fieldwork was done in costa rica , braulio carrillo national park from 21 march 2011 to 30 march 2011 . three colonies of m. foreli and three colonies of m. mondabora ( thief ant parasite of cyphomyrmex cornutus kempf ) were collected from el ceibo station ( 1020n , 08405w , 450550  m elevation , waterline trail ) . twelve colonies of m. wallacei and four colonies of m. modestus were collected from la selva biological station ( 102459n , 0840112w , 50  m elevation ) . ovaries and spermatheca were dissected in queens and workers of all species . except for m. mondabora , queen and ( longino 2010 , boudinot et al . 2013 ) and vouchers are at the ohio state university , museum of biological diversity . three m. foreli colonies were excavated from within a large wet log ( rmma110324 - 03 : workers  =  226 ; brood , excluding eggs  =  130 ; zero males ; one ergatoid queen ) , at the base of a pourouma tree ( rmma110323 - 01 : workers  =  455 ; brood , excluding eggs  =  219 ; zero males ; one ergatoid queen ) , and at the base of a small plant ( rmma110323 - 05 : workers  =  2,231 ; brood , excluding eggs  =  134 ; 64 males ; one ergatoid queen ) . the m. wallacei ergatoid queens were much less conspicuous with a gaster only slightly larger than workers , consistent with other reports ( boudinot et al . up to six ergatoid m. wallacei queens occurred together with 110    88 workers and brood ( n  =  12 ) . in both species , the queen s thorax was highly reduced , consistent with their ergatoid nature . distinct ocelli typical of flying queens , were not observed in m. wallacei queens and only one faint ocellus was present in the m. foreli queens . 1.comparison of ergatoid queen ( bottom right corner ) and workers in m. foreli , showing the large difference in gaster size . comparison of ergatoid queen ( bottom right corner ) and workers in m. foreli , showing the large difference in gaster size . megalomyrmex mondabora colonies live within the soil - based nests of c. cornutus that hang from vines and tree trunks ( adams and longino 2007 ) . two previously censused colonies contained ca . 250 parasite workers ( adams and longino 2007 ) ; our estimations for two colonies examined , ranged from ca . 50200 and one only had a queen ( 4 of 27 host colonies or 15% were parasitized , one was queenless ) . megalomyrmex modestus nests ( in logs and soil ) were diffuse in structure , with multiple queens and ca . the queens of both m. mondabora and m. modestus exhibit morphological characters typical of winged queens . megalomyrmex modestus was used as a reference for the flight thorax of a normal winged queen : segmentation is distinct , the pronotum is very small , and the mesonotum is the biggest sclerite ( reflecting size of the wing muscles ; fig . 2d ) , while the mesonotum is reduced due to the lack of wing muscles . there is a faint pro - mesonotal suture in ergatoid queens , while all sclerites are fused in workers . thoracic segmentation of three megalomyrmex queens , ( a ) dealate m. modestus ; ( b ) m. wallacei ; ( c ) m. foreli . pronotum ( blue ) is small in winged queens while the mesonotum ( red ) is reduced in ergatoid queens . note the absence of wing bases ( insert in a ) in the ergatoid queens b and c. scale bar = 1 mm . thoracic segmentation of three megalomyrmex queens , ( a ) dealate m. modestus ; ( b ) m. wallacei ; ( c ) m. foreli . pronotum ( blue ) is small in winged queens while the mesonotum ( red ) is reduced in ergatoid queens . note the absence of wing bases ( insert in a ) in the ergatoid queens b and c. scale bar = 1 mm . the big gaster of m. foreli queens ( n  =  3 ) was associated with 6080 tightly packed ovarioles ( fig . all three queens of m. foreli were mated and showed different degrees of ovarian activity . in the large colony ( 2,231 workers ) , the queen was physogastric ( i.e. , intersegmental membranes stretched ) with many big yolky oocytes and dark  yellow bodies  indicating that many eggs had been previously laid . in the two small colonies ( 455 and 226 workers ) , queens lacked dark  yellow bodies  and had fewer yolky oocytes , suggesting they were recently mated . accordingly 3 . developed ovaries of ergatoid queens in ( a ) m. foreli and ( b ) m. wallacei compared to winged queens ( c ) m. modestus and ( d ) m. mondabora . scale bar = 1 mm . 
