Polyrhachis epinotalis

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Polyrhachis epinotalis
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Formicinae
Tribe: Camponotini
Genus: Polyrhachis
Subgenus: Myrma
Species group: militaris
Species: P. epinotalis
Binomial name
Polyrhachis epinotalis
Santschi, 1924

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Specimen Labels

Nothing has been reported about the biology of Polyrhachis epinotalis.

Identification

Rigato (2016) - A large species in the militaris group with relatively slender body, oval head, abundant, long and, at least partially, golden pubescence, and upturned propodeal spines.

Santschi (1924) pointed out the epinotalis head shape as its main distinctive feature. Principal differences separating epinotalis from militaris workers (and, in part, gynes) are as follows:

Polyrhachis epinotalis Polyrhachis militaris
In full face view head distinctly oval, usually wider anteriorly than behind the eyes; sides convex, clearly converging posteriorly. In full face view head subrectangular, about as wide anteriorly as behind the eyes; sides weakly convex, almost parallel.
Behind the eye the head dorsum smoothly curves into the side. Behind the eye an obtuse margination runs from the posterior margin of the eye to the posterior head corner separating the dorsum from the side.
Sculpture of head dorsum mostly reticulate-granulate, only partially rugulose. Sculpture of the head dorsum mainly longitudinally rugulose throughout.
Propodeal teeth upturned and long, spine-like. In profile they usually approach the height of the propodeal declivity. Propodeal teeth upturned and short. In profile, they are much shorter than the height of the propodeal declivity.

The size difference of propodeal teeth between epinotalis and militaris is usually remarkable. Forel (1913a) stated that epinotalis’ teeth appear as upturned spines, much longer than in militaris and other related species. However, this feature is subject to some variability. In addition, epinotalis is usually more slender than militaris, with only the mesonotum distinctly transverse, but that is not always true. I examined a robust worker from Kenya (Arabuko-Sokoke Forest at HLMD) which looks militaris-like, but it has a round head and spiniform, although relatively short, propodeal teeth. Peter Hawkes (pers. comm.) faced the same difficulties with some epinotalis specimens (as well as with some slender militaris), but confidently identified them using head and propodeal teeth shapes.

Almost all specimens I examined look relatively consistent and the species seems about as widespread as P. militaris, with which it probably co-occurs. The golden colour of the pubescence in P. epinotalis could be as variable as in militaris: some specimens look more or less greyish. The petiolar spines are slightly variable in length and the long and diverging dorsal pair is more or less apically bent backward; the lateral pair is always relatively well developed, varying from sharp teeth to short spines.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Afrotropical Region: Central African Republic, Democratic Republic of Congo (type locality), Equatorial Guinea, Gabon, Kenya, Rwanda, Uganda, Zambia.


Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Castes

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • epinotalis. Polyrhachis militaris st. epinotalis Santschi, 1924b: 222 (w.) DEMOCRATIC REPUBLIC OF CONGO (in key). [First available use of Polyrhachis militaris r. cupreopubescens var. epinotalis Forel, 1913h: 357; unavailable name (Bolton, 1973b: 313).] Junior synonym of militaris: Dorow, 1995: 36. Status as species: Rigato, 2016: 17.

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

Description

Worker

Rigato (2016) - Lectotype. HL 2.68, HW 2.05, CI 76, SL 3.21, SI 157, FW 0.74, FI 36, PW 1.66, WL 3.52, HTL 3.60. Anterior clypeal border medially bearing a laterally obtusely angled shallow lobe. Head in full face view oval, with moderately convex sides strongly converging to the short posterior margin. Eyes moderate in size and strongly convex. Mesosoma strongly, often flange-like marginate along its sides. Promesonotal suture well marked; metanotal suture deeply incised and narrow. Disc of pronotum and mesonotum approximately transverse; propodeal dorsum longer than wide. Pronotal spines long and sharp. Propodeal teeth long, upturned and spine-like; in profile nearly as long as the height of the propodeal declivity. Petiole with four sharp spines, the dorsal pair much longer than the lateral pair.

The entire body mostly reticulate-punctate and dull, longitudinally rugulose on occiput and vertex, including the space between eyes and frontal carinae. Mandibles finely longitudinally striolate. Pubescence abundant throughout, long and golden especially dorsally where it mostly hides the sculpturation. Standing hairs abundant on body and appendages; relatively short on antennae, longer on the legs and even longer on most of the dorsum of the body. Integument mostly black, mostly hidden by the long and dense golden pubescence.

Paralectotype. (same data as the lectotype). HL 2.50, HW 1.92, CI 77, SL 3.05, SI 159, FW 0.71, FI 37, PW 1.58, WL 3.48, HTL 3.40. Very similar to the Lectotype.

(n=12). HL 2.51–2.86, HW 1.90–2.17, CI 72–82, SL 2.95–3.52, SI 143–174, FW 0.67–0.83, FI 34–40, PW 1.54–1.88, WL 3.28–3.92, HTL 3.48–4.00.

Type Material

Rigato (2016) - Lectotype worker and one paralectotype worker (by present designation), Democratic Republic of the Congo: Elizabethville [= Lubumbashi], ix.1911 (Miss. Agric Leplae).

Forel described this taxon using an unavailable name combination (a quadrinomen) and later Santschi (1924) made that name available considering epinotalis as a subspecies of militaris. I have designated as lectotype one of Forel’s syntypes at Musee d'Histoire Naturelle Genève. The lectotype is in quite good condition, but misses its right foretibia and tarsus.

References

  • Bolton, B. 1973b. The ant genus Polyrhachis F. Smith in the Ethiopian region (Hymenoptera: Formicidae). Bull. Br. Mus. (Nat. Hist.) Entomol. 28: 283-369 (page 313, [First available use of Polyrhachis militaris r. cupreopubescens var. epinotalis Forel, 1913h: 357; unavailable name (Bolton, 1973b: 313).] )
  • Dorow, W. H. O. 1995. Revision of the ant genus Polyrhachis Smith, 1857 (Hymenoptera: Formicidae: Formicinae) on subgenus level with keys, checklist of species and bibliography. Cour. Forschungsinst. Senckenb. 185: 1-113 (page 36, Junior synonym of militaris)
  • Rigato, F. 2016. The ant genus Polyrhachis F. Smith in sub-Saharan Africa, with descriptions of ten new species. (Hymenoptera: Formicidae). Zootaxa. 4088:1–50.
  • Santschi, F. 1924b. Descriptions de nouveaux Formicides africains et notes diverses. II. Rev. Zool. Afr. (Bruss.) 12: 195-224 (page 222, worker described (in key))