Xyloperga halidaii vs. Xyloperga amenaida — Life in a Southern Forest

Xyloperga halidaii and Xyloperga amenaida are very similar in appearance.

The original descriptions of these species by Kirby (1882) and Westwood (1880) are brief, unclear and ambiguous, making it difficult to separate them confidently from field photographs.

On this page, I have detailed the morphology of 3 Xyloperga specimens collected in the field. My goal is to use this information to align features visible in field photographs with the original species descriptions of X. halidaii and X. amenaida.

Summary of findings to date

A comparison of specimens A, B and C with published descriptions of X. halidaii and X. amenaida strongly suggests that A and B are a female and male of X. halidaii while C is a female of X. amenaida.
This conclusion is supported by the strong similarity between specimen B and a BOLD specimen of a male identified as X. halidaii.
Discrepancies between features in these specimens and the published descriptions may stem from the brevity of the latter. I hope to obtain photos of the holotypes of both species to clarify the situation.

Observations of specimens

Specimen A

Specimen A is a female, collected by Marianne Broug (iNaturalist observation) at Belair SA in January 2026 (specimen #PW076). It was found dead on a road. Antennae and some leg segments are missing, the mesonotum split but otherwise the insect is intact. While lacking antennae, it shows the following characters which are diagnostic of genus Xyloperga: scutellum convex, with well developed hind lobes; head swollen behind the eyes; clypeus with a transverse fold in the middle.

Featured

body length 13.7mm
- all segments of all legs orange
- lateral folds of tergites yellow, venter black
- mesosternum black
- genae, inner orbits, mandibles (except black tip), labrum yellow

right side of body
- coloured body parts bright yellow
- abdomen dorsum black, yellow laterally; T1-T4 with yellow stripes
- all segments of all legs yellow, basal region of all coxae black
- mesepisternum black with wide, transverse yellow stripe
- genae narrower than eye viewed laterally

left side of body
- mesepisternum black with wide, transverse yellow stripe
- genae narrower than eye viewed laterally

- vertex bright yellow with 3 wide, longitudinal black stripes which extend anteriorly to cover ocellar region
- pronotum black with broad yellow hind border
- mesoscutum black with orange patch near rear of middle lobe
- abdomen dorsum black

- scutellum semi-oval, convex, solid yellow with long obtuse orange hind lobes
- fore wings pale yellow hyaline, costa and stigma orange, venation brown

dorsal view of head
- vertex bright yellow with 3 wide, longitudinal black stripes which extend anteriorly to cover ocellar region
- post-ocellar region of vertex with few hairs, densely punctured
- antennal tubercles, inner orbits, clypeus and labrum yellow
- clypeus emarginate

higher magnification view of vertex
- sparsely pilose, a few, short, brown hairs
- heavily punctured with bare, unpunctured area in anterior part of yellow stripes, just behind lateral ocelli

- pronotum black with broad yellow hind border, black region densely punctured and covered in short, brown, erect hairs
- mesoscutum black with pale orange spot towards rear of middle lobe; middle lobe densely punctured and pilose in medial region
- scutellum convex, solid yellow with obtuse long orange hind lobes and shallow midline furrow; anterior border black
- long yellow extensions from anterior corners towards tegulae

lateral view of saw and sawsheath

ventral view of saw and sawsheath

ventral view of saw (refers to lancet or lancet and lance), sawsheath and tergite X after dissection from body and clearing in KOH
- circular, brown cerci present on tips of tergite X
- ventral surface of sheath (valvula 3) covered in stout dark brown bristles, arranged in rows
- fine hairs extend from lateral sides and tip of valvula 3
- lance (valvula 2) and lancet (valvula 1), each paired, visible between the sheath

dorsal view of saw, sheath and tergite X dissected from body

ventral view of lance, lancet and sheath after removal of tergite X

ventral view of lancet after removal of sheath and lance

lateral view of lancet, ventral side below
- divided into repeating units, annuli
- approx 13 sharp sawteeth present on distal third of lancet
- some fine serrations apparent further proximally, but no clear teeth

detailed view of distal end of lancet, showing large, sharp sawteeth

lateral view of middle region of lancet
- broad, finely serrated areas apparent but no sharp teeth

similar to drawing of saw of Xyloperga halidaii in Benson (1939), fig. 37 - contrast drawing of saw of Xyloperga amenaida, fig. 35

proximal region of lancet
- teeth not apparent, but cutting edge separated into units aligned with annuli

from Benson (1939)

