Metapone tillyardi Wheeler, 1919

Taylor, Robert W. & Alpert, Gary D., 2016, The myrmicine ant genus Metapone Forel (Hymenoptera: Formicidae): a global taxonomic review with descriptions of twelve new species, Zootaxa 4105 (6), pp. 501-545 : 537-539

24. Metapone tillyardi Wheeler, 1919

( Figs 131 –140)

M. tillyardi Wheeler, 1919b: 187 , Fig 6 a, b—Worker; Type locality: Dorrigo , New South Wales.

Distribution, material examined. AUSTRALIA: QUEENSLAND: Lords Table, W slopes, 22°39'5''S, 148°00'7''E, nest in rotting log, vine scrub, 60m (C. Burwell, 7 March, 2006, QMBA) dealate gyne, 8 workers on 3 pins; Stony Creek, via Samford, 27°20'S, 153°48'E, 850m (HJ &GBM, 22 Oct–2 Feb 1995, open forest, flight intercept trap), Gyne. Banyo [27°22’S, 53°04’E], branch of ‘pine’ tree (October 2005 J. Gray acc 12394) 7 alate queens (QMBA). Lamington National Park: 11 alate gynes with various data, as follows: 28.142°S, 153.133°E, Plot #IQ-300-D, 248m, 13–23 Jan 207 (GBM, 22162, n=1); 28.151°S, 153.138°E, Plot #IQ-300-C, 260m, 13–23 Jan 207 (GBM, 22161, n=2); 28.155°S, 153.139°E, Plot #IQ-300-B, 282m, 13–23 Jan 2007 (GBM & RM, 22183, n=1); same data (IBSCA 22139, GL & NS, n=4); same data (Plot #IQ-300-C, 260m, n=1); 28.193°S, 153.128°E, IBISCA 700c, 2 Nov–9 Dec, 2008 (GBM, n=1); 28.227°S, 153.131°E, Plot #IQ-900-D, 920m, 14–24 Jan 2007 (CL & NS, 221s, n=1) (QMBA). NEW SOUTH WALES: Acacia Plateau (28;152) (J. Armstrong, 3.1.48, ANIC) alate gyne. Brooklana (30;152) (W.W. Froggatt, ANIC) dealate gyne. Dorrigo (30;152) 5 syntype workers from the following collections: ANIC (3 specimens on 2 pins), MCZC (2-1), QMBA (1). Sunshine Bay 35°45’ S 150°13’ E ex Willow ( Salix sp.) branch in caravan park J.A.L Watson & RWT 5 v 1990 ANIC. All Queensland labels from localities except Lords Table indicate collection in rainforest by Malaise or flight intercept trap. Note that the word “pine” on the Banyo labels is given in parentheses. It presumably does not refer to an exotic tree of genus Pinus .

Apparently widespread in S.E. Queensland and northeastern NSW, at least between S latitudes 22 and 35. The types were almost certainly collected in rainforest at Dorrigo National Park (30°22'S, 152°45'E). Worker/gyne identity of unassociated specimens is confirmed by the Lords Table series.

Worker diagnosis. General and diagnostic features as illustrated and keyed here, and in Wheeler’s detailed (1919b) description and figures. Note however that the original description ( Wheeler, 1919b) did not mention that some of the worker types have reduced eyes, and less massive propodeal and waist node configuration than that of the lectotype (see above). Clypeus projecting anteriorly less than in M. mjobergi ; anterior border somewhat obscurely bicuspid, with a pair of blunt projections at approximately its outer quarters, the space between them shallowly excavated, concave and raised almost to their apices. Eyes and waist nodes as discussed above. Subpetiolar process differing from M. mjobergi as in couplet 6 of the key to Australian species above. Posterior subpetiolar face as in M. mjobergi . The Sunshine Bay specimens are relatively small and gracile and have reduced petioles. They were taken from a colony which might not have been large enough ergonomically to produce large, less-gracile workers.

