Austroplebeia essingtoni Cockerell
Creators: name: Dollin, Anne E.
name: Dollin, Leslie J.
name: Rasmussen, Claus
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Apidae
Austroplebeia
Austroplebeia essingtoni

description: Austroplebeia essingtoni (Cockerell)
(Figures 1–11, 13–17, 19–24, 28–29, 32)
Trigona essingtoni Cockerell 1905: 220.
Austroplebeia essingtoni — Moure 1961: 196, 197; Michener 1990: 102, 130, 133, 134. Trigona (Plebeia) essingtoni — Michener 1965: 230.
Diagnosis. In workers and males, frons and mesepisternum with plumose hair (Figs 22 c, 23b), metepisternum maculation almost always absent, head width ≤ 1.67 mm (Figs 10, 14). In workers, clypeus with an extensive cream maculation but extending barely above antennal sockets (Face Grades usually 5–6, ranging 4–8, Figs 1, 3), scutum with lateral cream bands (Thorax Grades 7–8, 10–14, Figs 5, 7), HBW usually 0.25–0.30 mm (Fig. 11). In males, gonostylus with distinct subapical curve (Figs 21 b, d), dorsal scutellum with extensive maculation (Thorax Grades 11–14, Figs 5, 8), HBW 0.18–0.22 mm (Fig. 13). Distribution WA and NT (Fig. 28 b).
Description. As in general Austroplebeia description, except for the following characters.
Worker. Body 3.2–3.9 mm. Forewing (including tegula) 3.3–3.8 mm. All other measurements are listed in Table 2.
Structure. Head width 1.44–1.67 mm, 1.2x head length. Interocellar distance 1.7–2.1x ocellorbital distance. Clypeus length 0.4–0.5x width. Malar area 0.1–0.4x basal mandibular width. Mandible preapical teeth more widely spaced than in A. cincta (Fig. 17 e). Scape length 0.7–0.8x alveolus–lateral ocellus distance.
Scutellum length 0.4x width. Wing venation similar to that shown in Fig. 18 but veins slightly paler. First transverse cubital vein vestige present in 20% of wings examined and slight trace in 50% (n=50). Vein M of forewing terminates at or before position of anterior end of first recurrent vein (n=50). Cell second Cu of forewing undefined or defined by unpigmented vein traces in 89% of wings examined (n=46). Hamuli 5 per wing. HBW very narrow (Figs 11, 19 h), usually 0.25–0.30 mm.
Sting rudiments. Gonostyli shoulder width moderately broad, 0.12–0.14 mm. Apex of sting stylet broadly rounded, with a narrowly rounded or acute protrusion in over half of specimens examined (n=9). Sting lancet length short, 0.23–0.29 mm (Figs 15, 16 c).
Colour. Face markings usually Grades 5–6, ranging 4–8 (Figs 1, 3). Thorax markings usually Grades 12–13, ranging 7–14 (Figs 5, 7). (Grade 14 only seen in the most brightly coloured specimens collected from flowers in Hamersley Ranges, WA, not included in Fig. 7.)
Other areas with cream or yellow markings: ventral scape, labrum (sometimes yellow-brown), upper edge of pronotal collar except medially (sometimes just two to four spots), pronotal lobe, tegula (sometimes just a spot), apical terga and trochanters (sometimes yellow-brown); sometimes metanotum and margins of medial terga. Apical spots usually on femur I and often femora II and III. Tibia I variable: mostly cream or yellow, ranging to a basal spot. Tibia III usually with a basal spot. Basitarsi I and II sometimes yellow-brown.
Mandible ranging red-brown to cream medially (Fig. 9). Scape dark brown or red-brown dorsally, cream ventrally. Unmarked areas of tegula red-brown to yellow-brown or transparent. Basal and medial terga usually dark brown, ranging black to yellow-brown, sometimes with cream margins. Apical terga usually cream (Fig. 9). Sterna ranging dark brown to cream. Tibia I dark brown to brown, usually with extensive cream or yellow maculations.
