Research Article |
Corresponding author: Xiaodan Lin ( 994239@hainanu.edu.cn ) Corresponding author: Dong Ren ( rendong@mail.cnu.edu.cn ) Academic editor: Nina Sinichenkova
© 2022 Yizi Cao, Xiaodan Lin, Chungkun Shih, Dong Ren.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Cao Y, Lin X, Shih C, Ren D (2022) Two new species of Itaphlebia (Insecta, Mecoptera, Nannochoristidae) from the late Middle Jurassic of China. ZooKeys 1108: 175-188. https://doi.org/10.3897/zookeys.1108.85378
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Two new species of Itaphlebia Sukatsheva, 1985, I. procera sp. nov. and I. elegana sp. nov., are described and illustrated from the latest Middle Jurassic Jiulongshan Formation of Daohugou, Inner Mongolia, China. Based on fossil specimens with wings, these new species are established and assigned to Itaphlebia by a combination of three forewing characters: Sc with three branches ending at C, the four-branched Rs (R2 to R5) originating distad of M (vs. three-branched RS (R2+3 undivided) in all other fossil and extant nannochoristids), and M forking with four branches; and a hind wing character of Sc simple and short, terminating at C well before the pterostigma. Furthermore, this is the first report of long and robust setae present on the anal veins of the forewing for I. elegana sp. nov. in fossil Nannochoristidae.
Insect fossil, Jiulongshan Formation, nannochoristid, taxonomy
Mecoptera Packard, 1886 is an order of insects, comprising nine extant families with more than 600 species (
Due to limited specimens of well-preserved compression fossils for nannochoristids, it was difficult to study detailed morphological characters to classify, diagnose and describe species or genera of these specimens. Therefore, the classifications of fossil species and genera of Nannochoristidae are in a state change and revision. So far, six genera: Dahurochorista Sukatsheva, 1985, Dahurolarva Sukatsheva, 1985, Itaphlebia Sukatsheva, 1985, Namdyrus Sukatsheva, 1993, Tarantogus Sukatsheva, 1985, and Undisca Sukatsheva, 1990, and one subgenus: Eunannochorista Novokshonov, 1997, from the Middle Jurassic and the Lower Cretaceous have been described (
All specimens were collected from the Jiulongshan Formation at Daohugou Village of Ningcheng County in Inner Mongolia. This locality is one of the richest Middle Jurassic fossil-bearing sites in China. The Jiulongshan Formation has yielded abundant and diverse mecopteran fossils (
The new type specimens are collected from the latest Middle Jurassic, Jiulongshan Formation; Daohugou Village, Shantou Township, Ningcheng City, Inner Mongolia, China and housed in the insect fossil collection of the Key Laboratory of Insect Evolution and Environmental Changes, College of Life Sciences, Capital Normal University, Beijing, China (
These specimens were examined and photographed using a LEICA M165C dissecting microscope with a LEICA DFC 500 digital camera system with cool white transmitted light from double optical fibers, irradiating the specimens from two sides simultaneously, and illustrated with the aid of a drawing tube attachment. Enlarged photos were taken by using a Nikon SMZ 25 microscope with a Nikon DS-Ri 2 digital camera system. The line drawings were edited with Adobe Photoshop CS5. We use the venational nomenclature of
Order Mecoptera Packard, 1886
Family Nannochoristidae Tillyard, 1917
Chrysopanorpa Ren, 1995, p. 91.
Netropanorpodes Sun, Ren & Shih, 2007, p. 867.
Stylopanorpodes Sun, Ren & Shih, 2007, p. 865.
Protochoristella Sun, Ren & Shih, 2007, p. 405.
Small to moderately-sized insect (forewing length 5.1–15.4 mm); body slender; wing nearly oval or rounded apically. Forewing: Sc with two or three branches ending at C; Rs (R2 to R5) origination distad of M origination; Rs forking with four (in some cases with five) branches; M forking with four (in some cases with five) branches. Hind wing: Sc simple and short, terminating at C well before pterostigma; Rs forking with four branches; M forking with four branches (in some cases with five).
