首都师范大学生物论文(英文)

Accepted by E. Bernard: 9 Feb. 2010; published: 7 Apr. 2010 37ZOOTAXA ISSN 1175-5326 (print edition)ISSN 1175-5334
(online edition)Copyright © 2010 · Magnolia Press Zootaxa 2420: 37–45 (2010)
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Article Two new fossil species of Itaphlebia (Mecoptera: Nannochoristidae) from
Jiulongshan Formation, Inner Mongolia, China
NAN LIU, YUNYUN ZHAO & DONG REN 1
College of Life Science, Capital Normal University, Beijing 100048, China
1Corresponding author. E-mail: rendong@
Abstract
Two new species, Itaphlebia exquisita sp. nov and Itaphlebia laeta sp. nov., were collected from the Jiulongshan Formation (Middle Jurassic) of Daohugou, Inner Mongolia, China. A key to the species of the genus Itaphlebia is provided and diagnosis of the genus is revised. Itaphlebia exquisita sp. nov differs from other species in having an extra medial vein branch. Itaphlebia laeta sp. nov shows a transitional character to the extant genera by having a simple Sc. These new findings expand the distribution of Itaphlebia from middle-southern Russia to northeastern China.
Key words: new species, Itaphlebia, Nannochoristidae, Mecoptera, Middle Jurassic, Jiulongshan Formation
Introduction
Nannochoristidae, a family of Mecoptera, consists of two extant genera: Nannochorista Tillyard, 1917 and Microchorista Byers, 1974. The genus Nannochorista was reported in Australia and the South America: three species in Tasmania, one subspecies in New South Wales (Tillyard 1917, Riek 1954), and three species in Chile and Argentina (Byers 1989). Only one species of the genus Microchorista was discovered in New Zealand (Tillyard 1917, Byers 1974).
The classification of fossil nannochoristid genera is in a state of change and revision. The earliest fossil record of Nannochoristidae is in the Upper Permian of Australia, consisting of three genera: Nannochoristella Riek, 1953, Neochoristella Riek, 1953 and Robinjohnia Martynova, 1948 (Riek 1953, Carpenter 1992). However, the familial assignment of these genera is still being disputed. Grimaldi and Engel considered the assignment of Nannochoristella to Nannochoristidae to be incorrect (Grimaldi & Engel 2005). Novokshonov (1994) transferred Nannochoristella and Neochoristella into the subfamily Pseudonannochoristinae, and later moved Robinjohnia to Robinjohniidae (Novokshonov 1997b). Three genera, Dahurochorista Sukatsheva, 1985 (Early-Middle Jurassic), Dahurolarva Sukatsheva, 1985 (Early-Middle Jurassic) and Namdyrus Sukatsheva, 1993 (Upper Jurassic-Lower Cretaceous) were erected for Russian specimens (Sukatsheva 1985, 1993). Tarantogus Sukatsheva, 1985 (Middle Jurassic, Russia) and Undisca Sukatsheva, 1990 (Lower Cretaceous, Russia) were originally regarded as Mesopsychidae (Sukatsheva 1985, 1990). Itaphlebia Sukatsheva, 1985 and Chrysopanorpa Ren, 1995 (Middle Jurassic, China) were originally regarded as genera of Mesopanorpodidae (Sukatsheva 1985, Ren et al . 1995). These four genera were transferred later into Nannochoristidae and Chrysopanorpa Ren, 1995 (Middle Jurassic, China) was regarded as junior synonym of Itaphlebia Sukatsheva, 1985 (Novokshonov 1997a, 1997b). Jichoristella Ren, 1995 (originally described in Nannochoristidae) was considered by Novokshonov (1997a) to be closer to Bittacidae. Protochoristella Sun, Ren & Shih, 2007 (Middle Jurassic) was erected in China (Sun et al . 2007). Nannochorista (Eunannochorista ) sibirica Novokshonov, 1997 (Middle Jurassic) is the earliest fossil record of Nannochorista (Novokshonov 1997a).
We describe two new species of the genus Itaphlebia, which is the first report of this genus in China. Based on these well-preserved fossil specimens, the diagnosis of the Itaphlebia is revised and a key to the species is provided. The fossil specimens were collected from the Jiulongshan Formation, Daohugou Village. The age of the Daohugou fossil-bearing beds is considered to be Middle Jurassic (Ren et al. 2002, Gao & Ren 2006, Huang et al. 2006).
