Suborder Zygoptera
Family Platycnemididae and the Papuan Argiinae

Family Platycnemididae figure 1

The damselflies in these two families (or subfamilies) have relatively straight wing venation, long quadrilaterals, and (generally) long legs with long spines on femur and tibia (as shown below). This makes them fairly easy to tell apart from the main body of Coenagrionidae. They rest with wings closed over their backs, which will suffice to distinguish them from the Lestidae, Lestoideidae, and Papuan Megapodagrionidae. But taken together, they are a motley assortment, difficult to characterize broadly, and equally difficult to differentiate as two separate taxa. Because of their numerous outward similarities this site treats them together. (The Argiinae are also included in the key to Papuan Coenagrionidae, since they are presently considered part of that family.) The taxonomic issues are complex, and getting moreso.

 

 

Family Platycnemididae figure 2
Leg spines (Palaiargia).
Hylaeargia magnifica
by Stephen Richards

As such, this site differentiates 10 extant groups of Papuan Argiinae and Platycnemididae as follows
(with the "Argiinae" marked by an asterisk):

* Archboldargia Lieftinck 1949 (3 sp.)
   Arrhenocnemis Lieftinck 1933 (3 sp.)
   Cyanocnemis Lieftinck 1949 (1 sp.)
* Hylaeargia Lieftinck 1949 (2 sp.)
   Idiocnemis Selys 1878 (22 sp. and ssp.)
   Lieftinckia Kimmins 1957 and related taxa (8 sp.)
* Palaiargia Förster 1903 (25 sp.)
* Papuargia Lieftinck 1938 (1 sp.)
   Paramecocnemis Lieftinck 1932 and related taxa (9 sp.)
   Thaumatagrion Lieftinck 1932 (1 sp.)

 

Key to the genera of Papuan Platycnemididae and Argiinae

1 R4+5 arises at or slightly distal to the subnodus, IR3 a long way beyond that level, viz, at Px3 to Px5 in both pairs of wings, hence nearer to R3 than to R4+5 (as shown below). Posterior femora with 6-8 robust short spines, which are barely two times as long as intervening spaces.Arrhenocnemis Lieftinck (2 sp.)

- R4+5 arises a little before, at, or slightly beyond the subnodus, IR3 one cell (or less) further distad, hence much nearer to R4+5 than to R3 . Posterior femora not armed as above.2

 

Family Platycnemididae figure 3
Origin of IR3 in Arrhenocnemis

2 Insect of small size (abd.+ app. 25.0, hw 17.0 mm). Stature very slender with extreme delicacy of structure. Wings with membrane in male for the greater part dark brown, almost black (as shown below), in female tinged with greyish-brown. Median lobe of labium with wide U-shaped emargination, which is almost as deep as half the length of the lobe itself, lateral lobes narrow, almost pointed apicad. Third antennal joint shorter than second, the distal joints very long and fine. Tarsal claws toothless. Posterior margin of male S10 with a strong archwise excavation.Thaumatagrion Lieftinck (1 sp.)

- Insects of moderate size and normal appearance. Body not so slender. Wings of male never opaque, those of female hyaline or only vaguely tinged with brown. Median lobe of labium with a small apical incision, lateral lobes bluntly triangular. Third antennal joint about equal in length to second, the flagellar joints (including the third) only little longer than first two joints united. Tarsal claws each with a distinct intero- apical tooth. Posterior margin of male S10 almost or perfectly straight (at least not so excavated as in Thaumatagrion).
3

 

Family Platycnemididae figure 4
Darkened wings of Thaumatagrion.

3 The majority of the cells in the distal half of wing (between veins R2 and R4+5) tall and rectangular, about twice higher than long. Origin of R3 distinctly before half-way the length of forewing, situated approximately half-way between nodus and origin of IR2a. Wings with dense venation and a marked tendency to develop forked and intercalated crossveins or fragments of these. (as shown below). Cyanocnemis Lieftinck (1 sp.)


- The majority of the cells in distal half of wing (between veins R2 and R4+5, not counting those cells immediately below Pt) squarish. Origin of R3 beyond half-way the length of forewing, its point of origin situated much nearer to origin of IR2a than to the nodus. Wing venation not noticeably dense and without forked and intercalated crossveins. 4


Family Platycnemididae figure 5
Venation of Cyanocnemis.

