The Ants of Africa
Genus Dorylus - Subgenus Anomma
Dorylus (Anomma) rufescens Santschi

SJOESTEDTI group - characterised by the head being widest at the anterior end and narrowing significantly from front to back, with almost straight sides and sharp posterior angles; the latter never produced into distinct teeth (unlike wilverthi).

Dorylus (Anomma) rufescens Santschi

return to key {link to the Hymenoptera Name Server} Type locality Cameroun (Dorylus nigricans Ill. stirps rufescens Wasm., Santschi, 1915c: 247, worker and queen; redefining Dorylus nigricans ssp. sjoestedti variety rufescens, Wasmann, 1904b: 673) collected at Victoria, by the German Deep Sea Expedition, raised to species by Santschi (1931d: 407); workers and queen known (see Bolton, 1995) .


{Dorylus (Anomma) rufescens}Santschi's (1912b) notes are at {original description}. Santschi's (1915c) notes are at {original description}. A worker from the type collections is shown below and on the linked page; note that the size (TL ca 8.5 mm versus Santschi's major at TL 11 mm) and mandibles indicate it is a media 1 worker.

Raignier & van Boven (1955, page 27) cite Wasmann's description (1904b) as having the head of Dorylus sjoestedti and the red-brown colour of rubellus [the latter is held here as no more than pale specimens of burmeisteri]. Santschi (1912b: 157) took the view that the "variety" was a transition between the subspecies burmeisteri and sjoestedti, more likely to be a variety of the first, from the similar head to the media and the penultimate segment of the funiculus (which in sjostedti is twice as long as wide). Raignier & van Boven noted, however, that the media head was differently described by the two authors. They noted also that Menozzi (1942) considered it as a variety of burmeisteri. In their own studies of specimens from Yangambi, they found collection 34 to have small individuals with the head short and thick-set as burmeisteri but a few had the elongated head of sjoestedti. Their studies of queens enabled them to conclude with some certainty that rufescens was similar to sjoestedti and the queen differed significantly from nigricans.

Given that the surviving type worker appears to be a media and that such minor morphs are redder than the full majors, it seems quite likely that  rufescens and sjoestedti are synonymous, is so then the latter is the prior name and rufescens is a junior synonym.


Oxford University Museum specimens

Dorylus (Anomma) rufescens
B Taylor det.

Central African Republic
P Annoyer
GJ

22.ii.2005
Dzanga-Sangha
0255’04.8" N
1610’09.7" E
Camp 6; A vu dans une petite saline aux abords du camp, 12h-16h; 450 m asl
4
{album}

{Dorylus rufescens polymorphism}Polymorphism

The photomontages are of workers collected in the Central African Republic Dzanga-Sangha National Park, 0255’04.8" N 1610’09.7" E 450m environ; Camp 6; 22.ii.2005, A vu dans une petite saline aux abords du camp, 12h-16h; collector Philippe Annoyer. The major and two minor morphs are shown in detail on the Dorylus (Anomma) rufescens morphs page. This is very similar to the majors I have of sjoestedti butit is generally darker and has a rougher appearance making it less shiny and polished.


{Dorylus rufescens minima}WORKER
Raignier & van Boven (1955, p 74), summarized the 81 specimens from three collections, plus 25 specimens in the Congo Museum as - general colour red; TL ca 11-3 mm, smallest morphs more yellow to yellow brown; the major having the head CI 101-103 (slightly wider than long) matt in front and shiny behind; anterior border with a black band with the border varying from sharp to vague; posterior angles of head sharp, sometimes even extended; posteroventral lobes of petiole small to non-existent.

The defining separation from Dorylus ornatus seems that rufescens is a duller red, without the bright shiny appearance of ornatus.

Other Cameroun records include at Victoria (F. Silvestri), Yukaduma (Funck), and Grand Batanga and Lolodorf (G. Schwab); also from Congo (in Wheeler, 1922).


QUEEN
Santschi (1915c) described the female of "nigricans stirps rufescens Wasmann" as follows -
TL 38-40 (given in original text as 3.8-4, but obviously that is a printer's error, or is cm); head, in full face view, a rounded square, less rounded than wilverthi, but more than nigricans; HW 5.3, anterior height 4, occipital width 3.6; posterior angles less accentuated than wilverthi, but more than nigricans. Postclypeal notch deep, three small fossae indicating positions of ocelli. A larger fossa at the mid-point of the face indicates the position of the eye; a further tiny fossa is found on the front of the head about the posterior third of the laid back scape. Mandibles 3.4 mm, arcuate in apical third. Scape 2 mm; second segment of funiculus slightly more slender than long; the others longer than wide. Thoracic segments wider than long, but more slender than nigricans, pronotum 3 mm, mesonotum 2.8 mm and propodeum 3.3 mm; anterior angles of propodeum raised, formed by the elongated and vertical spiracles. Femora compressed, the two hind pairs a little twisted on their main axis. Tarsi generally missing, with the anterior legs of a single example formed as in the worker. Petiole as wilverthi (wilwerthi), centrally 2.9 mm; width 5.8 mm. Gaster segments a little wider than long, but smaller than in nigricans. Pygidium scalloped centrally, as in wilverthi, with the angles prolonged in a low point. Hypopygium like that of wilverthi, the external edge without denticles and the grooves deep.
Colour dull red; posterior angles of head, thorax sutures, appendages and edges of the gastral segments clearer red; rest of gaster, extremity of metatarsals and thoracic spiracles black brown. Smooth, sparsely and finely puncturate, shiny; front and dorsum of head, outer sides of mandible base, sides of thorax matte, densely reticulate with sparse large puncturations. Without hairs, only funiculi and sides of labrum pubescent.
Specimens from Gabon, Samkita, by F. Faure; 3 females received with workers, nymphs and eggs. Santschi noted the specimens were darker than those described by Wasmann, tending towards ornata [nigricans burmeisteri variety]. Apparently also related to nigritarsis Strand [junior synonym of wilverthi].


{Dorylus rufescens queen} The photomontage is of the type queen collated from http://www.antweb.org/specimen.do?name=casent09113188.

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