Key to Australian Heteroponera Species

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The following key to Australian Heteroponera species is based on Taylor (2011[1], 2015[2]).

1

  • Petiole armed dorsally with a small erect median spine. Propodeum with a pair of similarly proportioned posterodorsolateral spines or homologous lamellar spine-like processes. Second gastral segment in side view markedly reflexed, so that the gastral apex is directed strongly anteroventrally. Antennal scrobes and enclosing frontal carinae lacking (H. leae species-group) => 2
  • Petiole lacking a dorsomedial spine, though sometimes drawn to a tapering obtuse summit. Propodeum lacking slender erect spines, though sometimes with sculpturally jagged posterolateral edges and with very small accompanying spines in one species (known only from the Mt Elliot summit near Townsville). Reflexure of second gastral segment unexceptional. Antennal scrobes in most species bordered dorsally and posteriorly by extended frontal carinae, sometimes strongly developed, (Figs 23, 30, 31), otherwise vestigial or absent (Figs 34, 35, 42, 43) => 4

2

  • Head in square frontal view with the median vertexal (= "occipital") profile short, essentially straight, not broadly emarginate; the profile curving evenly towards the eye on each side. Propodeal spines represented as small flattened transverse tabs. Second gastral segment very strongly reflexed; in lateral view its dorsoposteroventral profile enclosing slightly less than a right-angle, with a relatively short, tightly curved median section. (South-west Western Australia) => Heteroponera majeri
  • Vertexal margin more broadly transverse and concave in outline. Propodeal spines acutely pointed, not tabulate. Second gastral segment less strongly reflexed. (eastern Australia) => 3

3

  • Dorsal profile of second gastral segment an even semicircular arc, its tergite moderately finely, longitudinally striate-reticulate with the longitudinal trend very distinct. (Northeast and eastern central New South Wales, 29°-34°S) => Heteroponera leae
  • Dorsal profile of second gastral segment not evenly semicircular, more strongly curved in the median section than elsewhere, its tergite moderately reticulate punctate-rugose with a less well-developed longitudinal trend. (Southeast Queensland and far northeast New South Wales, 20°-28°S) => Heteroponera crozieri

4

  • Size generally smaller (HW less than 1mm). Second gastral segment in dorsal view not notably narrower than first, or markedly tapered posteriorly. Antennal scrobes lacking, the scrobal areas sculpturally undifferentiated (widespread, all states (including Australian Capital Territory) except Tasmania. Doubtfully represented from the Northern Territory. (The group currently includes the only known New Zealand Heteroponera species, Heteroponera brounii) => H. imbellis species-group
  • Generally larger species (HW almost always exceeding 1mm (rarely as low as 0.92mm). Second gastral segment in dorsal view notably narrower than first—often tapering posteriorly (Figs 12, 13, 36, 37). Antennal scrobes and frontal carinae usually strongly developed (Figs 2, 3); the carinae vestigial in several species, in which the scrobal areas lack an enclosing carina but are differentiated from the frons as relatively finely-sculptured tracts above the eyes (Figs 42, 43). A species-group known only from NE coastal Queensland and adjacent highlands south from Cooktown to Cannonvale, between 15°S and 20°30'S. (H. relicta species group) => 5

5

  • Antennal scrobes fully configured—each almost completely enclosed frontally and posteriorly by a distinct extension of the frontal carina and by a similar ventral carina adjacent to the eye. Scrobe partly divided longitudinally by a median dividing carina. Gastral dorsum (usually much-) less coarsely sculptured than mesosomal dorsum (Figs 26, 27)(H. relicta species complex) => 6
  • Antennal scrobes vestigial, represented on each side by a shallowly concave tract above the eye differentiated from the frons by relatively light sculpturation; the enclosing frontal carinae barely defined; scrobal dividing carina vestigially represented or lacking. Body tagmata including the gastral dorsum almost uniformly very coarsely foveolate-rugose (Figs 42, 43)(H. ecarinata species complex) => '12

6

  • Vertexal (=occipital) border of head in square full-face view distinctly emarginate, never squarely transverse. Dorsal surfaces of head, mesosoma and node coarsely, sharply punctate-rugose; first gastral tergite with somewhat polished, effaced large punctures, readily interpreted as a somewhat reduced, smoothed-over version of the stronger, more clearly incised dorsal propodeal sculpturing but less defined and well-marked. Declivitous face of propodeum smooth and strongly shining, with no or very little trace of sculpturation; its lateral borders sculpturally defined, but lacking extra sculptural elements such as a minutely ragged or serrate edge or propodeal-spine-like extensions (Figs 2, 10) => 7
  • Vertexal border either as above, or more usually slightly emarginate or squarely transverse—the latter condition conclusive here. Sculpturation differing from the alternative: sculpture of first gastral tergite clearly dissimilar to that of pronotal and propodeal dorsa, always (and usually very distinctly) less strongly developed—ranging from smooth and shining with minute piligerous punctures, to sub-opaque, with very effaced scattered medium puncturation. Declivitous face of propodeum often with superficial sculpturation—shagreening or radial, dorsally-directed effaced striae; the lateral borders usually, but not always, defined by a jagged sculptural edge => 8

