Polycanthagyna ornithocephala ( McLachlan, 1896 )

Wong, Kwok-Ching, Yeh, Wen-Chi & Chan, Tsung-Wei, 2012, Description of the final stadium larvae of Polycanthagyna ornithocephala (McLachlan, 1896) from Taiwan, with a key to the known larvae of the genus (Odonata: Anisoptera: Aeshnidae), Zootaxa 3238, pp. 64-68 : 65-66

Polycanthagyna ornithocephala ( McLachlan, 1896)

( Figs. 1 a, 1b, 2c, 3c, 4c)

Material examined (all final stadium larvae). 13 and 2Ƥ, 5-VII-2007, Alibang (25°15’53N, 121°34’57E), Shimen, New Taipei City, Taiwan; and the adult emerged on 27-VII-2007.

Other materials. P. erythromelas- 33 and 1Ƥ, 24-V-2007, Guishan (24°53’59N, 121°32’28E), Xindian, New Taipei City, Taiwan; 33 and 1Ƥ, 24-X-2007, Aowanda (23°58’33N, 121°07’43E), Renai, Nantou County, Taiwan; 33 and 4Ƥ larvae, 19-I-2008, Chajiao (24°52’20N, 121°24’14E), Sanxia, New Taipei City, Taiwan.

P. m e l an ic t er a- 53 and 2Ƥ, 3-III-2007, Wudu (25°05’14N, 121°40’42E), Keelung, Taiwan; 23 and 1Ƥ, 31-III- 2008, Shuanglienpi (24°44’57N, 121°37’30E), Yuanshan, Yilan County, Taiwan.

Diagnosis: These larvae are easily distinguished from other anisopteran larvae by the long, flat mentum, antennae with 7 segments, and smooth abdomen without dorsal hooks. The head is a little flattened and its posterolateral margins broadly rounded. The legs are slender and pale, usually ornamented with rings of brown. The abdomen is widest in the middle and tapers to its slender tip.

Head: Dark brown without conspicuous spots. Labrum, anteclypeus and postclypeus brownish yellow. Labium flat and elongate, prementum approximately 1.6 times as long as broad. Movable hook sharp. Antennae filiform, 7-segmented ( Fig.1 b), length ratio of each segment 1.0:1.1:2.1:1.2:1.3:1.4:0.9. Compound eyes broadly protruding anterolaterally, occiput roundly obtuse.

Thorax: Wing sheaths parallel, hind wing sheaths reaching posterior margin of 4th abdominal segment. Supracoxal processes of prothorax short and obtuse, protruding at about 90° from each other. Legs brownish with black spots, tarsi 3-segmented.

Abdomen: Dark brown and broadly elongate. Lateral spines present on S6–S9 ( Fig. 3 c), dorsal hooks absent. Male larvae with a triangular projection above epiproct. Paraproct 2.0 times as long as cerci, cerci with inner margin strongly and suddenly curved outwards apically. Female ovipositor reaching 1/5 length of paraproct ( Fig. 4 c).

Measurements. Body length: 3 37.3 mm, Ƥ 40.1–41.6 mm; maximum head width: 3 8.0 mm, Ƥ 8.9–9.2 mm; length of hind wing sheaths: 3 8.9 mm, Ƥ 9.8–10.1 mm.

Figures

FIGURE 1. Polycanthagyna ornithocephala, final stadium larva (a) dorsal view; (b) left antenna.

FIGURE 3. Male anal appendages of larvae in three Polycanthagyna species, dorsal view: (a) erythromelas, (b) melanictera, (c) ornithocephala.

FIGURE 4. Female ovipositors of larvae in three Polycanthagyna species, ventral view: (a) erythromelas, (b) melanictera, (c) ornithocephala.