DRAGONFLIES (ODONATA) OF DINGHU SHAN BIOSPHERE RESERVE, GUANGDONG PROVINCE, CHINA

Seventy-six species of Odonata are recorded from Dinghu Shan Biosphere Reserve, Guangdong Province, China, following surveys completed during 1992-1998. A new species of Cephalaeschna (Aeshnidae) and a new species of Philosina (Megapodagrionidae) are described and illustrated. The previously unknown female of Stylurus nanningensis Liu (Gomphidae) is also described. Asiagomphus septimus (not of Needham) from Hong Kong is synonymised with Asiagomphus hainanensis Chao. Aciagrion tillyardi Laidlaw (Coenagrionidae) is recorded from Chinese Territory for the first time. Zygonyx takasago Asahina (Libellulidae) previously considered a Taiwanese endemic, is recorded from continental China. A key is provided to separate the three Chinese species of Zygonyx. A total of twenty-eight taxa are recorded from Guangdong Province for the first time. The odonate fauna of Dinghu Shan is compared with neighbouring Hong Kong and Taiwan.


Introduction
Dinghu Shan Biosphere Reserve is located near Zhaoqing, approximately 86 km west of Guangzhou and some 170 km north-west of Hong Kong on the Tropic of Cancer (23°09'21"-21 °ll'30"N and ll2°30'39"-ll2°33'42"E). A high proportion of the 1,155 ha reserve (79%) is covered by subtropical forest which includes areas of primary forest, which are at least 400 years old (Kong, 1993). The reserve was among the first of a series of Chinese National Nature Reserves established by the First Conference of the National People's Delegation in 1956. In 1979 it was recognised by UNESCO as a Man and Biosphere Reserve. The area has been occupied for many years by Buddhists who established temples in the area. The Buddhist monk Zhi Chang established the first temple there, the Baiyun Temple, in 678 AD during the Tang Dynasty. In the Song Dynasty (960-1279) the Yuelong Buddhist nunnery was founded. A third Buddhist temple was constructed in 1633 known as the Qingyun Temple. The Buddhists have undoubtedly been responsible for the protection of the forests in the area for many centuries. Although small the reserve is an important remnant of primary monsoon rainforest in central Guangdong. A diagram of the reserve is provided in Fig. 1.
The mean annual temperature is 20.9 oc with a mean maximum of 28.1 °C in July and a mean minimum of 12 oc in January. Rainfall is high with a mean of 1,956 mm but there is a distinct seasonal pattern, with most rainfall falling in the April to September period. During the June 1994 survey it rained torrentially for prolonged periods every day with widespread flooding and landslips throughout the region. The highest altitude in the reserve occurs at Jilong mountain peak at 1000.3 metres.

Surveys
Male -Head (Fig. 2, 26 A, B). Labrum pale yellow. Labium pale green or greenish yellow with central round black spot linked to fine black basal border. Postclypeus black. Genae glossy, greenish yellow. Base of mandibles yellow. Frons and top of head matt black. Large quadrangular yellow spot adjacent to lateral ocelli. Large yellow postocular spots. Prothorax (Fig. 3) matt black with broad, yellow, lateral stripes. Thorax (Fig. 3) black with broad, yellow, humeral stripes, which do not extend to wing border. Small isolated yellow spot at wing border. Metepisternum with broad yellow stripe covering the spiracle. Lower metepimeron with broad yellow stripe not extending to anterior border. Coxae black with outer margins yellow. Trochanters black with outer face yellow. Whitish pruinescence on head and thorax but pattern remains discernible. Legs dark blackish brown with inner margin of femora yellow at base. Wings uniformly hyaline with black venation. Pterostigma reddish brown. The fore-wing is illustrated in Fig. 4. Abdomen black with broad yellow stripe, lateral stripes. Segments 3-7 with triangular-shaped yellow, lateral stripes broadest at base and not extending to distal border. Segments 8-9 with narrow lateral, yellow stripes. Dorsum of segment 10 yellow finely bordered black at base. The dorsum and sides of the