The Ants of Africa
Genus Polyrhachis
Polyrhachis ayousi Taylor new species

Polyrhachis ayousi Taylor new species

return to key {link to the Hymenoptera Name Server} Type location Central African Republic

WORKER DESCRIPTION:

At first sight, this appears to be close to Polyrhachis militaris but it is separable on a number of counts. Most distinctive is the propodeum which has long upcurved spines and a sharp transverse carina between the bases of the spines. In Bolton's key (1973b) this separates P. militaris (which lacks a transverse ridge) from Polyrhachis latispina. The latter, however, otherwise is quite distinctive.

I have sighted specimens of P. militaris from six countries (Cameroun, CAR, Gabon, Liberia, Ghana and Nigeria) and overall the size of the new species is near the lower end of the P. militaris size range (Bolton, 1973b); see also the Antweb images of militaris varieties. However, the new species has a much narrower pronotum, measured at the base of the more flared spines, SPW 170-176; with the latter in P. militaris SPW = 135).

The propodeal spines appear to be significantly larger than on any of the "varieties" of militaris. The overall dense yellow-gold pubescence also seems distinctive, especially the very dense coarse covering on the alitrunk dorsum. The head in full-face view is ovoid with a strongly convex occipitum. In P. militaris the full face view generally is straight-sided or nearly so and the occiput is transverse, often near straight. The funiculus gradually thickens from base to apex, whereas it is more slender and uniformly narrow thoughout its length in P. militaris.
The underlying sculpturation mostly is concealed by the dense pubescence but that on the head is of a fine dense spiculation (rather than the fine striation seen on P. militaris) and the mandibles are more coarsely striate.

Holotype - TL ca 11.4 mm, HL 2.50, HW 2.00, CI 80; SL 3.10, SI 155; EL (eye length) 0.5, OI 25; PW 1.40 (spine width at apex 2.40; ratio SPW =170), HF (hind-leg femur) 3.80
Specimen 2 - TL ca 11.2 mm, HL 3.00, HW 2.20, CI 73; SL 3.50, SI 159; EL 0.60, OI 28; PW 1.50 (spine width at apex 2.65, ratio 176), HF 3.60

Apparently an inhabitant of primary forest canopy, as collected at 38 m above ground on Triplochiton scleroxylon, Sterculariaceae.

Collection details: Camp 6 GR; 0255’04.8" N 1610’09.7" E, 450m environ; 25.02.2005, U.V : 18h30-5h30, 38m du sol dans un Ayous (Triplochiton scleroxylon, Sterculariaceae), orage partir de 5h40 et ce jusqu’ midi, collected by Philippe Annoyer.

The name is derived from it being collected on an Ayous.

QUEEN: see below, two specimens.

Specimens deposited in the Oxford University Museum of Natural History.


Note - This may well be the same as Polyrhachis militaris F. r. cupreopubescens v. epinotalis n. v., Forel, 1913h: 357, worker) from Zare, Lumbumbashi (Elizabethville), Miss. Agric., Leplae; Forel's (1913h) description of epinotalis (TL 9-10.5 mm, propodeal spines long, compared with short spines on the type form) is at {original description}. Antweb images of epinotalis are shown below. Also shown is a very similar form from Kenya.

Santschi (1924b: 22) in his key to varieties of P. militaris separated P. militaris stirps epinotalis For. from all the other varieties by having the sides of the head narrowing immediately behind the eyes but gave no other information. Bolton (1973b: 313) merely noted this form as an unavailable name that he had examined. Antweb have it as a "Junior synonym of P. militaris" according to Dorow (1995a: 36). Dorow's paper is titled a "Revision of the ant genus Polyrhachis ... on subgenus level with keys, checklist of species and bibliography. His keys below subgenus level were to Asian and Australasian species. It is totally lacking in notes on methodology and lacks the norms of taxonomic revision.  His species checklist therefore has no verifiable merit.  The Antweb page then has "Revived from synonymy and raised to species: new status (unpublished).
" but without any statement of authority. The images were uploaded on 31 March 2014.


Oxford University Museum specimens

Polyrhachis ayousi
B Taylor det.
HOLOTYPE

Central African Republic
P Annoyer
GR-01
25.ii.2005
Dzanga-Sangha
0255’04.8" N
1610’09.7" E
U.V: 38m du sol dans un Ayous (Triplochiton scleroxylon, Sterculariaceae);
orage partir de 5h40 et ce jusqu’ midi; 450 m asl
1
{album}
Polyrhachis ayousi
B Taylor det.
Central African Republic
P Annoyer
GN
25.ii.2005
Dzanga-Sangha
0255’04.8" N
1610’09.7" E
U.V: 38m du sol dans un Ayous (Triplochiton scleroxylon, Sterculariaceae);
21h-6h30; 450 m asl
1
{album}
Polyrhachis ayousi
B Taylor det.
Central African Republic
P Annoyer
JW
19.x.2008
Dzanga-Sangha
0301'49.5" N
1608'31.7" E
567 m; Camp 2; 18h-2h; A la base du kungu, 50 m du camp
1
{album}
Polyrhachis ayousi
B Taylor det.
Central African Republic
P Annoyer
PO
30.xi.2010
Dzanga-Sangha
228'49.5"N
1612'55.9"E
392 m; jour, vue, camp de base lac 1
1
{album}

{Polyrhachis new species CAR}The photomontage is of the holotype specimen from Central African Republic, CAR GR-01


{Polyrhachis new species CAR GN spec}Second worker specimen,
0255’04.8" N 1610’09.7" E; 450m environ; Camp 6; 23.ii.2005, U.V : 21h-6h30, 38m du sol dans un Ayous (Triplochiton scleroxylon, Sterculariaceae) environ (CAR GN). 


Polyrhachis epinotalisThe photomontage of the type worker of epinotalis is collated from http://www.antweb.org/specimen.do?name=0910908.

Antweb also show have a specimen from Gabon on http://www.antweb.org/specimen.do?code=casent0906820


Polyrhachis epinotalisThe photomontage of a worker from Kenyan rainforest, labelled as P. militaris by R R Snelling, is collated from http://www.antweb.org/specimen.do?name=0178253.


Queen

As with the queen of Polyrhachis militaris (Bolton, 1973b), the spines on the alitrunk and petiole are reduced. The transverse ridge on the propodeum is visible, as in the worker. Other differences from the militaris queens, I have from the Central African Republic are: a larger head, with shiny black, striated mandibles; in full face view the head lacks well defined longitudinal striations; the promesonotum im lateral view is more domed; distinctive parallel rugulation on the propodeum dorsum; the petiole has shorter thicker based dorsal spines but better developed lateral spines.

Queen labelled JW; 0301'49.5" N 1608'31.7" E 567 m; Camp 2; 19.x.2008 18h-2h; A la base du kungu, 50 m du camp

{Polyrhachis ayousi CAR queen}

Contents Subfamily Formicinae
2008, 2009, 2010, 2012, 2014 - Brian Taylor CBiol FSB FRES
11, Grazingfield, Wilford, Nottingham, NG11 7FN, U.K.

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