Exilibittacus plagioneurus, Liu, Sulin, Shih, Chungkun & Ren, Dong, 2014

Liu, Sulin, Shih, Chungkun & Ren, Dong, 2014, Four new species of hangingflies (Insecta, Mecoptera, Bittacidae) from the Middle Jurassic of northeastern China, ZooKeys 466, pp. 77-94 : 84-86

Taxon classification Animalia Mecoptera Bittacidae

Exilibittacus plagioneurus sp. n. Figs 8, 9

Etymology.

From Greek “plagios” (oblique) and “neuron” (vein), referring to oblique crossveins of the wings.

Holotype.

Female, CNU-MEC-NN2013013 P/C, in dorsal view. Abdomen length 8.3 mm, forewing length 9.3 mm with a maximal width of 2.3 mm; hind wing length 8.4 mm with a maximal width of 2.2 mm.

Horizon and locality.

Jiulongshan Formation, late Middle Jurassic, Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia, China.

Diagnosis.

Forewing Sc terminating at the anterior margin at the same level of the R4+5 forking; Vein 1A terminating at the posterior margin distad of the origination of Rs from R1.

Description.

Female, small-sized, head not preserved but mesothorax and metathorax preserved. Legs partially preserved, one hind leg with five tarsomeres present but the pretarsal claw not preserved, the fifth tarsomere folded against the fourth; the first and second tarsomeres with several spines. (Fig. 8 A–D)

Forewing. Wing narrow basally with obviously dark pterostigma. Sc long, reaching the anterior margin at the same level of the R4+5 forking; R1 not forking, one subcostal crossvein (Scv) between Sc and R1, Scv about 1/6 as long as the Sc length between Scv and the apex of Sc; one pterostigmal crossvein (Pcv) and one crossvein between R1 and R2+3; Rs with four branches, one crossvein between R3 and R4, one between R2+3 and R4 and one between R4 and R5; M with four branches, M4 base bending sharply; the 'bittacid cross’ aligned, the posterior part of the 'bittacid cross’ reaching M3 distad of the M3+4 forking point; two crossveins between R5 and M1, one between M1 and M2 and one between M2 and M3; Cu1 ending before the forking of R4+5, one crossvein between M4 and Cu1, one between Cu1 and Cu2; one short crossvein between Cu2 and 1A; 1A terminating at the posterior margin distad of the origination of Rs; 2A ending proximad of the originations of Rs and M, one crossvein between 1A and 2A (Fig. 9A, C).

Hind wing. Sc short, reaching the anterior margin before the forking of R4+5, one crossvein (Scv) between Sc and R1; R1 smooth and not sagging through the pterostigmal area; one pterostigmal crossvein (Pcv) present. Rs with three branches; one crossvein between R1 and R2, one between R2 and R3 and one between R3 and R4; M with three branches; two crossveins between R4 and M1, one between M1 and M2 and one between M2 and M3; the 'bittacid cross’ not aligned; one between M3 and Cu1 and one between Cu1 and Cu2. Vein 1A terminating at the posterior margin distad of the origination of Rs, one crossvein between Cu2 and 1A (Fig. 9B, D).

Abdomen. Ten segments visible, genital segments not preserved (Fig. 8 A–C).

Remarks.

Exilibittacus plagioneurus sp. n. (Figs 8, 9) is assigned to Exilibittacus Yang, Ren & Shih, 2012 based on the following generic diagnostic characters: in forewing, Sc reaching the anterior margin at the same level of the forking of R4+5 and the 'bittacid cross’ aligned, and in hind wing, M with three branches. The new species is differentiated from Exilibittacus lii and Exilibittacus foliaceus sp. n. by characters shown in the key below.