4 Ac located basally; either near or distinctly before Ax1 (in which case there are one or two cells between distal end of quadrilateral and level of subnodus), or situated distinctly nearer Ax1 than Ax2, particularly in forewing (in which case there are three or four cells between distal end of quadrilateral and level of subnodus).5

- Ac located mid-way (or very nearly so) between Ax1 and Ax2, or nearer Ax2 than Ax1. Only one or two cells between distal end of quadrilateral and level of subnodus.9

5 One or two cells between distal end of quadrilateral and level of subnodus (below, left). Distribution: Solomon Islands.Lieftinckia s. lat. (Part) (7 species)
[including Salomocnemis]

 

- Three or four cells between distal end of quadrilateral and level of subnodus. (below, right). Distribution: New Guinea. [taxa currently classified as "Argiinae"] 6

 

Family Platycnemididae figure 6

6 Male abdomen + appendices 41.5-42.5 mm, hindwing 30.5-31.0; female 35.8-38.0, 29.0-31.5. Wings greatly attenuated, greatest width to length of forewing from 1:6 to 1:6.4. Prothoracic lobe of both sexes and terminalia of male large and of complex arrangement. Males vivid green, bright blue, and red contrasting with black. Archboldargia Lieftinck (3 sp.)

- Moderately sized (male abdomen + appendices typically from 30.0-35.0 mm). Wings not so greatly attentuated. Prothoracic lobe of both sexes and terminalia of male not so large or unusual.7

7 Four cells between quadrilateral and level of subnodus in hindwing. Labium with median lobe deeply cleft, free lobes about 1/3 of length of labium itself. Prothorax with median division provided with robust conical tubercle on either side of the middle. Legs comparatively short and robust, bristles strong, spine-like, less numerous and much shorter than in next two genera, those on basal portion of posterior tibiae scarcely three times longer than intervening spaces. Male cerci with apical tooth-like projection. Female genital valves not toothed along lower margin.Papuargia Lieftinck (1 sp.)

- Only three cells between quadrilateral and level of subnodus in hindwing. Median cleft of mid-lobe of labium short, free lobes much less than 1/3 of length of labium itself. Prothorax with median division unarmed. Legs comparatively long and slender; bristles of femora and tibiae long and fine, those on basal portion of posterior tibiae at least five times longer than intervening spaces (Fig. 465). Male cerci unarmed. Female genital valves with number of small teeth along lower margin.8

8 Wings shorter in relation to width, about 4.5 times as long as wide. Bristles on basal portion of posterior tibiae at least six times longer than intervening spaces. Male cerci about as long as S10, variable in shape, paraprocts also variable but always exposed in lateral view and usually at least half the length and often equal in length to cerci Palaiargia Förster (25 sp.)

- Wings much longer in relation to width, about 5.5 times as long as wide. Bristles on basal portion of posterior tibiae about 5-6 times longer than intervening spaces. Male cerci 1.0-1.5 times the length of S10, mitten-shaped in lateral view, paraprocts fingerlike, mostly hidden from side-view, about half as long as cerci Hylaeargia Lieftinck (2 sp.)

9 2 cell rows distal to pterostigma between C and R1. Distribution: Solomon Islands. Lieftinckia s. lat. (Part) (1 species)

- 1 cell row distal to pterostigma between C and R1. 10

10 Wing-border distinctly crenulate (below, left), beginning with the cell before pterostigma, which is distinctly concave, and continuing around apex of wing to about the point where 1A enters the wing margin (or even further basad); costal side of pterostigma also distinctly undulate. Male terminalia (as shown below), in lateral view, typically simple in form (as shown below), cerci tapering to a (typically) downturned, blunt or rounded apex; paraprocts, in lateral view, also simple in form, tapering to a (typically) upturned, broadly rounded or somewhat hooked apex, the paraprocts roughly half to three-quarters the length of cerci; the cerci and paraprocts not meeting or overlapping at their apices.Idiocnemis Selys (19 sp., 1 ssp.)

- Wing-border less distinctly crenulate (below, right), if at all; crenulation, when evident, greatly reduced basal to the point where R4+5 enters the wing margin; the cell preceding pterostigma barely, if at all, concave, costal side of pterostigma not or only slightly undulate. Male terminalia, in lateral view, widely varied, but not as described for Idiocnemis. "Paramecocnemis-group" (9 species)
(including Lochmaeocnemis, Rhyacocnemis,
Torrenticnemis, and Idiocnemis leonorae.)

 

 

Family Platycnemididae figure 7
Family Platycnemididae figure 8
Range in male terminalia, left-lateral view
(Idiocnemis chloropleura, I. fissidens, I. inornata).