Itaphlebia completa Sukatsheva, 1985
Type species, I. ruderalis comb. (= Chrysopanorpa ruderalis Ren, 1995 = Stylopanorpodes eurypterus Sun, Ren & Shih, 2007 = Protochoristella formosa Sun, Ren & Shih, 2007), I. jeniseica Novokshonov, 1997 (= Netropanorpodes sentosus Sun, Ren & Shih, 2007), I. multa Novokshonov, 1997 (= Protochoristella polyneura Sun, Ren & Shih, 2007), I. reducta Novokshonov, 1997, I. sharovi Novokshonov, 1997, I. generosa Novokshonov & Sukatsheva, 2003, I. decorosa comb. (= Netropanorpodes decorosus Sun, Ren & Shih, 2007), I. exquisita Liu, Zhao & Ren, 2010, I. laeta Liu, Zhao & Ren, 2010, I. longiovata Cao, Shih, Bashkuev & Ren, 2015, I. amoena Cao, Shih, Bashkuev & Ren, 2015, I. procera sp. nov. and I. elegana sp. nov.
The specific name is derived from the Latin adjective “procerus”, indicating the relatively large body size.
Holotype
: sex unknown, No. CNU-MEC-NN2009273 (Fig.
All specimens were collected from the Jiulongshan Formation, latest Middle Jurassic age (Bathonian–Callovian boundary interval) from Daohugou Village, Ningcheng County, Inner Mongolia Autonomous Region in China.
Body size ca 10 mm. On forewing, Sc forking with three branches; R2+3 forking before M1+2; crossvein r4-r5 before crossvein r5-m1; Cu1+M forking before the crossvein cu1-cu2; and crossvein cu1-m4 after M3+4 forking.
Mainly based on Holotype, unless indicated as paratype.
Head : Oval with large compound eyes. Antenna partially preserved, filiform with 33 and 27 segments as preserved respectively. Vertex of the head raised, mouthparts long and slender.
Thorax : Long and relatively well-preserved, pronotum (width 0.5 mm, length 0.25 mm), mesonotum (width 1.5 mm, length 1.25 mm), metanotum (width 1.25 mm, length 1.4 mm) and scutellum (heavy shadowed) clearly discernible.
Leg : Leg barely preserved and slender, tibia longer than femur, surfaces of all legs densely covered with short and irregularly arranged setae.
Wing : Forewing: Long and oval, basal part of the wing narrow, gradually broadening from the base toward the apex. Right forewing with the anterior area broad, a distinct pterostigma present; Sc with 3 branches, Sc1 and Sc2 ending at C before the middle of the wing length, Sc3 terminated at C right near pterostigmal area; R forking before Sc2, Rs forking with 4 branches, one short crossvein sc-r before pterostigma, crossvein r1-r2 under the pterostigma, approximately near the forking of R2+3, crossvein r3-r4 after the level of the crossvein r1-r2, R2+3 4 times as long as R4+5, crossvein r5-m1+2 emerged after the forking of R4+5, oblique crossvein r5-m1 present after the crossvein r4-r5; conspicuous thyridium at the forking of M; M with 4 branches, M3+4 divided beyond the forking of M1+2; straight crossvein m1+2-m3 between M1+2 and M3, near the forking of M1+2; crossvein m-cu1 after the forking of M3+4, somewhat S-shaped; Cu1 coalesced with M for a long distance and separated from M after the crossvein cu1-cu2; A1 and A2 are almost parallel; crossvein a1-a2 after the level as the base of Cu1; A3 absent. Hind wing: Shorter than forewing; the pterostigma slightly darkened. Sc simple, terminated at C in the first one third of wing, one crossvein c-r1 present at half-length of hind wing; R1 under pterostigma and connected with C by a short crossvein c-r1; posterior and anal margins in hind wings not preserved.
Abdomen : With six visible large abdominal segments, segments II–IV and segment VI distinctly smaller than segment V, the distal segments not preserved.
The new species shows great differences from other species of Itaphlebia in having relatively moderate body size, a broader thoracic notum and the presence and position of the crossvein r5-m1 that is in a more distal position than in other species, which is also a new finding for nannochoristid venation. So far, we have found two specimens of the new species, of which characters appear to be stable and therefore sufficient for establishing a new species.
