Strumigenys arnoldi

Strumigenys arnoldi
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Myrmicinae
Tribe:	Attini
Genus:	Strumigenys
Species:	S. arnoldi
Binomial name
Strumigenys arnoldi Forel, 1913 Specimen Labels

Collection records for this species are varied in their habitat information and other collection details. Habitat details include being found under fig trees with moist soil next to small stream, a grassland and primary forest. The specimens were gathered from the leaf litter, under a stone and from under a stone with Bothroponera kruegeri.

Identification

Bolton (1983,2000) - A member of the arnoldi complex in the Strumigenys arnoldi-group. Within the group the species Strumigenys tetraphanes, Strumigenys korahyla, Strumigenys arnoldi and Strumigenys omalyx are characterized by lacking pronotal flagellate hairs whilst retaining the usual mandibular dentition of 2 preapical teeth on each blade. Of the four tetraphanes is instantly recognized by its short broad head and enormous plate-like lobate extension of the antennal scapes. S. korahyla has long narrow mandibles and scapes (MI 48-50, SI 82-85), and has the scapes evenly tapering from base to apex. S. arnoldi is separated from omalyx by details of sculpture as in the latter the sides of the pronotum and the postpetiolar disc are strongly sculptured, and the reticulate-punctate sculpture of the pronotal dorsum is not overlaid by longitudinal rugulae. In arnoldi, on the other hand, the pronotal sides and postpetiolar disc are smooth, and the pronotal dorsum has longitudinal rugulae overlying the reticulate-punctate sculpture.

Keys including this Species

• Key to Afrotropical Strumigenys

Distribution

Latitudinal Distribution Pattern

Latitudinal Range: 19.9296° to -25.81564°.

North Temperate	North Subtropical	Tropical	South Subtropical	South Temperate

• Source: AntMaps

Distribution based on Regional Taxon Lists

Afrotropical Region: Kenya, Saudi Arabia, United Republic of Tanzania, Zimbabwe (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

Explore Overview of Strumigenys biology  Strumigenys were once thought to be rare. The development and increased use of litter sampling methods has led to the discovery of a tremendous diversity of species. Many species are specialized predators (e.g. see Strumigenys membranifera and Strumigenys louisianae). Collembola (springtails) and other tiny soil arthropods are typically favored prey. Species with long linear mandibles employ trap-jaws to sieze their stalked prey (see Dacetine trap-jaws). Larvae feed directly on insect prey brought to them by workers. Trophallaxis is rarely practiced. Most species live in the soil, leaf litter, decaying wood or opportunistically move into inhabitable cavities on or under the soil. Colonies are small, typically less than 100 individuals but in some species many hundreds. Moist warm habitats and micro-habitats are preferred. A few better known tramp and otherwise widely ranging species tolerate drier conditions. Foraging is often in the leaf litter and humus. Workers of many species rarely venture above ground or into exposed, open areas. Individuals are typically small, slow moving and cryptic in coloration. When disturbed individuals freeze and remain motionless. Males are not known for a large majority of species. ‎

Castes

Worker

Images from AntWeb

Worker. Specimen code casent0249002. Photographer Estella Ortega, uploaded by California Academy of Sciences.	Owned by AFRC, Pretoria, South Africa.

Nomenclature

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

• arnoldi. Strumigenys arnoldi Forel, 1913a: 114 (w.) ZIMBABWE. See also: Brown, 1954k: 26; Bolton, 1983: 365; Bolton, 2000: 591.

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

Description

Worker

TL 2.0-2.1, HL 0.54-0.60, HW 0.39-0.46, CI 74-78, ML 0.22-0.23, MI 38-41, SL0.30-0.32, SI 68-75, PW 0.24-0.26, AL 0.54-0.58 (3 measured).

