- broad vertex, high centrally
- small discal marks on mesoscutum

- vertex high (at least as high as eyetops)
- white bands on metasoma narrow, broken, slightly sinuate
- T6 black

- small white lateral markings on S2 and S3 (at least)

- eyes diverging above to a very broad vertex
- vertex high centrally
- clypeus with pair of large black spots basally, barely joined medially
- front basitarsus not broadly expanded, & with relatively small number of pecten spines
- mandible slender

- clypeus moderately protruberant, smoothly rounded
- head and mesosoma hairy
- thin yellow streak on posterolateral edge of mesoscutum
- narrow, sinuate, broken white bands on T1-5

- small number of pecten spines on front basitarsus
- vertex high centrally, above level of eye tops
- vertex very broad
- clypeus without lateral prominences
- mandible slender, tooth small

- vertex high, above eye tops
- eyes diverging above, vertex very broad
- without discal markings on mesoscutum, but with small yellow streaks on lateroposterior angles

Although I can’t be absolutely sure, I think this is the same individual as ‘01’.

- a bright, narrowly interrupted, posterior yellow band on mesoscutum (in addition to the paired discal streaks and lateral streaks)
- pair of yellow marks on scutellum are broad, approaching midline
- complete transverse band on metanotum

- vertex high centrally, at least reaching level of eye tops
- bright yellow discal streaks on mesoscutum
- very mesopleura with long, pale hairs

- white band on T1 reduced to a pair of spots (so presumably a pair on each side of the midline)
- white bands on T2-5 very narrow, broken medially
- T6 black

- vertex broad and high
- limited pale markings on mesoscutum
- narrow pale bands on T1-5, broken medially

- very broad vertex
- narrow, broken white (or slightly yellowish) bands on metasoma

Note the length of the pale marking on T1 … considerably longer than in most B. musca,

Even without details of the clypeus, mandible, or front basitarsus, the breadth of the vertex would just about convince me this was B. littoralis. Just about.

The clypeus and labrum are just visible here: the clypeus yellow, with black markings basally; the labrum yellow (at least laterally). That is probably enough to exclude the following:
- B. musca (which has black along the sides of the labrum)
- B. lamellata (in which the labrum and clypeus are wholly black)
- B. furcata & B. thooma (both with labrum wholly black)

I can also exclude B. trepida on the basis of:
- the long pecten spines (they are short in B. trepida)
- the clypeus looks smoothly rounded (not abruptly flattened as in B. trepida … although this may be difficult to judge from this angle)

It is this shot that confirms Wasp 03 as male. There are seven visible tergites. Female Bembix have just six.

The vertex looks high, about level with the eye tops. So that fits with B. littoralis … and B. variabilis, B. musca, B. lamellata, etc. The very broad apex also fits with B. littoralis … and B. variabilis males.

However, B. variabilis has much wider metasomal bands.

The inner eye margins diverge above, the vertex therefore very broad.

Note that the width of the frons is roughly the same in B. littoralis, B. variabilis and B. musca females. However, only in B. littoralis does the very broad vertex get a special mention by Evans & Matthews (1973).

Although not a key diagnostic feature, B. littoralis females “vestiture pale, very dense and relatively long over much of head and mesosoma” (p. 270, Evans & Matthews 1973). Well that fits!

Note too the broad vertex when viewed from this angle.

The centre of the vertex is clearly higher than the eyetops, when viewed frontally.

Note that in B. variabilis, the vertex is slightly below the eyetops (and in B. furcata it is much lower still).

The mandible is slender, somewhat curved at the extreme apex but otherwise relatively straight. This shape is typical of Bembix that nest in very friable sand.

Compare this with the figures from Evans & Matthews.

The length to width ratio is about 6 (compared to the 6.3 reported for B. littoralis and 7.0 for B. variabilis).

(In this image, one antenna has been removed. It shows a single focal plane, with no stacking, to support accuracy of measurement.)

The tooth is small (dotted arrow), as is the cutting edge (solid arrows). In B. variabilis the cutting edge is essentially absent.

Note that in their description of B. musca, Evans & Matthews (1973) referenced Figure 28 as an illustration of the shape (see Key Step 69).

The front basitarsus is weakly lobed, and bears 6 pecten spines. The smaller, basal spines are pale, while the strong apical ones are amber in colour.