(in mm). Holotype: No. CNU-MEC-NN2009273: head length 0.7 (excluding the antenna), head maximum width 1.0 (excluding the antenna), thorax length ca 3.0, thorax maximum width 1.9, forewing length 9.4, hind wing length 7.5 (all as preserved). Paratype: No. CNU-MEC-NN2009168: forewing length 11.5, forewing maximum width 4.4 (all as preserved).
The specific name is from Latin adjective “elegans”, referring to the elegant body posture.
Holotype
: female, No. CNU-MEC-NN2008228 p/c (Fig.
Itaphlebia elegana sp. nov., holotype, CNU-MEC-NN2008228 p/c. A photograph of part B enlarged details of basal forewing of part, anal veins with long and robust setae (under alcohol) C enlarged details of basal hind wing of counterpart (under alcohol) D photograph of counterpart E line drawing of counterpart F Line drawing of forewing of part, anal veins with long and robust setae G line drawing of hind wing of counterpart. Scale bars: 1 mm (A–G).
Itaphlebia elegana sp. nov., paratype, CNU-MEC-NN2015026 A photograph of paratype B enlarged details of base of right forewing (under alcohol) C enlarged details of base of left forewing (under alcohol) D line drawing of right forewing E line drawing of left forewing. Scale bars: 1 mm (A–E).
Itaphlebia elegana sp. nov., paratype, CNU-MEC-NN2016020 p/c. A photograph of part of paratype B enlarged details of base of forewing of counterpart of paratype (under alcohol) C photograph of right forewing of part D photograph of left forewing and part of hind wing of part E line drawing of right forewing F line drawing of left forewing and part of hind wing. Scale bars: 1 mm (A–F).
All specimens were collected from the Jiulongshan Formation, latest Middle Jurassic age (Bathonian–Callovian boundary interval) from Daohugou Village, Ningcheng County, Inner Mongolia Autonomous Region in China.
On forewing, costal area slightly broad; Sc forking with three branches; Rs (R2 to R5) forking with five branches; R2+3 forking before the crossvein r3-r4; R4+5 forking before the crossvein r5-m1+2; crossvein cu1-cu2 near the forking of Cu1+M, and crossvein cu1-m4 far before M3+4 forking. Long and robust setae present on anal veins of forewing.
Mainly based on Holotype, unless indicated as paratype.
Thorax : Incompletely preserved, setae discernible.
Wing : Long and oval, basal part of the wing narrow, gradually broadening from the base toward the apex. Forewing with the basal part of C somewhat convex, anterior area slightly broad, pterostigma incompletely preserved; Sc with three branches, Sc1 and Sc2 ending at C before the middle of the wing length, Sc3 near pterostigmal area; Rs forking with five branches, one short crossvein sc-r before pterostigma, crossvein r1-r2 under the pterostigma, approximately near the forking of R2+3, crossvein r2+3-r4 before crossvein sc-r, oblique crossvein r3-r4 between R3 and R4, R2+3 four times as long as R4+5, R4 forking with two branches (R4a, R4b), oblique crossvein r5-m1+2 emerged after the forking of R4+5, crossvein r5-m1 present before the crossvein r4-r5; conspicuous thyridium at the forking of M; M with four branches, M3+4 divided beyond the forking of M1+2; straight crossvein m1+2-m3 forking at the middle length of M1+2; crossvein m-cu1 before the forking of M3+4; Cu1 coalesced with M for a relatively short distance and separated from M near the crossvein cu1-cu2; long and robust setae present on veins A1 and A2, A1 and A2 almost parallel; crossvein a1-a2 at the same level of Cu1; A3 absent. Hind wing shorter and broader than forewing; pterostigma preserved in hind wing. Sc simple, terminated at C in the first one third of wing; R1 under pterostigma and connecting with C by a short crossvein c-r1, Rs with four branches, two crossveins between R2+3 and R4. Anal margins in hind wings not preserved, several long and robust setae preserved.
Abdomen : With 11 visible abdominal segments, segments VIII–XI distinctly smaller than segment VII, a pair of cerci at the end of abdomen, each one with three segments, setae discernible.
