L: 5.3 (5.5); ovipositor sheaths L: 1.28 (1.30); metafemur L/W: 1.64/0.51 (1.70/0.54); metatibia L: 1.96 (2.02); metatibia inner/outer spurs L: 0.76/0.47 (0.76/0.51); first metatarsus segment L: 0.97 (0.96); F1/2/3/14/15/16: 0.40/0.41/0.42/0.21/0.18/0.20 (0.40/0.43/0.43/0.24/0.20/0.21).

Male. As female.

Three barcode-compliant sequences, representing BIN BOLD:AAZ7880 in BOLD.

United States: FL. Only known from the type locality, Archbold Biological Station.

Named after the Archbold Biological Station in Florida, US, to recognize the extraordinary fauna of Microgastrinae (and certainly of many other taxa) that it harbors and protects.

In spite of the relatively strong morphological and molecular differences, Microgaster archboldensis still seems very close to M. syntopic, and both are at least partially sympatric in central Florida. See Notes above (under Diolcogaster ichiroi) for more details on the conservation value of all these species.