Specimen B

Specimen B is a male, collected by Chris Pease (@cole0ptera, iNaturalist observation) near Eumundi, Qld on 20/1/26 (specimen #PW085). It shows the following diagnostic characters of genus Xyloperga: 7-segmented antenna, shorter than the width of the head; scutellum convex, with well developed hind lobes; head swollen behind the eyes; clypeus with a transverse fold in the middle.

Featured

lateral view right side
- body length 11.5mm
- all segments of all legs orange, except base of coxa and distal tips of tibia and tarsi of hind legs black

lateral view, left side
- coloured body parts bright yellow
- genae yellow, narrower than width of eye viewed laterally
- lateral region of vertex orange
- pronotum black with yellow hind border
- mesepisternum black with wide, transverse yellow stripe
- abdomen dorsum black, with yellow stripes on some anterior terga
- lateral folds of terga and venter yellow
- mesosternum transparent orange
- hind femur dilated and dark orange colour
- hind tibia with apex black

dorsal view of pinned and spread specimen
- scutellum heavily punctured, with transparent orange, obtuse hind lobes
- tegulae transparent orange
- mesoscutum black with yellow uninterrupted V at rear of middle lobe; heavily punctured and short, recumbent golden hairs medially on lateral lobes and posterior half of middle lobe
- scutellum yellow with anterior extensions to tegulae on lateral sides of mesoscutum; transparent orange, obtuse, widely spaced hind lobes; heavily punctured
- dorsum of abdomen black, except T10 pale orange and pale orange stripes posteriorly on T1, T2 and anteriorly on T3, T4, T5.

frontal view of head
- genae, inner orbits, antennal tubercles, labrum yellow
- clypeus yellow with black base, emarginate
- mandibles orange with black tips
- scape, pedicel, flagellum and club all orange

detail of antenna
- scape pedicel, flagellum and club all orange

dorsal view of head
- vertex yellowish-orange with 3 wide, longitudinal black stripes which extend anteriorly to cover ocellar region, densely punctured
- vertex covered with golden and brown short, recumbent hairs, except for bare, unpunctured region immediately behind lateral ocelli

higher magnification view of post-ocellar region of vertex showing clear, unpunctured area immediately behind lateral ocelli

higher magnification view of the left side of the vertex showing dense covering of short black, recumbent hairs.

this area densely punctured, apart from area behind left ocellus, which is also bare

lateral view of left side of vertex showing fine, golden and black hairs covering surface, except for patch behind lateral ocellus

dorsal view of abdomen and thorax
- forewings pale yellow hyaline, orange costa and stigma, venation orange
- tegulae transparent orange
- scutellum yellow with anterior extensions to tegulae on lateral sides of mesoscutum; transparent orange, obtuse, widely spaced hind lobes
- mesoscutum black with yellow V at rear of middle lobe

detailed view of mesoscutum and scutellum
- scutellum heavily punctured, with transparent orange, obtuse hind lobes
- tegulae pale orange

lateral view of left side of mesonotum, showing fine golden hairs covering anterior and lateral lobes and pronotum. these areas heavily punctured.

