Pterygophorus from Windellama — Life in a Southern Forest

Workbook

Identification of adult sawfly collected by Penny Gullan at Windellama, SE of Goulburn near Budawang Range. The larvae of this species have been causing widespread defoliation on their property.

Roger Farrow thinks the same or a similar species may be responsible for defoliation and dieback of Melaleuca parvistaminea along the Kings Highway at the Doughboy TSR and Sandy Point-Oallen Ford roads.

Photographs of the female sawfly received from Penny on 23rd December

Featured

Dorsal view of intact insect

Head black

Antenna with 20 antennomeres: - scape and pedicel black; 7 basal flagellomeres yellow; apical 11 black; pecten directed antero-ventrally on each flagellum, becoming longer in apical flagellomeres; most apical antennomere is clubbed

Pronotum and mesoscutellum pale yellow, shining between sparse punctures

Mesoscutum black

Metascutellum black

Abdomen black with 2 yellow bands

Abdomen colour shown after removal of wings

Abdomen black with 2 yellow bands

Anterior band largely confined to T3 dorsally, just crosses into T2 anteriorly and T4 posteriorly

Posterior band is the exposed intersegmental membrane between terga 6 and 7 (this region pushed inwards here)

Lateral view, body length 10mm

anterior band fills tergum 3 laterally and crosses into tergum 4

posterior yellow band extends ventrally into tergum 7, expanding to its posterior edge

saw extended

Extended saw

Saw after dissection from insect

view of lancet (first valvula) showing teeth 1-11

area in square around tooth #10 shown in next image

photomicrograph of tooth #10

~26 denticulations (serrulae) on this tooth. Benson (1938) reports 28-40 serrulae present in P. cinctus.

Head and antennal morphology

Head black: short, fine pale pubescence; shining, without punctures

Antenna with 20 antennomeres: - scape and pedicel black; 7 basal flagellomeres yellow; apical 11 black

Thorax morphology and colour

short, fine, pale pubescence over thorax

mesoscutum black, pronotum yellow with black anterior border and black behind accessory furrow (black arrow)

accessory furrow subparallel with side margin of pronotum

side portion of pronotum cut off by accessory furrow (white double arrow heads) broader than length of malar space (white double arrow heads on head)

mesepisternum black with large central yellow area

Ventral view - showing colour of legs and body

femur solid black in all legs

fore and mid tibiae and tarsomeres - white basally, black apically

hind tibia and tarsi pale

pygidium (T10) yellow

saw sheath black, saw dark brown

venter black, except for pale yellow sternites 3 and 4

Detailed view of terminal segments

Fore wing removed from body

wing hyaline with dark brown band extending along anterior border to wing apex, covering 1st cubital and radial cells completely and half of 2nd and 3rd cubital cells and 1st discoidal cell

costa and stigma yellowish-brown

venation black in basal and anterior regions, dark brown in apical region

Summary:

This female is a good match to Pterygophorus cinctus. There are only minor differences (colour of hind tibia, number of serrulae on saw teeth, exact number of antennomeres) to the description by Benson (1938) and to other specimens I have collected at Wonboyn and Bellingen.

It differs in key diagnostic features from other Pterygophorus spp. P. insignis, P. facielongus and P. turneri, as detailed on this notes page.

References:

Benson, R.B. (1938) “A revision of the genus Pterygophorus Klug, sensu lato, with the description of two new genera (Hymenoptera, Symphyta)”. Annals and Magazine of Natural History 1: 610-625.

This is a workbook page … a part of our website where we record the observations and references used in making species identifications. The notes will not necessarily be complete. They are a record for our own use.