Pilosity. Face with numerous appressed short whitish plumose hairs admixed with sparse erect simple hairs (ca. 50 Μm). Paraocular area and supraantennal area with well-branched and dense plumose hair hiding most of the surface. Clypeus with sparse short fine plumose or simple hair, denser on apical margin, revealing most of the surface (Fig. 22 c). Vertex with long erect pale bristles (50–150 Μm). Malar space evenly covered with short fine whitish appressed hair. Gena with short whitish appressed plumose hair dorsally, grading to simple hair ventrally.
Scutum with numerous short (ca. 25 Μm) pale simple hairs, admixed with sparse longer (75 Μm) erect pale simple hairs, fringes of long (150–175 Μm) simple hairs on lateral and anterior margins. Scutellum with fine erect pale simple hairs and a fringe of longer (75–250 Μm) pale bristles. Mesepisternum with semi-erect whitish (75–100 Μm) simple hairs, becoming longer (up to 250 Μm) ventrally, admixed with long whitish plumose hair, denser dorsally. Pronotal lobe, hypoepimeral area, upper 60% of metepisternum and propodeal sides with dense whitish plumose hair. Propodeal triangle hairless. T1 to T6 apically with pale simple hairs, becoming denser and longer on posterior terga, minute on T1 and up to 150 Μm on T6. Sterna with erect pale simple hairs, most apically hooked.
Coxae II and III, all trochanters and basal femora I and II with long simple pale hairs, hooked apically. In mature, fully coloured specimens: anterior and posterior corbicular fringes with simple pale hairs, hairs on apical half of anterior fringe coarser but still pale, penicillum and rastellum bristles pale or slightly brown, basitarsus III inner surface evenly covered with coarse pale or slightly brown bristles.
Geographic variation. The A. essingtoni workers (ANIC) collected from flowers in the northwestern Kimberley area of WA were slightly larger (HTW up to 0.52 mm and HBW up to 0.32 mm) than other A. essingtoni, verging into the range of the Central Colour Morph of A. australis (compare Fig. 11).
Local populations of A. essingtoni varied markedly in the extent of their thorax colour markings. For instance, within western WA, specimens sampled at Cape Leveque and Marando were relatively dark (population averages 15.5% and 16.7% respectively), whilst specimens sampled near Millstream were very bright (population averages 20.2–27%). Head width and HTW/HBW scores for all of these populations were within the normal range for A. essingtoni.
The Grade 7 and 8 thorax markings were relatively rare forms only seen in A. essingtoni (Figs 5, 7), and found in populations with darker colouration e.g. Cape Leveque, WA, and 65 km S Maningrida, NT.
Male. Body 3.4–4.1 mm. Forewing (including tegula) 3.5–3.7 mm. All other measurements are listed in Table 5.
Structure. Head width 1.45–1.59 mm. Interocellar distance 3.0–4.0x ocellorbital distance. Clypeus length 0.6x width. Mandible preapical tooth weaker than in A. cincta (Fig. 17 j). Scape length 0.7x alveolus–lateral ocellus distance. Flagellum relatively longer than in A. cincta, flagellum length 4.1–4.5x scape length. Hamuli per wing 5. HBW narrow, 0.18–0.22 mm. HTW narrow, 0.37–0.40 mm (Fig. 13). HTL short, 0.97–1.09 mm (Fig. 14).
Terminalia and genitalia. Graduli of S3 and S4 gently curved. S5 gradulus transverse and usually very close to or touching antecosta, apical margin with narrow protruding lobes. S6 with median body relatively broad and tapering. S7 quadrangular, apical margin transverse (Figs 20 b, h, l). Gonostylus tip with distinct subapical curve. Base of penis valve relatively broad and short (Figs 21 b, d).
Colour. Face markings Grades 17–19 (Figs 2, 4). Thorax markings usually Grades 13–14, sometimes 11–12 (Figs 5, 8).
