Cataulacus egenus

Nests of Cataulacus egenus have been found in rotten branches of cocoa trees that are still attached to the trunk. The workers forage actively upon the bark and leaves but their diet is unknown.

Identification
A member of the huberi group. This species is most closely related to Cataulacus huberi, sharing the same pedicellar and gastral development, but is separated from it by the characters given in the key (Bolton 1974).

Distribution
Known from Ghana, Nigeria, Uganda, Zaire.

Distribution based on Regional Taxon Lists
Afrotropical Region: Congo, Democratic Republic of Congo, Ghana, Kenya, Nigeria, Uganda.

Nomenclature

 *  egenus. Cataulacus egenus Santschi, 1911c: 359, fig (w.) CONGO. Wheeler, G.C. & Wheeler, J. 1954b: 151 (l.); Bolton, 1974a: 18 (q.m.). Senior synonym of simplex: Bolton, 1974a: 18.
 * simplex. Cataulacus egenus st. simplex Santschi, 1914b: 111, fig 18 (w.) UGANDA. Junior synonym of egenus: Bolton, 1974a: 18.

Worker
Bolton (1974) - Bolton (1974) - TL 4.2 - 6.1, HL 1.10 - 1.48, HW 1.22 - 1.74, CI 101 - 120, EL 0.40 - 0.48, OI 27 - 33, IOD 1.00 – 1.48, SL 0.62 – 0.80, SI 46 - 52, PW 1.14 – 1.60, AL 1.32 - 176, MTL 0.66 – 0.88 (10 measured).

Occipital crest variously developed; either complete or incomplete medially or absent, the last occurring usually in small workers. When the crest is well developed it is little more than an acute angle separating the vertex from the occiput. Occipital corners with a dentiform angle projecting somewhat laterally or the corners merely acutely angled. Sides of head behind eyes smooth and regular, not denticulate nor crenulate. Pronotum marginate laterally, not denticulate, the margination not or only slightly expanded, either simple and following the shape of the segment or with a small, bluntly rounded dentiform process anteriorly. Remainder of alitrunk not marginate and not denticulate, the dorsum rounding smoothly into the sides. Propodeum with a pair of long, acute, slightly divergent spines. Dorsal alitrunk usually without sutures or with the location of the promesonotal suture indicated by a very faint impression. Rarely the metanotal groove is also indicated by an extremely faint marking upon the dorsum. Petiole with the dorsal surface strongly transverse, rectangular or subrectangular in shape; postpetiole also expanded transversely. First gastral tergite marginate basally and for part of the length of the sides; this structure paralleled on the sternite laterobasally by a raised ridge or carina.

Sculpturation of dorsum of head a fine, dense and very shallow reticulate-puncturation which is often more or less effaced, the whole overlaid by a fine, irregular, usually disorganized rugoreticulum. Pronotal dorsum usually similar to the head with the puncturation more distinct, especially upon the anterior half. Remainder of dorsal alitrunk finely reticulatepunctate with numerous very fine rugulae. These are predominantly longitudinal in direction but often a reticulum is present in places. On the propodeal dorsum the rugulae tend to diverge posteriorly towards the bases of the spines and rarely are they transverse upon the dorsum. Declivity of propodeum usually with some transverse rugulae, at least between the spines. Petiole and postpetiole coarsely transversely rugose or sulcate-rugose, the gaster densely reticulate-punctate with a few longitudinal rugulae.

Erect hairs absent from all dorsal surfaces of head, alitrunk, pedicel and gaster, but a few may be present upon the lateral margins of the head. The appendages bear numerous hairs.

Queen
Bolton (1974) - Bolton (1974) - TL 6.6 – 7.0, HL 1.40 – 1.50, HW 1.42 – 1.58, CI 101 - 105, EL 0.44 – 0.48, OI 30 - 31, IOD 1.20 – 1.34, SL 0.72 – 0.76, SI 48 - 50, PW 1.34 – 1.50, AL 1.88 – 1.92, MTL 0.76 – 0.88 (3 measured).

