Adamsochrysa is an extinct neuropteran genus in the green lacewing family Chrysopidae which is solely known from Eocene sediments exposed in northwestern North America. The genus contains two described species, the type species Adamsochrysa aspera along with Adamsochrysa wilsoni. An additional three specimens have been provisionally placed into the genus as Adamsochrysa Sp. A, Adamsochrysa Sp. B, and Adamsochrysa indet. The genus is placed into the green lacewing subfamily Nothochrysinae and considered as probably closest in relation to the living Australian and Tasmanian genus Dictyochrysa.
Distribution
Adamsochrysa fossils have been found at three sites belonging to the Eocene Okanagan Highlands of Washington and British Columbia. Of the two described species and several unnamed specimens, Adamsochrysa aspera and one tentative Adamsochrysa specimen are from the Tranquille Formation's McAbee Fossil Beds west of Cache Creek in central British Columbia. The lake sediments at McAbee were first radiometrically dated using the K-Ar method in the 1960s based on ash samples exposed in the lake bed. These samples yielded an age of ~; however, dating published in 2005 provided a 40Ar-39Ar radiometric date placing the McAbee site at .
The second named species and one unnamed specimen are known exclusively from fossils of the Klondike Mountain Formation exposed at Republic in Ferry County, northeast Central Washington. The named species, Adamsochrysa wilsoni is known only from the "Boot Hill" site UWBM B4131, while Adamsochrysa Sp. A is only known from the "Corner lot" site A0307. Tuffs of the Klondike Mountain Formation had been dated to , the youngest of the Okanagan Highlands sites, though a revised oldest age of was given based on isotopic data published in 2021. A final unnamed specimen, deemed Adamsochrysa Sp. B was recovered from the upper layers of Driftwood Shales in Driftwood Canyon Provincial Park, near Smithers, British Columbia. The same 2005 dating paper established the shales at Driftwood, which had not been formally described, as dating to around in accordance with the other sites of the highlands, a date supported by the presence of the hedgehog-relative Silvacola from the same site.
History and classification
Green lacewings are the second most common neuropterid lacewing family, with only antlions and kin being more diverse. The first report of Chrysopidae from the Okanagan highlands was in a 1995 article by Wesley Wehr and Lisa Barksdale where they noted the family to be present in the Klondike Mountain Formation. The next mention was by Bruce Archibald and Vladimir Makarkin in 2006, where they described the highlands Giant Lacewings, with a brief note on the recovery of the Fur Formation genus Protochrysa in the Okanagan Highlands. However neither of the mentions went into detailed taxonomic assessment and the group was left alone for several more years. In 2013 Makarkin and Archibald released a study of over 20 Chrysopid fossils from the highlands, with the description of six new species in 5 named genera, three of which were new as well.
Adamsochrysa was identified from the type species and an additional species plus several other species all preserved as compression fossils. The name of the genus was created as a combination of the traditional chrysopid genus ending chrysa, along with the surname "Adams". They noted the name was in honor of noted American neuropterologist Phillip Anthony (1929–1998). The type species Adamsochrysa aspera was described based on a holotype, number "CMNIF25", which along with one paratype was housed in the Canadian National Museum of Natural Sciences collections at Ottawa, Canada. The five other identified paratypes were all accessioned into the paleontology collections of Thompson Rivers University in Kelowna, British Columbia. The species has a species name derived from "asper", a Latin adjective meaning "difficult or hard", in reference to the difficulty at times in obtaining the lacewing specimens. The second named species, Adamsochrysa wilsoni, was described from a single type specimen holotype, number "SR 06-23-01", which was preserved in the Stonerose Interpretive Center paleoentomological collection. Makarkin and Archibald state the species was given a patronymic specific name which recognized the finder of the holotype, Gregg Wilson. Additionally the authors identified two specimens that were not well enough preserved to confidently ascribed to an Adamsochrysa species or name as new species, they were instead detailed as Adamsochrysa species A and Adamsochrysa species B.
Makarkin and Archibald (2013) placed the new genus into the lacewing family Chrysopidaes subfamily Nothochrysinae. The placement was based on a series of characters in the forewings. The Psm vein consists of a slightly modified series of crossveins running from a basal area to the middle region of the wing where a break happens, while in the subfamilies Apochrysinae and Chrysopinae the Psm continues uninterrupted to the apical area. The location of the 2m-cu crossvein as either to the basal side of the im cell or merging along the basal section of the cell is found in nothochrysines but not the extinct subfamily Limaiinae where the merge happens consistently along the apical region of the cell. Given the overall vein structure of the wings, it was suggested that the closest relative to Adamsochrysa is the living genus Dictyochrysa which lives only in Australia and Tasmania now.
