Melophorus perthensis Forel, stat n.

Heterick, Brian E., Castalanelli, Mark & Shattuck, Steve O., 2017, Revision of the ant genus Melophorus (Hymenoptera, Formicidae), ZooKeys 700, pp. 1-420 : 254-258

Melophorus perthensis Forel, stat n.

Melophorus turneri subsp. perthensis Wheeler 1934: 152.

Types.

Syntype major and minor workers: Rottnest Island and Kings Park, Western Australia [MCZ] (examined: images taken by S.O.Shattuck of MCZ specimens “cotype’ 23042, MCZ-ENT 00303602 [Kings Park] and “cotype’ 23042 [Rottnest Is.]. (Note. Series MCZ-ENT 00303602 includes a major worker of M. chauliodon .)

Other material examined.

New South Wales: Callubri Station (Greaves, T.), Mudgee (Lowery, B.B.), near Pooraka, 8mk E Florida, 10 km E Canbelego (Ward, P.S. [ANIC32-010587]), Pulletop Nature Reserve, near Griffith (Lowery, B.B.), Round Hill Reserve, 40 km NW Eubalong (Morton, S.R.). Northern Territory: 15 mi NW Mt Wedge Homestead (McInnes & Dowse), Johnstons Lagoon (Greaves, T.), Kunoth Paddock, near Alice Springs (Greenslade, P.J. M. ), Kunoth Paddock, near Alice Springs (Greenslade, P.J. M. ). Queensland: Mica Creek, Mount Isa (Burwell, C. J.), Illaweena St. Drewvale (QM Party), Tindaree, Hannaford Rd South via Tara (House, A./Brown, S.). South Australia: 10 km E Mt Ive Homestead, Gawler Ranges (Greenslade, P.J. M. ), 10 km E Mt Ive Homestead, Gawler Ranges (Greenslade, P.J. M. ), 10 km E Mt Ive Homestead, Gawler Ranges (Greenslade, P.J. M. ), 10 km E Mt Ive Homestead, Gawler Ranges (Greenslade, P.J. M. ), 16 mi SE Mt Wooltarlinna (McInnes & Dowse), 29 mi E Mt Davies, Tomkinson Range (McInnes, R. & Dowse, J.), 6 km W Wanilla, Eyre Peninsula (Greenslade, P.J. M. ), Brookfield (Greenslade, P.J. M. ), Calca (Lowery, B.B.), Gawler Ranges (Greenslade, P.J. M. ), Streaky Bay (Lowery, B.B.). Western Australia: 109.5 km SE of Newman (van Leeuwen, S. & Bromilow, R.N. [JDM32-001836]), 15 mi ESE Leonora (McInnes & Dowse), 2 km N Capricorn RH (Heterick, B.E. [M175/M176/M177]), 23 mi S Youanmi (Douglas, A. M. & M. J.), 27 mi SEbyS Zanthus (Taylor, R.W.), 32 mi WNW Mt Samuel (McInnes, R. & Dowse, J.), 34 mi WSW Ravensthorpe (Greaves, T.), 40 mi W Esperance (Lowery, B.B.), 44 mi NE Carnegie Homestead (McInnes, R. & Dowse, J.), 48 mi N Balladonia Homestead (Taylor, R.W.), 4 mi S Pingrup (Greaves, T.), 5.5 km E of Merredin (Jacobs, M. [JDM32-001837]), 6 mi W Yellowdine (Greaves, T.), Alcoa via Jarrahdale (collector unknown [JDM32-001858]), Bartons Mill (Majer, J.D. [JDM32-001850]), Beechboro, Perth (Lowery, B.B.), Blue Hill Range (Bokhari, F. [M147]), Blue Hill Range (Bokhari, F. [M149]), Chandlers Breakaway (Heterick, B.E. [JDM32-001832]), Christmas Tree Well (Heterick, B.E. [M21/M57]), Coomallo Downs (Heterick, B.E. [M10/M40/M43/M44]), Darlington, E Perth (Lowery, B.B.), Del Park (Wallace, J. [JDM32-001846]), Dwellingup (Majer, J.D. [JDM32-001839]), Dwellingup (Majer, J.D. [JDM32-001838]), Dwellingup (Wallace, J. [JDM32-001842]), Harrismith (Heterick, B.E. [JDM32-001834]), Int. Holland Tr./Norseman Rd. (Heterick, B.E. [JDM32-001833]), Kings Park, Perth (collector unknown [ANIC32-006437]), Kings Park, Perth (Lowery, B.B.), KW Road, Lancelin district (Heterick, B.E. [M79/M120]), KW Road, Lancelin district (Heterick, B.E. [M76/M117]), Marillana Ck. (Dunlop, N. [JDM32-001861]), Mundaring Weir (collector unknown), Palmyra (Heterick, B.E. [JDM32-001831]), Perth (Majer, J.D. [JDM32-001848]), Rabbit Proof Fence Rd. (Heterick, B.E. [JDM32-004572]), Reabold H. (Majer, J.D. [JDM32-001845]), Reabold H. (Majer, J.D. [JDM32-001844]), Sappers Rd (Heterick, B.E. [M160]), Serpentine Falls, Serpentine National Park (Shattuck, S.O.), Tardun (Mercovich, C.), Yamarna Homestead (Richardson, S. [ANIC32-032237]), Yarra Road (Douglas, A. M. & M. J.).

