Linepithema leucomelas

Linepithema leucomelas
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Dolichoderinae
Tribe:	Leptomyrmecini
Genus:	Linepithema
Species:	L. leucomelas
Binomial name
Linepithema leucomelas (Emery, 1894) Specimen labels
Synonyms
Iridomyrmex aspidocoptus Kempf, 1969

An arboreal species inhabiting Brazil's Atlantic forest.

Identification

Wild (2007) - Worker Strikingly bicolored, dark head contrasting with pale whitish yellow on all or part of the mesosoma and appendages; antennal scapes long (SI 106–125).

Linepithema leucomelas is unlikely to be confused with any other Linepithema species owing to its striking coloration. Workers of the closely-related Linepithema iniquum have a strong constriction of the mesonotum, while males of L. iniquum are nearly identical but the petiolar node is concolorous with the mesosomal dorsum.

Some worker specimens from Santa Catarina are darker in color than specimens from elsewhere, with a dark propodeum and more extensive infuscation. A few specimens from São Paulo state are larger and bear more than one pair of pronotal setae.

Male Forewing with 1 submarginal cell; petiolar node bearing a relatively low, rounded scale; propodeum with posterior face convex; antennal segment 3 more than twice as long as antennal scape; dorsum of petiole much lighter in color than mesosomal dorsum.

Keys including this Species

• Key to Linepithema males
• Key to Linepithema workers

Distribution

Southeastern Brazil

Latitudinal Distribution Pattern

Latitudinal Range: -24.11666667° to -29.48333333°.

North Temperate	North Subtropical	Tropical	South Subtropical	South Temperate

• Source: AntMaps

Distribution based on Regional Taxon Lists

Neotropical Region: Brazil (type locality).

Distribution based on AntMaps

Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.

Estimated Abundance

Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species.

Biology

Wild (2007) - This species is an Atlantic forest ant. Most records are from rainforest or wet forest. Linepithema leucomelas is one of only two primarily arboreal species in the genus, the other being L. iniquum. Kempf (1969: 294) observes that L. leucomelas nests “under bark, also in the cavities of bamboo, gourd trees, and arboreal ferns.” Leuderwaldt (1926) reports several nests from bamboo and one from a Hemitelia fern. Ketterl et al. (2003) note L. leucomelas nesting in bromeliads in Araucaria trees in Rio Grande do Sul. Among museum records, one nest is from under Jacaranda bark and two separate Port-of-Entry intercepts into the United States report the ant from orchid plants. Alate queens have been collected from nests in May and October, and alate males have been collected in October.

As noted in Emery’s original description and again by Kempf (1969), this ant shows similar coloration to an unrelated arboreal Atlantic forest species, Tapinoma atriceps Emery. The significance of this convergence is unknown.

Nomenclature

The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

• leucomelas. Iridomyrmex leucomelas Emery, 1894g: 378 (footnote) (w.q.) BRAZIL. Wild, 2007a: 83 (m.). Combination in Linepithema: Shattuck, 1992a: 16. Senior synonym of aspidocoptus: Wild, 2007a: 81.
• aspidocoptus. Iridomyrmex aspidocoptus Kempf, 1969: 295, figs. 10, 11 (w.) BRAZIL. Combination in Linepithema: Shattuck, 1992a: 16. Junior synonym of leucomelas: Wild, 2007a: 81.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Wild (2007):

Description

Worker

Lectotype: HL 0.69, HW 0.60, MFC 0.16, SL 0.70, FL 0.60, LHT 0.61, PW 0.37, ES 1.79, SI 116, CI 88, CDI 27, OI 26.

Worker: (n = 22) HL 0.60–0.78, HW 0.52–0.74, MFC 0.14–0.18, SL 0.64–0.79, FL 0.51–0.68, LHT 0.58–0.71, PW 0.33–0.58, ES 1.22–2.00, SI 106–125, CI 85–96, CDI 24–28, OI 20–26.