dorsal view of thorax
- pronotum black with broad yellow hind border
- mesoscutum black with yellow V-shape at rear of middle lobe, heavily punctured, medial part of lateral lobes pilose with golden hairs
- scutellum yellow, heavily punctured, sparsely pilose anteriorly, with black anterior border and yellow anterior extensions to tegulae

detail of scutellum
- solid yellow colour, with posterior border and hind lobes transparent orange
- heavily punctured
- shallow medial furrow
- some short brown hairs on anterior and posterior borders

lateral view of scutellum, showing fine golden hairs on anterior, lateral sides and on hind lobes

ventral view of body
- mesopleura black with wide transverse yellow streak
- mesosternum transparent with narrow pale yellow border to mesopleura
- lateral folds of terga and venter yellow

ventral view of thorax
- mesopleura black with wide yellow transverse stripe
- mesosternum transparent (internal organs visible beneath) with narrow pale yellow border to mesopleura
- fore leg coxa pale yellow, femur, tibia and tarsus orange

ventral view of abdomen
- lateral folds of all terga yellow
- venter all yellow

posterior view of end of abdomen showing genitalia

ventral view of mid and hind legs
- coxae pale yellow with black basal patch
- femora, tibiae and tarsi orange, with apex of hind tibia and tarsi black

forewing
- hyaline, pale yellow, basal half darker than apical half
- hairy patch underneath radial, 1st & 2nd cubital, 1st discoidal and medial cells
- costa orange, black hairs on outer edge
- stigma orange, less than half as long and broad as radial cell
- basal and median veins orange, same colour as other veins
- 3rd cubital vein almost straight and directed to point well outside apex of stigma
- basal and 1st recurrent veins subparallel

Specimen C

Specimen C is a female collected by James Peake, (iNaturalist observation) at Mt. Buller, Vic on 23/12/25 (specimen #PW077). It shows the following diagnostic characters of genus Xyloperga: 7-segmented antenna, shorter than the width of the head; scutellum convex, with well developed hind lobes; head swollen behind the eyes; clypeus with a transverse fold in the middle.

Featured

dorsal view
- mesoscutum black with yellow V-mark at rear of middle lobe, interrupted at midline, heavily punctured, many long golden hairs medially
- scutellum yellow, thickly punctured, covered in brown hairs, short black midline furrow anteriorly
- fore wings pale yellow hyaline, costa and stigma brown, venation brown

ventral view
- all segments of all legs orange, except pale basal patches on all coxae
- lateral folds of tergites pale yellow
- mesosternum pale brown with black V mark at midline
- mesepisternum pale brown with black lines at sutures with mesosternum
- clypeus, labrum and mandibles brown, except tip of mandibles black
- labial and maxillary palps brown

right side of body
- abdomen dorsum black, pale yellow on lateral folds
- mesepisternum solid pale brown
- lateral border of lateral lobe of mesocutum black and orange
- costa and stigma of fore wing brown

left side of body
- antennal flagellum orange, black scape and pedicel
- clypeus, labrum and mandibles brownish-yellow, with black tips to mandibles
- saw partially protruded
- lateral folds of terga, venter pale yellow
- mesepisternum brownish-yellow, thickly punctured, black line at junction with mesosternum
- mesosternum brownish yellow with black triangular mark at midline
- all segments of all legs yellow, with white patches on coxae

body length 17.8 mm

- vertex brown with two short, narrow black stripes on sides of post-ocellar area, covered in short black, recumbent hairs, densely punctured
- ocelli linked by an incomplete rectangular grid of black lines
- scape and pedicel black, flagellum brown
- antennal tubercles orange
- pronotum black with wide light brown hind border, covered in black hairs

ventral view of head
- antennal tubercles, clypeus, labrum, labial and maxillary palps, mandibles brown with mandible tips black
- scape and pedicel black, flagellum brown

dorso-lateral view of head
- scape and pedicel black, flagellum yellowish-orange (chestnut)
antennal tubercle yellow
- vertex covered in recumbent black hairs, densely punctured in post-ocellar area but unpunctured laterally
- genae smooth, chestnut, wider than width of eye

detail of left side of post-ocellar area
- covered in recumbent hairs, densely punctured

dorso-lateral view of front of thorax
- pronotum black with broad yellow posterior border, with long black hairs posteriorly
- tegula yellow
- lateral face of lateral lobe of mesoscutum orange posteriorly, black anteriorly
- mesepisternum yellow, moderately heavily punctated, with fine golden hairs

