Monomorium floricola

This very tiny ant is invasive and is a pest in greenhouses and other facilities throughout the world. Colonies have multiple queens and reproduce by budding.



Identification
Heterick (2006) - Workers of this species bear a striking resemblance in appearance and morphology to dark-headed, bicolored specimens of Monomorium termitobium, but can be distinguished by the combination of a uniformly dark brown or chocolate head and gaster. In M. termitobium the gaster is not uniformly dark brown or black, although it may be a dingy brownish-yellow or yellow with dark infuscation. The petiolar node in all Malagasy specimens of M. floricola that I have seen is also very low and broadly conical to tumular, barely higher than the postpetiole. The ventral surface of the petiole lacks a lobe of any description. Monomorium termitobium workers possess a petiolar node that is distinctly higher than the postpetiole, even when it is low conical in shape, and a subpetiolar lobe of varying degrees is always present.

Distribution based on Regional Taxon Lists
Afrotropical Region: Cameroun, Comoros, Ghana, Nigeria, Tanzania, Togo. Australasian Region: Australia, New Caledonia, Norfolk Island. Indo-Australian Region: Borneo, Cook Islands, Fiji, French Polynesia, Guam, Hawaii, Indonesia, Kiribati, Krakatau Islands, Marshall Islands, Micronesia (Federated States of), New Guinea, Niue, Northern Mariana Islands, Palau, Philippines, Samoa, Solomon Islands, Tokelau, Tonga, Vanuatu, Wallis and Futuna Islands. Malagasy Region: Mauritius, Mayotte, Réunion, Seychelles. Nearctic Region: United States. Neotropical Region: Anguilla, Bahamas, Barbados, Brazil, Cayman Islands, Chile, Colombia, Costa Rica, Cuba, Dominican Republic, Ecuador, El Salvador, French Guiana, Galapagos Islands, Greater Antilles, Guatemala, Guyana, Haiti, Lesser Antilles, Mexico, Paraguay, Puerto Rico, Suriname, Trinidad and Tobago. Oriental Region: India, Nicobar Island, Sri Lanka, Thailand, Vietnam. Palaearctic Region: China, Japan, Republic of Korea, United Kingdom of Great Britain and Northern Ireland.

Puerto Rico
Wheeler (1908): Common in Tillandsias, under the bark-scales of trees and in hollow twigs. All the females were apterous like those of this .. species seen in the Bahamas (Wheeler, Bull. Am. Mus. Nat. Hist. XXI, Pp- 87, 88, figg. D and E).

Nomenclature

 *  floricola. Atta floricola Jerdon, 1851: 107 (w.) INDIA. Forel, 1893g: 388 (q.m.); Wheeler, W.M. 1905b: 88 (q.m.); Donisthorpe, 1914: 136 (gynandromorph); Crawley, 1920d: 217 (gynandromorph); Wheeler, G.C. & Wheeler, J. 1955c: 121 (l.). Combination in Monomorium: Mayr, 1879: 671. Senior synonym of poecilum: Emery, 1894c: 151; of specularis: Mayr, 1879: 671; of cinnabari: Wheeler, W.M. 1913b: 486; of floreanum: Brown, in Linsley & Usinger, 1966: 175; of angusticlava, impressum: Bolton, 1987: 390; of furina, philippinensis: Heterick, 2006: 122. See also: Solis, Fox, Kato, et al. 2010: 15.
 * cinnabari. Monomorium cinnabari Roger, 1863a: 199 (w.) CUBA. Junior synonym of floricola: Wheeler, W.M. 1913b: 486.
 * poecilum. Monomorium poecilum Roger, 1863a: 199 (w.q.) CUBA. Junior synonym of floricola: Emery, 1894c: 151.
 * specularis. Monomorium specularis Mayr, 1866a: 509 (w.) SAMOA. Junior synonym of floricola: Mayr, 1879: 671.
 * impressum. Monomorium impressum Smith, F. 1876a: 447 (q.m.) RODRIGUEZ I. Junior synonym of floricola: Bolton, 1987: 390.
 * philippinensis. Monomorium floricola var. philippinensis Forel, 1910d: 123 (w.q.) PHILIPPINES. Junior synonym of floricola: Heterick, 2006: 122.
 * furina. Monomorium floricola var. furina Forel, 1911i: 221 (w.) SRI LANKA. Junior synonym of floricola: Heterick, 2006: 122.
 * floreanum. Monomorium floreanum Stitz, 1932a: 368, fig. 1 (w.q.) ECUADOR (Galapagos Is). Junior synonym of floricola: Brown, in Linsley & Usinger, 1966: 175.
 * angusticlava. Monomorium (Monomorium) angusticlava Donisthorpe, 1947d: 189 (w.) NEW GUINEA. Junior synonym of floricola: Bolton, 1987: 390.

