Monomorium subapterum Wheeler 1917

Sparks, Kathryn S., Andersen, Alan N. & Austin, Andrew D., 2014, Systematics of the Monomorium rothsteini Forel species complex (Hymenoptera: Formicidae), a problematic ant group in Australia, Zootaxa 3893 (4), pp. 489-529 : 520-523

Monomorium subapterum Wheeler 1917 stat. rev.

( Fig. 7 m–o, 9m –o, 10a–c, 11g)

Monomorium subapterum Wheeler 1917: 112 –114 .

Syntypes, 3 workers, Western Australia, Harding R., Dodd (MCZ—‘Cotype 23234’), 3 males, 2 queens, same data, (SAM). One worker ( MCZ, bottom point) here designated lectotype. The other 7 specimens here designated as paralectotypes.

Chelaner subapterum (Wheeler) ; Ettershank, 1966: 97

Monomorium subapterum Wheeler ; comb. Bolton, 1987: 300–301

Monomorium rothsteini Forel ; synonymy by Heterick, 2001: 408.

Diagnosis. A small, glossy dark brown species with large eyes and a slightly concave to sinuous clypeus. The mesonotum is without sculpture except in the posterior region, the propodeal dorsolateral angles clearly form an obtuse angle or are rounded and the petiole node is narrow.

Worker measurements (n=9). HW 0.68–0.82, HL 0.74–0.86, EL 0.14–0.2, PMH 0.27–0.35, PH 0.21–0.31, PNH 0.17–0.18, LHW 0.43–0.49, EW 0.10–0.12, PML 0.43–0.53, ML 0.64–0.88, PL 0.27–0.39, PNWdv 0.16–0.20.

Worker Description. Small species with a small, rectangular head; posterior cephalic margin shallowly depressed medially. Anterodorsal margin of the clypeus sinuous to almost straight, frontolateral carinae forming smooth ridges; anteroventral margin with or without a small median projection. Frons strigate, restricted to antennal lobes and area in between or with a few strigae only present on antennal lobes; coarse lateral cephalic strigae reach anterior eye margin or if not reaching then a few very fine strigae may reach eye margin. Eyes large, EW> 0.23 x LHW, 12–13 ommatidia in longest vertical axis, 11 in longest horizontal axis.

Mesonotum smooth and shining, metanotal groove sculpture extending just into lateral portion of posterior region in some specimens, in others with posterior mesonotum rugulose strigulate. Mesopleuron and lateral surface of propodeum alveolate, strigae restricted to metapleural gland bulla. Propodeum in lateral view with dorsolateral angles clearly forming an obtuse angle; dorsally with anterior transverse carinae weakly present, transverse and longitudinal strigae absent. Petiole node narrow, less than 2 x eye width when viewed from above; shape in posterior view tapering to a narrow point, in lateral view anterior and posterior faces converging to a narrowly rounded point. Petiole node smooth and shining, some specimens with fine reticulate sculpture along posterior basal margin, postpetiole without sculpture.T1 completely smooth and without sculpture.

Head and mesosoma brown to very dark brown, dorsally infuscated in lighter specimens; mandibles light brown, legs brown to dark brown, trochanters and apical margins of femur and tibia distinctly lighter in colour than remainder of legs, antennal scapes and metasoma dark brown to very dark brown, lighter in colour than flagellum, cuticle with a high gloss.

Queen measurements (n=2). HW 1.5–1.52, HL 1.35, EW 0.25–0.27, EL 0.35, ML 2.40–2.42, PeH 0.62–0.66, PNWdv 0.55–0.57, PPH 0.57.

Queen Description. Head triangular, broader behind the eyes that in front, vertex straight sculpture strigulate to smooth over frontal surface, laterally strigulate. Frontal clypeal margin very mildly concave. Mandibles strigate with a large apical and two smaller preapical teeth. When angled towards eye antennal scapes not surpassing dorsal eye margin.

