Suborder Zygoptera
Family Isostictidae

Family Isostictidae figure 1

Extremely long and thin damselflies, can be told from the Disparoneuridae (Protoneuridae) by their more muted body colors. Disparoneurids are primarily black with various splashes of fiery red, orange, yellow, blue, etcetera, whereas Isostictids are shades of green and brown.

There are presently four genera known from the region and as these are such cryptic and shadow-loving insects, other discoveries are certain to follow. Donnelly (1993) provides a good overview and discussion of the family.


 

 

Key to the Papuan genera of Isostictidae

1 Vein CuP essentially non-existent, at least not extending beyond quadrilaterial (as shown below). Male paraprocts vestigial. Legs short with very short spines; tarsal claws simple. Distribution: Halmahera, Misool, Morotai, New Guinea, Woodlark, D'Entrecasteau, Louisiade Archipelago Selysioneura (16 sp.)
- Vein CuP present, extending one to several cells beyond quadrilateral. Male paraprocts well-developed 2

Family Isostictidae figure 2

2 Vein CuP extends at most only slightly more than one cell beyond quadrilateral. Quadrilateral little more than 1/6 the length of basal space. Ac distinctly before Ax1 in hindwing (as shown below). Male paraprocts shorter than cerci, the apex pointed. Legs long and slender, posterior femora as long as synthorax; tarsal claws with distinct subapical tooth. Distribution: New Guinea, New Britain, Woodlark, Misool, Tanimbar Is
Tanymecosticta (6 sp.)
- Vein CuP extends at least two full cells beyond quadrilateral. Quadrilateral nearly 1/4
the length of basal space. Ac distal to Ax1 in hindwing. Male paraprocts longer and larger than cerci, spatulate or spoon-shaped 3


Family Isostictidae figure 3

3 CuP two cells long, vein R4+5 arising distal to subnodus; Ac close to Ax1 in forewing and slightly distal to Ax1 in hindwing (as shown below). Tarsal claws very small. Male abdomen + appendices 46.0-63.0 mm, hindwing 32.0-32.5; female hindwing 29.5-31.0. Distribution: New BritainTitanosticta (1 sp.)
- CuP 7-11 cells long, vein R4+5 arising proximal to subnodus; Ac just distal to Ax1 in forewing and 3/10 the distance from Ax1 to Ax2 in hindwing (as shown below). Tarsal claws of normal length. Male abdomen + appendices 37.0-47.5 mm, hindwing 24.0- 29.0; female 35.5-45.5, 26.5-32.0. Distribution: New Britain, Bougainville, Solomon Islands Cnemisticta (2 sp.)


Family Isostictidae figure 4

 

Genus Cnemisticta Donnelly, 1993

Family Isostictidae figure 5

This genus can be distinguished from all other isostictids by its much longer CuP. There are currently two known species – C. latilobata from the Solomon Islands, and C. angustilobata from New Britain.

Family Isostictidae figure 6

 

Genus Selysioneura Förster, 1900

Family Isostictidae figure 7

Medium to large-sized damselflies of slender build. Body yellowish, olivish or light brown, variegated with dark brown or black, not metallic. Male with cerci robust, much longer than S10, forcipate and toothed; paraprocts tiny. The females are known to oviposit in the leaf midribs of trees growing over running water.
There are currently sixteen recognized species of Selysioneura, one of which, S. bacillus, has not been illustrated, and one of which, S. venilia, is known only from the female. They are roughly split into a "spiny tailed" group and a "smooth tailed" group, with typical examples as shown below.

Group A: Male cerci in dorsal view with basal (intero-ventral) tooth.

S. arboricola (D'Entrecasteaux Islands (Fergusson I.)
S. capreola (N. & Central NG) -- (CuP extending two cells beyond quadrilateral)
S. cervicornu (N., Central & E NG)
S. ranatra (North and Central New Guinea)
S. rangifera (D'Entrecasteaux Islands (Normanby I.)
S. rhaphia (D'Entrecasteaux Islands (Normanby I.)

Family Isostictidae figure 8

Group B: Male cerci in dorsal view with no distinct basal (intero-ventral) tooth.

S. aglaia (Morotai)
S. bacillus (West New Guinea) – not illustrated -- "cerci with 2 distinct teeth along upper margin; abdomen of male enormously drawn     out, S5 11 mm long."
S. cornelia (Sorong, West New Guinea)
S. drymobia (Louisiade Archipelago (Misima I.)
S. phasma (North and Central New Guinea)
S. stenomantis (Northern New Guinea)
S. thalia (Halmahera)
S. umbratilis (North and Central New Guinea
S. virgula (Woodlark I.)

Family Isostictidae figure 9

Genus Tanymecosticta Lieftinck, 1935

Family Isostictidae figure 10

Six species are known. The females of T. capillaris, T. filiformis and T. leptalea appear to be undescribed. Tanymecosticta filiformis has apparently never been illustrated.

Family Isostictidae figure 11

 

Genus Titanosticta Donnelly, 1993

Family Isostictidae figure 12
Titanosticta (from Donnelly, 1993).

There is one species: Titanosticta macrogaster Donnelly. It is a large, obscurely marked species varying from pale gray brown to dark, shining brown, the legs yellow with contrasting dark spines. Male abdomen + appendices 46.0-63.0 mm, hindwing 32.0- 32.5. It is found in New Britain.

Family Isostictidae figure 13