Two new species of Trichoceridae from the Middle Jurassic Jiulongshan Formation of Inner Mongolia, China

Abstract Two new species, Eotrichocera (Archaeotrichocera) longensis sp. n. and Eotrichocera (Archaeotrichocera) amabilis sp. n. of Trichoceridae are described based on a combination of the following characters: Sc ending proximad of the forking of R2, shape of d cell and A2 rather short and bending sharply toward posterior margin. These fossil specimens were collected from the Middle Jurassic Jiulongshan Formation of Daohugou in Inner Mongolia, China.


Materials and methods
The wing venation nomenclature used in this paper is based on the interpretations and system proposed by Lukashevich (2004) and Krzemińska et al. (2009a). The fossil specimens were examined under a Leica MZ7.5 dissecting microscope and illustrated with the aid of a drawing tube attachment. Line drawings were prepared with Adobe Photoshop CS3 Extended graphics software. All specimens studied in the paper are housed in the Key Lab of Insect Evolution and Environmental Changes, College of Life Sciences, Capital Normal University, Beijing, China.  Etymology. "longensis" is a Latin word, referring to the long leg of this specimen. Diagnosis. Sc rather short about 0.65 times as long as the wing and ending at anterior margin proximad of R 2 ; Rs forking proximad of 2/3 (at about 0.55) times of wing length; the d-cell narrow and long (about 2.5 times as long as wide); A 2 short and bending sharply toward anterior margin (angle about 128°).
Holotype. An almost complete female specimen with well-preserved body, wings and head. Specimen number CNU-DIP-NN2013133. Wing length 9.0 mm, width 3.8 mm (Figs 1A, 2, 3A).  Description. Based on Holotype, different characters of the paratype CNU-DIP-NN2013131 in brackets. Medium-sized winter crane flies, body length (including head) 13 mm with well preserved wings, body and head, [paratype body length (excluding head) 10.5 mm].
Head: Antenna very long, about 3.5 times as long as the head length, palpi about two times as long as the head length, compound eyes preserved. Thorax: Much higher, in lateral view, than that of the abdomen, subcircular in shape, with robust and well-developed mesonotum. The halters spoon-type and the length of halters as long as thorax.
Wings: Wing is shorter than abdomen, not covering the end of the abdomen. Length 9.0 mm [Paratype with wing length of 7.7 mm], narrow and long (about 2.5 times as long as wide); venation clear, Sc rather short about 0.68 times as long as the wing [Paratype Sc rather short, about 0.65 times as long as the wing] and ending at anterior margin proximad of R 2 ; crossvein sc-r locating at 2/3 of Rs; Rs arising about one-fifth from the base of the wing; R 2+3 about 0.8 times as long as R 2+3+4 ; R 2 about one-tenth of length of R 3 ; R 3 almost three times as long as the R 2+3 ; dM 1+2 0.6 times as long as mM 1+2 , while M 1 2.5 times of the dM 1+2 ; a well developed m-m crossvein about three-fourth length of bM 3 , closing the d-cell and nearly 0.3 length of d-cell; bM 1+2 nearly 1.0 times as long as the length of the r-m and the latter at one-fifth of the d-cell; d-cell narrow and long (about 2.5 times as long as wide) and almost one-fifth length of wing; both crossveins m-m and m-cu intersecting with M 4 at the same point; Cu long, curved (angle about 135°) and reaching the wing posterior margin at 0.6 from the base of the wing; the stem of A divided into A 1 and A 2 ; A 1 long, slightly curving and reaching the wing posterior margin; A 2 short, 0.15 (right wing) [Paratype 0.14] times as long as wing and almost 0.3 times as long as length of A 1 , bending sharply (angle about 128°) and reaching the wing posterior margin.
Legs: Legs slender and long; the hind leg nearly 1.2 times as long as the abdomen and 1.3 times as long as the wing. Tarsus with five segments; the first segment of tarsus (t 1 ) is 1.2 times as long as t 2 in mid leg.
Abdomen: Abdomen relatively long and thin, with ten segments. Female genital discernible.