abdomen of mature males is uniformly pruinosed white. The yellow pattern on the sides is just discernible but the black dorsum is white. Superior appendages (Figs 7-8) black, forceps-shaped, and slightly broadened before tip, which is sharply pointed. Numerous short, stout spines on outer margin of superior appendages. Penile organ (Fig. 5) simple with tip forming a circle. Female ( Fig. 26C) -A stout damselfly with a strong resemblance to the female of Philo ganga. Markings of head, prothorax and thorax very similar to male but lacking pruinescence on thorax and abdomen. Pruinescence is present on coxae and sides of prothorax. Antehumeral stripe is yellow at base but distal 4/5's and isolated humeral spot are greenish yellow. Abdomen black with sides of segment 1 pale greenish yellow. Segment 2-7 with broad lateral stripe slightly expanded at base on segments 3-6. Segments 8-9 black. Dorsum of segment 10 white. The ovipositor, which is illustrated in Fig. 6 Needham (1930: 240-241, pl. 16, Fig. 17) described and recorded buchi from Fujian and Guangxi. Needham's drawing of the caudal appendages is reproduced here in Fig. 11. Asahina (1979: 330-332, Figs 1-5) also figured the caudal appendages ofPhilosina buchi from material taken from Shaowu, Fujian and Canton, Guangdong. These drawings are reproduced here in Figs 9-10. The buchi appendages are simple and very similar to alba but lack the sharply pointed, notched tip. The name Philosina was chosen due to the superficial structural resemblance to Philoganga (a large calopterygid), also from southern China. Philosina alba is about 25% smaller in length than buchi. It has a different head pattern and abdominal pattern. I have examined several male specimens of Philosina buchi from Guangxi Province during 1997. These specimens are much larger than alba and all possess bright brick red colouration on the dorsum of abdominal segments 7-9. The main differences between these two species are summarised below in Table I. Aciagrion tillyardi (Laidlaw, 1919) (Figs 12-13, 26(F) Aciagrion tillyardi : Laidlaw, 1924: 66: 3-5 (key), 6, pl. 1 (Fig. 15), "Singapore, Malaysia"; Lieftinck, 1935: 92/93: 12, "Sumatra". Material: 1 male, Dinghu Shan, 12.VI.l993, 1 male, do., 16.VI.19932 male, 2 female, do., 16.VI.1993;5 males, 2 females, do., 10.VI.1994;1 male, do., 3.VI.1995. Description: A medium-sized Aciagrion species; male with violaceous markings on head and thorax and violaceous blue tip on segments 8-9 of the abdomen.
Male -Labium pale yellow. Labrum, anteclypeus and frons violaceous. Small dark spot discernible at base of anteclypeus. Postclypeus black. Top of head black with small violaceous postocular spots linked by a narrow, violaceous, transverse stripe across the occiput. Prothorax with anterior lobe pale and sides bluish violet otherwise black. Thorax black dorsally which extends beyond the humeral suture into the metepisternum. Narrow violaceous antehumeral stripe. The remaining three-quarter of the metepisternum is bluish violet fading to a pale bluish green on the metepimeron. Legs white with femora broadly striped black on the outer surface. Wings hyaline with greyish pterostigma, which is much larger in fore wing than hind wing. Dorsum of abdominal segments 1-7 and 10 black with sides of segments 1-2 and lateral base of 3 pale blue. Segments 8-9 wholly violaceous blue. Dorsal base of segments 3-7 narrowly ringed with pale whitish yellow and black areas are narrowly expanded laterally at apical border. Distal third of segment 7 and segments 8-10 markedly dilated. Length of superior caudal appendages ( Fig. 12) half their width, when viewed laterally, and slightly longer than the inferior appendages; coloured black. Distal, ventral mark on inferior appendage pale which is otherwise black. The penile organ is illustrated in Fig. 13.
Female -Similar head and thoracic pattern to male but predominant colour is yellow. Abdomen black with tenth abdomen segment blue. Segment 9 with large blue spots laterally at distal margins. Intersegmental membrane between segments 7-8 and 8-9 blue.
