Cataulacus horridus

Cataulacus horridus has large polydomous colonies with thousands of workers. There nests are found in rotten logs. (Maschwitz and Moog 2000).

Identification
One of the largest species of the Indo-Australian and Oriental regions and certainly one of the most easily recognizable. The great development of spines at the occipital corners and the lack of alitrunk margination immediately sets the species aside from its congeners. (as per Bolton, 1974 under insularis, a junior synonym of horridus)

Distribution
Known from Borneo, Indonesia (Sumatra), Singapore and West Malaysia.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Indonesia, Malaysia, Singapore. Oriental Region: Thailand.

Genetics
Polymorphic microsatellites have been identified for this species. (Debout et al. 2002)

Nomenclature

 *  horridus. Cataulacus horridus Smith, F. 1857a: 81, pl. 2, fig. 3 (w.) BORNEO.
 * Crawley, 1924: 401 (q.); Wheeler, G.C. & Wheeler, J. 1954b: 151 (l.).
 * Combination in C. (Otomyrmex): Santschi, 1928h: 125.
 * Status as species: Smith, F. 1858b: 196; Smith, F. 1862d: 415; Mayr, 1863: 403; Roger, 1863b: 39; Smith, F. 1871a: 335; Dalla Torre, 1893: 138; Emery, 1893e: 216; Forel, 1907a: 12; Forel, 1913k: 83; Viehmeyer, 1916a: 140; Wheeler, W.M. 1919e: 93; Crawley, 1924: 401; Emery, 1924d: 298; Santschi, 1928h: 125; Donisthorpe, 1932c: 451; Chapman & Capco, 1951: 85; Bolton, 1995b: 138; Jaitrong & Nabhitabhata, 2005: 17; Pfeiffer, et al. 2011: 44.
 * Junior synonym of insularis: Bolton, 1974a: 84 (error).
 * Senior synonym of insularis: Wheeler, W.M. 1919e: 93; Bolton, 1995b: 138.
 * insularis. Cataulacus insularis Smith, F. 1857a: 80, pl. 2, fig. 4 (m.) BORNEO.
 * Junior synonym of horridus: Wheeler, W.M. 1919e: 93; Bolton, 1974a: 84.

Taxonomic Notes
Bolton, 1974a: 84, gave insularis as senior synonym, but horridus has priority on first reviser principle, based on Wheeler's, 1919e: 93, attribution (Bolton, 1995b: 138).

Cataulacus horridus

Two worker syntypes in, two worker syntypes in. All labelled “SAR.” except for one in that is “Mal. 23.” Both localities are given by Smith in the original description.

Cataulacus insularis

Holotype male in. Labelled “SAR.”

Worker
Length 3 lines. Black; the antennae short, thick and clavate; the apex rufo-testaceous; head reticulated, produced before the eyes and widely truncated, the lateral angles of the truncation rounded; the lateral margins with a short spine before the eyes; the vertex with the posterior margin emarginate its entire width, forming at the lateral angles large acute spines. Thorax: ruggedly sculptured on the disk, narrowed to the apex of the mesothorax, which is separated from the hinder portion by a deep transverse incision; produced posteriorly at the angles into long, stout, acute spines; the nodes of the abdomen rugose; abdomen rounded, emarginate and striated at the base; the entire insect sprinkled with short erect white setae.

Bolton (1974) - TL 4.8 – 7.0, HL 1.22 – 1.62, HW 1.38 – 1.80, CI 111 - 113, EL 0.46 – 0.56, OI 31 - 32, IOD 1.08 – 1.36, SL 0.76 – 1.00, SI 49 - 56, PW 1.00 – 1.36, AL 1.44 – 1.94, MTL 0.84 – 1.15 (10 measured).

Occipital crest absent; occipital corners prolonged into a pair of massive, subtriangular, broad, acute spines. Sides of head behind eyes denticulate, the denticles also present on the outer edges of the occipital spines and occasionally on the inner edges also. Alitrunk not marginate laterally, the dorsum rounding into the sides, but with a distinct, rather massive, broad tubercle on each side at the level of the promesonotal junction which may represent the last vestige of an ancestral margination. In profile the promesonotum forming a more or less continuous convexity and with a distinct step posteriorly at its junction with the propodeum; the dorsum of the latter on a lower level than that of the former. Propodeum with a pair of very long spines, broad at the base and tapering to an acute apex. Mesokatepisternum developed into a large tuberculiform structure projecting laterally and visible in dorsal view. Gaster not marginate laterally.