Head in full face view varying from relatively narrow to relatively broad (CI 85–96), lateral margins convex, posterior margin slightly convex to concave. Compound eyes of moderate size (OI 20–26), comprised of 55–80 facets. Antennal scapes long (SI 106–125), as long or longer than head length. In full face view, scapes in repose exceeding posterior margin of head by a length greater than the length of the first funicular segment. Frontal carinae narrowly to moderately spaced (CDI 24–28). Maxillary palps very long, well more than ½ HL, ultimate segment (segment six) longer than segment 2.

Mesosoma in lateral view with pronotum and mesonotum forming a single continuous convexity, mesonotal profile straight to very slightly impressed mesally. Metanotal groove slightly impressed to not at all impressed, propodeum low and quadrate-forward.

Petiolar scale sharp and inclined anteriorly, in lateral view falling short of the propodeal spiracle.

Cephalic dorsum (excluding clypeus) bearing 4–6 erect setae. Pronotum bearing 1–4 erect setae. Mesonotum without erect setae. Gastric tergite 1 bearing 1–3 erect setae (mean = 2.0), tergite 2 with 2–4 erect setae, tergite 3 with 4–6 erect setae. Venter of metasoma with scattered erect setae.

Surface of head and mesosomal dorsum finely reticulate-punctate and relatively dull. Pubescence dense on head and mesosomal dorsum. Mesopleura with pubescence fading to absent anteroventrally, surface smooth and shining. Metapleural bulla with moderate to sparse pubescence thinner than on propodeal dorsum but never completely absent. Gastric tergites 1–4 with dense pubescence, surface only slightly shining.

Body color variable, but always bicolored with head and part of gaster dark brown and with at least pronotum, petiole, and some appendages a pale whitish-yellow. Some specimens pale whitish yellow except for dark head and gastric infuscation, others dark except for light pronotum, petiole, funiculus, tibiae and tarsi. Most specimens show mesopleural infuscation.

Queen

(n = 2) HL 0.85, HW 0.78–0.79, SL 0.79–0.83, FL 0.78–0.80, LHT 0.88, EL 0.26–0.27, MML 1.65–1.66, WL 5.01, CI 92–94, SI 100–106, OI 31–32, WI 30, FI 47–49.

Moderately small species (MML < 1.7). Head longer than broad in full face view (CI 92–94), posterior margin slightly concave to slightly convex. Eyes small (OI 31–32). Ocelli small. Antennal scapes long (SI 100–106), in full face view scapes in repose surpassing posterior margin by a length greater than length of first funicular segment.

Forewings of moderate length relative to mesosomal length (WI 30). Forewings with Rs+M somewhat longer than M.f2. Legs moderately long relative to mesosomal length (FI 47–49).

Dorsum of mesosoma and metasoma with abundant standing setae. Mesoscutum bearing more than 10 standing setae. Head, mesosoma and metasoma medium to dark brown, trochanters, tibiae, and tarsi testaceous.

Male

(n = 2) HL 0.48–0.52, HW 0.44–0.47, SL 0.11–0.12, FL 0.52–0.55, LHT 0.49–0.54, EL 0.19–0.20, MML 0.87–0.94, WL 2.23, PH 0.19–0.21, CI 91–92, SI 23, OI 38–41, WI 26, FI 58–59.

Head relatively narrow in full face view (CI 91–92), lateral margins continuing to expand posterior of compound eyes. Eyes moderately small (OI 38–41), occupying much of anterolateral surface of head anterior of midpoint and separated from posterolateral clypeal margin by a length less than width of antennal scape. Ocelli small and in full frontal view emerging only slightly above adjoining posterolateral margins. Antennal scape short (SI 23), only 40–50% length of 3rd antennal segment. Anterior clypeal margin convex medially. Mandibles small, masticatory margin slightly longer than inner margin, apical tooth enlarged and followed by a series of 8–12 denticles. Inner margin and exterior lateral margin parallel to slightly diverging.