Diagnosis.

Melophorus perthensis can be placed in the M. biroi species-group on the basis of characters of the clypeus, propodeum, mandible and palps. The species is also placed in the M. fieldi species-complex because of the appearance of the anteriorly placed clypeal psammophore, the compact propodeum, the presence of more than one preapical spine on the metatibia, at least in the major worker, the long, even spindly legs, and the unmodified mandible in the major worker. Melophorus perthensis is a relatively large (HW 0.72-1.92 mm), smooth and shiny species. The appressed setae on the gaster are very small and well-separated. This ant is most likely to be confused with some populations of M. turneri . However, when viewed in profile, the smoothly rounded pronotum and the mesonotum that is elongate and broadly convex and arches above the level of the pronotum in all workers make this ant distinctive in most cases. In a few eastern states populations of M. turneri the pronotum and mesonotum are strongly convex, but these workers do not possess the very truncate propodeum seen in M. perthensis that usually arises above the metanotal groove.

Minor worker description.

Head. Head square; posterior margin of head planar or weakly convex; frons shining with superficial shagreenation or microreticulation only; pilosity of frons a mixture of a few well-spaced, erect setae interspersed with appressed setae only, or consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye moderate (eye length 0.20-0.49 length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae distinctly concave; frontal lobes straight in front of antennal insertion. Anteromedial clypeal margin broadly convex with anteromedial dimple; clypeal psammophore set at or above midpoint of clypeus; palp formula 6,4. Five mandibular teeth in minor worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately vertical or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron with weak to moderate sheen and superficial microreticulation (more pronounced on mesopleuron); anterior mesosoma in profile broadly convex; appearance of erect pronotal setae short, (i.e., longest erect setae shorter than length of eye) and unmodified, or erect pronotal setae absent; in profile, metanotal groove deep, V-shaped; propodeum shining and finely striolate and microreticulate; propodeum always smoothly rounded; propodeal dorsum and declivity confluent; erect propodeal setae variable in number, may be absent; appressed propodeal setulae short, separated by more than own length and inconspicuous; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length <0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform, or subcuboidal, vertex bluntly rounded; in full-face view, shape of petiolar node uniformly rounded; node shining and smooth throughout. Gaster. Gaster shining, shagreenate ('LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced, erect and semi-erect setae interspersed with regularly placed appressed setae. General characters. Colour of foreparts brown, gaster usually dark brown.

Major worker description.