Head reticulate-rugose, the interspaces reticulate-punctate. Dorsum of alitrunk very coarsely reticulate-foveolate with a fine reticulate-puncturation everywhere except the apical portions of the propodeal spines which are smooth and shiny. The sculpturation of the alitrunk is usually coarser and more rough-looking in larger individuals than in smaller. Gaster with a fine, dense rugoreticulum and reticulate-punctate interspaces, and usually also with a number of strong, longitudinal basigastric costulae.

All dorsal surfaces of head, alitrunk, gaster and appendages with numerous hairs.

Queen
Bolton (1974) - TL 6.8 – 7.8, HL 1.60 – 1.74, HW 1.80 – 2.00, CI 112 - 115, EL 0.52 – 0.60, OI 29 - 30, IOD 1.36 – 1.50, SL 1.02 – 1.08, SI 54 - 57, PW 1.60 – 1.70, AL 2.30 – 2.50, MTL 1.16 – 1.22 (3 measured).

As worker but the lateral tubercle of the alitrunk reduced to a low, broad swelling, less distinct than in the worker. A similar reduction is seen in the tubercle of the mesokatepisternum, whose apex is directed more anteriorly than in the above. Propodeal spines less well developed, very broad at the base, tapering rapidly to an acute apex. Sculpturation of head and pronotum as in worker, but the mesonotal sclerites and propodeal dorsum are longitudinally rugose; those on the propodeum diverging onto the basal parts of the spines.

Male
Bolton (1974) - TL 6.4 – 6.6, HL 1.30 – 1.34, HW 1.42 – 1.58, CI l09 - 117, EL 0.48 – 0.50, OI 32 - 34, IOD 1.18 – 1.22, SL 0.88 – 0.90, SI 55 - 63, PW 1.30 – 1.32, AL 2.12 – 2.14, MTL 1.08 – 1.12 (z measured).

Occipital spines proportionately as well developed as in worker, the sides of the head behind the eyes denticulate, as are the inner and outer borders of the occipital spines. Preocular tooth absent or reduced to a minute triangular prominence. Lateral tubercle of alitrunk not developed, but the tubercle of the mesokatepisternum distinct, directed forwards as in the female. Anterior arms of notauli distinct, the posterior arm reduced to a mere impression, not shining nor cross-ribbed like the anterior arms. Propodeal spines strongly developed, long and acute. Head reticulate-rugose with punctate interspaces, the rugae either longitudinal to the level of the posterior margin of the eyes and then becoming transverse, so that they form a broad arch around the ocelli, or irregularly distributed over the head.

Type Material
Holotype male, BORNEO: Sarawak (A. R. Wallace) (UM, Oxford,) [examined].

Cataulacus horridus Holotype worker, BORNEO: Sarawak (A. R. Wallace) (UM, Oxford) [examined].