 

Family Platycnemididae figure 9

 

Genus Arrhenocnemis Lieftinck, 1933

Lieftinck (1933) describes this as 'a strong and stoutly built insect with a large head, long and robustly spined legs (as shown below), and with highly specialized wing-venation.' No habitat or behavioural notes are provided. Arrhenocnemis was at one time reassigned by Lieftinck (1965, 1971) to the Megapodagrionidae, but Gassmann (2005) convincingly returned it to the Platycnemididae.

 

Family Platycnemididae figure 10
A. sinuatipennis, femural spines.
(photo by the author)

 

 

Family Platycnemididae figure 11
Same, male terminalia


Amongst the Platycnemididae, the genus is immediately distinguished by the extraordinary positioning of vein IR3, which is far distal to the subnodus (at Px3 to Px5 in both pairs of wings, therefore nearer to R3 than to R4+5). There are three described species and a fourth of indeterminate status (Orr & Kalkman, 2010). All are known from North and Central New Guinea.

 

Family Platycnemididae figure 12

 

Genus Cyanocnemis Lieftinck, 1949

An endemic monotypic genus.

Cyanocnemis aureofrons Lieftinck, 1949

Lieftinck (1949) describes this as 'a rather sturdy insect with a small head, hairy and stout thorax with projecting shoulders and a relatively short and slender abdomen.' He adds:

Excessively abundant round the Araucaria bivouac and obviously quite the commonest zygopter of this locality, though not found outside this restricted habitat. The male, with its bright orange face and deep blue body-markings, would seem to be a most conspicuous insect when observed on the wing.

Male abdomen + appendices 31.5-35.0 mm, hindwing 24.5-26.0; female 30.5-33.5, 25.0-26.5. Distribution: Central Northern New Guinea.

Family Platycnemididae figure 13
C. aureofrons.  Wings (top row), male terminalia (bottom row).

 

Family Platycnemididae figure 14

Genus Idiocnemis Selys, 1878

There are currently twenty recognized species and one subspecies (Not counting Idiocnemis leonorae, which better matches Paramecocnemis), all of which inhabit New Guinea and the neighbouring islands.

Altogether this is the largest genus of platycnemididines in the Papuan region.

 

 

 

Key to the species-groups of Idiocnemis

(from Gassmann, 1999)

1 Head, prothorax, synthorax and abdomen light-brown, frequently with bluish-green or yellowish markings, but never marked with purple or blue. Mid-dorsal carina of synthorax always marked with fine narrow black line; ligula (penis) with terminal lobes varying in shape or entirely reduced inornata-group

- Head, prothorax, synthorax and abdomen medium-brown to black with purple, blue, turquoise or yellowish markings; mid-dorsal carina of synthorax covered by black stripe varying in width from twice as broad as mid-dorsal carina up to double the size of antehumeral stripe; ligula (penis) with conspicuous subrectangular terminal lobes bidentata-group

 

Idiocnemis "inornata group" – sample male terminalia

Family Platycnemididae figure 15

 

Idiocnemis "bidentata group" – sample male terminalia

Family Platycnemididae figure 16

 

 

Family Platycnemididae figure 17

Genus Lieftinckia Kimmins, 1957 and Salomocnemis Lieftinck, 1987

These two genera are endemic to the Solomon Islands and comprise eight species (one in prep), which between them show some variability in certain venational characters, such as the degree of crenulation along the wing margin, the number of cell rows distal to the pterostigma between C and R1, and the position of Ac.

 

 

 

Family Platycnemididae figure 18
Lieftinckia lairdi
Family Platycnemididae figure 19
Lieftinckia salomonis
Family Platycnemididae figure 20
Salomocnemis gerdae

Genus Lieftinckia and Salomocnemis – sample male terminalia

Family Platycnemididae figure 21

 

Genus Lochmaeocnemis Lieftinck, 1949

See under "Paramecocnemis Group"

 

The "Paramecocnemis Group"

(treatment includes Paramecocnemis Lieftinck, 1932; Lochmaeocnemis Lieftinck, 1949; Rhyacocnemis Lieftinck, 1956; Torrenticnemis Lieftinck, 1949, and Idiocnemis leonorae Lieftinck, 1949.)