   developed ovaries of ergatoid queens in ( a ) m. foreli and ( b ) m. wallacei compared to winged queens ( c ) m. modestus and ( d ) m. mondabora . megalomyrmex wallacei queens had eight ovarioles ( n  =  21 ) ( fig . several queens were inseminated in each colony , but only some had active ovaries with yolky oocytes . other mated queens had few yolky oocytes and lacked dark  yellow bodies  . for comparison , m. modestus queens had 2228 ovarioles ( n  =  6 ) ( fig . 3c ) , and queens of m. mondabora had eight ovarioles ( n  =  3 ) ( fig . workers in all four species had two ovarioles ( n  =  14 ) . morphological and biological comparisons of ergatoid queens in two unrelated species of megalomyrmex revealed distinct levels of egg - laying specialization . their thorax is similarly reduced ( fig . the three m. foreli colonies examined had a single highly fecund queen with a worker - like thorax fig . 2c and d and a considerably larger gaster than the workers ( fig . , the gaster of m. wallacei queens is similar to workers , and the two castes differ slightly in body size . this may explain why brando ( 1990 ) reported gamergates ( i.e. , mated , egg - laying workers ) as reproductives in m. wallacei . similarly , longino ( 2010 ) noted that m. wallacei workers  show considerable size variation , and larger workers have an enlarged mesonotum and no morphologically distinct queen  . the fecundity of ergatoid queens underlies colony size , and this may be correlated with some aspects of the biology of colonies . megalomyrmex foreli builds shallow but large permanent nests in the soil that can be observed year after year ( r. m. m. adams , personal observation ) . ( leguminosae ) ( jones et al . 1991 ) , riodinid butterflies ( lepidoptera ) ( devries et al . 1992 ) , and build soil structures that cover membracids ( longino 2010 , boudinot et al . few foragers can be seen during the day but more can be drawn out with baits ( r. m. m. adams , personal observation ) . the three colonies that we dug took four researchers , large trash bags , and careful attention to collect the majority of workers and find the queen . colonies are widely spaced suggesting that foraging territories are established and perhaps their honeydew producing associates help drive this ( r. m. m. adams , personal observation ) . in contrast , m. wallacei colonies were found in dense populations within deep leaf litter . the population is stable and colonies have been retrieved from the same trails 8  years apart ( 2003 , 2005 , 2011 ) ( r. m. m. adams , personal observation ) . the nests however are temporary structures found in the litter between dead leaves and at the base of the leaves of short palms ( boudinot et al . high polygyny means a high probability that at least one mated queen will be present following accidental fragmentation , thus leading to autonomous colonies ( cronin et al . 2013 ) . unlike flightless insects that live and reproduce alone , flightless reproductives in most ant species have lost the ability to found new colonies independently , and they completely rely on nestmate workers during dependent colony founding ( dcf ) ( peeters 2012 ) . the multiple occurrences of ergatoid queens in megalomyrmex reveal that dcf ( fission or budding ) has replaced independent foundation ( icf ) repeatedly . however little data on colony founding behavior are available in megalomyrmex . as the two congeneric species studied here differ in queen number , it is evidence against the persistent belief in the literature that dcf species are always polygynous . the mosaic nature of ergatoid queens in megalomyrmex , ( i.e. , exhibiting traits specific to both workers and winged queens ) , suggests that morphological modules became recombined during development ( molet et al . ergatoid queens are novel phenotypes that evolved by uncoupling the growth of the thorax and abdomen . because they evolved convergently across the ants , the phenotypes of ergatoid queens are very heterogeneous . 2009 ) recognized two categories of ergatoid queens : ( 1 )  single - purpose  , few are produced in each colony , they are much bigger than workers and function exclusively for reproduction and ( 2 )  multi - purpose  , many are produced in each colony and they are similar in size to workers , only one or few reproduce while others remain virgin and function as labourers . this corresponds to the phenotypes of m. foreli and m. wallacei queens , respectively , which appear to be alternative solutions to the replacement of winged queens . within the modestus group , both ergatoid and winged queens have been recorded in separate populations of megalomyrmex goeldii ( brando 2003 ) . similarly , m. wallacei has winged queens in brazil ( brando 2003 ) but not in costa rica ( this study ) . molecular and/or morphological studies would help determine if brazilian populations represent a different species or an intraspecific polymorphism . both winged and ergatoid queens have also been described in the facultative thief ant social parasite , m. silvestrii ( boudinot et al . 2013 ) . although only one ergatoid was examined , it is slightly larger than workers and has a less voluminous thorax compared to the winged queens . the raiding behavior ( adams et al . 2015 ) , nesting habits ( boudinot et al . 2013 ) , and morphology suggest that the m. silvestrii ergatoids may be the studies of megalomyrmex species that include colony demography , ovarian development , and population genetics will advance our understanding of the evolutionary implications of queen winglessness at the ecological timescale and shed light on the plasticity of independent and dependent colony foundation . comparative studies conducted on the variety of megalomyrmex species with obligate ( e.g. , m. foreli , m. leoninus , and m. staudingeri ) and facultative ergatoid queens ( e.g. , m. wallacei , m. silvestrii , and m. goeldii ) will elucidate factors that influence the evolution of queen winglessness . furthermore , future work can draw on the developmental pathways identified in worker winglessness and link these to genomic changes within the obligate ergatoid species . finally , phylogenetic studies of megalomyrmex and other genera in the tribe solenopsidini ( ward et al . 2015 ) will reveal the number of independent evolutionary events of ergatoid queens ( e.g. , monomorium and megalomyrmex ) for broader comparative analyses .
megalomyrmex forel ( myrmicinae : solenopsidini ) consists of 44 species with diverse life history strategies . 
 most species are predatory and may also tend honeydew - producing insects . 
 a morphologically derived group of species are social parasites that consume the brood and fungus garden within fungus - growing ant nests . 
 the reproductive strategies of megalomyrmex queens are somewhat aligned with these life - style patterns . 
 predatory species in the leoninus species group are large in body size and have ergatoid ( i.e. , permanently wingless ) queens whereas the social parasitic species are smaller and typically have winged queens . 
 we examined two ergatoid phenotypes of megalomyrmex foreli emery and megalomyrmex wallacei mann and compared them to winged species , one a social lestobiotic or  thief ant 
 parasite ( megalomyrmex mondabora brando ) and the other a predator ( megalomyrmex modestus emery ) . 
 megalomyrmex foreli colonies have a single queen with an enlarged gaster that is morphologically distinct from workers . 
 megalomyrmex wallacei colonies have several queens that are similar in body size to workers . 
 queens in both species showed a simplification of the thorax , but there was a dramatic difference in the number of ovarioles . 
 megalomyrmex foreli had 6080 ovarioles compared to eight in m. wallacei and m. mondabora and m. modestus had 2228 . 
 along with flight loss in queens , there is an obligate shift to dependent colony founding ( also called budding or fission ) consequently influencing dispersal patterns . 
 these constraints in life history traits may help explain the variation in nesting biology among megalomyrmex species .