Description In general the wings of nothochrysine lacewings have a Psm formed from the altered upper gradate series of crossveins that does not extend to the apical region continually. The wings are lacking a tympanal organ, which is found in the modern subfamilies Apochrysinae and Chrysopinae. The forewing has a basal jugal lobe, which is only seen well developed in nothochrysine and Limaiime chrysopids, while they are either absent or reduced in Apochrysinae and Chrysopinae. The forewings have the "2m-cu" crossvein merging along the basal section of the "im cell", while it is absent in Apochrysinae, and merges in the apical region of the cell in Limaiinae. A frenulum is located along the basal fore edge of the hind wings, a feature missing or smaller in Apochrysinae and Chrysopinae.
In Adamsochrysa the overall wing venation pattern is most like Dictyochrysa. The key differences are the much more basal location of the first crossvein in the anterior gradate series for Adamsochrysa. In Dictyochrysa the plcement if closer to the wing apex. The majority of the radial crossveins are structured into four to five successive distinct gradate series Adamsochrysa, but are a reticulated mesh structure in Dictyochrysa. In the former the radial crossveins do not fully reach the Rs forks, while in the latter they do.
Additionally along the hind margins of Adamsochrysa? sp A structures that are interpreted to be possible trichosors are present. Trichosors are a feature found in a number of neuropteran families, but are considered absent in Chrysopidae as a rule. Consisting on thickenings along the wing margins from which one to several hairs sprout, trichorsors are typically placed at the terminations of wing veins in the wing margin. Given that trichorsors have not been detected on any of the other Adamsochrysa specimens, there is the possibility that Adamsochrysa? sp A may belong to a yet undescribed genus instead.
Adamsochrysa aspera Adamsochrysa aspera heads are smallish with long palpi around the mouthparts. The antennae have an inflated scape at the base and a stout pedicellus connecting the scape to the basal flagellomere that is nearly the same proportions as the flagellomere. The apical flagellomere segments are all between 2 and 2.5 times as long as they are wide. The thorax is only partially visible, with a short prothorax and indistinctly preserved mesothorax. The abdomen is fully preserved but not distinct, the terminal genitalia are noted to be similar in general appearance to Dictyochrysa terminalia. The legs are noted to be distinctly hairy.
The forewings range between long and wide with a probable hyaline coloration during life. The costal space, between the Costal vein along the fore margin of the wing, and the subcostal (Sc) vein is faired to a degree and has regularly spaced subcostal veinlets crossing it. Some of the veinlets are forked with different numbers on each forewing of a specimen. The Sc is long rung the wing length and terminating in the wing margin near the wing apex. The Radial 1 (R1) is of similar length and runs a mostly parallel course to the Sc, also terminating in the apical margin. Where they are preserved on wings, the space between the Sc and R1 have up to 20 crossveins basal to the pterostigmal area. The Rs branches off the R1 around the base region of the im cell, and runs a zigzag course into the wing apex branching between 22 and 24 times. The banches form a reticulate series of cells in the central area of the wing. The im cell is generally broad with up to seven sides.
Of the hind wing, less is known, with a single mostly complete wing described for the species. The length as preserved is and a full length that was estimated between . The width is at the deepest giving the hind wing an overall smaller and thinner outline than seen in the forewings. The costal space is narrower than in forewings and has widely spaced simple crossveins in the section before the perostigma. The Sc is incompletely preserved while the R1 is full, running into margin just shy of the wing apex. the Psc vein is distinctly developed and has a slight zig-zag along its length. There are a total of four gradate crossvein series developed in the central section of wing.
Adamsochrysa wilsoni The single known Adamsochrysa wilsoni wing is by , thus smaller than A. aspera and Adamsochrysa. sp A wings but similar in length to A. sp B. As with the other species the forewing was likely fully hyaline in life. The costal space is flared mildly and there are rather widely space crossveinlets in the space basal to the pterostigma, while the veinlets apical of the pterostigma are more densely packed. Both the Sc and R1 ae long and like A. aspera terminate along the apical margin and near the wing apex respectively. The space between the Sc and R1 and then the Sc and the costal margin are all noted to be narrow. The Rs vein begins closer to the wing base than in A. aspera and there are 24 total branches. The space between the R1 and Rs is narrow in both the base and apical sections, but widens during the middle stretch, while the crossveins between the two are closely spaces for the full length of the space. In contrast to A. aspera the im cell is elongated into a subtrapezohedral outline, rather than being a squat seven sided outline. In A. wilsoni the terminal sections of the Median (M) and Rs branches near the wing base enter the Psc vein at an acute angle, but in Adamsochrysa . sp A the veins terminate at wider obtuse angles. The Median Posterior (MP) and Cubitus Anterior (CuA) veins form parallel sides of the cell adjoining the im cell where the MP vein is shared between the two cells. This cell has subparallel sides in Adamsochrysa . sp B where the two veins are diverging from each other distinctly. The There are a total of either five or six gradate crossvein series traversing the A. wilsoni wing, though only the outer most is complete. All the series are irregular in course and there are up to 20 visible crossveins on the outer series. The Pseudo-cubital (Psc) and pseudo-median (Psm) veins are both present and zig-zagged in course, but only the Psc is distinctly developed and it straightens from the zig-zag course in its basal section. Its estimated the CuA vein has between four an five branches, while the CuP only had two elongated branches.
Unnamed species