Worker
Heterick (2006) - HEAD: Head rectangular; vertex planar or weakly concave; frons shining and smooth except for piliferous pits; pilosity of frons a mixture of well-spaced, distinctly longer erect and semi-erect setae interspersed with shorter decumbent setae or setulae. Eye moderate, eye width 1–1.5× greatest width of antennal scape; (in full-face view) eyes set above midpoint of head capsule; (viewed in profile) eyes set around midline of head capsule; eye elongate; Antennal segments 12; antennal club three-segmented. Clypeal carinae always well-defined; anteromedian clypeal margin emarginate, clypeal carinae terminating in small denticles; paraclypeal setae moderately long and fine, curved; posteromedian clypeal margin approximately level with antennal fossae. Anterior tentorial pits situated nearer antennal fossae than mandibular insertions. Frontal lobes straight, parallel. Psammophore absent. Palp formula 1,2. Mandibular teeth three, plus minute, basal denticle or angle; mandibles with sub-parallel inner and outer margins, smooth (except for piliferous pits); masticatory margin of mandibles approximately vertical or weakly oblique; basal tooth a small to minute denticle or angle, much smaller than t3 (four teeth present).

MESOSOMA: Promesonotum shining and mainly smooth, striolae, if present, usually vestigial and confined to lower anterior mesopleuron, in some populations entire lower mesopleuron distinctly striolate; (viewed in profile) anterior promesonotum smoothly rounded, thereafter more-or-less flattened, promesonotum on same plane as propodeum; promesonotal setae seven to twelve; standing promesonotal setae consisting of well-spaced, incurved, erect and semi-erect setae only; appressed promesonotal setulae few, mainly on sides of promesonotum. Metanotal groove strongly impressed, with distinct transverse costulae. Propodeum shining and smooth, with multiple hair like striolae on metapleuron; propodeal dorsum convex; propodeum always smoothly rounded; standing propodeal setae consisting of one prominent pair anteriad, with other shorter setae very sparse or absent; appressed propodeal setulae very sparse or absent; propodeal spiracle equidistant from metanotal groove and declivitous face of propodeum. Vestibule of propodeal spiracle absent or not visible. Propodeal lobes present as vestigial flanges or small strips of cuticle only.

PETIOLE AND POSTPETIOLE: Petiolar spiracle lateral and situated within anterior sector of petiolar node; node (viewed in profile) evenly tumular to roundly conical; appearance of node shining and smooth throughout; ratio of greatest node breadth (viewed from front) to greatest node width (viewed in profile) between 1:1 and 3:4; anteroventral petiolar process absent or vestigial; ventral petiolar lobe absent; height ratio of petiole to postpetiole between 4:3 and 1:1; height–length ratio of postpetiole about 1:1; postpetiole shining and smooth; postpetiolar sternite without anterior lip or carina, or this structure vestigial.

GASTER: Pilosity of first gastral tergite consisting of well-spaced, erect and semi-erect setae interspersed with a few short, appressed setulae.

GENERAL CHARACTERS: Color head, gaster brown, mesosoma tawny yellow or variegated yellow-and-brown, appendages yellow or yellowish-brown. Worker caste monomorphic.

LECTOTYPE MEASUREMENTS (M. specularis): HML 1.09 HL 0.42 HW 0.33 CeI 77 SL 0.28 SI 86 PW 0.20.

LECTOTYPE MEASUREMENTS (M. angusticlava): HML 1.15 HL 0.43 HW 0.34 CeI 79 SL 0.29 SI 87 PW 0.21.

OTHER WORKER MEASUREMENTS: HML 1.00–1.21 HL 0.39–0.43 HW 0.31–0.34 CeI 79–85 SL 0.27–0.31 SI 81–90 PW 0.20–0.23 (n=19).

Queen
Heterick (2006) - HEAD: Head rectangular; vertex weakly concave or planar; frons shining and smooth except for piliferous pits and striolae around antennal sockets, frontal carinae and below the eyes; frons a mixture of well-spaced, distinctly longer erect and semi-erect setae interspersed with shorter setae or setulae, which are decumbent or appressed, longer setae thickest on vertex. Eye elliptical, curvature of inner eye margin may be more pronounced than that of its outer margin; (in full-face view) eyes set at about midpoint of head capsule; (viewed in profile) eyes set around midline of head capsule.

