Phaenandrogomphus tonkinicus ( Fraser 1926 ), 2009

Wilson, Keith Duncan Peter & Xu, Zaifu, 2009, Gomphidae of Guangdong & Hong Kong, China (Odonata: Anisoptera) 2177, Zootaxa 2177, pp. 1-62 : 48-50

Phaenandrogomphus tonkinicus ( Fraser 1926)

Figs. 25 (a–h)

Onychogomphus saundersii nec Selys 1854 : Martin (1904: 212, Inde et Indo-Chine).

Onychogomphus tonkinicus Fraser 1926 : Fraser (1926: 481–482, type-loc. Tonkin).

Phaenandrogomphus tonkinicus ( Fraser 1926) : Lieftinck (1969: 210–214, figs 7–14, Tonkin); Asahina (1986: 30–31, figs 100–103, Thailand); Wilson & Reels (2001: 190–191, figs 120–123, Hainan).

Phaeandrogomphus chaoi Zhu & Liang 1994 : Zhu & Liang (1994: 113–116, figs 1–9, type-loc. Dawuling, Guangdong). syn. nov.

Shaogomphus sp. – Fellowes et al. (2003a: 36, Guangdong: Dadingshan & Chengjia, Nanling 2000).

Specimens: 1 ♀, Dadingshan (Nanling), 30 vi 2000, coll. KW; 1 ♀, Chengjia, 4 vii 2000, leg. BH; 1 ♂ (No. 23710), 1 ♀, Chengjia, 25 vii 2002, coll. ZX.

Description. Male P. tonkinicus specimens have been very adequately described by Fraser (1926), Lieftinck (1969), Asahina (1986) and Z hu & Liang (1994), the latter as P. chaoi . The male caudal genitalia are figured in Figs. 25g –h. Although female specimens of P. tonkinicus have been described by Lieftinck (1969), and as P. chaoi by Z hu & Liang (1994), to clear up any potential misunderstandings fresh specimens from Guangdong are described here. Female: Relatively small-sized onychogomphine; occiput with large domeshaped tubercle and pair of small nodule-like protrusions behind eyes. Labium pale. Lower gena, basal mandibles pale yellow. Labrum black with very broad, yellow transverse stripe across the middle and small central brownish-black central spot ( Fig. 25a). Antefrons black with pair yellow lateral spots broadly invaded above by yellow crest stripe. Postfrons black basally with narrow yellow transverse stripe across frontal crest ( Fig. 25b). Top head black with pair bulbous protrusions above lateral ocelli. Occiput with prominent domeshaped tubercle extending from occipital margin to vertex. Pair of small nodule-like protrusions behind each eye. Prothorax black with yellow frontal lobe, posterior lobe with a broad yellow border, central lobe with a pair of tiny yellow dorsal spots and yellow lateral margins. Synthorax black with yellow dorsal stripes linked to collar to form 7-shaped stripes, left side ‘7’ stripe inverted, ( Figs. 25c–d) characteristic of the genus. Antehumeral stripe reduced to round yellow superior spot in two Guangdong females and almost complete save for small interruption below superior spot in the third specimen (complete in Hainan and Tonkin female specimens). Side of synthorax with broad yellow stripes across mesepimeron and metepisternum almost connected at centre and briefly connected at centre on one specimen ( Fig. 25c). Metepimeron yellow with broad black border at metapleural suture. Legs black with femora predominantly brownish-yellow. Hind femur shorter than width of head (i.e. typical onychogomphine). Wings hyaline with black pterostigma, braced at proximal base and subtending 5 cells ( Fig. 25f). Distal primary antecostal crossvein closer to proximal primary antecostal crossvein than midpoint between nodus and proximal primary antenodal crosvein. Abdominal sides S1–2 black above, yellow below, with broad sinuous yellow stripe along dorsal carina, broadest at base of S2. S3 mainly black distally, but entirely yellow at base with fingers of yellow extending along dorsal carina and ventero-lateral margin. S4–5 black with a broad yellow ring at base, narrow isloated central yellow spot along dorsal carina. S6 mainly black with broad yellow base. S7 mainly yellow with distal third black. S8–10 black. Base S8 sternite with medial longitudinal ridge and basal half S9 sternite scleritized and shiny. Cerci pale yellow. Subgenital plate large, well developed with elongate, truncated flaps ( Fig. 25e) falling just short of S 10 in two specimens and extending to S 10 in one specimen.

Measurements (mm): ♂ abd. + app. 42.0–42.3, hw 31.8–32.0; ♀ abd. + app. 39.5–42.5, hw 32.0–34.5.

Remarks: The first female description of P. tonkinicus , provided by Lieftinck (1969), was from a specimen sent to him by Mrs L.K. Gloyd from the Michagan University Museum, labelled by Förster: "Mau Son Berge, 3000 Fuss, Tonkin, H. Fruhstorfer/ Heterogomphus naninus Foerster Type ♀ " (for further details see Lieftinck 1937; 1969). In his original descrption of H. naninus Förster (1905) referred to the female as: "unbekannt" i.e. unknown. Male naninus has recently been shown to be a valid species belonging to Orientogomphus (Wilson 2008) .

Z hu & Liang (1994) described Phaenandrogomphus chaoi based on a single male and a single female collected from Dawuling, Guangdong. Zhu & Liang (1994) considered: "The present new species comes near to P. tonkinicus in size, colours, shape of male hamulus and anal appendages. However, it differs obviously from P. tonkinicus by having incomplete humeral stripes, apex of penis being concave inside oppositely, penis vescicle being more slender, female occiput with only one swollen tubercle in the median portion and vulvar scale being longer, its rounded apex exceeding the apex of the 9 th segment." There are several misuderstandings in the list of differences highlighted by Z hu & Liang. Lieftinck (1969) figured the rear edge of the occiput of topotypical female P.toninicus with an undulating m-shaped margin. Zhu & Liang appear to have erroneously interpreted this feature as a double tubercle located on the occipital plate. In fact Lieftinck (1969) described a single tubercle on the female occiput as follows: "Median portion of the occipital plate raised to form a tubercular swelling on either side of which the plate is smooth and impressed". Lieftinck (1969) did not figure this tubercle but also referred to: "A pair of distinct conical postocellar tubercles" in his female description. These latter tubercles are the same pair of nodule-like features located behind the eyes referred to in the above description ( Fig. 25b) and described by Zhu & Liang as: "flat black spines on either side behind the eye-margin". The single raised dome-shaped tubercle on the occipital plate, and the small postocular nodule-like protrusions observed in Guangdong female specimens, are identical to the description and drawings of topotypical P.toninicus ( Lieftinck 1969) . The presence of the occipital plate tubercle and the postocular nodule-like protrusions are both unusual and unique features which underline the conspecifiity of P. chaoi and P. tonkinicus . Moreover, all three of the females examined from Guangdong possess postgenital plates which are truncated at the end and in two specimens they fall short of S10, identical to Lieftinck's (1969) drawing, and not angulate and extending beyond S9, as figured by Zhu & Liang (1994). In the third female Guangdong specimen examined the subgenital plate extends to S10. It is apparent that the differences listed by Zhu & Liang, such as incomplete antehumeral stripe, length of subgenital plate, shape of the penile organ and vescicle are minor and no more than phenotypic variation as shown by the variation encountered in Guangdong specimens. It has been shown here that no significant differences exist among Chinese specimens collected from Guangdong when compared with P. tonkinicus specimens described from north Vietnam. The two taxa are clearly synonymous.

Distribution: China (Guangdong, Hainan), Thailand & Vietnam.