Other areas with cream or yellow markings: ventral scape, labrum, mandible, upper edge of pronotal collar except medially (sometimes just two to four spots), pronotal lobe, tegula (sometimes just a spot), and usually metanotum, apical terga, trochanters and basitarsi. Femora and tibiae range from completely cream or yellowbrown, to small patches of cream.
Scape red-brown dorsally, cream ventrally. Flagellum red-brown to yellow-brown. Tegula usually cream, sometimes unmarked areas red-brown or transparent. Basal and medial terga ranging black to yellow-brown, sometimes with cream patches on margins. Apical terga usually red-brown with variable extents of cream markings (Fig. 9). Sterna ranging black to cream. Unmarked areas of tibiae red-brown to yellow-brown.
Pilosity. Face with numerous appressed short whitish plumose hairs admixed with sparse erect simple hairs (ca. 75 Μm) (Fig. 23 b). Paraocular area and supraantennal area with well-branched and dense plumose hair hiding most of the surface. Clypeus with sparse short fine plumose or simple hair, slightly less dense than in A. cassiae. Vertex with long erect pale bristles (100–250 Μm). Malar space with short fine whitish appressed hair. Gena with short whitish appressed plumose hair dorsally, grading to simple hair ventrally.
Scutum with numerous short pale simple hairs (ca. 35 Μm), admixed with sparse longer erect pale simple hairs ca. 100 Μm, fringes of longer simple hairs (up to 250 Μm) on lateral margins. Scutellum with numerous long curved erect pale simple hairs (up to 300 Μm). Mesepisternum with semi-erect whitish simple hairs (125–200 Μm), becoming longer ventrally, admixed with whitish plumose hair, denser dorsally, plumose hairs with long sparse barbs. Pronotal lobe, hypoepimeral area, upper 60% of metepisternum and propodeal sides with dense whitish plumose hair. T1 to T7 apically with pale simple hairs, sparce and minute on T1, becoming dense, long (up to 275 Μm) and curved on posterior terga.
Coxae II and III, all trochanters and basal femur I with long simple pale hairs. In mature, fully coloured specimens: basitarsus III inner surface bristles pale.
Surface sculpture. Scutum shiny with numerous fine punctures, spacing 1– 2 x puncture diameter. Propodeal triangle, terga and some areas of legs with fine reticulate sculpturing.
Queen. Body 4.1–5.6 mm. Forewing (including tegula) 3.6–3.8 mm.
Structure. HBW 0.22–0.23 mm.
Colour. Face markings up to Grade 8 (Fig. 24 b). Thorax markings up to Grade 13.
Pilosity. Clypeus with fine simple hair. Scutellum bristles pale and up to 425 Μm. T1–T5 with sparse fine short hairs, sparse longer (up to 350 Μm) coarse bristles on lateral and dorsal surfaces of T2–T5, more numerous in queens from WA. T6 with short dense hair and an apical fringe of long (up to 300 Μm) simple hairs. Basitarsus III inner surface bristles pale gold.
Material examined. Holotype. (BMNH 17b.1138, worker), labelled as follows: “SYN-TYPE (blue border), “B.M. TYPE / HYM. / 14B.1138, “Pt. Essing / ton / 42-[1], “ Trigona / essingtoni Ckll / TYPE
Paratype. (worker), labelled as follows: “ Trigona / essingtoni Ckll / Cotype”, “SYN-TYPE” (blue border), “Pt / Essing / -ton”, “42.1”
Provenance of types: The label code indicates that these specimens were purchased by the British Museum (Natural History), London, as part of Lot 1 in 1842. According to the register this lot contained a total of 242 insects (including 18 Hymenoptera) and originated from “N. Holland (Port Essington). Bought of Mr. Gould (G. Else, pers. comm. to AED, 1987).
John Gould (1804–1888) was an English ornithologist and bird artist who travelled to Australia in 1838–1840 together with naturalist and collector, John Gilbert (1812–1845). Gilbert collected birds for John Gould's bird illustrations in Tasmania and Western Australia. Then in June 1840, John Gilbert sailed to Port Essington where he stayed and made collections. In March 1841, he sailed to Singapore and then to London.
