Austroplebeia australis

Dollin, Anne E., Dollin, Leslie J. & Rasmussen, Claus, 2015, Australian and New Guinean Stingless Bees of the Genus Austroplebeia Moure (Hymenoptera: Apidae) — a revision, Zootaxa 4047 (1), pp. 1-73 : 45-46

Austroplebeia australis –Central Colour Morph

Diagnosis. As in general diagnosis of A. australis with the following exceptions:

Worker HBW 0.29–0.35 mm ( Fig. 11 ). Most workers have the following characteristics: thorax markings Grades 9–11 ( Figs 5 , 7 ), ventral scape cream, upper edge of pronotal collar with a continuous cream band except medially, apical terga cream or yellow-brown ( Fig. 9 ), tibia I, II and III with cream maculations. Male HBW 0.23– 0.27 mm, HTW 0.40–0.48 mm ( Fig. 13 ). Distribution northeast WA, NT and northwest QLD ( Fig. 28 c).

Description. As in A. australis –Eastern Colour Morph, except for the following characters.

Worker. Body 3.3–4.9 mm. Forewing (including tegula) 3.6–4.3 mm. All other measurements are listed in Table 3 .

Structure. Head width 1.59–1.85 mm, 1.2–1.3x head length. Interocellar distance 1.6–2.1x ocellorbital distance. Scape length 0.7–0.9x alveolus–lateral ocellus distance.

Wing venation similar to that shown in Fig. 18 . First transverse cubital vein vestige present in 16% of wings examined and slight trace in 60% (n=73). Vein M of forewing terminates at or before position of anterior end of first recurrent vein in 93% of wings examined (n=72). Cell second Cu of forewing completely indicated by pigmented vein traces in 59% of wings examined (n=71). HBW moderately narrow ( Figs 11 , 19 h), 0.29–0.35 mm.

Sting rudiments. Gonostyli shoulder width moderately broad, 0.12–0.15 mm. Apex of sting stylet usually broadly rounded, occasionally with a narrowly rounded protrusion. Sting lancet length short, 0.24–0.30 mm ( Figs 15 , 16 e).

Colour. Face markings usually Grades 3–4, ranging 1–5 ( Figs 1 , 3 ). Thorax markings usually Grades 10–11, ranging 4–13 ( Figs 5 , 7 ).

Other areas with cream or yellow markings: upper edge of pronotal collar except medially (sometimes just two to four spots), pronotal lobe, usually ventral scape, labrum, apical terga and a spot on tegula, and sometimes trochanter. Basal spot on tibia I and usually tibiae II and III. Femora I and II sometimes with an apical spot. Basitarsus I sometimes yellow-brown or cream.

Labrum cream or yellow-brown, sometimes red-brown. Mandible ranges dark brown to brown medially ( Fig. 9 ). Scape dark brown dorsally, cream or yellow-brown ventrally. Unmarked areas of tegula yellow-brown, sometimes red-brown or transparent. Apical terga usually cream, sometimes orange-brown to yellow-brown ( Fig. 9 ).

Pilosity. As in A. australis –Eastern Colour Morph.

Geographic variation. The extent of thorax colour markings in the Central Colour Morph was generally 12– 17% ( Fig. 10 ). Some specimens collected from flowers in the MacDonnell Ranges, Central Australia, NT, had darker thorax colouration (9–10%). However, structural data indicate that they were still part of the Central Colour Morph population (see A. australis Remarks).

Another specimen collected from flowers at Cooper Creek, (ca. 30 km NE Oenpelli) in Arnhem Land, NT, was similar in thorax colouration and HTW/HBW to the Eastern Colour Morph. Further sampling in this area may reveal another coastal population of A. australis with relatively dark colouration and relatively large HTW/HBW scores, similar to the Eastern and Western Colour Morphs.

A bright orange abdomen ( Fig. 26 ) was found in many workers and males in the Central Colour Morph. It was common in western QLD areas such as western Cape York, Croydon, Mt Isa, Cloncurry, Hughenden, and was also seen at Bowen (eastern QLD).

All workers and males in a colony may have orange abdomens, whilst other colonies, even in the same locality, may have some individuals with orange abdomens and others with black. Other abdomen colours observed include red, orange-brown and yellow-brown. Three colonies kept by A. Beil and by AED & LJD changed their abdomen colour over a period of time. Although the vividly coloured abdomen of these bees is highly distinctive, we consider this characteristic to be a simple colour variant within A. australis .

Male. Body 3.9–4.5 mm. Forewing (including tegula) 3.8–4.3 mm. All other measurements are listed in Table 5 .

Structure. Head width 1.66–1.76 mm. Interocellar distance 2.6–3.3x ocellorbital distance. Flagellum relatively longer than in A. cincta , length 4.2–4.6x scape length.

