| Republica weatbrooki | |
|---|---|
 | |
| holotype wing | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Odonata |
| Suborder: | Zygoptera |
| Family: | Euphaeidae |
| Genus: | †Republica |
| Species: | †R. weatbrooki |
| Binomial name | |
| †Republica weatbrooki Archibald & Cannings, 2022 | |
Republica is an extinctzygopteran genus in thedamselfly familyEuphaeidae with a single described species,Republica weatbrooki. The species is solely known from theEarly Eocene sediments exposed in the northeast of the U.S. state ofWashington.
Republica weatbrooki is known from a single location in theEocene Okanagan Highlands, an outcrop of theYpresianKlondike Mountain Formation inRepublic.[1] Theholotype was recovered from theUWBM site B4131, which is designated thetype locality, on May 24, 2006. Modern work on the fossil-bearing strata of the formation viaradiometrically dating has given an estimated age in the LateYpresian stage of the early Eocene, between49.4 ± .5 million years ago at the youngest,[2] with an oldest age estimate of51.2 ± 0.1 million years ago, given based ondetritalzircon isotopic data published in 2021.[3]
Republica weatbrooki was identified from only thetype specimen, theholotype, number SR 06–59–08, which is acompression fossil preserved in theStonerose Interpretive Centerpaleoentomological collection. The holotype was found at the Klondike Mountain Formations "B4131" locality,[1] also called the "Boot hill" site.[4] The fossil was described by paleontologist S. Bruce Archibald and entomologist Robert Cannings in 2021 and they coined thespecific epithetweatbrooki as apatronym honoring Alex Weatbrook who found the fossil and donated it to Stonerose. They chose the genus name as aLatinized feminine form of the city name Republic.[1]
Archibald and Cannings (2022) placed the new genus into the damselfly familyEuphaeidae, extending the known range of the fossil lineage in the family to the Ypresian northwestern North American. The placement was based on the angle and thickened appearance in the quadrangle cells distal wall, densely reticulate venation, plus a smoothly "S"-curved CuA vein, which match Euphaeidae while being contrary to the familyZacallitidae. Within Euphaeidae,Republica was placed in subfamilyEodichromatinae based on the presence of enlarged and thickened Ax1 and Ax2 veins near the base of the wing. Of the members of Eodichromatinae, the closest genus toRepublic seems to beLabandeiraia, known from Ypresian species described from theGreen River Formation in North America and theFur Formation andOise Amber in Europe.[1][5] Modern Euphaeidae species are found in theAustralasian,Indomalayan, andPalearcticbiogeographic realms, while the known fossil record restricted to Europe and North America.[1]
With the naming of the genus, Archibald and Cannings created ahemihomonym. The damselfly is the second Klondike Mountain Formation genus namedRepublica with the enigmatic plantRepublica being named byJack Wolfe andWesley Wehr in 1987.[6][1]
The only known forewing is 40.7 mm (1.60 in) long and 10.4 mm (0.41 in) at its widest giving it a length to width ratio of 3.9, narrower than several other eodichromatines. The length between wing base and nodus is 14.0 mm (0.55 in) while the length topterostigma is 33.3 mm (1.31 in). The pterostigma is elongate, being 4.0 mm (0.16 in) long and only 0.7 mm (0.028 in) wide, and has slanted cell walls on both the basal and apical sides.[1]
Due to poor preservation of the finer venation of the wing, many of the delicate crossveins between more robust major veins are missing making total vein counts impossible from the holotype. The space between the Costa, which forms the frontal wing edge, and the Subcosta has at least 26 crossveins and likely more, all positioned between the Ax1 crossvein near the wing base and thenodus. Both the An isolated crossvein is present between the Ax1 and Ax2 veins of the other C-Sc space, both of which are distinctly more robust than any crossveins in the space.[1]
The wing was possibly slightly darkened across the basal region of the wing, with a lighter to hyaline window across the apical 1/3 of the wing surrounding a darkened tip area. However Archibald and Cannings noted the possibility of this "coloration" being a result of preservation artifacts and not coloration during life.[1]
The formation preserves an upland lake system surrounded by a mixed conifer–broadleaf forest with nearby volcanism.[7] The pollen flora has notable elements ofbirch andgolden larch, and distinct trace amounts offir,spruce,cypress, andpalm.[8] Wolfe and Tanai (1987) interpreted the forest climate to have beenmicrothermal,[9][6] having distinct seasonal temperature swings which dipped below freezing in the winters. However, further study has shown the lake system was surrounded by a warm temperate ecosystem that likely had amesicupper microthermal tolower mesothermal climate, in which winter temperatures rarely dropped low enough for snow, and which were seasonably equitable.[8][10]
The Okanagan highlands paleoforest surrounding the lakes have been described as precursors to the moderntemperate broadleaf and mixed forests of Eastern North America and Eastern Asia. Based on the fossilbiotas the lakes were higher and cooler than thecoeval coastal forests preserved in thePuget Group andChuckanut Formation of Western Washington, which are described aslowland tropical forest ecosystems. Estimates of thepaleoelevation range between 0.7–1.2 km (0.43–0.75 mi) higher than the coastal forests. This is consistent with the paleoelevation estimates for the lake systems, which range between 1.1–2.9 km (1,100–2,900 m), which is similar to the modern elevation 0.8 km (0.50 mi), but higher.[10]
Estimates of themean annual temperature for the Klondike Mountain Formation have been derived fromclimate leaf analysis multivariate program (CLAMP) analysis andleaf margin analysis (LMA) of the Republicpaleoflora. The CLAMP results after multiple linear regressions for Republic gave a mean annual temperature of approximately 8.0 °C (46.4 °F), while the LMA gave 9.2 ± 2.0 °C (48.6 ± 3.6 °F). This is lower than the mean annual temperature estimates given for the coastal Puget Group, which is estimated to have been between 15–18.6 °C (59.0–65.5 °F). The bioclimatic analysis for Republic suggests mean annual precipitation amounts of 115 ± 39 cm (45 ± 15 in).[10]
Media related toRepublica at Wikimedia Commons