Mesoscutum in profile evenly rounded from pronotum to scutellum, scutellum rounded and raise only slightly above surface of mesoscutum, surface smooth and shining except for pitted setal insertion points and lateral margins which are rugulose strigate. Pronotum finely reticulate, mesopleuron above central groove finely reticulate to smooth, strigate along posterior margin; below central groove medially reticulate, strigate on anterior and posterior third. Propodeum strigate with many raised ridges over entire surface, finely reticulate in between ridges on posterior surface. Petiole node triangular in profile, trapezoidal in posterior view with a rounded dorsal margin, petiole and postpetiole alveolate to reticulate, petiole laterally with transverse ridges on ventral half, postpetiole with irregular ridges on lateral and posterior surfaces. Metasomal tergites and sternites finely reticulate.

Colour entirely dark reddish-brown, head and mesosoma slightly darker than antennal scapes, anterior clypeal margin and metasoma. Head and mesosoma with many long and short, erect, dull setae except for a broad glabrous area of that spans entire length of mesoscutum.

Male Measurements (n=3). HW 1.39–1.40, HL 1.0, EW 0.33, EL 0.45–0.46, ML 2.34–2.40, PeH 0.57–0.6, PNWdv 0.55–0.59, PPH 0.52–0.56.

Male Description. Head triangular with three ocelli. Eyes large, bulbous, oval in shape and positioned at an angle in lateral view such than longest axis point towards nearest lateral ocellus. Clypeus raised and rounded centrally, anterior margin straight. Mandibles with large apical tooth and two smaller teeth. When angled towards the eye antennal scapes, not surpassing dorsal eye margin. Sculpture coarsely rugose over entire surface, a few raised, transverse strigae present on clypeus and in between antennal insertion points.

Mesoscutum in profile evenly convex from anterior to posterior margin, sculpture coarsely aerolate-rugose tending towards rugulose-strigate anteriorly except for a narrow triangle that runs centrally from anterior margin to approximately one third of length is finely reticulate. Parapsidal lines present. Pronotum reticulate, rugose along dorsal margin. Scutellum large and bulbous with a central depression, sculpture aereolate-rugose. Mesopleuron aereolate, rugose along anterior margin to strigate along posterior margin. Propodeum aereolate laterally to reticulate on dorsal and posterior surfaces, a few raised ridges on ventral third of lateral surfaces. Petiole and postpetiole with a flattened dorsal surface in lateral view, in dorsal view with a small median depression giving a slightly bilobed appearance, sculpture aereolate to reticulate, rugulose strigate on posterior surface of petiole, and posterolateral corners of postpetiole, petiole only slightly taller than postpetiole.

Metasomal tergites and sternites finely reticulate over entire surface.

Head and mesosoma dark brown to black, mandibles, scape and femora and metasoma dark brown, antennal flagellum and remainder of legs and posterior margin of tergites light brown. Head mesosoma and ventral surface of legs and metasomal with large numbers of long, erect light brown setae except for central triangle on mesoscutum which is glabrous.

Distribution. This species has the broadest distribution of all the species dealt with here and can be found throughout most of the arid interior of Australia. Its range overlaps with M. eremoides sp. nov., M. eremum sp. nov., M. hoffmanni sp. nov., M. humilior , M. kidman sp. nov., M. mayannae sp. nov., M. oodnadatta sp. nov., M. pilbara sp. nov., M. speculum sp. nov. and M. tenebrosum sp. nov.

Remarks. See Remarks under M. bogischi regarding the validity of the name M. subapterum and Remarks under M. speculum sp. nov., a species that is morphologically indistinguishable from M. subapterum . The additional material examined here is considered to be conspecific with M. subapterum and not M. speculum sp. nov. as this material was genetically similar or identical to material that was taken from the type locality of M. subapterum where M. speculum was not found ( Sparks et al. 2014). Specimens of this species have been observed feeding at flowers of Melelauca sp. in the northwest of Australia.

COI sequences. Genbank accession numbers for this species are KC572878 , KC572885 – KC572888 , KC572895 – KC572897 , KC572901 , KC572907 , KC572909 , KC572910 , KC572922 , KC572940 , KC572946 , KC572954 , KC572960 – KC572965 , KC572967 – KC572969 , KC572971 – KC572976 , KC572984 , KC572987 – KC572991 and KC572993 – KC572996 .