References based on Global Ant Biodiversity Informatics

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 * Chapman, J. W., and Capco, S. R. 1951. Check list of the ants (Hymenoptera: Formicidae) of Asia. Monogr. Inst. Sci. Technol. Manila 1: 1-327
 * Crawley W.C. 1924. Ants from Sumatra, with biological notes by Edward Jacobson. Annals and Magazine of Natural History (9)13: 380-409
 * Davidson D. W., S. C. Cook, R. R. Snelling and T. H. Chua. 2003. Explaining the Abundance of Ants in Lowland Tropical Rainforest Canopies. Science 300: 969-972.
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 * Emery, C.. "Voyage de MM. Bedot et Pictet dans l'Archipel Malais. Formicides de l'Archipel Malais." Revue Suisse de Zoologie 1 (1893): 187-229.
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 * Field Museum Collection, Chicago, Illinois (C. Moreau)
 * Forel A. 1913. Wissenschaftliche Ergebnisse einer Forschungsreise nach Ostindien ausgeführt im Auftrage der Kgl. Preuss. Akademie der Wissenschaften zu Berlin von H. v. Buttel-Reepen. II. Ameisen aus Sumatra, Java, Malacca und Ceylon. Gesammelt von Herrn Prof. Dr. v. Buttel-Reepen in den Jahren 1911-1912. Zoologische Jahrbücher. Abteilung für Systematik, Geographie und Biologie der Tiere 36:1-148.
 * Gillison A.N. 2000. Above ground biodiversity assesment working group summary report 1996-99: Impact of different land uses on biodiversity and social indicators. ASB Working Group Report, ICRAF, Nairobi, 160pp. http://www.asb.cgiar.org/PDFwebdocs/ASB Biodiversity Report.pdf
 * Hashimoto Y., S. Yamane, and T. Itioka. 1997. A preliminary study on dietary habits of ants in a Bornean rain forest. Japanese Journal of Entomology 65(4): 688-695.
 * Jaitrong W., and T. Ting-Nga. 2005. Ant fauna of Peninsular Botanical Garden (Khao Chong), Trang Province, Southern Thailand (Hymenoptera: Formicidae). The Thailand Natural History Museum Journal 1(2): 137-147.
 * Jaitrong W.; Nabhitabhata, J. 2005. A list of known ant species of Thailand. The Thailand Natural History Museum Journal 1(1): 9-54.
 * Katayama M., K. Kishimoto-Yamada, H. O. Tanaka, T. Endo, Y. Hashimoto, Sk. Yamane, and T. Itioka. 2015. Negative correlation between ant and spider abundances in the canopy of a Bornean tropical rain forest. Biotropica (in press).
 * Malsch A. K. F., K. Rosciszewski, and U. Maschwitz. 2003. The ant species richness and diversity of a primary lowland rain forest, the Pasoh Forest reserve, West Malaysia. in T. Okuda, N. Manokaran, Y. Matsumoto, K. Niiyama, S. C. Thomas, and P. S. Ashton, eds. Pasoh: Ecology and Natural History of a Southeast Asin Lowland Tropical Rain Forest, pp 347-374.
 * Pfeiffer M., and D. Mezger. 2012. Biodiversity Assessment in Incomplete Inventories: Leaf Litter Ant Communities in Several Types of Bornean Rain Forest. PLoS ONE 7(7): e40729. doi:10.1371/journal.pone.0040994
 * Pfeiffer M.; Mezger, D.; Hosoishi, S.; Bakhtiar, E. Y.; Kohout, R. J. 2011. The Formicidae of Borneo (Insecta: Hymenoptera): a preliminary species list. Asian Myrmecology 4:9-58
 * Robson Simon Ant Collection, 05-Sept-2014
 * Santschi F. 1928. Fourmis de Sumatra, récoltées par Mr. J. B. Corporaal. Tijdschrift voor Entomologie 71: 119-140.
 * Smith, F.. "Catalogue of the hymenopterous insects collected at Sarawak, Borneo; Mount Ophir, Malacca; and at Singapore, by A. R. Wallace." Journal of the Proceedings of the Linnean Society of London, Zoology 2 (1857): 42-88.
 * Sukimin S., M. Mohamed, and H. Aris. 2010. Ant diversity of Maliau Basin Conservation Area, Sabah, Malaysia. Journal of Tropical Biology and Conservation 6:89-101.
 * Tanaka H. O., S. Yamane, and T. Itioka. 2012. Effects of a fern-dwelling ant species, Crematogaster difformis, on the ant assemblages of emergent trees in a Bornean tropical rainforest. Ann. Entomol. Soc. Am. 105(4): 592-598.
 * Wheeler W. M. 1919. The ants of Borneo. Bulletin of the Museum of Comparative Zoology 63:43-147.
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 * Yamane S.; Nona, A. R. 1994. Ants from Lambir Hills National Park, Sarawak. Pp. 222-226 in: Inoue, T.; Hamid, A. A. (eds.) 1994. Plant reproductive systems and animal seasonal dynamics. Long-term study of dipterocarp forests in Sarawak. Kyoto: Center for Ecological Research, Kyoto University, vii + 255 pp.
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