Material and methods
All of the specimens of the new species were collected from the Middle Jurassic Jiulongshan Formation at Daohugou Village, Ningcheng County, Inner Mongolia, China. They are deposited at the Key Lab of Insect Evolution & Environmental Changes, Capital Normal University, Beijing, China.
Specimens were examined with a Leica MZ12.5 dissecting microscope and illustrated with the aid of a drawing tube attached to the microscope. Line drawings were made with CorelDraw 12 graphic software. The description of the terminal female abdomen is based on Mickoleit (1975) and Willmann (1987). We followed Byers (1989) for nomenclature of the wing venation with several modifications: C, costa; Sc, subcosta; R
1
,
anterior radius; R
2, R
3
, R
4
and R
5
, branches of radial veins; M
1
, M
2
, M
3
and M
4
, branches of medial vein; M
1a
,
anterior branch of M
1; M
1b
, posterior branch of M
1
; Cu
1
, anterior cubitus; Cu
2
, posterior cubitus; 1A, 2A and
3A, branches of anal vein; r
1-r
2
, cross-vein connecting R
1
and R
2
; r-m, cross-vein connecting R
4+5
and M
1+2
; m-
cu, cross-vein connecting M
3+4 and Cu
1
.
Systematic Palaeontology
Mecoptera Packard, 1886
Nannochoristidae Tillyard, 1917
Itaphlebia Sukatsheva, 1985
Itaphlebia Sukatsheva 1985: 96–114; Novokshonov 1997a: 126-135; Novokshonov 1997b: 107-109; Novokshonov & Sukatsheva 2003:501–506.
Type species. Itaphlebia completa Sukatsheva, 1985
Revised diagnosis. Small to medium size, (forewing length 5.1–15.4 mm), body slender. Forewings: Sc with one or two branches ending at C; Rs with 4 branches; M with 4–5 branches. Hind wings: Sc simple, terminating at C well before pterostigma.
Remarks.Itaphlebia is similar to Undisca Sukatsheva, 1990 in the hind wings, but differs from the latter by the following characters: the fork of Rs occurs after the fork of M rather than level with the fork of M, and it has more cross-veins than the latter. It differs from other genera by having Rs with 4 branches and M with 4–5 branches. Other genera usually have Rs 3-branched and M 4-branched. The characters of cerci in female are accord with that in extant species. Including the species described in this paper, Itaphlebia now contains 8 species (Table 1; Figure 1A–H).
Key to species of Itaphlebia based on characters of the forewing
1. Sc simple, costal area narrow (2)
-. Sc 2-branched, costal area little broad (3)
2. Length of R
2 one-fifth the stem of R
2+3
.......................................................................................................... I. reducta
-. Length of R
2 2/
3 equal to the stem of R
2+3
............................................................................................I. laeta sp. nov.
LIU ET AL.
38 · Zootaxa 2420 © 2010 Magnolia Press
Zootaxa 2420 © 2010 Magnolia Press . 39FOSSIL NANNOCHORISTIDAE FROM JURASSIC OF CHINA 3. Cross-vein r-m located proximal to fork of R 4+5 (4)
-. Cross-vein r-m located at or distal to the fork of R 4+5 (5)
4. Cross-vein m 4-cu 1 located distal to the fork of M 3+4................................................................................... I. generosa
-. Cross-vein m-cu located proximal to the fork point of M 3+4.......................................................................... I. sharovi
5. Cross-vein m-cu close to the fork of M 3+4 (6)
-. Cross-vein m-cu located well before the fork of M 3+4 (7)
6. Cu 1+M forked beyond the cross-vein cu 1+m-cu 2........................................................................................ I. completa
-. Cu 1+M forked before the cross-vein cu 1-cu 2............................................................................................... I. jeniseica
7. M 4-branched.................................................................................................................................................... I. multa -. M 5-branched................................................................................................................................. I. exquisita sp. nov.FIGURE 1. Forewing line drawings of Itaphlebia spp. A. I. multa ; B. I. sharovi ; C. I. jeniseica ; D. I. completa ; E. I. reducta ; F. I. generosa ; G. I. exquisita sp.nov.; H. I. laeta sp. nov. A–C, E: after Novokshonov 1997b; D: after Novokshonov 1997a; F: after Novokshonov & Sukatsheva 2003. All scales = 1 mm.