- scutellum thickly punctured, covered in brown hairs, black midline furrow anteriorly
- hind lobes pale yellow, close to midline

- mesoscutum black with yellow V, interrupted at midline
- heavily punctured, covered medially in long golden hairs in the posterior half
- lateral border of lateral lobes yellow posteriorly, black anteriorly
- tegula yellow

ventral view of abdomen, showing saw and sawsheath

ventral view of saw partially protruded from sheath

detail of apical region of saw showing lancet and lance

detail of more basal region of saw

Latero-ventral view of extended saw showing lancet (valvula 1) and lance (valvula 2)
These blades are divided into repeating units, annuli, each of which bears a sawtooth

ventral view of saw, sheath and tergite X after dissection from body and clearing in KOH
- circular, brown cerci visible on tergite X

magnified view of end of saw, sheath and tergite X

tergite X separated from sheath and saw, showing dense hairs laterally

ventro-lateral view of saw after removal of sawsheath (3rd valvula)

ventral view of tip of saw
- a row of sawteeth present along each lancet

basal region of saw viewed latero-ventrally
campaniform sensillae are sensory organs

tip of saw
- lancet above, showing teeth
- lance below

sawteeth at distal end of lancet

from Benson (1939)

Comparison of specimens A, B, C from above observations

Click on the image below to download a high resolution pdf version (54KB).

Summary:

There are few differences between specimen A (a female) and specimen B (a male) - indicated by the red text in the Specimen A row. These include degree of punctation of the scutellum, size of the yellow patch on the middle lobe of the mesonotum, degree of pilosity of the mesoscutum and colour of mesosternum (black vs. transparent orange) and venter (black vs yellow).
In contrast, there are many differences between specimens A and C - indicated by the bold text in the Specimen A and C rows. The most significant are head colour and morphology (pattern of stripes on vertex, relative genae vs. head width), scutellum colour and morphology, different V-mark on middle lobe of mesoscutum, mesepisternum colour and saw morphology.

The last two characters - mesepisternum colour and saw morphology - are included in published descriptions of X. halidaii and X. amenaida and therefore play a key role in species delimitation. The other characters - head morphology and scutellum morphology/colour - were either not recorded or only superficially described in published descriptions.

How representative are Specimens A, B, C of other iNaturalist observations?

The descriptions of specimens A, B, C will be used to assist species identification of X. amenaida and X. halidaii in iNaturalist field photos. It is therefore important to know whether these specimens are representative of iNaturalist observations.

The following table shows whether the iNaturalist observation listed matches specimens A, B or C. Features that don’t match that specimen are noted.

Click on the thumbnail to download a full PDF version (59KB).

Summary:

iNaturalist observations of X. amenaida/halidaii fall clearly into 2 groups, corresponding to specimens A/B (female/male) and specimen C (female).

I conclude that the specimens are representative of iNat observations.

There are minor differences between individuals within each of these groups:
- some insects in group C are strongly melanistic, showing thick black stripes on the vertex reaching to the ocelli, rather than narrow, short stripes and thicker black stripes on the scutellum
- the apex of the otherwise orange hind tibia is black in some individuals in group B
- the hind femur is clearly dilated in some individuals in group B but not in others

Differences between X. amenaida and X. halidaii in published descriptions

The matrix below compares features of X. amenaida and X. halidaii extracted from published descriptions of these species by a range of authors.

Red text highlights features that differ between these species.

Click on the image to download a pdf of the matrix (871KB).