HBW moderate, 0.23–0.27 mm. HTW moderate, 0.40–0.48 mm ( Fig. 13 ). HTL moderate, 1.11–1.21 mm ( Fig. 14 ).

Colour. Face markings usually Grade 17, sometimes 15–16 ( Figs 2 , 4 ). Thorax markings usually Grades 11– 13, sometimes 10 ( Figs 5 , 8 ).

Other areas with cream or yellow markings: ventral scape, labrum, mandible, upper edge of pronotal collar except medially (sometimes just four spots), pronotal lobe, all femora and tibiae, and apical terga; usually sterna, basitarsi, and a spot on tegula; sometimes metanotum.

Scape dark brown to brown dorsally, cream to yellow ventrally. Flagellum orange-brown to yellow-brown. Unmarked areas of tegula red-brown, yellow-brown or transparent. Metanotum ranging dark brown to cream. Basal and medial terga dark brown to yellow. Apical terga cream or yellow ( Fig. 9 ). Sterna ranging dark brown to yellow.

Queen. Body 5.1–6.1 mm. Forewing (including tegula) 3.8–4.1 mm.

Structure. HBW 0.22–0.25 mm.

Colour. Face markings up to Grade 8 ( Fig. 24 d).

Pilosity. Scutellum bristles pale gold and up to 450 Μm.

Figures

FIGURE 1. Face colour marking grades used to classify Austroplebeia workers. In many specimens, these cuticle markings may be obscured by hair on the clypeus and paraocular area. Visualisation of these markings can be improved by tilting the bee's head back and viewing the face obliquely.

FIGURE 2. Face colour marking grades used to classify Austroplebeia males.

FIGURE 3. Variation in worker face colour grades observed within all Austroplebeia taxa except A. cincta. Data show 300 workers from 114 colonies, in addition to 50 workers from 10 flower samples of A. australis – Western Colour Morph. Colour grades are as illustrated in Fig. 1.

FIGURE 4. Variation in male face colour grades observed within all Austroplebeia taxa except A. cincta and A. australis – Western Colour Morph. Data show 186 males from 38 colonies. Colour grades are as illustrated in Fig. 2.

FIGURE 5. Thorax colour marking grades used to classify workers and males of Austroplebeia.

FIGURE 7. Variation in worker thorax colour grades observed within all Austroplebeia taxa except A. cincta. Data show 2503 workers from 158 colonies, in addition to 59 workers from 15 flower samples of A. australis – Western Colour Morph. Colour grades are as illustrated in Fig. 5.

FIGURE 8. Variation in male thorax colour grades observed within all Austroplebeia taxa except A. cincta and A. australis – Western Colour Morph. Data show 196 males from 38 colonies. Colour grades are as illustrated in Fig. 5.

FIGURE 9. Variation in colour of the clypeus, mandible (middle part) and apical terga in workers and males of all Austroplebeia taxa. (No males are known in A. cincta NG and A. australis – Western Colour Morph.) Data are based on 120 workers and 62 males.

FIGURE 10. Ratio of head width and extent of thorax colour marking in workers of all Austroplebeia taxa except A. cincta. Data from 121 colonies are shown, in addition to five flower samples from A. australis – Western Colour Morph and one A. australis flower sample with mixed Western / Central characteristics. Data points are averages from 10 – 49 workers per colony, or 5 – 12 workers per flower sample. Data from eight individual type specimens are also shown. The T. symei and T. ornata types, in which the eyes are collapsed preventing accurate head width measurement, are not shown. The T. essingtoni holotype has a missing head, so data from the paratype are shown. 1. Colony F 31 from the northern tip of Cape York Peninsula, QLD, which has characteristics similar to A. australis – Eastern Colour Morph despite its geographic isolation. Names given in brackets in the legend are groups in our Halcroft et al. (2015) preliminary analysis.

FIGURE 11. Ratio of tibia III width and basitarsus III width in workers of all Austroplebeia taxa. Data from 173 colonies are shown, in addition to 26 flower samples: A. australis – Western Colour Morph (14 x), A. australis with mixed Western / Central characteristics (4 x) and NG A. cincta (8 x). Data points are averages from 2 – 4 workers per colony, or 1 – 12 workers per flower sample. Data from 12 individual type specimens are also shown. 1. Colony F 31 from the northern tip of Cape York Peninsula, QLD, which has characteristics similar to A. australis – Eastern Colour Morph despite its geographic isolation. Names given in brackets in the legend are groups in our Halcroft et al. (2015) preliminary analysis.

FIGURE 13. Ratio of tibia III width and basitarsus III width in males of all Austroplebeia species. Data points are averages from 2 – 3 males per colony. Data from the male paratypes of A. magna sp. nov. are also shown. Names given in brackets in the legend are groups in our Halcroft et al. (2015) preliminary analysis.