7

  • Body tagmata uniformly dark chocolate-brown; mandibles, antennae and legs dark reddish-brown. Size relatively large: worker HW 1.20–1.47mm (mean 1.36mm), with ca 40% of specimens larger (by HW measurement) than the alternative H. rhodopygea, which has maximum known HW 1.39mm. Distribution more southerly (known from Endemism Areas 4, 6, 7, 8, 9, 10, 11, 12 and 13)(Figs 2–5) => Heteroponera relicta
  • Bicolored: head, mesosoma and node dark reddish-brown: the gaster contrasting orange brown, matching the mandibles, antennae and legs. Workers smaller on average: HW 1.18–1.39mm (mean 1.32mm), HW not known to exceed 1.39mm. Distribution more northerly (Endemism Areas 1, 2 and 3)(Figs 10–13) => Heteroponera rhodopygea

8

  • First gastral tergite shining, but without smooth areas; closely sown with dense fine puncturation, with a few very weak vestiges of small foveate punctures. Propodeal declivity smooth and shining with its lateral borders sculpturally unelaborated (Known only from EA16, in the Paluma area) => Heteroponera darlingtonorum
  • First gastral tergite moderately strongly shining, either virtually lacking sculpturation, or smooth, with scattered point-punctures and somewhat obscure, separated, smoothed-over larger foveate punctures. (Including species from most other EAs) => 9

9

  • Exposed section of second gastral tergite (abdominal 4) on each side near its base with an unusual, minute, anterolaterallydirected denticle (or “gastral II spur” —see description in text above) which may extend beyond the outline of the gaster in dorsal view (Figs 26, 28, 34, 36). First gastral tergite in dorsal view smooth and shining, with scattered minute piligerous point-punctures visible in reflected light, and no trace of larger foveate punctures or other sculpture. Southern species from EAs 17 and 18. (The gastral II spurs may be obscured if the tubulate second gastral exoskeleton is deeply telescoped into the first gastral segment.) => '11
  • Lateral spurs lacking from second gastral tergite. First gastral tergite in dorsal view with relatively strong point punctures and somewhat obscure scattered foveate punctures, or densely microsculptured and subopaque. Northern species from EAs 2, 3 or 4 => 10

10

  • Larger species (HW 1.24–1.31mm). Mesosomal proportions as in H. relicta and most other group species (Figs 18 -22). Petiole including its summit generally punctate. Self-colored, dull orange-brown; gaster, antennae and legs slightly paler than elsewhere => Heteroponera wilsoni
  • Smaller species (HW 1.07–1.19mm). Mesosoma relatively short and compact (Figs 22–25). Petiole generally punctate, but with the summit smooth and shining. Bicolored: head, mesosoma and node bright mahogany- brown, gaster, mandibles, antennae and legs bright reddish/orange-brown => Heteroponera viviennae

11

  • Mesosomal dorsum distinctly punctate-rugose; declivitous face of propodeum smooth and shining, with effaced, very fine, obscure vestigial striae radiating from the center of its base (best seen in reflected light). The declivity separated from the sides and dorsum of the sclerite by a minutely ragged sculptural margin, with no trace of lateral bordering carinae or dorsolateral denticles. (Figs 26–29)(Known only from the Conway Range area (EA18) near Cannonvale) => Heteroponera monteithi
  • Mesosomal dorsum less-distinctly ornamented, with somewhat effaced sculpture, including vaguely longitudinal elements; declivitous face of propodeum smooth and shining, lacking the fine sculpturing described above, or with only faint vestiges of similar sculpture. The declivity bordered on each side by a fine carina, which is extended dorsally to form a small obtusely triangular denticle somewhat resembling a minute propodeal tooth. (Figs 34–37)(Known only from sites near the summit of Mt Elliot (EA17) southeast of Townsville) => Heteroponera lioprocta

12

  • Body tagmata generally overall dull medium- to dark-brown; often bicolored, with the gaster dull light reddish-brown. Pronotal epaulets relatively less developed (Figs 42–45). Frons very finely longitudinally striate, with several larger additional striae on each side, each of the larger elements about as distinct as the median frontal carina (Fig 43). Known only from the far northern Endemicity Areas EA1 (Mt Finnigan) and EA2 (Thornton Peak) => Heteroponera trachypyx
  • Body tagmata uniformly very dark blackish-brown, almost black; legs and antennae lighter, medium to dark reddish-brown. Pronotal -epaulets relatively strongly developed (Figs 46–49, 50–53). Sculpturation of frons otherwise—either moderately coarsely longitudinally striate without intervening fine striae, or much less regularly sculptured, as in Fig 43. Known from more southerly Endemicity Areas => 13

13

  • Petiolar dorsum generally rounded in lateral view, sometimes slightly extended posteroapically, but never as strongly as the alternative. Declivitous face of propodeum with dorsally-directed radiating striae on a shining background, with or without accompanying shagreening. Known from EA8, EA10 & EA12 => Heteroponera ecarinata
  • Petiolar dorsum relatively tall and narrow in lateral view, extended above to form a distinct broadly tooth-like posteroapical process. Declivitous face of propodeum smooth and shining, with at most only vague traces of dorsally-directed radial sculpturation. Known only from EA7 (Lamb Range) => Heteroponera pendergrasti

References

  1. Taylor,R.W. 2011. Australasian ants of the subfamily Heteroponerinae (Hymenoptera: Formicidae): (1) General introduction and review of the Heteroponera leae (WHEELER, 1923) species group, with descriptions of two new species. Myrmecological News 15, 117-123.
  2. *Taylor, R.W. 2015. Australasian ants of the subfamily Heteroponerinae (Hymenoptera: Formicidae): (2) the species-group of Heteroponera relicta (Wheeler) with descriptions of nine new species and observations on morphology, biogeography and phylogeny of the genus. Zootaxa 3947, 151-180.