Summary of distinguishing features in published descriptions:

Post-ocellar region of X. halidaii is densely punctured, apart from a patch behind the hind ocelli, whereas it is unpunctured in X. amenaida
Scutellum of X. halidaii is yellow and thickly punctured. In X. amenaida the midline furrow is deep and yellow in colour, sometimes with a brownish-black (in male) or reddish-yellow (in female) area in the apical half.
Mesepisternum of X. amenaida is yellow (in male) or red (in female), whereas in X. halidaii it is shiny black with a yellow transverse band
Saw of X. halidaii has large teeth with numerous fine secondary teeth, whereas in X. amenaida it has numerous primary teeth
Hind femur of male of X. amenaida is dilated. There is no mention of this in X. halidaii.
Thickened (incrassate) hairs on apex of front tibia in X. amenaida, whereas these are absent in X. halidaii.
Hind basitarsus in X. amenaida is only as long as breadth of apex of tibia and scarcely 1.5x its own apical breadth, whereas in X. halidaii it is longer than the apex of hind tibia and more than 2x as long as its own apical breadth.

Comparing specimens A, B, C to published descriptions

I have chosen features 1-5 from the list above. Features 6 and 7 could not be assessed with confidence in the specimens.

Click on the image to download a pdf of the table (29KB)

Conclusions:

There is a match between features in specimen A and diagnostic characters for X. halidaii. Notably, this includes saw morphology.

Features in specimen B match the diagnostic characters for X. halidaii except for the hind femur morphology. X. amenaida males are reported to have a dilated hind femur, but there is no mention of this for X. halidaii. However, iNaturalist observations of males indicate this may be a variable feature within a species and therefore not a suitable diagnostic character.

There is a match between features in specimen C and nearly all of the diagnostic characters for X. amenaida, including the saw morphology. The one character that does not match is the punctation of the middle region of the vertex, which is reported to be unpunctured in X. amenaida but which appears to be densely punctured in specimen C.

Examination of the holotype specimen of X. amenaida may help to clarify this discrepancy.

Additional information for species delimitation

BOLD specimen of male Xyloperga halidaii - SICOD1430-19 Specimen determination: Jeremy deWaard

Specimen B matches this BOLD specimen of X. halidaii closely in all visible features.

2. Images of type specimens of X. halidaii and X. amenaida from SAMA,

determined by Forsius (1927). Images kindly supplied by Ben Parslow, SAMA.

Xyloperga amenaida type specimen

Xyloperga amenaida - male left, female right

Xyloperga amenaida - male

Xyloperga amenaida - female

Male specimen shares following features with BOLD specimen of male X. halidaii above:
- genae narrower than eye width
- mesepisternum with a wide yellow transverse stripe (however background colour is brown rather than black)
- hind femur dilated

This may suggest that the species determination of either the SAMA specimen or the BOLD specimen is incorrect. Further information - in particular, images of the holotype of both X. halidaii and X. amenaida - is required to decide between these alternatives.

Xyloperga halidaii type specimen

Xyloperga halidaii - unit tray

Xyloperga halidaii - female (missing head, most thorax)

The preservation of this specimen is too poor to decide whether the species determination by Forsius of X. halidaii is correct or incorrect.

Images of holotypes of X. amenaida and X. halidaii

I hope to obtain images of the holotypes of X. amenaida (from BMNH) and X. halidaii (from OXUM).

This information should help species identification of specimens A, B, C and the overall goal of aligning features visible in field photographs with the original species descriptions of X. halidaii and X. amenaida.

References:

Benson, R.B. 1939. A revision of the Australian sawflies of the genus Perga Leach, sens. lat. (Hymenoptera, Symphyta). The Australian Zoologist 9: 324-357

Kirby, W.F. 1882. List of Hymenoptera, with descriptions and figures of the typical specimens in the British Museum. Vol. I. Tenthredinidae and Siricidae. London: British Museum, xxviii

Morice, F.D. 1919. Notes on Australian sawflies, especially the “Authors' Types” and other specimens in the British Museum of Natural History and the Hope Collections of the Oxford University Museum; with diagnostic synopses of the genera and species, and photographs illustrating their structural characters. Transactions of the Entomological Society of London 66: 247-333, pls XI-XV.

Westwood, J.O. 1880. A monograph of the sawflies composing the Australian genus Perga of Leach. Proceedings of the Zoological Society of London 1880: 359-379

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, but we are happy to share this information with others.