Freshwater Macroinvertebrates in Hong Kong


The total number of odonate species in Hong Kong is 124 comprising six families of the suborder Anisoptera (dragonflies) and nine families of the suborder Zygoptera (damselflies). The terrestrial adults are well-known and have been extensively studied, but the aquatic larvae of many species neither have been described nor yet been figured, it is worthy creating this pictorial guide as an aid to identify species of larval odonates in Hong Kong. In order to facilitate the identifications of some larvae, rearing larvae for adult emergence have been carried out in HKU Freshwater Aquarium.

For a species identification, its body size and shape would be the most general appearance at the first glance. However, mis-identification might be apparent by using such body traits solely because the appearance might look greatly different under some circumstances. We need to consider other features as many as possible to conclude what the species is.

Body color comparison

Damselflies, larvae have three (or rarely two) external gills situated at the tip of the abdomen forming expanded sacs or flat blades, but dragonfly larvae lack external gills but have internal gills within the rectum, and respiration involves muscles that force water in and out through the anus.


Caudal gills are diverse and species specific, and their shape and marking can be used for identification. However, caudal gills may be easily shed. The regenerated gills may be smaller and different from their original form.

Regenerated gill

ID features

For families or genera identification, the examination of larval features should be conducted as follow:
1. Shape of head & angle of protruding eyes e.g. pentagonal with postocular lobes rounded & large eyes in Coenagrionidae
2. Any distinct markings or setae on head e.g. white curved marking at the centre of frons in Crocothemis servilia servillia
3. Shape of antennae e.g. elongated 1st antennal segment in Calopterygidae & stout club-shaped 3rd antennal segement in Gomphidae
4. Shape of labium, arrangement of labial hooks, setae & spines e.g. prementum long, flat in Aeshnidae & mask-shaped in Libellulidae
5. Any distinct markings or setae on legs
6. Number of tarsal segments & shape of claws
7. Wing buds developing in parallel or divergent
8. Shape of abdomen, color pattern & presence of setae, spines or projections on lateral margin
9. Shape of gills, pattern of trachea, presence of markings, setae & spines e.g. long, notate lamellae gills in Pseudagrion
or shape of anal pyramid, length of epiproct, paraproct and cerci e.g. to distinguish species in Aeshnidae



Checklist of Hong Kong Anisoptera (Dragonflies)

- Anaciaeschna jaspidea
- Anax guttatus
- Anax immaculifrons
- Anax indicus **
- Anax nigrofasciatus nigrofasciatus
- Anax parthenope
- Cephalaeshna klotsi
- Gynacantha japonica
- Gynacantha ryukyuensis
- Gynacantha saltatrix
- Gynacantha subinterrupta
- Planaeschna skiaperipola
- Polycanthagyna erythromelas
- Tetracanthagyna waterhousei

- Anotogaster klossi

- Epophthalmia elegans
- Macromia berlandi
- Macromia katae
- Macromia urania

- Idionyx claudia
- Idionyx victor
Macromidia ellenae
- Macromidia rapida


- Anisogomphus koxingai
- Asiagomphus hainanensis
- Burmagomphus vermicularis
- Fukienogomphus choifongae
- Gomphidia kelloggi

- Heliogomphus retroflexus
- Heliogomphus scorpio
- Ictinogomphus pertinax
- Labrogomphus torvus
- Lamelligomphus hainanensis
- Leptogomphus hongkongensis
- Megalogomphus sommeri
- Melligomphus guangdongensis

- Ophiogomphus sinicus
- Paragomphus capricornis
- Sieboldius alexanderi
- Sieboldius deflexus ***
- Sinictinogomphus clavatus
- Stylogomphus chunliuae
- Stylurus kreyenbergi **

Libellulidae (ID key as follow)
- Acisoma panorpoides panorpoides
- Aethriamanta brevipennis brevipennis
- Brachydiplax chalybea flavovittata
- Brachythemis contaminata
- Crocothemis servilia servilia
- Diplacodes nebulosa
- Diplacodes trivialis
- Hydrobasileus croceus
- Lyriothemis elegantissima
- Macrodiplax cora