Head. Head horizontally rectangular, broader than wide; posterior margin of head planar or weakly concave; cuticle of frons shining with superficial shagreenation or microreticulation only; pilosity of frons a mixture of a few well-spaced, erect setae interspersed with appressed setae only, or consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye moderate (eye length 0.20-0.49 length of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical. In full-face view, frontal carinae concave; frontal lobes straight in front of antennal insertion. Anterior clypeal margin broadly convex with anteromedial dimple; clypeal psammophore set at or above midpoint of clypeus; palp formula 6,4. Five mandibular teeth in major worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately aligned vertically or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron shining with indistinct microsculpture that is most pronounced on lower surfaces; anterior mesosoma in profile broadly convex; erect pronotal setae long (i.e., longer than length of eye) and unmodified, or short, (i.e., shorter than length of eye) and unmodified; in profile, metanotal groove shallow, broadly V- or U-shaped; propodeum shining and finely striolate and microreticulate; propodeum smoothly rounded or with indistinct angle; propodeal dorsum and declivity confluent; erect propodeal setae present and sparse to moderate (1-12); propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length less than 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node uniformly rounded, or generally rounded with median indentation, node shining and faintly shagreenate-microreticulate. Gaster. Gaster weakly shining with indistinct shagreenation; pilosity of first gastral tergite consisting of well-spaced, erect and semi-erect setae interspersed with regularly spaced appressed setae. General characters. Colour reddish-brown, gaster darker.

Measurements.

Worker (n = 8): CI 97-119; EI 17-32; EL 0.23-0.33; HL 0.74-1.61; HW 0.72-1.92; ML 1.06-2.02; MTL 0.69-1.36; PpH 0.11-0.19; PpL 0.44-0.74; SI 70-123; SL 0.89-1.35.

Comments.

This is a very common species and one of the few Melophorus for which there is detailed ecological information. Melophorus perthensis is characterized by the rounded mesonotum, giving this sclerite an arcuate appearance in profile. In some populations, particularly on the east coast, this trait is not so accentuated, and other characters are required to discriminate between the species and its relatives, particularly M. turneri . The truncated propodeum is commonly helpful for identifying minor workers, and M. perthensis is generally larger than M. turneri (ML 1.06-2.02 mm compared with 0.90-1.57 mm). This species has been recorded from all mainland Australian states except Victoria, but probably also occurs there. However, its occurrence in Tasmania is problematic. Genetically, the ant is distinct from M. turneri , and is raised to species in this revision. However, on individual gene trees, members of this taxon cluster close to some M. turneri populations.

As with Melophorus sulla , the type material reveals confusion, with more than one species included in the syntype series. A media or small major worker collected in Kings Park, Western Australia on 20 October 1931 by the Harvard Australian Expedition led by William Morton Wheeler and held at MCZ ('co-type 23042') is actually Melophorus chauliodon (sp. n. this paper). Melophorus chauliodon and Melophorus perthensis are by far the two most common Melophorus in the Perth metropolitan area, frequently occur together and bear a superficial resemblance to one another.

Majer et al. (2011) found M. perthensis was a key dispersal agent of seeds in a variety of woodland sites in the Darling Plateau and the Swan Coastal Plain between Perth in the north and Manjimup in the south (Two other non- Melophorus ants were also studied). Major findings connected with M. perthensis were as follows:

• this species was seasonally active between October and April, with peaks of activity in December and January. No activity was recorded between May and September,

• peak diurnal activity was in the early afternoon,

• fire caused a decline in activity in three out of four site studied, with 1.7 times as many individuals active before burns than after burns,

• this species prefers low ground cover and low understorey shade for its nest sites,

• the nests themselves comprise a vertical channel with a series of side galleries at regular intervals,

• mean number of workers per nest was 230.4,

• food items comprised seeds (29.1% of forage), miscellaneous plant fragments (25.3%) and invertebrates (54.6%),

• regression models relating ant foraging activity to myrmechore flowering revealed a four month lag time, and

• seedling emergence was much higher around nests of this species (and other ant nests) than elsewhere.

The researchers also found nests of this species in the sandplain were deeper than in lateritic soils, and colony sizes were much lower than for Melophorus bagoti . Label data reveals these ants can be found in mallee scrub and in red soil in other parts of Australia. This species is the commonest Melophorus found in the Perth metropolitan area, along with M. chauliodon . In the summer season, active nests can be seen in sandy soils in yards, gardens, beside footpaths, and, indeed, in any area where there is sufficient soil for ants to nest. Probably because of its thermophilic behavior, this is one native ant species that is not fazed by the presence of aggressive invasive exotics such as the Big-headed ant Pheidole megacephala (Fabricius) and the Argentine ant Linepithema humile (Jerdon).