Itaphlebia exquisita

Liu, Nan, Zhao, Yunyun & Ren, Dong, 2010, Two new fossil species of Itaphlebia (Mecoptera: Nannochoristidae) from Jiulongshan Formation, Inner Mongolia, China, Zootaxa 2420, pp. 37-45 : 39-41

Itaphlebia exquisita s p. nov.

( Figure 2 A–E, Figure 3 F–L)

Material. Holotype female, CNU-MEC-NN2009145-1 and CNU-MEC-NN2009145-2, positive and negative. Paratype, female, CNU-MEC-NN2009236.

Horizon and locality. Jiulongshan Formation, Middle Jurassic, Daohugou Village, Ningcheng County, Inner Mongolia, China.

Diagnosis. Costal area slightly broad. M with 5 branches. Cu1+M forked beyond the cross-vein cu1+mcu2.

Description. Antenna filiform, with 16 segments visible. Legs slender. Tibia with 2 tibial spurs at apex longer than femur. Tarsus with 5 tarsomeres; basitarsus approximately equal to half tarsus. Two claws at end of pretarsus. Surface of all legs covered with setae. Setae irregularly arranged.

In forewings, front edge of C somewhat convex. Costal area slightly broad. A distinct pterostigma present. Sc with 2 branches. Sc1 ending at C less than half length of forewing, and Sc2 terminating at C near pterostigmal area. One short cross-vein sc2-r1 before pterostigma. Cross-vein r1-r2 under pterostigma. Crossvein r3-r4 at same level of cross-vein r1-r2. Cross-vein r5-m1+2 approximately at middle of wing length. Crossvein r5-m1 before cross-vein r4-r5. Rs with 4 branches. Conspicuous thyridium at the fork of M. M with 5 branches. M1 with 2 branches (M1a, M1b). M3+4 divided beyond the fork of M1+2. Cross-vein m1+2-m3 between M1+2 and M3. Cross-vein m-cu not straight, somewhat S-shaped. Cu1 coalesced with M for a short distance and separated from M beyond cross-vein cu1+m-cu2. 1A and 2A almost parallel, one cross-vein a1-a2 between them. 3A absent.

Hind wings shorter than forewings. Sc simple, terminating at C much earlier before pterostigma. R1 curved under pterostigma and connected with C by a cross-vein c-r1. M1 divided into 2 branches in right hind wing, but not forked in left hind wing; Anal vein absent.

Abdomen of female with 11 segments, segments 9–11 distinctly smaller than segment 8. A pair of cerci at the end of abdomen, each one with 3 segments, basal segments fused the eleventh abdomen segment. Body length 9.3 mm; forewing length 10.2 mm, width 3.5 mm; hind wing length 8.7 mm, width 3.3mm.

Etymology. The specific epithet derives from Latin word exquisitus (exquisite), for its well-preserved condition.

Remarks. I.exquisita sp. nov. resembles I. multa in venation pattern: a distinct pterostigma, similar pattern of longitudinal veins, Rs 4-branched; and the same number and location of cross-veins. However, it differs from the latter by having M 5-branched in the forewings and right hind wing, although the left hind wing has M 4-branched. A 5-branched M, also seen in the paratype, appears to be a relatively stable character.

Figures

FIGURE 2. Itaphlebia exquisita sp. nov. A. Holotype, part CNU-MEC-NN 2009145 - 1; B. Holotype, counterpart CNU- MEC-NN 2009145 - 2; C. Middle leg; D. Paratype, CNU-MEC-NN 2009236; E. Portion of wings of paratype.

FIGURE 3. Itaphlebia exquisita sp. nov. Line drawings of holotype. A. Ventral view of body with wings; B. Dorsal view of body with wings. C. Left forewing; D. Left hind wing; E. Right forewing; F. Right hind wing; G. Left middle leg.