Pseudomyrmex malignus

An inhabitant of the eastern Amazon basin.

Identification
Ward (1999) - The workers and queens of this species can be distinguished from all other members of the viduus group by the combination of well separated frontal carinae (MFC >> basal scape width), laterally angulate median clypeal lobe, and the absence of erect hairs from the posterior margin and upper sides of the head (full-face view). The short dorsal face of the propodeum and shiny integument are also characteristic.

Distribution based on Regional Taxon Lists
Neotropical Region: French Guiana, Guyana, Suriname, Trinidad and Tobago.

Biology
Ward (1999) - This is a Tachigali-inhabiting species, less frequently encountered than Pseudomyrmex concolor or Pseudomyrmex penetrator, but broadly sympatric with them in eastern Hylaea (Humboldt's term for the rainforests of the Amazon basin). Wheeler (1921a, 1942) presented observations on the biology of this species and P. concolor in Guyana, where the host tree was T. paniculata. A collection from Salto Salas, Venezuela was made from Tachigali rusbyi Harms; for other localities the plant (if mentioned) is identified only as Tachigali sp.

Nomenclature

 * cholerica. Pseudomyrma maligna var. cholerica Wheeler, W.M. 1921f: 146 (w.) GUYANA. Combination in Pseudomyrmex: Kempf, 1961a: 400. Junior synonym of malignus: Ward, 1989: 440.
 * crucians. Pseudomyrma maligna var. crucians Wheeler, W.M. 1921f: 147 (w.) GUYANA. Combination in Pseudomyrmex: Kempf, 1961a: 400. Junior synonym of malignus: Ward, 1989: 440.
 *  malignus. Pseudomyrma maligna Wheeler, W.M. 1921f: 143, fig. 14 (w.q.m.) GUYANA. Wheeler, G.C. & Wheeler, J. 1990a: 464 (l.). Combination in Pseudomyrmex: Kempf, 1961a: 400. Senior synonym of auripes, cholerica, crucians: Ward, 1989: 440. See also: Ward, 1999b: 496.
 * auripes. Pseudomyrma auripes Wheeler, W.M. 1922c: 5 (q.) TRINIDAD. Combination in Pseudomyrmex: Kempf, 1961a: 400. Junior synonym of malignus: Ward, 1989: 440.

Worker
Ward (1999) - Measurements (n=10). HL 0.91–1.18, HW 0.84–1.11, MFC 0.117–0.154, LHT 0.57–0.82, CI 0.90–0.96, REL 0.32–0.38, REL2 0.35–0.43, FCI 0.12–0.17, SI 0.39–0.41, FLI 1.14–1.42, FI 0.40–0.44, PLI 0.86–1.05, PWI 0.84–1.08, PPWI 1.48–1.84.

Similar to Pseudomyrmex concolor (q.v.) except as follows. Median clypeal lobe laterally angulate and its anteromedial surface not deflected ventrally. Head slightly broader, on average, and the frontal carinae tending to be slightly more separated (compare FCI). Metanotal groove less deeply impressed in some workers. Dorsal face of propodeum shorter than the declivitous face (PDI 0.83–0.99). Petiole generally shorter and broader than that of P. concolor but the relevant indices overlap (compare PLI and PWI); least overlap with PWI2 (0.65–0.69, compared to 0.58–0.66 in P. concolor). Anteroventral petiolar process well developed and often conspicuously recurved. Mandible smooth and shining, with scattered punctulae, striolae weak and confined to apical portion. Punctulae on upper two thirds of head finer (most with diameter < 0.010 mm) and better separated, and the head correspondingly shinier. Mesosomal punctulae also tending to be finer and less dense. Standing pilosity less dense; erect hairs usually absent from the sides of the head (at most one or two may be present below the eyes), and absent from the posterior margin of the head (frontal view); pilosity sparser on the mesosoma dorsum and external faces of tibiae (MSC 6–35, HTC 1–6). Appressed pubescence less well developed, the appressed hairs separated by more than their lengths on abdominal tergite V and parts of abdominal tergite IV. Body colour more variable, ranging from orangebrown to dark brown; head and terminal segments of gaster usually medium to dark-brown, one or more of the remaining parts of body (from the pronotum to the fourth abdominal segment) may be concolorous or a contrastingly lighter orange-brown.

Type Material
Ward (1999):

Syntype workers, males, queens, Kartabo, Guyana (W. M. Wheeler) [Examined].

Pseudomyrma maligna var. cholerica Wheeler, 1921b:146. Syntype workers, Kartabo, Guyana (W. M. Wheeler) (MCZC) [Examined].

Pseudomyrma maligna var. crucians Wheeler, 1921b:147. Syntype workers, Kartabo, Guyana (W. M. Wheeler) (MCZC) [Examined].

Pseudomyrma auripes Wheeler, 1922:5. Holotype queen, Trinidad (W. M. Wheeler) (MCZC) [Examined].

References based on Global Ant Biodiversity Informatics

 * Brandao C. R. F., F. A. Esteves, and L. P. Prado. 2010. A catalogue of the Pseudomyrmecinae ant type specimens (Hymenoptera, Formicidae) deposited in the Museu de Zoologia da Universidade de Sao paulo, Brazil. Papeis Avulsos de Zoologia 50(45): 693-699.
 * Brandao, C.R.F. 1991. Adendos ao catalogo abreviado das formigas da regiao neotropical (Hymenoptera: Formicidae). Rev. Bras. Entomol. 35: 319-412.
 * Enzmann E. V. 1944. Systematic notes on the genus Pseudomyrma. Psyche (Camb.) 51: 59-103.
 * Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
 * Franco W., N. Ladino, J. H. C. Delabie, A. Dejean, J. Orivel, M. Fichaux, S. Groc, M. Leponce, and R. M. Feitosa. 2019. First checklist of the ants (Hymenoptera: Formicidae) of French Guiana. Zootaxa 4674(5): 509-543.
 * Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
 * Ward P. S. 1990. The Ant Subfamily Pseudomyrmecinae (Hymenoptera: Formicidae): Generic Revision and Relationship to Other Formicids. Systematic Entomology 15: 449-489
 * Ward P. S. 1992. Ants of the genus Pseudomyrmex (Hymenoptera: Formicidae) from Dominican amber, with a synopsis of the extant Antillean species. Psyche (Cambridge) 99: 55-85
 * Ward P. S. 1999. Systematics, biogeography and host plant associations of the Pseudomyrmex viduus group (Hymenoptera: Formicidae), Triplaris- and Tachigali-inhabiting ants. Zoological Journal of the Linnean Society 126: 451-540
 * Wheeler W. M. 1921. The Tachigalia ants. Zoologica (New York) 3: 137-168.
 * Wheeler W. M. 1922. The ants of Trinidad. American Museum Novitates 45: 1-16.
 * Wheeler W. M. 1942. Studies of Neotropical ant-plants and their ants. Bulletin of the Museum of Comparative Zoology 90: 1-262.