FIGURE 14. Ratio of head width and tibia III length in males of all Austroplebeia species. Data points are averages from 2 – 3 males per colony. Data from the male paratypes of A. magna sp. nov. are also shown. Names given in brackets in the legend are groups in our Halcroft et al. (2015) preliminary analysis.

FIGURE 15. Worker sting rudiments metric data: ratio of maximum length of sting lancet (A) and shoulder width of gonostyli (B) in all Austroplebeia taxa. Data points are averages for 1 – 3 workers per nest or flower sample. 1. The geographically isolated colony, F 31, from the northern tip of Cape York Peninsula, QLD, which has colouring and HTW / HBW similar to A. australis – Eastern Colour Morph. 2. Colonies C 58 and D 55 from the ‘ intermediate’ group of Halcroft et al. (2015) which are consistent with A. australis – Eastern Colour Morph in this analysis. 3. CS- 8 workers, with Grade 4 Thorax Colour Markings, collected from flowers in the MacDonnell Ranges, NT. They are consistent with A. australis – Central Colour Morph in this analysis, despite their relatively dark colouration. 4. GS- 10 workers collected from flowers on the far western edge of the A. cassiae range. 5. NS- 7 workers collected from flowers on the far eastern edge of the A. magna sp. nov. range. Names given in brackets in the legend are groups in our Halcroft et al. (2015) preliminary analysis.

FIGURE 16. Austroplebeia worker sting rudiments: a, A. cincta NG; b. A. cincta QLD; c, A. essingtoni; d, A. australis – Eastern Colour Morph; e, A. australis – Central Colour Morph; f, A. australis – Western Colour Morph; g, A. cassiae; h, A. magna sp. nov. All drawn to same scale. Abbreviations: Gon—gonostylus; Sty—sting stylet (bulb); Lan—sting lancet (first valvula or first ramus).

FIGURE 18. Austroplebeia wings. Dotted lines indicate pigmented vein traces. Figs a – c. Forewings, showing variation observed in the vestige of the first transverse cubital vein: a, A. magna sp. nov. forewing with a short vein vestige; b, Detail of an A. australis – Eastern Colour Morph forewing with a thickening of vein M at this position; c, Detail of an A. australis – Eastern Colour Morph forewing with a long vein vestige. Fig. d. Hindwing of A. magna sp. nov. Fig. e. Diagram of a forewing showing how the following measurements were made: (1) forewing length without tegula; (2) forewing width; (3) wing diagonal (Sakagami 1978); (4) 1 st abscissa of M length; (5) 1 st abscissa of Cu length. Figs a – d drawn to same scale: scale bar = 0.25 mm. Abbreviations: M—vein M; 1 st R—first recurrent vein; 2 nd Cu—second cubital cell; Ham—hamuli.

FIGURE 19. Austroplebeia legs. Figs a – b. Worker tibia III and basitarsus III of A. australis – Central Colour Morph: a, inner surface; b, outer surface. Fig. c. Cross-sectional view of A. australis worker tibia III, inner surface uppermost. Fig. d. Worker leg II of A. australis – Eastern Colour Morph, showing mesotibial spur near junction of tibia and basitarsus. Figs e – f. Male tibia III and basitarsus III of A. australis – Central Colour Morph: e, inner surface; f, outer surface. Fig. g. Queen tibia III and basitarsus III of A. australis – Central Colour Morph, outer surface. Fig. h. Variation in size of worker basitarsus III (shaded segment), all drawn to same scale: A. cincta QLD is shown on the left, then remaining species are shown in order of increasing basitarsus III width. Abbreviations: Kei—keirotrichia; Pos—posterior corbicular fringe; Ant—anterior corbicular fringe; Rasrastellum; Cor—corbicula; Pen—pencillum.

FIGURE 24. Austroplebeia queen faces: a, A. cincta QLD; b, A. essingtoni; c, A. australis – Eastern Colour Morph; d, A. australis – Central Colour Morph; e, A. cassiae; f, A. magna sp. nov. Scale bars = 0.25 mm.

FIGURE 26. An A. australis worker with the distinctive orange abdomen, that is common in western QLD populations (photograph by D. Clarke).

FIGURE 28. Observed distribution of all Austroplebeia species in Australia and the island of New Guinea: a, A. cincta; b, A. essingtoni; c, A. australis; d, A. magna sp. nov. and A. cassiae. In all maps, square symbols represent nest samples and circles represent samples collected from flowers or traps. The type locality for each named species, including those now synonymised, is indicated with arrows. Where the type locality was a general area such as ' Central Australia' or ' Cape York', these areas are indicated with shading.