Description of the final instar larva of Cephalaeschna risi Asahina, 1981 with notes on its semi-terrestrial lifestyle (Odonata: Aeshnidae)

Abstract

The final instar larva of Cephalaeschna risi Asahina, 1981 is described for the first time based on material from Taiwan. In Taiwan, the larva of C. risi can be separated from other aeshnid larvae by its relatively short antennae and presence of small protuberances on the legs. Diagnostic characters to distinguish it from other known larvae of Cephalaeschna are also discussed. A comprehensive description, detailed illustrations, bionomics and observations of the semi-terrestrial lifestyle of C. risi are presented. Finally, a key to the genera of Aeshnidae in Taiwan is proposed.

Full text

139
International Journal of Odonatology, 24.2021, 139–148
OpenAccess. ©2021 Ulf Norling, published online 1 Jan 2021 by Wachholtz This work is
licensed under the Creative Commons Attribution 4.0 Public License.
OpenAccess.
OpenAccess. ©2021 Ulf Norling, published online 1 Jan 2021 by Wachholtz This work is
licensed under the Creative Commons Attribution 4.0 Public License.
2021 Fang-Shuo Hu, published online 8 Jul 2021 by Wachholtz
OpenAccess. ©2021 Ulf Norling, published online 1 Jan 2021 by Wachholtz This work is
licensed under the Creative Commons Attribution 4.0 Public License.
This work is licensed under the Creative Commons Attribution 4.0 Public License.
Fang-Shuo Hu1*, Tsung-Wei Chan2, Lung-Chun Huang3, I-Lung Lee4
Description of the final instar larva of Cephalaeschna risi Asahina,
1981 with notes on its semi-terrestrial lifestyle (Odonata: Aeshnidae)
ht t p s: //doi.org/10.23797/ 2159 - 6719_ 24_10
Received: 1 August 2020 – Accepted: 2 February 2021 – Published: 8 July 2021
Abstract:Cephalaeschna risi
C. risi
   
 Cephalaeschna-
-
C. risi
Keywords: 
Introduction
Cephalaeschna
20202013
20132 0172018; 2021). Cephalaeschna risi

198119842019).
Cephalaeschna
1930Cephalaeschna-
1943C. orbifrons
1961Cephalaeschna species
2006C. klotsi-
 2008 C. patrorum

Cephalaeschna
1 C. risi.
 C. risi  

Material and methods
Specimen examination, measurement and photographs


1 Department of Entomology, National Chung Hsing University, No. 145, Xingda Rd., South Dist., Taichung
City 402, Taiwan; e-mail: fangshuo_hu@smail.nchu.edu.tw
2 Gaoyi Elementary School, No. 28, Gaoyi, Fuxing Dist., Taoyuan City 336, Taiwan; e-mail: s88b1001@
gmail.com
3 Conservation and Research Center, Taipei Zoo No. 30, Sec. 2, Xinguang Rd., Taipei City, Taiwan. e-mail:
death0207@gmail.com
4 Taipei Wego Private Senior High School, NO. 50, Zhuhai Rd., Beitou Dist., Taipei City, Taiwan; e-mail:
cgicdf@gmail.com
* c
orresponding author: Email fangshuo_hu@smail.nchu.edu.tw

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Hu et al.: Description of the nal instar larva of Cephalaeschna risi Asahina





              
         
 
2020


-


Specimen depositories.
 
 
 
 
Results
Figure 1. Newly emerged adult female of Cephalaeschna risi Asahina, 1981 in the laboratory (Photo by
Hsin-Hisung Chen).

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Material examined



 

Measurements
                 

       


Description
Habitus

Figures 2–3. Habitus of the final instar larva of Cephalaeschna risi Asahina, 1981. (1) Dorsal view; (2)
Ventral view. Scale bar: 10 mm. The photo of the right hind legs is enlarged, the arrows indicate the small
protuberances on femur and tibia.

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Hu et al.: Description of the nal instar larva of Cephalaeschna risi Asahina
Head.
4-

4
 

  
             
-
6–8
-

           
-
  5     
                 


 

Figures 4–8. Head, thorax, prementum and mandibles of the final instar larva of Cephalaeschna risi Asa-
hina, 1981. (4) Head and thorax (dorsal view); (5) Prementum (dorsal view); (6) Mandibles (dorsal view);
(7) Mandibles (lateral view); (8) Mandibles (ventral view). Scale bars: 4 = 2.5 mm, 5–8 = 1 mm. The arrows
indicated the comb-shaped protrusion on the occipital lobe.