Another known collector in Port Essington during this same period was John Armstrong (?–1847). He had been appointed in 1838 as gardener to the Government Gardens at Port Essington and botanical collector for the Royal Botanic Gardens at Kew. John Armstrong was at Port Essington until he sailed for Timor at the end of 1840. He sent dispatches of botanical specimens from the Port Essington area back to the Kew Gardens in February and December 1840. He died in Timor in 1847.
Either of these two men could have been the collector of the A. essingtoni types. However, given that the specimens came to the BMNH from Gould and John Gilbert had been actively collecting for Gould during their joint Australian trip, it is probable that John Gilbert was the collector. Nevertheless both Gilbert and Armstrong lived in Victoria Settlement at Port Essington and collected in the surrounding inland areas and islands during this period. So these bees were probably collected in that area by either John Gilbert (in 1840 or 1841) or John Armstrong (in 1838–1840). Cockerell would as usual label his holotype as the type and any subsequent paratypes as the cotype. The specimen labelled as type is therefore a holotype, not a syntype, and the second specimen is a paratype. Both specimens are deposited in BMNH.
Other worker and male specimens examined. Northern Territory: Nest samples, collected by AED & LJD except where otherwise stated: Cobourg Peninsula, Port Essington, 17–19 Aug 1987 (Nest N11, 20 workers, 12 males; Nest N15, 20 workers, 10 males); Dukuladjarran, S of Kolorbidahdah outstation, 65k S Maningrida, 3–4 Aug 2014 (all by Aung Si: Nest D61, 12 workers; Nest D63, 15 workers; Nest D64, 19 workers); 50k W Timber Creek, 26 Sep 1985 (Nest W12, 20 workers, 7 males). —Samples collected from flowers or traps: Birraduk Ck, 18k EbyN Oenpelli, 4–5 Jun 1973, JC Cardale, ANIC, 1 worker, 1 male; Magela Ck, 9k SSE Mudginbarry HS, 7–8 Nov 1972, JC Cardale, ANIC, 6 workers; Nourlangie Ck, 8k E Mt Cahill, 17–18 Nov 1972, JC Cardale, ANIC, 2 workers; 40K N Pine Ck, 29 Sep 1985, AED & LJD, WS-20: 3 workers; 55k WSW Timber Creek, 19 Apr 1980, G Anderson & D Symon, WAM, 2 workers; Keep River National Park, 15 Jul 1990, RP McMillan, WAM, 1 worker. Western Australia: Nest samples, collected by AED & LJD except where otherwise stated: Middle Springs, 15k N Kununurra, 23 Sep 1985 (Nest W8, 20 workers, 2 males; Nest W9, 12 workers, 10 males; Nest W11, 10 workers, 9 males); Home Valley Station, 19 Sep 1985 (Nest W5, 20 workers, 5 males; Nest W6, 10 workers, 1 male); 2k S Windjana Gorge, 9 Sep 1985 (Nest W1, 10 workers); Broome, Apr 2013 (all by T. Heard and K. Dixon: Nest W24, 20 workers; Nest W25, 23 workers; Nest W26, 3 workers). —Samples collected from flowers, water sources (e.g. dams) or traps: 12k S Kalumburu, CALM Site 13/4, 7–11 Jun 1988, TA Weir, ANIC, 3 workers; 1k W Walsh Point, 10 May 1983, ID Naumann & JC Cardale, ANIC, 3 workers; Mitchell Plateau, surveyor's pool, 15 May 1983, ID Naumann & JC Cardale, ANIC, 2 workers; Mitchell Plateau, Mining Camp, 