The length to width ratio is 3.0 … exactly as reported for B. littoralis. Note that in B. variabilis the front basitarsus is more slender, with a ratio of 3.3.

left leg, frontal view, tibia at top

Initially the colour of the front basitarsus made me question the identity as B. littoralis. The blackened margin to the basitarsus is not mentioned in their description of B. littoralis (Evans & Matthews 1973) but is a described feature of B. musca, B. variabilis and B. lamellata. However I am now convinced that this is simply another aspect of the additional melanisation of such ‘darker variants’. Specimen 2511M is consistent with B. littoralis in too many other, diagnostic features (including vertex height, mandible shape, and clypeus colour).

The clypeus is protruberant and smoothly rounded. That is, there is no abrupt flattening of the apex as seen in species such as B. trepida and B. tuberculiventris.

Note that this general shape is shared by all members of the Littoralis species group (B. lamellata, B. littoralis, & B. variabilis) and also B. musca, although the latter is more strongly protruberant.

[antenna on right removed in order to better view the clypeus]

A broad black band at the base of the clypeus, with an emargination at the apical midline. This is one of the differences between B. musca and B. littoralis. In B. musca, the black band extends forward medially, towards the apex.

Note too the lack of any lateral prominences or medial ridge, both of which are features of B. furcata.

The discal marks are small (solid, curved arrows), and there is just a couple of traces of the posterior mark (dotted, straight arrows).

Thin, broken, slightly sinuate white bands on T1-T5. T6 is entirely black.

Note that in combination with the very limited markings on the mesoscutum, this is entirely consistent with descriptions of dark variants of B. littoralis. In contrast, B. variabilis with limited mesoscutum markings have much broader metasomal bands.

Consistent with B. littoralis:
- overall body length 12-13mm
- forewing length 9mm

Consistent with Bembix:
- eyes essentially parallel, diverging (usually slightly) above and below

Consistent with B. littoralis:
- upper front (frons) covered in long, erect, pale hairs

Consistent with Bembix:
- labrum prominent and long

Consistent with B. littoralis:
- labrum and mandibles pale (yellow, in this case)
[labrum cream in type specimen]

- sternite 2 with strong punctures
- small pale spot at one side of S3 (suggesting a more extensive pattern of pale / yellow markings in lighter variants)

Consistent with Bembix:
- gaster sessile, with T1 nearly as broad as T2

Bands appear white, in contrast to Type in which they grade into yellow laterally. Again, this variation accords with that reported for the species.

Consistent with Bembix:
- forewing media diverging slightly before cu-a
- 3 submarginal cells
- SCI greatly elongated before stigma
- SCII four-sided, and not petiolate
- veinlet between SCI & SCII crooked

Evans & Matthews found “no noteworthy differences in wing venation among Australian species” (p. 10)

As with the mesoscutum, pale markings elsewhere on the mesosoma are limited. In more heavily marked B. littoralis individuals, there are transverse yellow marks on the scutellum and metanotum, and the propodeum is extensively yellow. In 2511M, there are just a pair of lateral spots on the scutellum, a thin broken band on the metanotum, and the propodeum is entirely black.

Such extensive melanisation is known in B. littoralis. Although Evans & Matthews didn’t specifically mention the range of colour variation for the scutellum, propodeum, etc, they did state that in some males from coastal locations “there may be no pale maculation at all on the mesosoma” and that in females “colour variation is as striking as in males” (p. 271).

Consistent with B. littoralis:
- base colour of pronotum & mesopleuron yellow

However, the type female had only limited black markings: laterally on the pronotum; along sutures of the pleuron. The more extensive dark marks here I attribute to intraspecific variation … the degree of which this species is well known for!

Consistent with B. littoralis:
- front basitarsus bearing pecten spines
- coxae yellow, with limited black markings
- front femora largely yellow, streaked black
- tibiae yellow, also with limited black markings
- tarsi pale (yellow in this case)

Consistent with B. littoralis:
- clypeus in profile evenly rounded
- vestiture pale, very dense and relatively long over much of head and mesosoma

Consistent with B. littoralis:
- tergite 6 tapering evenly to a narrowly rounded apex, its surface covered with strong punctures “except midline more or less smooth and polished” (p. 270).