Aenictus decolor

Aenictus decolor
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Dorylinae
Genus:	Aenictus
Species group:	decolor
Species:	A. decolor
Binomial name
Aenictus decolor (Mayr, 1879) Specimen Labels
Synonyms
Aenictus batesi Forel, 1911

This species has been reported as collected in forests (coastal lowland rainforest, primary forest), on cocoa and in a canopy fogging sample.

Identification

Gomez (2022) - A member of the Aenictus decolor species group. The workers of this species answer to the Aenictus bidentatus description, except for its more developed mesosomal sculpture, consistently larger size and relatively longer scapes. (See discussion under Aenictus bidentatus).

Gotwald and Leroux (1980) - Most conspicuous among the features of this species is the large, distally rounded, second subapical tooth situated midway along the medial border of the worker mandible. The The worker mandible, with its large second subapical tooth, is so distinctive that it alone separates this species from all other African species of which we are currently aware.

The queen is easily distinguished from the queens thus far described from other sub-Saharan species (A. congolensis and A. eugenii) because (1) its mandibles are provided with subapical teeth, and (2) it possesses the pygidial spines. As a general rule, the mandibles of army ant queens in both the New World (Ecitoninae) and Old World (Dorylinae) are devoid of subapical teeth (Gotwald, 1969).

Keys including this Species

• Key to the Afrotropical Aenictus

Distribution

Latitudinal Distribution Pattern

Latitudinal Range: 6.216666667° to -0.317°.

North Temperate	North Subtropical	Tropical	South Subtropical	South Temperate

• Source: AntMaps

Distribution based on Regional Taxon Lists

Afrotropical Region: Benin, Cameroun, Gabon, Ghana, Guinea, Ivory Coast, Kenya, Nigeria.

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

Association with Other Organisms

 Explore: Show all Associate data or Search these data. See also a list of all data tables or learn how data is managed.

• This species is a associate (details unknown) for the phorid fly Aenictacantha crassitarsalis (a associate (details unknown)) (Quevillon, 2018).

Castes

Known from the worker and queen castes. Table of castes known for all Afrotropical Aenictus species.

Worker

Gomez 2022, Figure 8c-e.

Gotwald and Leroux 1980, Figure 3

Gotwald and Leroux 1980, Figure 4

Images from AntWeb

Holotype of Aenictus bidentatus. Worker. Specimen code casent0902685. Photographer Z. Lieberman, uploaded by California Academy of Sciences.	Owned by NHMUK, London, UK.

Syntype of Aenictus batesi. Worker. Specimen code casent0907024. Photographer Z. Lieberman, uploaded by California Academy of Sciences.	Owned by MHNG, Geneva, Switzerland.

Queen

• 

  Gotwald and Leroux 1980, Figure 1.
• 

  Gotwald and Leroux 1980, Figure 2.

Nomenclature

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

• decolor. Typhlatta decolor Mayr, 1879: 668 (diagnosis in key) (w.) “East Africa”.
  • Type-material: syntype workers (number not stated).
  • [Note: Gómez, 2022: 22, cites 3w syntypes (2 BMNH, 1 NHMW).]
  • Type-locality: “Ost Afrika”: (no further data).
  • Type-depositories: BMNH, NHMW.
  • Gotwald & Leroux, 1980: 602 (q.).
  • Combination in Aenictus: Dalla Torre, 1893: 7.
  • Status as species: Dalla Torre, 1893: 7; Emery, 1895j: 746; Emery, 1910b: 31; Arnold, 1915: 143; Wheeler, W.M. 1922a: 751; Gotwald & Leroux, 1980: 600; Bolton, 1995b: 59; Hita Garcia, et al. 2013: 201; Gómez, 2022: 22 (redescription).
  • Senior synonym of batesi: Gotwald & Leroux, 1980: 600; Bolton, 1995b: 59; Gómez, 2022: 23.
  • Distribution: Gabon, Ghana, Guinea, Ivory Coast, Nigeria.
• batesi. Aenictus batesi Forel, 1911e: 255 (w.) NIGERIA.
  • Type-material: syntype workers (number not stated).
  • [Notes (i): Baroni Urbani, 1977e: 66, cites 2w syntypes NHMB; (ii) Gómez, 2022: 23, cites 4w syntypes MHNG.]
  • Type-locality: Nigeria: Old Calabar (H.W. Bates).
  • Type-depositories: MHNG, NHMB.
  • Status as species: Wheeler, W.M. 1922a: 751.
  • Junior synonym of decolor: Gotwald & Leroux, 1980: 600; Bolton, 1995b: 58.