9–19 May 1983, ID Naumann & JC Cardale, ANIC, 3 workers; Mitchell Plateau, 4k S by W Mining Camp, 13 May 1983, ID Naumann & JC Cardale, ANIC, 1 worker; Mitchell Plateau K. C. S., 27 Sep 1982, FP Berry, WAM, 4 workers; Mitchell River Falls, 12 May 1983, ID Naumann & JC Cardale, ANIC, 2 workers; Weaber Plain, 6 Jun 1992, MS Harvey et al., WAM, 14 workers; 19k NW Kununurra, 8 May 1983, ID Naumann & JC Cardale, ANIC, 5 workers, 1 male; Miriwun Rockshelter, Ord River, Argyle Downs Station, mid Oct 1971, M&E Archer, WAM, 5 workers; Spring Creek on HWY 1, 26 Sep 1983, E Schlinger & M Irwin, NMV, 2 workers; 20k NNE Turkey Creek on Great Nth Hwy, 17 Apr 1980, G Anderson & D Symon, WAM, 2 workers; 97k NNE Halls Creek on Great Nth Hwy, 17 Apr 1980, G Anderson & D Symon, WAM, 2 workers; 45k NNE Halls Creek on Great Nth Hwy, 17 Apr 1980, G Anderson & D Symon, WAM, 2 workers, 11k NE Halls Creek, 7 Jan 1989, TF Houston, WAM, 1 worker; Moola Bulla Station, Halls Creek, 1 Oct 1994, R Patterson, WAM, 6 workers; 158k ESE Fitzroy Crossing, 13 May 1973, CA&TF Houston, WAM, 3 workers; 25k N Gibb River Station, 12 Sep 1985, AED & LJD, WS-7: 4 workers; Nth Mt Barnett Station, airstrip of Gibb River Road, 13 Apr 1980, G Anderson & D Symon, WAM, 1 worker; 1k NE Mt Bell, 28 Jul 1988, TF Houston, WAM, 3 workers; King Leopold Ranges, 10 Sep 1985, AED & LJD, WS-6: 1 worker; King Leopold Ranges, 4k NW Rifle Point, 12 Apr 1980, G Anderson & D Symon, WAM, 2 workers; 6k SE Windjana Gorge, 15 Apr 1980, G Anderson & D Symon, WAM, 8 workers; 21k SE Windjana Gorge, 15 Apr 1980, G Anderson & D Symon, WAM, 5 workers; 8k W Ellendale Homestead on Great Nth Hwy, 7 Apr 1980, G Anderson & D Symon, WAM, 6 workers; 45k NW Fitzroy Crossing, 7 Apr 1980, G Anderson & D Symon, WAM, 2 workers; 25k W Fitzroy Crossing on HWY 1, 25 Sep 1983, E Schlinger & M Irwin, NMV, 11 workers; 4k W King Cascade, CALM Site 28/3, 12–16 Jun 1988, TA Weir, ANIC, 1 worker; Valentine Rockhole, 8 May 1983, ID Naumann & JC Cardale, ANIC, 2 workers; Charnley R, 2k SW Rolly Hill, CALM Site 25/2, 16–20 Jun 1988, TA Weir, ANIC, 2 workers; Mt Amy & vicinity, 3 Apr 1980, TF Houston, WAM, 6 workers; Barker Gorge in Napier Range, 13 Apr 1988, TF Houston, WAM, 1 worker; Lennard Crossing, Gibb River Road, 1 Apr and 17 Jul 1988, TF Houston, WAM, 17 workers; Blina Station, 7 Apr 1988, TF Houston, WAM, 3 workers; ca. 50k S Derby, 3k S Willare Bridge Roadhouse, 8 Apr 1980, G Anderson & D Symon, WAM, 1 worker; Gnamagun 5k S Cape Leveque, Jul 1982, M Smith, WAM, 27 workers, 4 males; 8k S Cape Bertholet, 22 Apr 1977, DH Colless, ANIC, 1 worker; 15k E Broome on Derby Road, 19 Jun 1990, RP McMillan, WAM, 6 workers, 1 male; 10k E Broome, 20 Jun 1990, RP McMillan, WAM, 1 worker; Broome, June 1990, RP McMillan, WAM, 4 workers; Mardie Station, Dec 1958, G Sharpe, WAM, 6 workers, 2 males; Palm Springs, 15k N Millstream, 16 Jun 1984, TP McMillan, WAM, 2 workers; Millstream, 24 Oct 1970, JC Cardale, ANIC, 2 workers, 31 Aug 1985, AED & LJD, WS-1: 10 workers, WS-2: 10 workers, Sept 1985, RP McMillan, WAM, 3 workers; Deep Reach