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Pseudomyrmex ultrix
| Pseudomyrmex ultrix | |
|---|---|
| |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Hymenoptera |
| Family: | Formicidae |
| Subfamily: | Pseudomyrmecinae |
| Genus: | Pseudomyrmex |
| Species: | P. ultrix |
| Binomial name | |
| Pseudomyrmex ultrix Ward, 1999
| |
Only known from the type locality in Ecuador.
| At a Glance | • Ant-plant specialist |
Identification
Ward (1999) - This species is easily recognized in the worker and queen castes by the very broad petiole such that worker PWI>1.00, worker PWI3 <0.43, queen PWI 0.92–0.99 and queen PWI3 0.40–0.42. The otherwise similar Triplaris-inhabiting species, Pseudomyrmex dendroicus, Pseudomyrmex mordax, Pseudomyrmex triplaridis and Pseudomyrmex triplarinus, have worker PWI <1.00, worker PWI3 0.42–0.59, queen PWI 0.63–0.86 and queen PWI3 0.48–0.62. The angular protuberance on the worker propodeum (at the junction of the dorsal and declivitous faces), the small size of the subpetiolar process, and the densely punctate head sculpture are also distinctive features of P. ultrix.
Distribution
Latitudinal Distribution Pattern
Latitudinal Range: -0.8° to -13.03333333°.
| North Temperate |
North Subtropical |
Tropical | South Subtropical |
South Temperate |
- Source: AntMaps
Distribution based on Regional Taxon Lists
Neotropical Region: Ecuador (type locality).
Distribution based on AntMaps
Distribution based on AntWeb specimens
Check data from AntWeb
Countries Occupied
| Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species. |
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Estimated Abundance
| Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species. |
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Biology
Mature and incipient colonies were found in the type locality, inhabiting Triplaris dugandii trees. Observations made at the time of collection provide evidence that P. ultrix queens compete with, and act as temporary social parasites of, Pseudomyrmex triplaridis queens during colony initiation. In a partially-cut Triplaris tree I found colony-founding, dealate queens of both species occupying internodes of new shoots, together with eggs and pseudococcids. For eight internodes the contents were individually tallied, with the following results. Four internodes housed single P. ultrix queens while the other four internodes contained (i) 7 P. triplaridis queens, (ii) 6 P. triplaridis queens and 1 P. ultrix queen, (iii) 5 P. triplaridis queens and 1 P. ultrix queen, and (iv) 1 P. ultrix queen, 9 P. ultrix workers (nanitics) and 1 P. triplaridis worker (also nanitic). This last nest also had larvae and worker pupae of unknown specific identity. In no case were multiple queens of P. ultrix found within a single internode. The data suggest the hypothesis that P. ultrix queens exploit a pleometrotic tendency in P. triplaridis by temporarily entering into associations with — and presumably mimicking — P. triplaridis queens, while excluding conspecific queens. It is worth noting that P. ultrix queens are considerably larger than those of P. triplaridis: HW 1.43–1.50 (n=6) compared with 1.07–1.25 (n=11) in P. triplaridis.
Castes
Nomenclature
The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.
- ultrix. Pseudomyrmex ultrix Ward, 1999b: 509, figs. 6, 17, 28, 72, 78, 98 (w.q.m.) ECUADOR.
Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.
Description
Worker
Measurements (n=8). HL 1.09–1.34, HW 1.04–1.28, MFC 0.112–0.143, LHT 0.77–1.01, CI 0.95–0.97, REL 0.39–0.41, REL2 0.41–0.43, FCI 0.10–0.13, SI 0.44–0.47, FLI 1.55–2.20, FI 0.36–0.39, PLI 0.96–1.05, PWI 1.04–1.14, PPWI 1.55–1.89.
Similar to P. triplarinus except as follows. Median lobe of antennal sclerite better exposed, PFC/ASD 0.60–0.70. Legs shorter, LHT/HL 0.70–0.77. Junction of dorsal and declivitous faces of propodeum marked by slight angular protuberance, laterally on either side. Petiole short and high (PLI »1.00) with broad posterolateral expansion (PWI >1.00, PWI2 0.73–0.80, PWI3 0.38–0.42). Anteroventral petiolar process reduced in size, in the form of a small spine or tooth, directed ventrally. Sculpture on dorsum of head coarser, the punctures 0.010–0.020mm in diameter, and separated by about their diameters or less. Body pilosity common (MSC 47–75, HTC 10–16), with some standing hairs visible in outline on the posterior margin of the head (frontal view). Pubescence on head more conspicuous than in P. triplarinus, the hairs tending to be decumbent, giving the worker a scruffier appearance. Body dark brown, mandibles and anterior third of head a lighter orange-brown, tarsi yellow-brown.
Type Material
Holotype worker. ECUADOR, Napo: 13 km NNE Archidona, 0°48’S, 77°47’W, 960 m, 7.viii.1991, P. S. Ward# 11393 (Museum of Comparative Zoology). HW 1.19, HL 1.24, EL 0.50, LHT 0.90, PL 0.52, PH 0.52.
Paratypes. Same locality and date as holotype: series of workers, queens and males (to be deposited in The Natural History Museum, Instituto de Zoologia Agricola, Los Angeles County Museum of Natural History, MCZC,MECN, Museo de Historia Natural, Museu de Zoologia da Universidade de Sao Paulo, Philip S. Ward Collection, Museo de Zoologia, University of California, Davis, Museo de Historia Natural).
References
- Sanchez, A. 2015. Fidelity and promiscuity in an ant-plant mutualism: A case study of Triplaris and Pseudomyrmex. PLoS ONE 10 (doi:10.1371/journal.pone.0143535).
- Ward, P. S. 1999b. Systematics, biogeography and host plant associations of the Pseudomyrmex viduus group (Hymenoptera: Formicidae), Triplaris- and Tachigali-inhabiting ants. Zool. J. Linn. Soc. 126: 451-540 (page 509, figs. 6, 17, 28, 72, 78, 98 worker, queen, male described)
References based on Global Ant Biodiversity Informatics
- Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
- Ward P. S. 1999. Systematics, biogeography and host plant associations of the Pseudomyrmex viduus group (Hymenoptera: Formicidae), Triplaris- and Tachigali-inhabiting ants. Zoological Journal of the Linnean Society 126: 451-540