Mandibles in full-face view broadest near the base and gradually tapering towards the apex. Apical fork of each mandible with 2 spiniform teeth, without intercalary teeth or denticles. Pre apical armament of each mandibular blade of 2 teeth, the proximal pre apical much longer than the distal and the distance separating their bases less than the height of the distal preapical tooth. Both pre apical teeth situated in the apical third of the length of the blade. Upper scrobe margins forming a feeble rim or flange, the eyes not visible in full-face view. Eyes small, the maximum diameter distinctly less than the maximum width of the scape. Preocular notch absent, the ventral surface of the head without a preocular transverse impression or groove on each side. Antennal scapes shallowly curved in the basal third, the leading edges weakly convex and equipped with a row of apically curved spoon-shaped hairs which are about the same size as those fringing the upper scrobe margins. Dorsum of head with dense anteriorly curved hairs which are scale-like to stud-like in full-face view, the upper scrobe margins fringed with similar hairs. Dorsum of head everywhere finely and densely reticulate-punctate. Pronotal humeri without flagellate hairs. Mesonotum with a single pair of stout standing hairs. Ground-pilosity of dorsal alitrunk like that of cephalic dorsum but the hairs tending to be smaller and sparser. Posterior portion of mesonotum depressed, the metanotal groove absent. Propodeal teeth broadly triangular and conspicuous, subtended by broad sinuate infradental lamellae. Sides of alitrunk smooth except for some punctures on the upper portion of the mesopleuron. Entire dorsal alitrunk finely reticulate-punctate, on the pronotum this sculpture overlaid by some fine longitudinal rugulation. Dorsum of petiole node finely punctate, the postpetiolar disc smooth and shining. Spongiform appendages of pedicel segments well developed, the petiole with a broad ventral strip which has its ventral free margin indented before the midlength. Ventral spongiform lobe of postpetiole larger than the exposed area of the postpetiolar disc in profile and distinctly larger than the lateral spongiform lobe. Basigastral costulae short and sparse, widely spaced on each side of a broad central clear area. Petiole, postpetiole and first gastral tergite with stout standing hairs which are swollen to clavate apically. Colour dull yellow.

Type Material

Holotype worker, ZIMBABWE: Bulawayo, under stone in nest of Bothroponera kruegeri (Forel) (G. Arnold) (Musee d'Histoire Naturelle Genève) [examined].

References

• Arnold, G. 1917. A monograph of the Formicidae of South Africa. Part III. Myrmicinae. Ann. S. Afr. Mus. 14: 271-402 (page 376, redescription of worker)
• Bolton, B. 1983. The Afrotropical dacetine ants (Formicidae). Bull. Br. Mus. (Nat. Hist.) Entomol. 46: 267-416 (page 365, redescription of worker)
• Bolton, B. 2000. The ant tribe Dacetini. Memoirs of the American Entomological Institute. 65:1-1028. (page 591, redescription of worker)
• Brown, W. L., Jr. 1954k. The ant genus Strumigenys Fred. Smith in the Ethiopian and Malagasy regions. Bulletin of the Museum of Comparative Zoology 112:1-34. (page 26, redescription of worker)
• Emery, C. 1924f [1922]. Hymenoptera. Fam. Formicidae. Subfam. Myrmicinae. [concl.]. Genera Insectorum 174C: 207-397 (page 320, catalogue)
• Forel, A. 1913a. Fourmis de Rhodesia, etc. récoltées par M. G. Arnold, le Dr. H. Brauns et K. Fikendey. Ann. Soc. Entomol. Belg. 57:108-147. (page 114, worker described)
• Sharaf M.R., Fisher B.L. and Aldawood S.A. 2014. Notes on ants of the genus Strumigenys F. Smith, 1860 (Hymenoptera: Formicidae) in the Arabian Peninsula, with a key to species. Sociobiology. 61:293-299.
• Wheeler, W. M. 1922j. Ants of the American Museum Congo expedition. A contribution to the myrmecology of Africa. VIII. A synonymic list of the ants of the Ethiopian region. Bull. Am. Mus. Nat. Hist. 45:711-1004. (page 917, catalogue)

References based on Global Ant Biodiversity Informatics

• Bolton B. 1983. The Afrotropical dacetine ants (Formicidae). Bulletin of the British Museum (Natural History). Entomology 46: 267-416.
• El-Hawagry M. S., M. R. Sharaf, H. M. Al Dhafer, H. H. Fadl, and A. S. Aldawood. 2015. Addenda to the insect fauna of Al-Baha Province, Kingdom of Saudi Arabia with zoogeographical notes. Journal of Natural History http://dx.doi.org/10.1080/00222933.2015.1103913
• Garcia F.H., Wiesel E. and Fischer G. 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(2): 127-222
• IZIKO South Africa Museum Collection
• Sharaf M. R., B. L. Fisher, and A. S. Aldawood. 2014. Notes on Ants of the genus Strumigenys F. Smith, 1860 (Hymenoptera: Formicidae) in the Arabian Peninsula, with a key to species. Sociobiology 61(3): 293-299.
• Yeo K., T. Delsinne, S. Komate, L. L. Alonso, D. Aidara, and C. Peeters. 2016. Diversity and distribution of ant assemblages above and below ground in a West African forest–savannah mosaic (Lamto, Cote d’Ivoire). Insectes Sociaux DOI 10.1007/s00040-016-0527-6