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. Cu 1+M forked beyond the cross-vein cu 1+m-cu 2.
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. Sc 1 ending at C less than half length of forewing, and Sc 2 terminating at C near
pterostigmal area. One short cross-vein sc 2-r 1 before pterostigma. Cross-vein r 1-r 2 under pterostigma. Cross-
vein r 3-r 4 at same level of cross-vein r 1-r 2. Cross-vein r 5-m 1+2 approximately at middle of wing length. Cross-
vein r 5-m 1 before cross-vein r 4-r 5. Rs with 4 branches.
Conspicuous thyridium at the fork of M. M with 5
branches. M
1 with
2 branches (M
1a
, M
1b
). M
3+4
divided beyond the fork of M
1+2
. Cross-vein m
1+2
-m
3
between
M
1+2 and M
3
. Cross-vein m-cu not straight, somewhat S-shaped. Cu
1
coalesced with M for a short distance and
separated from M beyond cross-vein cu
1+m-cu
2
. 1A and 2A almost parallel, one cross-vein a
1
-a
2
between
them. 3A absent.
FIGURE 2. Itaphlebia exquisita sp. nov. A. Holotype, part CNU-MEC-NN2009145-1; B. Holotype, counterpart CNU-MEC-NN2009145-2; C. Middle leg; D. Paratype, CNU-MEC-NN2009236; E. Portion of wings of paratype.
Hind wings shorter than forewings. Sc simple, terminating at C much earlier before pterostigma. R
1
curved under pterostigma and connected with C by a cross-vein c-r
1. M
1
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.
LIU ET AL.
40 · Zootaxa 2420 © 2010 Magnolia Press
Zootaxa 2420 © 2010 Magnolia Press · 41FOSSIL NANNOCHORISTIDAE FROM JURASSIC OF CHINA 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. 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.Itaphlebia laeta s p. nov.
(Figure 4 A–D, Figure 5 E–F)
Material . Holotype female, CNU-MEC-NN2009311-1 and CNU-MEC-NN2009311-2, positive and negative. Paratype, CNU-MEC-NN2009222-1 and CNU-MEC-NN2009222-2, positive and negative.
Horizon and locality . Jiulongshan Formation, Middle Jurassic, Daohugou Village, Ningcheng County,
Inner Mongolia, China.
LIU ET AL.42 · Zootaxa 2420 © 2010 Magnolia Press Diagnosis . Costal area narrow. In forewing, Sc simple, terminating at C near pterostigma; M with 4 branches; Cu 1 and M forked before the cross-vein cu 1-cu 2.
Description . Antenna filiform, incompletely preserved. Femur shorter than tibia. Tibial spurs not present. Setae irregularly arranged.
Costal area narrow, one cross-vein c-sc between C and Sc. Sc simple, ending at C and extending to pterostigmal area. One short cross-vein sc 2-r 1 before pterostigma. Rs arised at the same level to cross-vein c-
sc. Rs with 4 branches. Length of R 2 two-thirds that of stem of R 2+3. Cross-vein r 1-r 2 at level of pterostigma.
Cross-vein r 3-r 4 at level of cross-vein r 1-r 2. Cross-vein r 5-m 1+2 approximately at middle of wing length. Cross-
vein r 5-m 1 proximal to cross-vein r 4-r 5. One cross-vein r 4-r 5 dividing cell R 4 into 2 cells. Conspicuous
thyridium at fork of M, which has 4 branches. M 3+4 divided beyond the fork of M 1+2; cross-vein m 1+2-m 3between M 1+2 and M 3; cross-vein m-cu not straight, slightly S-shaped. Cu 1 coalesced with M for a short
distance and separated from M before cross-vein cu 1-cu 2. One cross-vein a 1-a 2 connected 1A and 2A. 3A
absent.
Female abdomen with 11 segments, segments 9–11 smaller than segment 8. One pair of cerci located at apex of abdomen. Right cercus with 3 segments. Third segment of left cercus not preserved. Basal segments fused with abdomen segment 11.
Body length 7.8 mm, forewing length 8.2 mm, width 2.6 mm.
Etymology. From the Latin word laetus (clear), indicating venation is very clearly.