Libellulidae (continued)
- Nanophya pygmaea
- Nannophyopsis clara
- Neurothemis fulvia
- Neurothemis tullia tullia
- Onychothemis tonkinensis
- Orthetrum chrysis
- Orthetrum glaucum
- Orthetrum luzonicum
- Orthetrum melania
- Orthetrum poecilops poecilops
- Orthetrum pruinosum neglectum
- Orthetrum sabina sabina
- Orthetum triangulare triangulare

- Palpopleura sexmaculata sexmaculata
- Pantala flavescens
- Potamarcha congener
- Pseudothemis zonata
- Rhodothemis rufa
- Rhyothemis fuliginosa ***
- Rhyothemis triangularis
- Rhyothemis variegata arria
- Sympetrum darwinianum ***
- Sympetrum fonscolombii
- Tholymis tillarga
- Tramea transmarina euryale **
- Tramea virginia
- Trithemis aurora
- Trithemis festiva
- Trithemis pallidinervis
- Urothemis signata
- Zygonyx asahinai
- Zygonyx iris insignis
- Zyxomma petiolatum

** species regarded as vagrant
*** species at uncertain status


Checklist of Hong Kong Zygoptera (Damselflies)

- Philoganga vetusta

Matrona basilaris *
- Mnias mneme
- Neurobasis chinensis

- Rhinocypha perforata

- Euphaea decorata
- Euphaea opaca *



- Aciagrion approximans
- Agriocnemis femina oryzae
- Agriocnemis lacteola
- Agriocnemis pygmaea
- Ceriagrion auranticum ryukyuanum
- Ischnura asiatica *
- Ischura senegalensis
- Ischnura sp. Cf rufostigma group *
- Mortonagrion hirosei
- Paracercion calamorum dyeri
- Paracercion hieroglyphicum *
- Paracercion melanotum

- Pseudagrion microcephalus
- Pseudagrion pruinosum fraseri
- Pseudagrion rubriceps rubriceps
- Pseudagrion spencei

- Calicnemia sinensis
- Coeliccia cyanomelas
- Copera marginipes
- Onychargia atrocyana
- Prodasineura autumnails
- Prodasineura croconota
- Pseudocopera ciliata

- Drepanosticta hongkongensis
- Protosticta beaumonti
- Protosticta taipokauensis
- Sinosicta ogatai



- Lestes nodalis
- Lestes praemorsus praemorsus *

- Agriomorpha fusca
- Rhipidolestes janetae






* species known from historical records (i.e. pre-1980s) - regarded locally extinct

Apart from the examination of larvae, we could collect the exuviae from vegetation near their habitats in some occasions. It is another way to find out some lurking species. Since the characteristics would be fully developed in the final instar larvae, it would be reliable for species identification by examination of exuviae. However, it would be still difficult for doing this particularly for damselflies because their fragile caudal gills might be lost easily.



By comparison of pictures in each families, it is not difficult to match the corresponding genus or species. However, Libellulidae is the largest odonate family in Hong Kong. Here, the characteristics of local species of libellulids are compared to indicate their diversity.

Comparison of some heads in Libellulidae

The examination of head including inspecting eye size and angle of eye projection should be needed for species identification. Besides, the other character traits like any distinct marking or setae should be considered as well. Coloration in this case might not be a reliable clue because some specimens have been preservated, their colorations are quite different from the originals.

Comparison of libellulid heads

The following tentative key for Libellulidae has been prepared using available descriptions from other keys and in-house species emergence for confirmation.

****** Presence of dorsal spine on abdomen ******

Features for ID Scientific name

* Dorsal spines on abdomen segments IV - VII (S4 - S7)

Labial premental Setae

--> 8 palpal setae; 4 or more outer premental setae on each side; large dark marking between eyes

Orthetrum glaucum

--> 5 palpal setae; 3 outer premental setae

Orthetrum luzonicum

--> 8 palpal setae; 3 outer premental setae; abdominal segments 6-10 reddish brown

Orthetrum sabina

--> 7 palpal setae; 3-4 outer premental setae

Orthetrum triangulare

Comparison of heads

* Dorsal spines on S3 - S8

--> head triangular shaped; long lateral spines, nearly double length of each segment on S8 and S9