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

Description

Worker

Gomez (2022) - HL: 0.69 [0.67-0.72]; HW: 0.65 [0.60-0.70]; SL: 0.60 [0.57-0.63]; WL: 1.16 [1.12-1.21]; PL: 0.25 [0.23-0.26]; PH: 0.19 [0.18-0.21]; PPL: 0.20 [0.18-0.22]; PPH: 0.18 [0.15-0.19]; CS: 0.67 [0.63-0.71]; CI: 93 [87-98]; SIL: 86 [83-89]; SIW: 93 [87-100]; WL/HW: 179 [170-190]; PI: 127 [119-138]; PPI: 113 [100-133]; CSR: 111; (n=9).

Gotwald and Leroux (1980) - Composite description (n=8). Total length 2.90-3.28 mm, head length 0.60-0.67 mm, head width 0.54-0.63 mm, cephalic index 87.0-95.4, trunk (thorax + propodeum) length 0.96-1.03 mm, petiole length 0.27 mm, length of petiolar node 0.13-0.22 mm, width of petiolar node 0.13-0.18 mm, postpetiole length 0.18-0.24 mm, length of post-petiolar node 0.13-0.18 mm, width of postpetiolar node 0. 18-0.22 mm, gaster length 0.85-1.08 mm, scape length 0.40-0.45 mm, and hind femur length 0.67-0.76 mm.

Head, trunk, and waist (petiole plus postpetiole) orange brown; gaster, legs, and antennae, lighter, yellow orange.

Head sutureless on dorsal and lateral surfaces; without eyes; dorsal surface glossy, without conspicuous punctures, occipital margin clearly defined as in queen. Antenna! fossae with elevated, sharply defined medial borders; lateral borders not as well developed but ending caudally in slightly elevated points in lateral view. Clypeal process excavated medially. Mandible with 2 subapical teeth, proximal tooth large and rounded apically; maxillary palpus 2-segmented; labial palpus 2-segmented. Antenna IO-segmented.

Anterior dorsal slope of pronotum densely punctate, balance of dorsal surface and pleurae glossy, without conspicuous punctures. Remainder of trunk coarsely sculptured with densely-packed, deep punctures and, on pleurae, longitudinal rugae. Declivity of propodeum bordered by sharply produced ridge. Distal margin of bulla covering metapleural gland orifice prominent. Petiolar and postpetiolar nodes densely and coarsely punctured; subpetiolar tooth well-developed but variable in shape, rounded apically and densely punctured.

Gaster. Integument of gaster glossy, without conspicuous punctures.

Pubescence yellow, consisting of sparsely but generally distributed, often erect, setae. Tarsal claws simple.

Queen

Gotwald and Leroux (1980) - Composite description (n=4). Total length 6.69-7.30 mm, head length 1.08-1.17 mm, head width l.08-1.12 mm, cephalic index 92.3-100, trunk (thorax + propodeum) length 1.53-1.62 mm, petiole length 0.54-0.63 mm, length of petiolar node 0.45-0.49 mm, width of petiolar node 0.66-0. 76 mm, gaster length 3.45-3.88 mm, scape length 0.54-0.58 mm, and hind femur length 0.94-0.99 mm.

Head, trunk, petiole, and gaster orange brown, darkest on dorsal surface of gaster; antennae and legs lighter, orange to orange yellow.

Head sutureless on dorsal and lateral surfaces; without eyes; dorsal surface glossy, occipital region bordered, except ventrally, by clearly defined, sharp ridge; antennal fossae moderately impressed, each fossa bordered medially by slightly elevated ridge; clypeus produced anteriorly as a truncated process. Mandible with 2 subapical teeth, proximal tooth large and smoothly rounded; maxillary palpus 2-segmented; labial palpus I-segmented. Antenna 10-segmented.

Trunk without conspicuous sutures, punctures sparse, integument glossy; meso- and metathoracic spiracles elevated but inconspicuous, propodeal spiracle large, elevated, and directed posteriorly. Distal margin of bulla covering metapleural gland orifice prominent, parallel to longitudinal axis of trunk; margin begins at point directly ventral to propodeal spiracle. Declivity of propodeum with distinct cariniform margins that ~re continuous between dorsal and declivitous propodeal surfaces; Declivity in lateral view straight or only slightly concave.

Dorsal surface of petiolar node clearly defined by precipitous angle with which it joins pleural surfaces; node glossy. Subpetiolar tooth large, directed posteriorly.

Gaster. Integument of gaster glossy without conspicuous punctures; tergite of 5th gastral segment with pair of laterally placed pygidial spines; spines with numerous setae. Tip of ovipositor prominent.

Pubescence yellow, sparse, and most conspicuous on lateral surfaces of propodeum, petiole, on 1st gastral tergite, and on pygidial spines. Tarsal claws simple.