MESOSOMA: Anterior mesoscutum smoothly rounded, thereafter more-or-less flattened; pronotum, mesoscutum and mesopleuron shining and mainly smooth, vestigial striolae, if present, confined to anterior katepisternum; length–width ratio of mesoscutum and scutellum combined about 2:1. Axillae narrowly separated (i.e., less than width of one axilla). Standing pronotal/mesoscutal setae a mixture of well-spaced, distinctly longer, erect and semi-erect setae which are curved distally, interspersed with much shorter, incurved, decumbent setae; appressed pronotal, mescoscutal and mesopleural setulae few, mainly on sides of pronotum and mesopleuron. Propodeum shining and smooth, metapleuron with a few distinct striolae; propodeum always smoothly rounded; propodeal dorsum convex; standing propodeal setae consisting of up to a dozen or more longer erect and shorter sub-erect setae; appressed propodeal setulae well-spaced and sparse; propodeal spiracle nearer metanotal groove than declivitous face of propodeum; propodeal lobes present as vestigial flanges only, or absent.

WING: Wing not seen (queens dealated).

PETIOLE AND POSTPETIOLE: Petiolar spiracle lateroventral and situated within anterior sector of petiolar node; node, in profile conical, vertex rounded; appearance of node shining and smooth; ratio of greatest node breadth to greatest node width about 1:1. Anterior petiolar process absent or vestigial; height ratio of petiole to postpetiole about 1:1; height–length ratio of postpetiole between 3:2 and 4:3; postpetiole shining and smooth; postpetiolar sternite without anterior lip or carina, or this structure vestigial.

GASTER: Pilosity of first gastral tergite consisting of well-spaced, erect and semi-erect setae interspersed with a few appressed setulae.

GENERAL CHARACTERS: Color head, gaster brown, mesosoma and nodes yellowish. Brachypterous alates not seen. Ergatoid or worker-female intercastes not seen.

LECTOTYPE MEASUREMENTS (M. impressum): HML 1.88 HL 0.72 HW 0.59 CeI 81 SL 0.60 SI 103 PW 0.42.

OTHER QUEEN MEASUREMENTS: HML 1.75–1.88 HL 0.54–0.55 HW 0.44–0.46 CeI 82–85 SL 0.39–0.40 SI 85–89 PW 0.31–0.33.

Male
Heterick (2006) - HEAD: Head width–mesosoma width ratio between 4:3 and 1:1; frons smooth to finely striolate. Compound eyes protuberant and elliptical; margin of compound eye nearly abutting clypeus. Ocelli weakly turreted. Ratio of length of first funicular segment of antenna to second funicular segment between 3:4 and 2:3. Maximum number of mandibular teeth and denticles three.

MESOSOMA: Mesoscutum broadly convex; pronotum and mesoscutum shining and mainly smooth, vestigial striolae, if present, confined to anterior katepisternum. Parapsidal furrows vestigial or absent; notauli absent. Axillae narrowly separated (i.e., less than width of one axilla).

WING: Wing veins predominantly depigmented, with distal segments reduced to vestigial lines; vein m–cu absent; vein cu–a absent.

PETIOLE AND POSTPETIOLE: Petiolar spiracle lateral and situated within anterior sector of petiolar node. Petiolar node, (viewed in profile) conical, vertex rounded; appearance of node shining and smooth; ratio of greatest node breadth (viewed from front) to greatest node width (viewed in profile) between 4:3 and 1:1. Anterior petiolar process absent or vestigial. Height ratio of petiole to postpetiole between 4:3 and 1:1; height–length ratio of postpetiole between 2:1 and 3:2; postpeti- ole shining and microreticulate.

GASTER: Pilosity of first gastral tergite consisting of well-spaced, semi-erect setae interspersed with a few appressed setulae.

GENERAL CHARACTERS: Color uniformly brown.

MALE MEASUREMENTS: HML 1.68 HL 0.46 HW 0.50 CeI 109 SL 0.16 SI 0.32 PW 0.44.

Type Material
Heterick (2006):

Atta floricola Jerdon 1851:107. Syntype ☿s, India [no types known to exist].

Monomorium cinnabari Roger 1863a:199. Syntype ☿s, CUBA [whereabouts of type material unknown]. Syn. under M. floricola (Jerdon): Wheeler, W.M. 1913:388.

Monomorium poecilum Roger 1863a:199. Syntype ☿s, CUBA [whereabouts of type material unknown]. Syn. under M. floricola (Jerdon): Emery 1894b:51.

Monomorium specularis Mayr 1866:09. Syntype ☿s (see comments below – lectotype here designated) SAMOA: Upolu (NMW) [examined]. Syn. under M. floricola (Jerdon): Mayr 1879:71.