Remarks: There has been some confusion over records ofAciagrion from China. Needham (1930) provides records and a description ofAciagrion hisopa Selys from Sichuan, Taiwan and Fujian. Lieftinck et al (1984) assigned Needham's Chinese hisopa records toAciagrion migratum (Selys, 1891). Aciagrion migratum is the only Aciagrion hitherto recognised from China. Nine species ofAciagrion are known from Indo-China and 13 species in total are known from the oriental region. These Dinghu Shan records of tillyardi are the first records for Chinese territory. I have also collected identical tillyardi material from Da Ming Shan, Guangxi. Distribution: China (Guangdong and Guangxi), Indonesia (Sumatra) and India.

Description
Female -When viewed frontally, face approximately half the width of the head. Labium pale ferruginous brown. Basal half of labrum, creamy yellow with lateral margins and distal border mid brown. Anteclypeus brown. Postclypeus and sides of frons pale yellow. Top of frons tumid and pointed with dorsal surface mid brown, bordered yellow. The front of the frons is also mid brown, bordered pale yellow. The front of the head is illustrated in Fig. 14. Vertex black, raised. Occiput mid brown, raised. Thorax matt black with fine yellow antehumeral stripes which are angled towards each other. Dorsal carina of thorax raised with a distinct peak. The antehumeral stripes are closest to each other towards the wings and fall well short of the mesepisternum. The side of the thorax is dark matt brown with two broad yellow stripes on the mesepimeron and the metepimeron. A third smaller triangular-shaped yellow stripe is located on the metepisternum. The lateral pattern of the thorax is illustrated in Fig. 15. Legs distinctly bicoloured. Trochanters and basal two-thirds of femora very pale brown, almost white and distal one-third of femora, tibia and tarsi dark brown. Wings hyaline. Medial space with 3-5 cross-veins. No extensions of subcostal vein beyond the nodus in holotype but all wings of second female with extensions into first cell. Pterostigma dark brown, braced, covering 5-6 cells. Dorsal surface of abdomen blackish brown with only segments 2 and 3 with dorsal markings. These consist of pairs of yellow triangular spots posterior and parallel to the transverse carina. Entire ventrum of segments 1-2 yellow. Ventrum of segments 3-8 black with basal yellow spots. Caudal tip of abdomen is illustrated in Fig. 18. Segments 9-10 entirely blackish brown. Segment 10 with dentigerous plate, not elongated into two long spines, but slightly elongated with ventral tip possessing numerous small, stout spines. Cerci, the longest in the genus (4.5 mm) and more than twice the length of segment 10 (2.0 mm). Ovipositor does not extend beyond the tip of segment 10.
Male -(poor condition teneral). Similar to female. Face approximately half the width of the head coloured as female. Trochanters and basal three-quarters of femora very pale brown, almost white and distal one-quarter of femora, tibia and tarsi dark brown. Wings hyaline. Pterostigma braced, pale brown. Subcostal vein extended into first post-nodal cell on all wings which is a feature seen in some wings of Cephalaeschna acutifrons (cf. Asahina, 1983: 55, Fig. 12). Dorsum of abdomen mid-brown and dorsum of segment 1 unmarked. Ventral half of abdominal segments 1-2 yellow. Dorsum of segment 2 with five triangular yellow spots; one at the base, two posterior to the transverse carina and two at the posterior border. Basal half of segment 2 narrows, when viewed from the dorsum, to less than half its maximum width with one small, central pale yellow spot and two lateral pale yellow spots at the base. Segment 2-8 with two small triangular yellow spots posterior to and parallel to the transverse carina. Segment 9 and 10 black, each with a large, basal yellow spot occupying most of the dorsal surface. Caudal appendages are illustrated in Figs 16-17. Superior caudal appendages, when viewed dorsally, have flattened rounded blades with sharply pointed tips to apices. When viewed laterally the apices of the superior appendages are flat, without dorsal or ventral bulges. The inferior appendage is long more than half the length of the superior appendages.