Dimensions: (MCZC Syntype, the 2 intact ANIC syntypes, other specimens not syntypes, Sunshine Bay series: TL ca: 6.3, 6.4, 6.7, 6.9, 5.6, 6.6; HL: 1.30, 1.32, 1.42, 1.47, 1.24, 1.45; HW: 1.01, 1.04, 1.11, 1.17, 0.99, 1.14; CI: 78, 79, 78, 79, 80, 79; CpL: 0.42, 0.40, -, 0.48, 0.40, 0.48; CpI: 32, 30, -, 33, -, -; MSL: 1.83, 1.86, 2.05, 2.00, 1.56, 1.85; PML: 1.02, 1.08, 1.15, 1.27, 1.00, 1.00; PMW: 0.91, 0.93, 0.98, 0.96, 0.75, 0.85; PMI: 56, 58, 56, 63, 64, 54; PDW: 0.84, 0.88, 0.94, -, 0.65, 0.72; PetL: 0.56, -, 0.61, 0.53, 0 42, 0.49; PetW: 0.83, 0.91, 0.89, 0.78, 0.57, 0.68; PetH: -, -, -, -, 0.70, 0.84 PpetL: 0.51, -, 0.55, 0.52, 0.37, 0.42; PpetW: 0.78, 0.81; 0.86, 0.77, 0.58, 0.67; PpetH: -, -; -, -; 0.59, 0.70; GW: 1.20, 1.21, 1.33, 1.45, 1.01, 1.1. Two damaged, otherwise unmeasured ANIC syntypes lacking waist nodes and gasters have HW 1.01 and 1.11 mm. Some syntype measurements were not possible due to glue or anatomical obstruction. Note also the differences in petiole and postpetiole dimensions in the two ANIC syntypes. The larger specimen has a relatively small petiole and postpetiole and virtually imperceptible, vestigial eyes, while the smaller specimen has large eyes, much as illustrated in Figs 131 and 132 , and more massive propodeal and waist node structure. Possible significance of these details is unknown.

Gyne diagnosis. General features as illustrated. Clypeus and subpetiolar process as in worker. Mesosoma in dorsal view more bulky than in gynes of M. mjobergi .

Dimensions: The available gynes vary little in size (HW 1.11–1.19 mm, N = 17). One from Banyo with mean HW has: TL: ca 8.4, HL: 1.47, HW: 1.13, CI: 77, CpL: 0.42, CpI: 29, MSL: 2.38, PetL: 0.58, PetW: 0.64, PetH: 0.72, PpetL: 0.48, PpetW: 0.66, PpetH: 0.67, GW: 1.21.

Discussion: M. tillyardi is apparently a relatively widespread species ranging at least from southeast Queensland to the vicinity of Sunshine Bay on the south shore of Batemans Bay, NSW. Its worker caste is significantly morphologically variable, possibly evidencing incipient caste polymorphism, on the following grounds: (1) The available Dorrigo worker types include specimens with relatively large eyes and robust propodeal, petiolar and postpetiolar structure (as illustrated in Figs 131–136 ), along with others which are more gracile, with less robust propodea and petiolar nodes, and with eyes very reduced to absent. Wheeler’s original description and illustrations ( Wheeler, 1919b) featured only the former, overlooking this variability in the typeseries. (2) Ten workers from Sunshine Bay satisfy the M. tillyardi diagnosis but the specimens are mostly relatively small. They have even less-robust propodeal and waist structure than the gracile, optically-reduced Dorrigo syntypes. They also have small, essentially vestigial eyes similar to those of the more gracile Dorrigo types. This interpretation depends in part on a reasonable assumption that the Dorrigo and Batemans Bay series are genuinely conspecific. The alternative possibility that two species are represented in Wheeler’s type series, with one of them present also at Sunshine Bay, seems improbable.

Illustrations. The illustrated gyne ( Figs 136 –140) is the confidently identified Brooklana, NSW, specimen listed above.

Remarks. M. tillyardi and M. mjobergi are similar, possibly related species.

Congeneric sympatric associations. The Lamington National Park Record implies that M. tillyardi is sympatric there with M. leae .

Figures

FIGURES 131 – 136. M. tillyardi, worker, Brooklana, NSW, HW 1.01, PMW 0.91, MSL 1.83; FIGURES 137 – 140. gyne, HW 1.15, MSL 2.38.

FIGURES 5 – 7. Metapone emersoni, worker, Perinet, Madagascar, HW 0.75, PMW 0.56, MSL 1.20.