Fukienogomphus prometheus ( Lieftinck, 1939 )

Hu, Fang-Shuo, Chen, Szu-Lung, Song, Rui-Bin & Yeh, Wen-Chi, 2021, Variation in Fukienogomphus prometheus (Lieftinck, 1939) reveals Stylurus takashii (Asahina, 1966) as a junior synonym, with discussion on the status of F. choifongae Wilson & Tam, 2006 (Odonata: Gomphidae), Zootaxa 5072 (1), pp. 23-33 : 24-27

Fukienogomphus prometheus ( Lieftinck, 1939) 火AEƌffi×深山Oiƌffi

( Figs 1–5 , 7–11 , 13–14 )

Gomphus prometheus, Lieftinck 1939: 278

Fukienogomphus prometheus, Chao 1954: 39

Gomphus takashii, Asahina 1966: 113 , syn. nov.

Asiagomphus takashii, Asahina 1985: 7

Stylurus takashii, Zhao 1990: 140

Materials examined. Holotype of S. takashii , ♀, NSMT; TAIWAN: JUN.20.1965, 南山ffl [=Nanshanshi; blue words stamped on triangular envelope] / Gomphus takashii Asahina Holotype [hand writing black words on the triangular paper bag] / Holotypus [red rectangular label, print]. TAIWAN: Yilan County: 1 ♀, Fushan [AE山], Yuanshan Township, 28-IV-1995, leg. W.-C. Yeh ( MSC); 2 ♂♂, ditto, 27-VI-1995, leg. W.-C. Yeh ( MSC); 1 ♀, Shenme Lake [AEṀae], Nanao Township, 22-VIII-2005, leg. W.-C. Yeh ( TFRI). New Taipei City: 1 ♂ & 1 ♀, Pingan [平廣], Xindian District, 10-V-1998, leg. W.-C. Yeh ( TFRI); 1 ♂, ditto, 30-VI-2004, leg. W.-C. Yeh ( TGC); 1 ♂, Guishan [M山], Xindian District, 02-V-2008, leg. W.-C. Yeh ( TFRI); 1 ♀, ditto, 11-V-2008, leg. W.-C. Yeh ( TFRI); 1 ♂, Tonghou [桶後], Wulai District, 31-V-2003, leg. W.-C. Yeh ( TFRI); 1 ♂, ditto, 06-VI-2007, leg. W.- C. Yeh ( KPMN); 1 ♂, Xikeng Forest Trail [OEnjẆdz], Wulai District, 23-V-2012, leg. W.-C. Yeh ( TFRI); 1 ♂, Manyueyuan [滿月圓], Sanxia District, 15-VI-2008, leg. W.-C. Yeh ( TFRI). Taipei City: 1 ♂, Neishuangxi [內Ṟ ffl], Shihlin District, 22-VI-2008, leg. W.-C. Yeh ( TFRI).

The body pattern of F. prometheus is variable within its range but more constant in Taiwanese specimens we have examined, either in specimens or the images of live insects. The two lateral black stripes of synthorax, the second and the third according to Zhao (1990), are usually distinct and entire in males ( Fig. 1 ); the variation of this character seems sex-related, as the females exclusively have the second stripe broken at the middle for a distance around 1/3–1/2 length of the stripe, and the third stripe becomes narrower and indistinct toward the lower end ( Figs 2 & 11 ). Other variations of body pattern in the Taiwanese F. prometheus include the paired spots on the labrum and the extent of antehumeral stripes. The paired yellow labral spots are usually absent ( Fig. 3 ) but can be present in few specimens. The antehumeral stripes are usually vestigial, leaving only an upper spot and rarely also a lower short stripe ( Figs 1 & 2 ); in few female specimens, a short lower stripe is present and sometimes even connected to the upper spot to form a short antehumeral stripe ( Fig. 11 ). Considering the variations mentioned above, the body pattern of the holotype of S. takashii as shown here ( Figs 4 & 7 ) does not differ from those found in the female Taiwanese F. prometheus .

In morphology, the female F. prometheus is characterized mainly by a short spine locating on the outer-posterior corner of the lateral ocellus, in additional to a larger, low and obtuse tubercle on the inner-posterior corner ( Fig. 3 ). Further, the female subgenital plate of F. prometheus is equilaterally triangular, with the length as long as 1/4 of the 9th abdominal segment; the plate is divided by a middle slit running from the apex to around basal 1/2 of the plate ( Fig. 5 ). These morphological characters fit well also with those of the holotype of S. takashii mentioned by Asahina and examined by us ( Figs 4 & 8 ).

Distribution. China (Zhejiang, Fujian, Guangdong and Hainan); Taiwan (Taipei, New Taipei, Taoyuan, Keelung, Hsinchu, Miaoli and Nantou), Vietnam ( Lieftinck et al. 1984; Kompier 2015; Zhang 2019; this study). The distributional map of F. prometheus in Taiwan is shown in Fig. 15 .

Ecology. The habitats of F. prometheus observed in northern Taiwan are mainly shaded creeks ( Fig. 12 ) or tiny muddy trenches in well-forested areas. The females usually oviposit alone at the shallow margins of small pools in creeks, or in trenches fed by the water from nearby seepage. The territorial males often perch on undergrowth vegetation near the female oviposition sites, sometimes as low as 10 cm above the ground. In Guangdong, F. prometheus inhabits shady seepages, narrow creeks with slow-flow and marshes or pools with thick bottom silt. In Pingan and Tonghou where the oviposition sites are semi-shaded tiny trenches, the ovipositing behaviors of females were stealth and difficult to discover, usually undertook under the coverage of dense weeds growing along the banks of trenches. The females perform egg-gathering behaviors before each dipping to release the eggs, either by hovering still low in the air above the water or sitting on vegetation adjacent to the dipping site. The larvae dwell on muddy seepages with weedy vegetation or amongst the detritus accumulated at the bottom of tiny trenches or pools in creeks. In Taiwan, F. prometheus is confined in low mountainous areas in the north, ranging from 40–1100 m.a.s.l. in elevation; the only exceptional record is the type locality of S. takashii in Nanshanshi where it is located in Nantou County in central Taiwan ( Fig. 15 ).

Figures

FIGURE 15. Distributional map of Fukienogomphus prometheus in Taiwan. The yellow star is the type locality of Stylurus takashii; green triangles represent additional specimen records; black dots represent the records from the Observation Database of Taiwanese Odonata (Chi-Ming Lou, personal communication, February 2021).

FIGURES 1–5. Specimens of Fukienogomphus prometheus: 1, male habitus, lateral; 2, female habitus, lateral; 3, female head, dorso-lateral (the blue arrows indicate the spines on the outer-posterior corner of the lateral ocellus); 4, the female head of the holotype of Stylurus takashii, dorso-lateral (photo by Takuya Kiyoshi); 5, female subgenital plate of fresh specimen, ventral.

FIGURES 6–8. Holotype of Stylurus takashii: 6, triangular envelope used to store the holotype; 7, female habitus, lateral; 8, female subgenital plate, ventral (photos by Takuya Kiyoshi).

FIGURES 9–10. Fukienogomphus prometheus of Guangdong, China: 9, male, lateral; 10, female, lateral.

FIGURES 11–12. Fukienogomphus prometheus of Taiwan and its habitat: 11, female, lateral; 12, habitat.

FIGURES 13–14. Fukienogomphus prometheus of Vietnam: 13, male; Huu Lien NR, Lang Son Province, lateral; 14, female; Cuc Phuong, Ninh Binh Province, lateral (photos by Tom Kompier).