Mesosoma not well developed and subequal in length to metasoma. Mesoscutum not greatly enlarged, not projecting forward over pronotum. Propodeum in lateral view not well developed and not overhanging petiole, posterior face slightly convex and rounding gradually into dorsal face. Forewings of moderate length (WI 26) and bearing one submarginal cell. Wings transparent, with pale brown wing veins and stigma. Legs of moderate length relative to mesosoma (FI 58–59).

Petiolar node bearing a low, rounded scale, node height shorter than node length. Venter of node bearing a convex posteriorly-pointing process. Gaster ovoid in dorsal view, about 2 times as long as broad. Gonostylus produced as triangular pilose lobe. Volsella with cuspis present, digitus short and downturned distally.

Dorsal surfaces of body with erect setae sparse, mesoscutum with 0–4 fine erect to suberect setae. Venter of gaster with scattered setae. Pubescence dense on body and appendages, becoming sparse only on medial propodeal dorsum. Sculpture on head and mesoscutum not well developed, surface shining through pubescence.

Head, mesosoma, and metasoma medium brown. Mandibles, petiole, antennae, and legs pale whitish-yellow to light brown, much lighter than head and mesosoma.

Type Material

Lectotype worker, by present designation National Museum of Natural History, examined, and 1 worker paralectotype, Rio Grande do Sul, Brazil USNM, examined.

References

• Emery, C. 1894h. [Untitled.]. Pp. 373-401 in: Ihering, H. von. Die Ameisen von Rio Grande do Sul. Berl. Entomol. Z. 39:321-447. (page 378, (footnote) worker, queen described)
• Shattuck, S. O. 1992a. Review of the dolichoderine ant genus Iridomyrmex Mayr with descriptions of three new genera (Hymenoptera: Formicidae). J. Aust. Entomol. Soc. 31: 13-18 (page 16, Combination in Linepithema)
• Wild, A. L. 2007a. Taxonomic revision of the ant genus Linepithema (Hymenoptera: Formicidae). University of California Publications in Entomology. 126:1-159.
• Wild, A.L. 2004. Taxonomy and distribution of the Argentine ant, Linepithema humile (Hymenoptera: Formicidae). Annals of the Entomological Society of America 97, 1204-1215.

References based on Global Ant Biodiversity Informatics

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• Clemes Cardoso D., and J. H. Schoereder. 2014. Biotic and abiotic factors shaping ant (Hymenoptera: Formicidae) assemblages in Brazilian coastal sand dunes: the case of restinga in Santa Catarina. Florida Entomologist 97(4): 1443-1450.
• Clemes Cardoso D., and M. Passos Cristiano. 2010. Myrmecofauna of the Southern Catarinense Restinga sandy coastal plain: new records of species occurrence for the state of Santa Catarina and Brazil. Sociobiology 55(1b): 229-239.
• Favretto M. A., E. Bortolon dos Santos, and C. J. Geuster. 2013. Entomofauna from West of Santa Catarina State, South of Brazil. EntomoBrasilis 6 (1): 42-63.
• Fernandes T. T., R. R. Silva, D. Rodrigues de Souza-Campana, O. Guilherme Morais da Silva, and M. Santina de Castro Morini. 2019. Winged ants (Hymenoptera: Formicidae) presence in twigs on the leaf litter of Atlantic Forest. Biota Neotropica 19(3): http://dx.doi.org/10.1590/1676-0611-bn-2018-0694
• Fernandes T. T., W. Dattilo, R. R. Silva, P. Luna, C. M. Oliveira, and M. Santina de Castro Morini. 2019. Ant occupation of twigs in the leaf litter of the Atlantic Forest: influence of the environment and external twig structure. Tropical Conservation Science 12: 1-9.
• Forel A. 1908. Ameisen aus Sao Paulo (Brasilien), Paraguay etc. gesammelt von Prof. Herm. v. Ihering, Dr. Lutz, Dr. Fiebrig, etc. Verhandlungen der Kaiserlich-Königlichen Zoologisch-Botanischen Gesellschaft in Wien 58: 340-418.
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• Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
• Luederwaldt H. 1918. Notas myrmecologicas. Rev. Mus. Paul. 10: 29-64.
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