Camping Area, Millstream Station, 24 Dec 1985, M Peterson & B Coulson, WAM, 4 workers; 15k E Millstream, 21 Oct 1970, JC Cardale, ANIC, 1 worker; Yandeearra Station, 1974, J d'Espeissis, WAM, 2 workers, 1 male; Chichester Range, 3 Sep 1985, AED & LJD, WS-5: 8 workers; Wittenoom Gorge, 23 Aug 1972, SM Wade, WAM, 1 worker, 3 Sep 1985, AED & LJD, WS-4: 3 workers; Dales Gorge, 2 Sep 1985, AED & LJD, WS-3: 10 workers; Yampire Gorge, 21 Sep 1983, E Schlinger & M Irwin, NMV,> 20 workers; Yampire Creek, Fig Tree Soak, 20 Sep 1983, E Schlinger & M Irwin, NMV,> 20 workers; NE foot of Mt Bruce, 6–15 May 1980, TF Houston et al., WAM, 2 workers; 2k N Mt Bruce, 6–15 May 1980, TF Houston et al., WAM, 10 workers; Marando, 17 Apr 1982, AG Wells, 6 workers; Hamersley Range, 6 Sep 1985, RP McMillan, WAM, 1 worker.
Queen specimens examined. Nest samples collected by AED & LJD, 10 queens: Northern Territory: Cobourg Peninsula, 17–19 Aug 1987 (Nest N11, 2 virgin; Nest N15, 3 virgin). Western Australia: Middle Springs, 15k N Kununurra, 23 Sep 1985 (Nest W9, 4 virgin; Nest W11, 1 gravid).
Remarks. The holotype and paratype specimens of T. essingtoni in BMNH agree well in structure (Fig. 11, Table 2), pilosity and colouration (Face Grade 6, Thorax Grades 11–12, Figs 1, 3, 5, 7, 10) with recently collected A. essingtoni specimens in this study. The head of the holotype is missing. Their type locality, Port Essington, on the north coast of Arnhem Land, NT, is within the current distribution of this species, which extends from NT to WA (Fig. 28 b).
No A. essingtoni were found in QLD in this study. Moure (1961) stated that specimens from Inkerman, near Townsville, QLD, were very similar to A. essingtoni, especially in their yellow markings on the terga. These Inkerman specimens (W. Stalker, 1908–151, BMNH, examined) are not A. essingtoni. They probably belong to the Central Colour Morph of A. australis, a taxon which occurs in that area and has similar maculations on the terga to A. essingtoni (Fig. 9).
Later Moure (1961) described an Austroplebeia male from QLD (Tarlton Rayment Collection), which he stated may be A. essingtoni. This male probably belonged to a QLD population of either A. australis or A. cassiae. Males of all three species share bright markings on the scutellum and lateral scutum, which resemble those of A. essingtoni workers (Figs 7, 8). Unfortunately the structural characteristics of A. australis and A. cassiae males are very similar (Fig. 13) and it is not possible to identify the species from Moure's description.
Austroplebeia essingtoni workers are relatively easy to identify. Their small size and bright colouring resemble only those of A. cincta, which does not occur within the A. essingtoni distribution (Figs 28 a–b).
description: Published as part of Dollin, Anne E., Dollin, Leslie J. & Rasmussen, Claus, 2015, Australian and New Guinean Stingless Bees of the Genus Austroplebeia Moure (Hymenoptera: Apidae) — a revision, pp. 1-73 in Zootaxa 4047 (1) on pages 33-43, DOI: 10.11646/zootaxa.4047.1.1, http://zenodo.org/record/290024