Type Material

• Typhlatta decolor
  • Syntype EAST AFRICA. (Smith) (1w) [CASENT0919639] NMHW: Coll. Mayr [Examined by Gomez, 2022]; Syntypes, same data (1w each) [NHMUK012849174 to NHMUK012849177] BMNH [Examined by Gomez, 2022].
• Aenictus batesi
  • Syntype NIGERIA: Alt. Calabar (H. N. Bates) (1w) [CASENT0907024] NHMB [Examined by Gomez, 2022]; Syntype, same series (1w) [Examined by Gomez, 2022]; Syntype, same data, MHNG Coll. Forel (4 pins, 1w each) [Examined by Gomez, 2022].

References

• Dalla Torre, K. W. von. 1893. Catalogus Hymenopterorum hucusque descriptorum systematicus et synonymicus. Vol. 7. Formicidae (Heterogyna). Leipzig: W. Engelmann, 289 pp. (page 7, Combination in Aenictus)
• Gomez, K. 2022. A revision of the Afrotropical species of the Dorylinae ant genus Aenictus (Hymenoptera: Formicidae) based on the worker caste. Belgian Journal of Entomology 124: 1–86 (doi:10.5281/zenodo.5898821).
• Gotwald, W. H., Jr.; Leroux, J. M. 1980. Taxonomy of the African army ant, Aenictus decolor (Mayr), with a description of the queen (Hymenoptera: Formicidae). Proceedings of the Entomological Society of Washington. 82:599-608.
• Mayr, G. 1879. Beiträge zur Ameisen-Fauna Asiens. Verh. K-K. Zool.-Bot. Ges. Wien 28: 645-686 (page 668, worker described)
• Mbenoun Masse, P.S., Ebolo, G.L.M., Titti, G.E., Mony, R. 2021. Ant species richness, abundance and functional groups along an elevation gradient in Central Cameroon. Biodiversity Journal 12(1): 179-194 (doi:10.31396/biodiv.jour.2021.12.1.179.194).
• Taylor, B., Agoinon, N., Sinzogan, A., Adandonon, A., Kouaguou, Y. N., Bello, S., Wargui, R., Anato, F., Ouagoussounon, I., Houngbo, H., Tchibozo, S., Todjihounde, R., Vayssieres, J.F. 2018. Records of ants (Hymenoptera: Formicidae) from the Republic of Benin, with particular reference to the mango farm ecosystem. Journal of Insect Biodiversity 8(1): 6-29 (doi:10.12976/jib/2018.08.1.2).

References based on Global Ant Biodiversity Informatics

• Baroni Urbani C. 1977. Katalog der Typen von Formicidae (Hymenoptera) der Sammlung des Naturhistorischen Museums Basel (2. Teil). Mitt. Entomol. Ges. Basel (n.s.) 27: 61-102.
• Chapman, J.W. and S.R. Capco. 1951. Check list of the ants (Hymenoptera: Formicidae) of Asia. Monographs of the Institute of Science and Technology (Manila) 1: 1- 327
• Donisthorpe H. 1942. New species of ants (Hym., Formicidae) from the Gold Coast, Borneo, Celebes, New Guinea and New Hebrides. Annals and Magazine of Natural History (11)9:701-709.
• Gotwald W. H. Jr., J.M. Leroux. 1980. Taxonomy of the African army ant, Aenictus decolor (Mayr), with a description of the queen (Hymenoptera: Formicidae). Proceedings of the Entomological Society of Washington 82:599-608.
• Hita Garcia F., E. Wiesel, G. Fischer. 2013. The ants of Kenya (Hymenoptera: Formicidae)—faunal overview, first species checklist, bibliography, accounts for all genera, and discussion on taxonomy and zoogeography. Journal of East African Natural History 101: 127-222.
• Hita Garcia, F., G. Fischer, M.K. Peters, R.R. Snelling and H.W. Wagele. 2009. A preliminary checklist of the ants (Hymenoptera: Formicidae) of Kakamega Forest (Kenya). Journal of East African Natural HIstory 98(2): 147-165.
• Kone M., S. Konate, K. Yeo, P. K. Kouassi, K. E. Linsemair. 2010. Diversity and abundance of terrrestrial ants along a gradient of land use intensification in a transitional forest-savannah zone of Cote d'Ivoire. Journal of Applied Biosciences 29: 1809-1827.
• Medler J. T. 1980: Insects of Nigeria - Check list and bibliography. Mem. Amer. Ent. Inst. 30: i-vii, 1-919.
• Taylor B., N. Agoinon, A. Sinzogan, A. Adandonon, Y. N'Da Kouagou, S. Bello, R. Wargui, F. Anato, I. Ouagoussounon, H. Houngbo, S. Tchibozo, R. Todjhounde, and J. F. Vayssieres. 2018. Records of ants (Hymenoptera: Formicidae) from the Republic of Benin, with particular reference to the mango farm ecosystem. Journal of Insect Biodiversity 8(1): 006–029.