Additional material examined ( NTM, QM, SAM, WAM). Northern Territory. Davenport Ra., old policeman’s waterhole, -20.7528, 135.1852, 9 Jun 2009, K.S. Sparks, KSS88; Conkerberry paddock, Kidman Springs, -16.1167, 130.9667, May 2011, A. Andersen, ANA11–19; ANA11–20; ANA11–21; Simpson's Gap, nr Alice Springs, -23.6735, 133.7175, 11 Dec 2010, A. Andersen, ANA11–2; ANA11–7; Telegraph Station, Alice Springs, -23.6693, 133.8835, 12 Dec 2010, A. Andersen, ANA11–8; ANA11–9; Uluru NP, -25.3512, 131.0636, Oct 2011, A. Andersen, ANA11–43; ANA11–45; ANA11–46; ANA11–50. Queensland. Miyumbah Bush Camp, Lawn Hill NP, -19.0182, 138.7215, 6 Jun 2009, K.S. Sparks, KSS72 (QM). South Australia. Oodnadatta Tk, 57km E Mala, -27.2842, 134.1455, 15 Jun 2009, K.S. Sparks, KSS110; Oodnadatta Tk, 160km E Mala, -27.3039, 135.0443, 15 Jun 2009, K.S. Sparks, KSS116. Western Australia. Carnarvon Region, Callagiddy Rd turnoff, - 24.0308, 113.8408, Nov 2008, B. Heterick, BH002; 270 km S Broome, -19.3643, 121.5371, 13 Oct 2009, K.S. Sparks, C. Petit, KSS128; KSS131;KSS132; 80 Mile Beach caravan park, -19.7552, 120.6717, 14 Oct 2009, K.S. Sparks, C. Petit, KSS133; KSS134; KSS135; Mornington Wildlife Sanctuary, Kimberley, -17.5167, 126.1000, 7 Jul 2009, L. Marshall, ANA09–39; 8 Jun 2009, L. Marshall, ANA09–40; Port Hedland area, -20.3795, 118.6387, 14 Oct 2009, K.S. Sparks, C. Petit, KSS146; KSS150; Port Hedland area, -20.4058, 118.6964, 14 Oct 2009, K.S. Sparks, C. Petit, KSS149; 85 km S Port Hedland, -20.8579, 117.9785, 15 Oct 2009, K.S. Sparks, C. Petit, KSS157; KSS158; Point Samson, -20.6267, 117.1969, 15 Oct 2009, K.S. Sparks, C. Petit, KSS160; Honeymoon Cove, Point Samson, -20.6356, 117.1964, 16 Oct 2009, K.S. Sparks, C. Petit, KSS161; Roebourne, -20.7732, 117.1468, 16 Oct 2009, K.S. Sparks, C. Petit, KSS163; KSS166; 4 km S Newman, -23.3657, 119.7839, 19 Oct 2009, K.S. Sparks, C. Petit, KSS187; Meekatharra, -26.5949, 118.4936, 19 Oct 2009, K.S. Sparks, C. Petit, KSS194; Wiluna, -26.5902, 120.2250, 21 Oct 2009, K.S. Sparks, C. Petit, KSS210; KSS211; KSS214; KSS215; Morapoi station, -29.4033, 121.3779, 23 Oct 2009, K.S. Sparks, C. Petit, KSS222; 72km S Leonora, -29.5063, 121.2404, 23 Oct 2009, K.S. Sparks, C. Petit, KSS224; KSS225; KSS231.

Figures

FIGURE 7. Workers of the M. rothsteini (Forel) species complex in lateral, head and dorsal view of the mesosoma. Fig. 7 a – c: M. pilbara, holotype (4 km S Newman, WA, KSS 188), d – f: M. rothsteini, (Alice River, QLD, ES 38), g – i: M. speculum paratype (Niagara Dam, WA, KSS 218), j – l: M. stagnum, holotype (Mitchell Falls, WA, TERC 11), m – o: M. subapterum, (160 km E Mala, SA, KSS 116). Scale bars are 0.5 mm for all views.