Measurements (mm):
Male abd. + app. 47.0, hw. 43.5; female abd. 48.0, abd. + app. 52 (app = 4.5), hw. 48-48.5. Remarks: Currently, there are four closely related genera of Oriental Brachytroninae: Brachytronini, which possess cross-veins in the medial space. These include Cephalaeschna, Gynacanthaeschna, Periaeschna and Petaliaeschna. Fraser (1936), in his key to the Indian genera of Aeshnidae, isolated Petaliaeschna from these genera, inter alia, by the lack of a braced pterostigma. He used the lack of a dentigerous plate in Cephalaeschna to separate it from Petaliaeschna and Gynacanthaeschna. Fraser differentiated Gynacanthaeschna from Petaliaeschna by the nature of the elongate spines on the female dentigerous plate i.e. Gynacanthaeschna with 2 robust opposed spines and Petaliaeschna with 2 long divaricate spines. Asahina (1981a) produced a revised key to Cephalaeschna and its allies. He used the same principle feature as Fraser to separate Petaliaeschna but dropped the dentigerous plate character as a means of enumerating the remaining three genera. He chose, instead, to separate Periaeschna due to the presence of a narrow frons, the width being smaller than the head width. Asahina then differentiated Cephalaeschna from Gynacanthaeschna by, inter alia, the juxtaposition of the pterostigmal brace with the pterostigma (it is located on the inner border of the pterostigma in Cephalaeschna and slightly external to the inner border in Gynacanthaeschna) and the lack of any projections from the female ventral abdominal segment 10 in Cephalaeschna.
There are twelve species of Cephalaeschna recorded from Burma, Butan, China, India and Nepal and six of these are known from China. These are listed in Table II. The closest congeners to dinghuensis are risi Asahina (1981b), needhami Asahina (1982) and chaoi Asahina (1982) from southern China. These species also have a relatively narrow frons for the genus and the males have pointed superior appendages. Cephalaeschna dinghuensis is easily separated from these taxa by the bicolour nature of the leg colouration, the presence of a reduced female dentigerous plate possessing numerous small spines, and elongate female cerci which are more than two times the length of segment 10.

FAMILY: Gomphidae
Anisogomphini sp. Material: 1 teneral female, Dinghu Shan, 3.VI.1995. Remarks: This species is likely to belong to Merogomphus or Anisogomphus. It does not belong to any of the known Chinese members of these genera. Since the specimen is female and teneral there is little point in naming it as a new species.

Description
Female -Labium black, labium black with pair of small yellow spots. Anteclypeus black with milky colouration. Postclypeus black. Frons with broad transverse yellow stripe. No horns on the vertex. Occipital ridge uniform with no significant features. Thorax black with yellow collar stripe and a pair of narrow dorsal stripes. No antehumeral stripes. Sides of thorax difficult to discern due to teneral nature of the specimen. Mesepimeron with isolated yellow spot towards base of wings. Metepisternum with vague yellow stripe. Metepisternum yellow with lower anterior border black. Wings with anal loop wanting. A2 of hind wing adjoins triangle. Hind leg femora are long extending to mid point of abdominal segment 2. Hind leg femora possess two rows of long, numerous well-spaced spines. Abdomen dark brown marked with yellow pattern. Ventral half of segment 1 yellow. Segment 2 with mid dorsal spot, basal yellow band and ventral, basal three quarters yellow. Segment 3 with basal third of dorsum yellow and basal ventral half yellow. Basal one quarter of segments 4-7 yellow. Segments 8-10 dark brown/black. Subgenital plate deeply divided into two outwardly curved, bluntly pointed horn-like processes.
Anisogomphus anderi Lieftinck, 1948 Anisogomphus anderi: Zhao, 1990: 186-188, pl. 5-9.1 (Figs 1-6 (Chao, 1953) but the female has distinct characteristics indicating that the pair may represent a separate taxon. Description: Male -Top of head has a narrowly divided frontal ridge and there are no small spines outside the lateral ocelli. The 1st and 2nct yellow lateral thoracic stripes are well separated. The posterior hamulus and penile organ are very similar to hainanensis (cf. Chao, 1953: 406, Figs 23 & 25). Female -Top of head, as male, with a narrowly divided post frontal ridge lacking any small spines outside the lateral ocelli. Occipital margin, illustrated in Fig. 20, is uniformly straight.