Hydrobasileus croceus

--> head triangular shaped; short lateral spines on S8 and S9

Urothemis signata

--> head pentagonal shaped; lateral spines nearly reaching middle way of anal pyramid

Macrodiplax cora


* Dorsal spines on S4 - S8

--> head elongated laterally, almost in abdominal width

Brachythemis chalybea

--> head quadragular shaped; abdomen oval shaped, the latter abdominal segments seem squeezed forward & upwardly; 6 palpal setae, 3 long outer premental setae on each side

Orthetrum chrysis

--> head quadragular shaped; abdomen comparatively elongated; 5 or 5+1 palpal setae, 2-3 long outer premental setae on each side

Orthetrum pruinosum

Larval species not yet described/ unavailable, but some suspicious individuals having 7 palpal setae & 3 long premental setae are found

Orthetrum melania (S? - S8)


* Dorsal spines on S2 - S9

--> head quadragular shaped; 3 palpal setae; dorsal spines large and hooked

Orthetrum poecilops


* Dorsal spines on S3 - S9

--> body color reddish brown; head with large area of reddish brown markings behind eyes; less markings on wing sheaths

Trithemis aurora

--> body color greenish brown; small or scattered reddish brown markings on head, but getting larger at late stage; conspicuous dark spots pairs on abdomen; more darken markings on wing sheaths

Trithemis festiva

Larval species not yet described/ unavailable

Trithemis pallidinervis

Comparison of Trithemis spp
Comparison of wing sheath

* Dorsal spines on S4 - S9

--> anal pyramid large & protruding

Brachythemis contaminata

--> anal pyramid short & somewhat embraced by abdominal segment IX
--> 1 premental seta (in addition 1 to 2 short setae on inner side); 5 palpal setae

Rhyothemis variegata

--> anal pyramid short & somewhat embraced by abdominal segment IX
--> 8 premental setae (in addition 3 short setae on inner side); 6 - 7 palpal setae

Rhyothemis fuligonosa

Larval species not yet described/ unavailable

Rhyothemis triangularis


* Dorsal spines on S5 - S9

--> lateral spines long; 9 palpal setae; 10 - 11 prementum setae

Lyriothemis elegantisima

--> head with posterior occipital lobe highly concave; legs with dark markings

Onychothemis tonkinensis (S?-S9)


* Dorsal spines on S2 - S10

--> abdomen wide & large (cf. to its head), ovate shaped with some pale spots on each sides

Pseudothemis zonata

--> head with 4 conspicuous proturberances on occipital margin
--> lateral spines long on S9 nearly to the length of its abdominal segment

Zygonyx iris

--> length of lateral spines much shorter than Z. iris

Zygonyx asahinai


* Dorsal spines on S3 - S10

body relatively large sized, up to about 22mm long; head with small eyes and conspicuous large area of dark marking; legs short, slender with conspicuous dark markings on femur; abdomen comparatively large, ovate shaped with dark median markings, especially noticeable black stripes on abdominal segment IX; dorsal spines on abdominal segments III - X and lateral spines on abdominal segements VIII - IX

Tholymis tillarga


* Dorsal spines on S4 - S10

body medium sized, up to 17mm long; abdomen elongated with pair of white markings on abdominal segment IX; dorsal spines on abdominal segments IV - X (tiny on S10) and lateral spines comparatively long on abdominal segments VIII - IX with pale tip

Zyxomma petiolatum



****** Absence of dorsal spine on abdomen ******

* Absence of lateral spine on abdomen

body small sized, about 10mm long; head trapezoid-shaped with cluster of setae at posterior margin; legs short, last tarsal segement darken; abdomen oval shaped having transverse row of long setae situated at middle of dorsum and near tip of abdomen; no dorsal spine or lateral spine

Acisoma panorpoides


* Presence of LARGE/LONG lateral spines on abdomen

--> epiprot as long as, or longer than paraprots

Pantala flavescens

--> epiprot short, about 2/3 length of paraprots; 10-11 palpal setae, 12-13 premental setae on each side

Tramea virginia

--> epiprot short, about 2/3 length of paraprots; 10-11 palpal setae, 13-15 premental setae on each side