Answering the description of the worker but with the usual thoracic modifications. Occipital crest usually developed as an angle. Pro notal marginations less distinct, propodeal spines reduced to a pair of short, broad and blunt teeth. Sculpturation basically as worker but the mesoscutellum may lack rugulae and the propodeal dorsum is usually transversely rugulose. The female of this species was first described by Wheeler (I922a: 199).

Male
Bolton (1974) - Bolton (1974) - TL 5.1 – 5.5, HL 0.92-1.00, HW 1.10 – 1.16, CI 116-119, EL 0.36, OI 31 - 32, IOD 0.90 – 0.96, SL 0.48 – 0.50, SI 42 - 43, PW 1.00 – 1.02, AL 1.58 – 1.68, MTL 0.82 – 0.86 (2 measured).

Occipital crest not present, the occipital corners dentiform. Sides of head behind eyes with one or two denticulae. A pair of small, shallow impressions present upon the vertex, situated just behind and laterad of the posterior ocelli, and almost in a straight line between this and the median (anterior) ocellus. Pronotum weakly marginate laterally, the sides almost straight, not denticulate. Anterior arms of notauli developed and cross-ribbed, fading out medially; the posterior arm absent. Propodeum with a pair of short, broad but acute spines. Segments of pedicel in dorsal view developed as in the worker, but less strongly so. First gastral tergite not marginate, the sternite without a carina.

Sculpturation of head reticulate-punctate in the vicinity of the ocelli, but elsewhere also with sparse rugulation which tends to form a reticulum in places. Pronotal dorsum similar to the last, with a marked rugoreticulum; the sc1erites of the mesonotum predominantly reticulate-punctate, with few or no rugulae. Propodeal dorsum coarsely rugose; the segments of the pedicel with marked transverse rugae, especially the petiole. Gaster finely and densely reticulate-punctate. Erect hairs sparse upon the head and alitrunk, numerous on the gaster.

Type Material
Bolton (1974):

Holotype worker, CONGO (BRAZZAVILLE): Madingou (R. P. Zimmermann) (NM, Basle) [examined].

Cataulacus egenus st. simplex. Holotype worker, UGANDA: Central Region, i. 1909 (Ch. Alluaud) (location of type not known).

References based on Global Ant Biodiversity Informatics

 * Bolton B. 1974. A revision of the Palaeotropical arboreal ant genus Cataulacus F. Smith (Hymenoptera: Formicidae). Bulletin of the British Museum (Natural History). Entomology 30: 1-105.
 * Bolton B. 1982. Afrotropical species of the myrmicine ant genera Cardiocondyla, Leptothorax, Melissotarsus, Messor and Cataulacus (Formicidae). Bulletin of the British Museum (Natural History). Entomology 45: 307-370.
 * Davis L. R., and L. E. Alonso. 2007. Ant species collected from the Atewa Range Forest Reserve during the 2006 RAP survey. Pp 171-172. McCullough, J., L.E. Alonso, P. Naskrecki, H.E. Wright and Y. Osei-Owusu (eds.). 2007. A Rapid Biological Assessment of the Atewa Range Forest Reserve, Eastern Ghana. RAP Bulletin of Biological Assessment 47. Conservation International, Arlington, VA.
 * 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.
 * IZIKO South Africa Museum Collection
 * Medler J. T. 1980: Insects of Nigeria - Check list and bibliography. Mem. Amer. Ent. Inst. 30: i-vii, 1-919.
 * Santschi F. 1924. Descriptions de nouveaux Formicides africains et notes diverses. II. Revue Zoologique Africaine (Brussels) 12: 195-224.
 * Taylor B. 1979. Ants of the Nigerian Forest Zone (Hymenoptera: Formicidae). III. Myrmicinae (Cardiocondylini to Meranoplini). Cocoa Research Institute of Nigeria Research Bulletin 6: 1-65.
 * Wheeler W. M. 1922. 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. Bulletin of the American Museum of Natural History 45: 711-1004