Remarks
There is some considerable confusion concerningAsiagomphus septimus (Needham, 1930) and Asiagomphus hainanensis (Chao, 1953). In order to assess the status of the Dinghu Asiagomphus some misconceptions regarding Asiagomphus septimus and Asiagomphus hainanensis require clarification. Asiagomphus septimus Needham was described from continental male material from Fujian. Asiagomphus hainanensis Chao was also described, solely from male material, from Hainan. The male septimus was comprehensively illustrated by Chao (1953: 404, Figs 12-19) and similarly hainanensis by Chao (1953: 406, Figs 20-25). Chao (1953) did not describe or figure any female material of either species. The males of these two species are separated by the nature of the posterior hamulus. The tip of the male outer hamulus of septimus (Chao, 1953: 404, Fig. 14;Asahina, 1966: 109, Fig. 4) is much smaller when viewed in profile than that of hainanensis (cf. Chao, 1953: 406, Fig. 22;Asahina, 1966: 110-111, Figs 11 & 14). In addition the shaft of the posterior hamulus of septimus is much straighter than the stouter, humped posterior hamulus of hainanensis.
Females of hainanensis and septimus must be separated with considerable caution. Asahina (1978a: 3, 5-6, Figs 3-9) illustrated male and female septimus material from Fujian including the female occipital margin. The occipital crest in female continental septimus is strongly arched with a large U-shaped or semi-circular notch at the centre. Both the male and female continental Septimus possess 1st and 2nd yellow lateral stripes which are joined at their middle section. Asahina (1966: 111, Figs 15-16) described female hainanensis for the first time, from Hong Kong material. However, in Asahina (1988a: 689-690) he reidentified this material as septimus. These females have strongly arched occipital crest with a V-shaped notch bordered by several short, stout spines. I have taken many female specimens in Hong Kong with these characteristics. Having now studied considerable Hong Kong Asiagomphus material, both male and female, I am now convinced that Asahina had originally identified the Hong Kong female hainanensis correctly in his 1966 paper. Asahina (1988a: 690-691, Fig. 1) also described female hainanensis with an uniformly straight occipital margin with a very small v-shaped notch at the centre. I have obtained just one specimen of this form of Asiagomphus hainanensis female in Hong Kong which appears to be similar, if not identical, to Asahina's (1988a) hainanensis female from Taiwan. This Hong Kong female was attributed to hainanensis in Wilson (1995a: 320-321, "1 female, She Shan, Lam Tsuen Valley, coll. as larva ll. VII.1993, emerged 30.VII.1993. The occipital margin of this aberrant or 'masculine' hainanensis female form is illustrated in Fig. 23. Asahina (1966: 109-110, 114, Figs 4-8, 24) has described septimus from Taiwan with well separated 1st and 2nd thoracic yellow stripes. In Hong Kong septimus males and females should both conform to the continental form with 1st and 2nd thoracic yellow stripes joined at the middle. All Asiagomphus in Hong Kong have well separated 1st and 2nd thoracic yellow stripes characteristic of hainanensis. I have also checked a large number of final instar Asiagomphus larvae in Hong Kong. The female larvae are all of the hainanensis type i.e. with very small valvula vulvae protruding from the ventral base of the 9th abdominal segment (cf. Matsuki, 1978;Zhao, 1990: 92, Fig. 25).
The typical form of the female continental hainanensis occipital margin is illustrated in Fig. 22 and in Asahina (1966: 111, Fig. 15). The female occipital margin illustrated in Fig. 23, and in Taiwanese female illustrated inAsahina (1988a: 690-691, Fig. 1), is the less common 'masculine' form of hainanensis (i.e. less common continental form). Apart from the nature of the occipital margin and the presence of small spines outside of the lateral ocelli this form of the hainanensis female is identical to the common Hong Kong hainanensis form. All Hong Kong records of septimus should be reidentified as hainanensis. The Hong Kong records for septimus are thus synonymised with hainanensis and amended as follows: Asiagomphus hainanensis (Chao, 1953) Gomphus sp.: Asahina, 1965 Fig. 21). This later feature is also seen in some Hong Kong hainanensis females common form and in the less common form. Asiagomphus hainanensis from Hong Kong has a postclypeus with narrower lateral prominences than the Dinghu Shan species. In addition the post frontal tubercles of hainanensis are separated by a widely divided ridge whereas the Dinghu species is separated by a narrowly divided ridge (see Figs 19 and 20).
