Strumigenys horvathi group

Strumigenys horvathi group Bolton (2000)

Austral
Apical fork of mandible of 2 spiniform teeth. Three intercalary denticles between the apicodorsal and apicoventral teeth; upper may be vestigial and difficult to see. A single conical to spiniform preapical tooth present close to the apicodorsal tooth. Mandibles linear, the inner margin usually with a translucent cuticular crest or lamella that arises near the base and terminates just proximal of the preapical tooth. MI 30-55.

Anterior clypeal margin broad, transverse to very shallowly evenly concave.

Scape subcylindrical to slightly dorsoventrally flattened, but not greatly expanded; length short to moderate, SI 57-81.

Apical antennomere not strikingly attenuated basally nor narrowly constricted to its articulation with the preapical segment.

Ventrolateral margin of head almost straight to broadly shallowly concave in front of the eye but without a preocular notch. With head in profile postbuccal groove shallow to moderate, ventral surface posterior to it shallowly convex and without indentations or impressions.

Propodeal teeth subtended by a carina or a lamella.

Spongiform appendages of waist segments all present, usually lateral lobe of petiole small and slender, little more than a continuation of the posterior collar; a thin pad sometimes present at base of first gastral sternite.

Pilosity. Cephalic dorsum (sometimes also promesonotum) densely clothed with conspicuous ground-pilosity that may be broadly spatulate, broadly spoon-shaped or orbicular; usually without standing hairs anywhere. Dorsolateral margin of head without apicoscrobal hair, with a uniform row of anteriorly curved spatulate to spoon-shaped hairs. Pronotal humeral hair present or absent. Pronotal dorsum without standing hairs. Mesonotum either without erect hairs or 1-3 short pairs present. First gastral tergite with numerous stiff suberect to erect hairs that are simple to remiform. Long filiform or flagellate hairs entirely absent; basitarsi without elongate standing hairs.

Sculpture. Head and alitrunk reticulate-punctate dorsally, the sculpture may be partially to mostly concealed by the ground-pilosity. Alitrunk sometimes with smooth areas laterally. Disc of postpetiole smooth to reticulate-punctate. Gaster un sculptured except for moderate basigastral costulae.

Malesian-Oriental-East Palaeartic
Apical fork of mandible of 2 spiniform teeth. Three intercalary denticles between the apicodorsal and apicoventral teeth; upper may be vestigial and difficult to see. A single conical to spiniform preapical tooth present close to the apicodorsal tooth. Mandibles linear, the inner margin usually with a translucent cuticular crest or lamella that arises near the base and terminates just proximal of the preapical tooth. MI 30-55.

Anterior clypeal margin broad, transverse to very shallowly evenly concave.

Scape subcylindrical to slightly dorsoventrally flattened, but not greatly expanded; length short to moderate, SI 57-81.

Apical antennomere not strikingly attenuated basally nor narrowly constricted to its articulation with the preapical segment.

Ventrolateral margin of head almost straight to broadly shallowly concave in front of the eye but without a preocular notch. With head in profile postbuccal groove shallow to moderate, ventral surface posterior to it shallowly convex and without indentations or impressions.

Propodeal teeth subtended by a carina or moderate lamella.

Spongiform appendages of waist segments all present, usually lateral lobe of petiole small and slender, little more than a continuation of the posterior collar; a thin pad sometimes present at base of first gastral sternite.

Pilosity. Cephalic dorsum (sometimes also promesonotum) densely clothed with conspicuous ground-pilosity that may be broadly spatulate, broadly spoon-shaped or orbicular; usually without standing hairs anywhere. Dorsolateral margin of head without an apicoscrobal hair, with a uniform row of anteriorly curved spatulate to spoon-shaped hairs. Pronotal humeral hair present or absent. Pronotal dorsum without standing hairs. Mesonotum either without erect hairs or 1-3 short pairs present. First gastral tergite with numerous stiff suberect to erect hairs that are simple to remiform. Long filiform or flagellate hairs entirely absent; basitarsi without elongate erect hairs.

Sculpture. Head and alitrunk reticulate-punctate dorsally, the sculpture may be partially to mostly concealed by the dense ground-pilosity. Alitrunk sometimes with smooth areas laterally. Disc of postpetiole smooth to reticulate-punctate. Gaster unsculptured except for moderate basigastral costulae.

Austral
Identified by the presence of three intercalary denticles, universal lack of apicoscrobal hairs and usually also of pronotal humeral hairs (in Australian species present at humeri only in Strumigenys nummula), and presence of broad cephalic ground-pilosity. Seven species are recognised in Australia which, together with the two Malesian members of the group, form the following complexes.

buleru complex
Strumigenys buleru, Strumigenys cochlearis

Ventral intercalary denticle the largest. Preapical tooth stout and conical, its length about equal to width of mandible at point where tooth arises, or slightly more. Inner margin of mandible proximal of preapical tooth sharply carinate or with a narrow lamella. Scrobe well developed behind eye, with sharply defined margins. Concavity in ventrolateral margin of head in front of eye absent or at most very shallow. Cephalic dorsum and promesonotum with curved spatulate ground-pilosity. Mandibles and scapes with MI 40-56, SI 73-84.

The two species included in this peculiarly Australian complex are very closely related (Brown, 1988b, 1988c) and are only loosely associated with the members of the following complexes. I suspect that the seemingly diagnostic shared characters mentioned above may have been acquired convergently.

horvathi complex
Strumigenys guttulata, Strumigenys horvathi, Strumigenys snellingi

Median intercalary denticle the largest. Preapical tooth slender and spiniform, its length much greater than width of mandible at point where tooth arises. Inner margin of mandible proximal of preapical tooth with a very broad lamella. Scrobe reduced or effaced, very shallow behind eye and without sharply defined margins. Concavity in ventrolateral margin of head in front of eye deep, usually roughly semicircular. Cephalic dorsum and promesonotum with spoon-shaped to orbicular ground-pilosity. Mandibles and scapes with MI 32-46, SI 60-73.

Of the three species described in this complex one is known from Indonesia and New Guinea (horvathi), one from New Guinea alone (snellingi) and one from Queensland (guttulata). As yet no species has been found in both regions, though the possibility of this happening must be born in mind. This complex was first delineated by Brown ( l973c), as the horvathi-group.

emdeni complex
Strumigenys emdeni, Strumigenys enanna, Strumigenys nummula, Strumigenys semirex

Median intercalary denticle the largest. Preapical tooth slender and spiniform, its length much greater than width of mandible at point where tooth arises. Inner margin of mandible proximal of preapical tooth with a crest or very narrow lamella. Scrobe well developed behind eye, with sharply defined margins. Concavity in ventrolateral margin of head in front of eye shallow. Cephalic dorsum with scale-like to orbicular ground-pilosity which may also be present on promesonotum. Mandibles and scapes with MI 30-48, SI 57-66.

The four species of this complex are all Australian.

Malesian-Oriental-East Palaeartic
Of the nine species described in this group, first recognised by Brown (1973c), seven are Australian, one is known from Indonesia and New Guinea (Strumigenys horvathi) and one from New Guinea alone (Strumigenys snellingi). The two Malesian species are dealt with here. The remainder, and the species complexes into which the group is divided, are discussed under the Austral fauna. As yet no species has been found in both regions, though the possibility of this happening must be born in mind.