Itaphlebia elegana sp. nov. demonstrates an individual aberration of the sixth branch of R vein by the forking of R4, providing a character for understanding the evolution of wing venation. Although the hind wing has R with five branches, the diagnosis of Itaphlebia should be revised to indicate that the forewing Rs forking with four or five branches. CNU-MEC-NN2008228 p/c has two crossveins between R1+2 and R3+4, but only one crossvein is visible in CNU-MEC-NN2016020 p/c and CNU-MEC-NN2016026 p/c. Considering these three specimens have many similarities regarding other characters, we regard them as the same species. The difference in crossveins between R2+3 and R4 might have been due to the intraspecific difference or inheritable mutations.
(in mm). Holotype: female, No. CNU-MEC-NN2008228 p/c: Abdomen length 6.0, forewing length 9.4, hind wing length 7.5 (all as preserved). Paratypes: sex unknown, No. CNU-MEC-NN2015026: thorax length 1.8, thorax maximum width 1.1, forewing length 7.5, forewing maximum width 3.0 (all as preserved); female, CNU-MEC-NN2016020 p/c: head length 1.1 (excluding the antenna), head maximum width 0.8 (excluding the antenna), thorax length 2.2, thorax maximum width 1.7, forewing length 8.4, forewing maximum width 3.5 (all as preserved).
Taxonomic and morphological characters for fossil nannochoristids from the latest Middle Jurassic Jiulongshan Formation in Northeastern China have been investigated. Itaphlebia elegana sp. nov. is unique in having a forewing with R4 forking with two branches and remarkable long setae on the anal veins.
Itaphlebia elegana sp. nov. has distinct and short setae on the anal veins of the forewing, which was described in only one extant species of Nannochoristidae, Nannochorista andina (
Furthermore, such setae in Itaphlebia elegana sp. nov. are apparently shorter and less powerful, compared to the many stout bristles (dinotrichia) on the basal anterior margin of the forewings of fossil eomeropids of Tsuchingothauma shihi Ren & Shih 2005 from the latest Middle Jurassic and Typhothauma yixianensis Ren & Shih 2005 from the Early Cretaceous, both in Northeastern China (
Compared with other species of Itaphlebia, I. procera sp. nov. has unique venational characters: crossvein r5-m1 distad of the levels of crossveins between R1 and Rs, namely the forking of M1+2 originates basal (for Fig.
Eight extant species of Nannochoristidae Tillyard, 1917 have been documented in the Southern Hemisphere. The fossil sites of nannochoristids are in Siberia in Russia, Kazakhstan and Inner Mongolia and Liaoning in China. Due to limited specimens of well-preserved compression fossils, it was difficult to study detailed morphological characters to classify, diagnose and describe species or genera of these fossil nannochoristids.
We describe two new species of an extinct genus, Itaphlebia procera sp. nov. and I. elegana sp. nov., in the family Nannochoristidae, based on five fossil specimens from the latest Middle Jurassic Jiulongshan Formation of Daohugou, Inner Mongolia, in Northeastern China. Itaphlebia elegana sp. nov. demonstrates a new and unique forking of R4 into two branches (R4a, R4b), providing a character for understanding the evolution of wing venation. Furthermore, we report long and robust setae present on the anal veins of the forewing in I. elegana sp. nov. It is the first time that these two characters of Itaphlebia are documented for the fossil records in Nannochoristidae.
These new species not only broadened the diversity of the Itaphlebia in the mid-Mesozoic ecosystems but also provided new taxonomic information to emend the generic diagnosis.
We thank Longfeng Li and Jiajia Wang of the CNU for their improvement of our manuscript. We appreciate the help and assistance provided to the first author by Chen Wang and He Ding in the CNU Key Laboratory. Xiaodan Lin was supported by the National Natural Science Foundation of China (32000289 and 42288201), Hainan Provincial Natural Science Foundation of China (320QN201), and Startup Foundation for Introduced Talents of Hainan University (KYQD(ZR)20026). Dong Ren was supported by National Science Foundation of China (grants 31730087 and 32020103006). The authors declare no conflict of interest.