The Dinghu posterior hamulus of this taxon is very similar to Hong Kong hainanensis. The female is also very close to hainanensis but with a difference in the form of the occipital margin (see Fig. 20) which is uniformly straight and lacks any notch. It also lacks the small spines on the top of the head just outside of the lateral ocelli. Asahina (1988a) remarked that hainanensis female from Taiwan has a prominent post frontal tubercle forming a widely divided ridge directed backwards with small sharply pointed spines on the side of the lateral ocelli. The Dinghu Shan Asiagomphus possesses a narrowly divided post frontal ridge without spines outside the lateral ocelli.

Description
Female -It is significantly smaller than clathratus. Central lobe of labium black with its base and lateral lobes yellow. Labrum glossy black with a pair of minute basal yellow spots. Mandible yellow, finely bordered black. Anteclypeus, postclypeus and front of frons black. Top of frons with broad, transverse yellow stripe. Top of head black with small tubercle above lateral ocelli but no hint of horns. Occipital ridge uniform with no distinctive features. Prothorax dark brown/black with large lateral yellow spots. Side of thorax illustrated in Fig. 24. Dorsum of thorax with frontal transverse stripe not linked to a pair of dorsal stripes. Antehumeral stripes reduced to a yellow spot at each end; the anterior spot confluent with katepisternum. Coxae dark brown/black with outer, posterior faces yellow. Mesepimeron and metepisternum with isolated broad yellow stripes. Metepimeron yellow bordered black at anterior margin. Abdomen black with conspicuous yellow markings. Dorsum of segment 1 and 2 with central yellow stripe and lateral ventral halves yellow. Dorsal base of segments 3-7 with small yellow spots. Base of segment 8 yellow bordered dark brown/black laterally. Segments 9-10 dark brown. Sub-genital plate of female illustrated in Fig. 25. Measurements (mm): Female abd. + app. 45.0, hw. 35.0. Remarks: The female nanningensis is remarkably similar to the female of clathratus (Needham) and differs only in two major respects. These differences include the absence of horns on the vertex and the lack of an antehumeral stripe. According to Zhao (1990) there are fourteen species of Stylurus described from China which is over half the total number of species assigned to this genus; the rest are mostly known from North America. Of these fourteen species, the females of clathratus (Needham), erectocornis Liu & Chao, nobilis Liu & Chao, flavicornis (Needham), placidus Liu & Chao, takashii (Asahina) pos-sess small horns on the vertex above the lateral ocelli. Of the remaining taxa, amicus (Needham), endicotti (Needham), flavipes (Charpenier), kreyenbergi (Ris) and occultus (Selys) have complete or near complete antehumeral stripes. The last three species include gaudens (Chao), gideon (Needham) and nanningensis Liu. The lateral thoracic patterns of gaudens and gideon are distinctive with the first and second yellow lateral stripes fused together (Zhao, 1990: 129-130, Figs 4 &6). The thoracic pattern of the female specimen from Dinghu is identical to the males described from Nanning in the neighbouring Guangxi Province. Distribution: China (Guangdong and Guangxi).

Guangdong, Taiwan
Zygonyx takasago: Asahina, 1966: 118-120, Figs 43-44, "Taiwan";Lieftinck et al., 1984: 58, "Taiwan";: 49, "2 males, 13-14.VI.1994 (Kirby, 1900) and Zygonyx asahinai Matsuki & Saito (1995). All three Chinese Zygonyx are immediately recognisable as distinct species. A comparison to the three Chinese species of Zygonyx is given in Table III Table IV. No details of the material or the recorder are given so it is not possible to comment on their accuracy. Four of these species, Cercion sexlineatum (Selys), Anax parthenope julius Brauer, Diplacodes nebulosa (Fabricius), and Neurothemis tullia tullia (Drury) occur in neighbouring Hong Kong and have wide distributions. Their occurrence at Dinghu Shan would not be unexpected. These four species have been included in the faunal comparisons and checklist presented in Tables V & VI. The remaining species have been omitted from consideration until their presence at Dinghu Shan can be confirmed. Paragomphus pardalinus Needham is known from Guangdong and Macromia clio Ris from Taiwan and Japan. The last three species, Anisogomphus maacki (Selys), Lyriothemis pachygastra (Selys) and Sympetrum croceolum croceolum (Selys) are known from northern China, eastern China and western/northern China respectively.