Family Platycnemididae figure 22
Specimen "72x040"
Family Platycnemididae figure 23
Idiocnemis leonorae (original wing scan)
Family Platycnemididae figure 24
Lochmaeocnemis malacadora
Family Platycnemididae figure 25
Torrenticnemis filicornis
Family Platycnemididae figure 26
Paramecocnemis erythrostigma
Family Platycnemididae figure 27
Paramecocnemis stilla-cruoris (original wing scan)
Family Platycnemididae figure 28
Rhyacocnemis prothoracica
Family Platycnemididae figure 29
Rhyacocnemis sufficiens

 

The "Paramecocnemis Group" – male terminalia

Family Platycnemididae figure 30
Family Platycnemididae figure 31
Family Platycnemididae figure 32
Family Platycnemididae figure 33
Family Platycnemididae figure 34
Lochmaeocnemis malacadora

 

Genus Rhyacocnemis Lieftinck, 1956

See under "Paramecocnemis Group"

 

Genus Salomocnemis Lieftinck, 1987

See under Lieftinckia.

 

Genus Thaumatagrion Lieftinck, 1932

Family Platycnemididae figure 35
T. funereum (left, original body scan), fw and hw quadrilaterals (right).

An endemic monotypic genus. Apart from Rhinocypha (easily recognizable by its short, stout abdomen and black-and-blue colouration) and Pseudagrion fumipennis (in which only the apices of the wings are tinted brownish), this is probably the only small zygopteran in New Guinea with dark brownish-black wings.

Thaumatagrion funereum Lieftinck, 1932

Distribution: Central Northern New Guinea.

Family Platycnemididae figure 36
Thaumatagrion funereum, male terminalia.

 

Genus Torrenticnemis Lieftinck, 1949

See under "Paramecocnemis Group"

 

Genus Archboldargia Lieftinck, 1949

Family Platycnemididae figure 37

These are very large damselflies, the abdomen being around 40 mm, the hindwing around 30 mm in length. Lieftinck (1949a) describes them as

'brightly coloured insects, with long narrow wings, strongly modified posterior lobe of prothorax and conspicuous, very intricately built male anal appendages.' [p. 139]

All three species are known only from the central mountains of Indonesian New Guinea (Papua); A. gloriosa and A. edwardscissorhandsi were found in the vicinity of the pass between Jayapura and the Baliem Valley, while A. mirifica was found further to the west in the Wissel Lakes area near the 'neck' of the 'Vogelkop.'

Family Platycnemididae figure 38
A. mirifica

 

Family Platycnemididae figure 39

Genus Hylaeargia Lieftinck, 1949

Two species of medium sized damselflies, of sturdy build, alert and strong-flying.

 

 

 

 

 

 

 

Family Platycnemididae figure 40
Hylaeargia simulatrix.

The type locality of H. magnifica is a small clear brook less than one meter across and only ankle deep. The adults perch in full sunlight on tall grasses and branches over the small ravine through which the stream runs, in behaviour similar to the American Argia with their vigorous flight, frequent perching in sunny places and, it seemed at the time, fairly high population density.

Family Platycnemididae figure 41
Male terminalia, H. simulatrix
Family Platycnemididae figure 42

 

Genus Palaiargia Förster, 1903

20 published species. Lieftinck (1957) writes:

"[...] the total number of Papuasian species so far known [...] is very probably only a fraction of the total actually occuring in New Guinea alone, for most Argiinae have retiring habits and are not easily noticed. [p. 43] ... The males [of Palaiargia] are very inconspicuous insects, which frequent small rocky streams in deep ravines, keeping close to the water's edge. [p. 64]"


Of Palaiargia micropsitta, he writes: "The females when captured exhibit a conspicuous and beautiful colour-design of blue and black, but when flying low or resting on gravel bars and pebbles are all but invisible on account of their strongly disruptive pattern. [pp. 57-58]"

Family Platycnemididae figure 43
Palaiargia charmosyna.

 

Genus Palaiargia – sample male terminalia

Family Platycnemididae figure 44

Genus Papuargia Lieftinck, 1938

Family Platycnemididae figure 45
Papuargia stüberi.

An endemic monotypic genus.

Papuargia stüberi Lieftinck, 1938

From Lieftinck's description, the main thoracic colours are light olive-green with reddish-brown bands along the carina and sutures, legs are light green with broad exterior bronze-brown stripes, abdomen olive-green with brown articulations, turning bronze-brown above and green on the sides, terminalia dark brown, almost black. Distribution: northern New Guinea (Upper Tami River area).

Family Platycnemididae figure 46
P. stüberi, male terminalia.