143
Hu et al.: Description of the nal instar larva of Cephalaeschna risi Asahina
Thorax.
              
              
    



Abdomen.


   -


   
              
 9–10
               
9–10
11–12
11–12).
Figures 9–12. Abdominal terminalia of both sexes of the final instar larva of Cephalaeschna risi Asahina,
1981. (9) Male (dorsal view); (10) Male (ventral view); (11) Female (ventral view); (12) Female (lateral
view). Scale bars: 1 mm.

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Diagnosis.
Cephalaeschna  C. risi  C. partrorum
2008C. risi
C. partrorum    
 9 C. partrorum C.
patrorumC. risi
 5). Cephalaeschna risi C. orbifrons  1943)) by the
  9
C. orbifronsC. klotsi
2006C. risi
  C. klotsi -
C. risi-

Microhabitat and behavior
C. risi
  18)

Figures 13–16. Photos of live specimens of Cephalaeschna risi Asahina, 1981. (13) First instar larva stood
on moss in the field; (14) Final instar larva on moist leaf litters in the wild; (15) Final instar larva hanging
under the leaf of a Cyperaceae plant in the wild; (16) Final instar larva hunting prey on the ground in the
laboratory.

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Figure 17. The hunting behavior of a larva of Cephalaeschna risi Asahina, 1981.
Figures 18–19. Habitats of adults and larvae of Cephalaeschna risi Asahina, 1981. (18) The habitat where
adults are active in Manyueyuan, New Taipei City, Taiwan (photo by C.-H. Ma); (19) The habitat of the lar-
vae in Qilan, Yilan County, Taiwan.

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Hu et al.: Description of the nal instar larva of Cephalaeschna risi Asahina
C. risi
   14        
19
   15    
 C. risi   Rhipidolestes aculeatus aculeatus

Remarks
C. risi
      

    
Gryllus assimilisTenebrio molitor
C. risi 16 –17C. risi


19-
-
12).

Key to the final instar larvae of Taiwanese genera of Aeshnidae
(Modified from Chan (2009)
   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Periaeschna
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
 . . . . . . . . . . . . . . . . . . . . . . . . . Cephalaeschna
 . . . . . . . . . . . . . . . . . . . . . . . . . . 3
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sarasaeschna
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
 . . . Anax
 . . . . 5
   
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Planaeschna

 . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
 . . . . 8
  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Gynacantha
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Polycanthagyna
  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Anaciaeschna
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aeshna

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Hu et al.: Description of the nal instar larva of Cephalaeschna risi Asahina
Discussion
Cephalaeschna
C. patrorum2008).
2008C. patorum

Planae-
schna199620102011
C. patrorum2008Planaeschna species.
Antipodophle-
bia asthenesPseudocordulia
19801982C. risi



1954 
 C. risi 
Pseudocordulia1982
C. risi  Pseudocordulia1982  


C. risi
  Cephalaeschna  
-
C. risi.
Acknowledgements
 
 

    



   

References
AKontyû–246.
             Cephalaeschna    
Tombo24 
Taxonomic studies of the larval stage of Aeshnidae (Odonata) in Taiwan (Master
thesis)-

    Cephalaeschna   
     C. acanthifrons  
C. viridifrons                       https://doi.org/10.11646/


148
Hu et al.: Description of the nal instar larva of Cephalaeschna risi Asahina
FraserProceedings of the Royal Entomological Society
of London. Series B12
Monograph of Odonata larva in Japan

Miobdelus           Zootaxa 4768 
334 –360. 
JCephalaeschna patrorum Need-
  Planaeschna shanxiensis        Odonatologica 37 
273–277.
J     
Zootaxa4300
Catalogue of Taiwanese dragonies (Insecta: Odo-
nata)
NZoologia Sinica11 
    ).    
    -

Cephalaeschna-
Zootaxa4471         https://doi.org/10.11646/

Smithsonian Miscellaneous Collections123
  
Journal of the Australian Entomological Society21
  TAntipodophlebia asthenes-
Odonatologica 9
2006). Fukienogomphus choifongae
Cephalaeschna klotsiOdonato-
logica35
              Planaeschna
suichangensis        Zootaxa  

          

Cephalaeschna
International Journal of Odonatology16https://doi.
org/10.108 0/1388789 0.2 013.820977
Plan-
aeschna      Zootaxa   https://doi.
    
          Cephalaeschna    
    
International Journal of Odonatologyht t ps://doi.o rg/10.1080/1388789 0.2013.78
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