Tramea transmarina euryale

Comparison of epiprot length

* Presence of SMALL lateral spines on abdomen

--> body relatively small sized, <10mm long; head wide with bulbous eyes protruding anterolaterally; abdomen with longitudinal dark band across S6 - S9 in which a pale spot on each side; conspicuous lateral spines on S7 - S9 and no dorsal spine

Nannophyopsis clara

--> body relatively small sized, <10mm long; head wide with bulbous eyes protruding anterolaterally; abdomen with whitish midline and some pale markings on each side; conspicuous lateral spines on S8 - S9 and no dorsal spine

Nannophya pygmea

--> body relatively small sized, about 10mm long; eyes bulging anterolaterally; spidery legs with dark tarsus near claw on hind legs; abdomen short and round shaped; inconspicuous lateral spine on S9 only, but without dorsal spine

Rhodothemis rufa

--> body relatively small sized, about 10mm long; head very wide with eyes protruding laterally; abdomen with purplish midline and some markings on each side, tip of abdomen curled upward, lateral spines inconspicuous on S8 - S9 and no dorsal spine

Diplacodes trivialis

larval species not yet described/ unavailable

Diplacodes nebulosa

--> body relatively medium sized, about 15mm long; head pentagonal with two clusters of setae behing eyes; two markings on femur; wing sheath straight up to abdominal segment VII; abdomen ovate shaped with prominent longitudinal pale strip enclosed by dark bands; lateral spines on S8 - S9, but no dorsal spine; long setae present near anal pyramid

Neurothemis fulvia

larval species not yet described/ unavailable

Neurothemis tullia

--> body relatively medium sized, up to 20mm long; head wide with bulbous eyes; legs with faint dark markings; abdomen oval shaped, conspicuous lateral spines on S8 - S9 and no dorsal spine

Crocothemis servilia

--> body up to 21.5mm long, hairy, head rectangular, eyes projected anterolaterally

Potamarcha congener

larval species not yet described/ unavailable

Aethriamanta brevipennis

--> body body relatively small sized, about 10mm long;

Palopopleura sexmaculata




I would like to thank Graham Reels generously shared a lot of references and carried out strenuous field work for species collection. Ken So and Alphonse Tsang kindly gave me invaluable individuals in alive, that was the best way to record larval development and to confirm species ID by rearing larvae to adult emergence. Nicole Kit and Kestrel Lam provided a high quality of species imaging, underwent tedious image cleanup work and well-managed our inventory of odonate species. Philip Yip who is working in Allied Environmental Consultants Limited for sharing their specimens for imaging. e.g. Epophthalmia elegans and Rhyothemis variegata. Last but the least, Professor David Dudgeon is gratefully acknowledged for his full support and patience. Without him, this species guide never happened.

Lily Ng Chiu Yee


Some references

Shida, S., Ishida, K., Kojima, K. Sugimura, M. (1988) Illustrated guide for identification of the Japanese Odonata. Tokyo University Press, 328pp.

Soltesz, K. (1996) Identification Keys to Northeastern Anisoptera Larvae. Workshops on Invertebrate Biodiversity: Dragonflies and Damselflies
Theischinger, G. and Hawking, J. (2009) Identification guide to the Australian Odonata. Department of Environment, Climate Change and Water NSW, 283pp.

Theischinger, G. and Endersby, I. (2014) Australian Dragonfly (Odonata) Larvae: Descriptive history and identification. Memoirs of Museum Victoria 72: 73–120.

Kawai, T. (1992) An illustrated Book of Aquatic Insects of Japan. Tokyo University Press, 409pp.

Wilson, K.D.P. (1995) Hong Kong Dragonflies. Urban Council, Hong Kong, 211pp.

Wilson, K.D.P. (1995) The Gomphid dragonflies of Hong Kong, with descriptions of two new species (Anisoptera: Gomphidae). Odonatologica 24(3): 319-340.

Yeh, W-C. & Lien, J-C. (1995) Proven distribution of Nannophyopsis clara in Taiwan and morphological description of the ultimate instar larva. Tombo XXXVIII 1995 Tokyo: 24-26.