Remarks . The new species shows a similarity to Itaphlebia reducta but differs from the latter by location of the fork of R 2+3 and length of R 2 compared with R 2+3.
FIGURE 4. Itaphlebia laeta sp. nov. A. Holotype, part CNU-MEC-NN2009311-1; B. Holotype, counterpart CNU-MEC-NN2009311-2; C. Paratype, part CNU-MEC-NN2009222-1; D. Paratype, counterpart CNU-MEC-NN2009222-2. All scales = 2mm.
Discussion
Itaphlebia was originally placed in Mesopanorpodidae, but was transferred later to Nannochoristidae (Novokshonov, 1997b). The cercal segment numbers of these species are the same as for extant species. In venation pattern, this genus shows similar characters to extant species, except that Rs is 4-branched rather than 3-branched. In I. sharovi and I. reducta , however, the bifurcation of R 2+3
occurs more lately than other
Zootaxa 2420 © 2010 Magnolia Press · 43FOSSIL NANNOCHORISTIDAE FROM JURASSIC OF CHINA species. This shows one trend that R 2+3 may be non-branched, which reveals one possibility the branches of Rs
will reduce to three. I . exquisita sp. nov. is the first species of Nannochoristidae with extra vein by the branching of M 1. Two forewings show the stable character of 5 M branches, although the left hind wing has M
with 4 branches. This new species may be regarded as transitional. Therefore, we support the assignment of Itaphlebia to Nannochoristidae. The family diagnosis should be revised to indicate that Rs 3 or 4 branches, and that M usually has 4 branches, but occasionally has 5 branches.
FIGURE 5. Itaphlebia laeta sp.nov., line drawings of holotype. A. Ventral view of body with wings; B. Left forewing.
M-veins with 5 branches usually occur in Choristidae and Orthophlebiidae occasionally occur in Panorpidae and Bittacidae. The emergence of the fifth medial branch is caused by the branching of M 4 among
these families. Itaphlebia exquisita sp. nov. demonstrates a different development of 5 M veins by the branching of M 1, providing a robust character for understanding the evolution of wing veins.
Itaphlebia laeta sp. nov. showed a length difference between left forewing and right forewing. This difference may be due to distortion of the insect specimen during the fossilization process or to inherent asymmetrical development of the wings.
These two new species of Itaphlebia reported here are the first records from China. Other previously reported species are distributed in Russia (Table 1). Our findings expand the distribution of Itaphlebia from middle-southern Russia to northeastern China. However, extant Nannochoristidae occur only in the southern hemisphere. This distribution may be the result of insect migration caused by the changes in palaeoclimate or
tectonic movement.
LIU ET AL.44 · Zootaxa 2420 © 2010 Magnolia Press TABLE 1. Currently known species of Itaphlebia.
Acknowledgements
We are grateful to Dr. Shih Chung-Kun (College of Life Science, Capital Normal University) for his improvement of our manuscript. We express our thanks to Professor Michael S. Engel and Ms Jennifer Thomas (Division of Entomology, University of Kansas) and Dr. Thomas A. Hegna (Dept. of Geology and Geophysics, Yale University) for providing significant references. We express our gratitude to Dr. Ernest C. Bernard and another anonymous reviewer for careful and critical review of the manuscript. This research was supported by the National Natural Science Foundation of China (No. 40872022), the Nature Science Foundation of Beijing (No.5082002) and the Scientific Research Key Program and PHR Project of the Beijing Municipal Commission of Education.
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Species
Distribution Geological age Itaphlebia completa Sukatsheva, 1985
Krasnoyarsk Krai, Russia Middle Jurassic Itaphlebia exquisita sp. nov.
Inner Mongolia, China Middle Jurassic Itaphlebia generosa Novokshnov & Sukatsheva, 2003
Chita, Russia Upper Jurassic Itaphlebia jeniseica Novokshonov, 1997
Krasnoyarsk Krai, Russia Middle Jurassic Itaphlebia laeta sp. nov.
Inner Mongolia, China Middle Jurassic Itaphlebia multa Novokshonov, 1997
Krasnoyarsk Krai, Russia Middle Jurassic Itaphlebia reducta Novokshonov, 1997
Krasnoyarsk Krai, Russia Middle Jurassic Itaphlebia sharovi Novokshonov, 1997Kazakstan, Russia Upper Jurassic
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