Discussion
The present surveys were conducted principally during June i.e. Spring. The majority of odonate populations in Southern China begin their emergence during the onset of the rainy season which commences in late April. However, it is likely that a number of late season species would be discovered if surveys were also conducted during the mid-summer and autumn periods. Late summer species such as Diplacodes trivia/is (Rambur) and a number of Palaearctic Sympetrum species would be expected to occur at Dinghu Shan.  (Selys, 1883) In total, 76 odonate species were recorded at Dinghu Shan during the 1992-95 surveys. Including the four species acknowledged as previously recorded, the total fauna known from Dinghu Shan is 80 species. For comparison, 107 species are known from Hong Kong, which has a total land area of 1,092 km 2 , and 135 species are known from Taiwan (Lieftinck et al, 1984). Dinghu Shan supports a high number of species for such a small reserve. The highest number of species for a single site in Hong Kong is 68, found within the Sha Lo Tung basin (Wilson, 1997c). However, Sha Lo Tung at approximately 200 ha, is considerably smaller than the Dinghu Shan Reserve. A comparison of the Dinghu Shan odonate fauna with the odonate fauna of Hong Kong and Taiwan reveals some interesting differences. Seventy-four percent of the Dinghu Shan odonate fauna is also found in neighbouring Hong Kong and 64% is found in Taiwan. Considering the proximity of Hong Kong to Dinghu Shan and the greater distance and isolation of Taiwan from Dinghu Shan a much higher similarity with Hong Kong might have been anticipated. Hong Kong lies in the tropical zone whereas Dinghu Shan and much of Taiwan lies in the subtropical zone and there appears to be significant differences in the faunal composition. The main differences, disregarding the Amphipterygidae, Lestidae, Synlestidae, Megapodagrionidae and Cordulegastridae families, which only have one or two species occurrences, arise within the Gomphidae family.
Fourteen species of gomphid were recorded at Dinghu Shan of which 12 have not previously been recorded from Guangdong Province. Only five of these 14 species are also found in Hong Kong and six of them are reported from Taiwan. Zhao (1990) listed 173 gomphid species for China and Fujian Province was credited with the richest gomphid fauna with 27 genera and 60 species. Zhao (1990) listed just 7 genera and 11 species from Guangdong. Guangdong is a large province (197,100 square kilometres), just over a one third the size of France. The discovery of high numbers of unrecorded gomphids from just one area indicates a very high gomphid diversity within the Guangdong region. The province is likely to yield in excess of 60 species of gomphid. In 1994 Phaenan-drogomphus chaoi (Zhu & Liang, 1994) was described from Guangdong. Wilson (1995a) described Lamelligomphus hongkongensis and Melligomphus moluami from Hong Kong. Wilson (1995a;) also recorded several gomphid species from Hong Kong hitherto not recorded from Guangdong. The combined gomphid total for the Hong Kong SAR and Guangdong Province is now raised to 32 taxa.
Dinghu Shan has a slightly higher proportion of dragonflies with Palaearctic origins than Hong Kong. Dinghu has 7.5% (see Table V) and Hong Kong 6.5% (Wilson, 1997b: 4, Table II). The most noteworthy species with Palaearctic origins are the representatives of the genera Anotogaster and Sympetrum, which have never been recorded from Hong Kong.

Checklist of species with summary of distribution details
Details of records for Guangdong, neighbouring provinces in China, Taiwan and Hong Kong are provided. A summary of distribution details for Dinghu Shan, Hong Kong, Taiwan and South China is given in Table VI.