Remarks. Eotrichocera (Archaeotrichocera) longensis sp. n. is assigned to Thrichocerinae based on the following characters: d-cell medium, m-cu present; A 2 short, antennae long, flagellomeres thin, much longer than two times of the head length. It belongs to Eotrichocera (Archaeotrichocera) because of wing length from 7.7 to 9.0 mm and d-cell almost one-fifth of wing length. In addition, it differs from all other known Thrichocerinae by its A 2 rather short and bending sharply toward anterior margin (angle about 128°), R 2 relatively long, Sc forking proximad of 2/3 (at about 0.55) times of wing length, and d-cell narrow and long. To compare the key characters among the new species and other species of Eotrichocera (Archaeotrichocera), we set up the Table 2.
Diagnosis. Body small and wing short; Sc 0.71 times as long as wing; the d-cell broad (about 1.7 times as long as wide); A 2 short and bending sharply toward posterior margin (angle about 128°).
Description. Based on Holotype, different characters of the paratype CNU-DIP-NN2013132 in brackets. Medium-sized winter crane flies, head length 0.47 mm, body length (including head) 5.8 mm with well preserved body and wings. [Paratype with partial body and wings with partial venation].
Head: antenna very long, about 5.7 times as long as the head length, palpi about two times as long as the head length, compound eyes preserved (Figs 4C, 6).
Thorax: Much higher, in lateral view, than that of the abdomen, subcircular in shape, with robust and well-developed mesonotum.
Wings: Wing is shorter than abdomen, not covering the end of the abdomen. Wing length of 5.2 mm [Paratype with wing length 5.0 mm], narrow and long (L/W=2.2); ve- . Eotrichocera (Archaeotrichocera) amabilis sp. n. Holotype, specimen CNU-DIP-NN2013134 A Photograph B Photograph, under alcohol C Line drawing D Tarsus of the mid leg. Paratype, specimen CNU-DIP-NN2013132 E Photograph. Scale bars = 1 mm; t 1 = the first segment of tarsus; t 2 = the second segment of tarsus. nation clear, Sc rather short about 0.71 times as long as the wing and terminating clearly proximad of R 2 ; crossvein sc-r locating at 1/3 [Paratype 1/2] of Rs, and distad to the Sc ending; [Paratype Rs arising about one-fourth from the base of the wing]; Rs forking at 0.55 [Paratype 0.64] times of wing length; R 2+3 about 1.9 times as long as R 2+3+4 ; R 2 about 0.18 of length of R 3 ; R 3 almost 3.7 times as long as the R 2+3 ; R 5 9.0 times as long as R 2+3+4 ; M 1 1.6 times of the dM 1+2 ; crossvein m-m well developed about 0.73 times as long as bM 3 , closing the d-cell and nearly 0.17 [Paratype 0.21] times as long as wing; bM 1+2 nearly 2.1 times as long as the length of the r-m and the latter at one-fourth of the d-cell; d-cell broad (W/L=0.58 [Paratype 0.56]) and almost 0.17 times of length of wing; Cu long, curved (angle about 121°) and reaching the wing posterior margin at 0.67 from the base of the wing; the stem of A divided into A 1 and A 2 ; A 1 long, slightly curving and reaching the wing posterior margin; A 2 short, 0.13 times as long as wing and almost 0.25 times as long as length of A 1 , bending sharply and reaching the wing posterior margin.
Legs: Legs slender and long; the hind leg nearly 1.5 times as long as the abdomen and 1.4 times as long as the wing. Tarsus with five segments; the first segment of tarsus (t 1 ) is 1.2 times as long as t 2 in mid leg.
Remarks. The new species is compared and differentiated from all other species in Eotrichocera (Archaeotrichocera) in Table 2.  Due to limitation of fossil preservation, some of the morphological characters of previously described fossil are not objective or clear. We set up an aforementioned key based on the Sc length and ending location at anterior margin, wing length, crossvein sc-r position, Rs forking location and A 2 length, to differentiate the species of subgenus Archaeotrichocera. These characters may help future morphological and taxonomic studies in differentiating fossil species of Trichoceridae.