Nematodes

Ants can serve as developmental, definitive, intermediate, or carrier hosts of a variety of nematodes. Parasitic ant nematodes include members of the families Mermithidae, Tetradonematidae, Allantonematidae, Seuratidae, Physalopteridae, Steinernematidae, and Heterorhabditidae. Those nematodes that are phoretically associated with ants, internally or externally, are represented by the Rhabditidae, Diplogastridae, and Panagrolaimidae. Fossils of mermithids, tetradonematids, allantonematids, and diplogastrids associated with ants show the evolutionary history of these relationships, some of which date back to the Eocene (40 mya). (Poinar, 2012)

Photo Gallery

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  Mermithid exposed in the gaster of Camponotus sp. from the Sierra Nevada, California (Poinar, 2012, Fig. 2).
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  Parasitic juveniles of Allomermis solenopsi removed from the gaster of a fire ant worker. Photo courtesy of S. D. Porter, USDA-ARS (Poinar, 2012, Fig. 2).
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  The fossil nematode, Heydenius formicinus, emerging from a male Prenolepis henschei in Baltic amber (Poinar, 2012, Fig. 3).
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  Heydenius formicinus adjacent to its worker ant host in Baltic amber (Poinar, 2012, Fig. 4).
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  Heydenius myrmecophila adjacent to its Linepithema ant host in Dominican amber (Poinar, 2012, Fig. 5).
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  Two mermithid-infected soldiers (mermithostratiotes) (arrows) of Pheidole pallidula adjacent to smaller workers and an uninfected soldier (with large head). Note smaller heads on infected soldiers. Photo courtesy of Luc Passera (Poinar, 2012, Fig. 7).
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  Pheromermis villosa in a carpenter ant from Holland (Poinar, 2012, Fig. 8).
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  Mature female of Myrmeconema neotropicum in the early stages of egg production removed from a pupa of Cephalotes atratus. Arrow shows position of vulva (Poinar, 2012, Fig. 9).
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  Mature females of Myrmeconema neotropicum packed with eggs in the gaster of a Cephalotes atratus worker in Peru (Poinar, 2012, Fig. 10).
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  Eggs of Myrmeconema neotropicum released from the gaster of an infected Cephalotes atratus worker in Peru (Poinar, 2012, Fig. 11).
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  Worker of Cephalotes atratus infected with Myrmeconema neotropicum. The raised, red abdomen occurs when the nematode eggs are infective and ready for transport by birds. Photo courtesy of Stephen P. Yanoviak (Poinar, 2012, Fig. 12).
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  Worker of Cephalotes serratus infected with Myrmeconema antiqua in Dominican amber. Note microscopic eggs widely distributed in the amber that were released from a hole in the ant’s gaster (Poinar, 2012, Fig. 13).
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  Detail of eggs of Myrmeconema antiqua in various stages of development in Dominican amber (Poinar, 2012, Fig. 14).
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  Female of the allantonematid Formicitylenchus oregonensis removed from the body cavity of Camponotus vicinus in Oregon, USA (Poinar, 2012, Fig. 15).
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  Parasitic female of an undescribed allantonematid from workers of Cephalotes christopherseni in Peru (Poinar, 2012, Fig. 17).
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  Three dauer juveniles of Formicodiplogaster myrmenema adjacent to a worker of Azteca alpha in Dominican amber (Poinar, 2012, Fig. 23).
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  Detail of a dauer juvenile of Formicodiplogaster myrmenema adjacent to a worker of Azteca alpha in Dominican amber (Poinar, 2012, Fig. 24).
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  Developing stages of Steinernema carpocapsae removed from the body of an infected queen of Solenopsis invicta (Poinar, 2012, Fig. 25).
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  From: Steiner et al. 2019; five immature nematodes removed from a worker of Myrmica sabuleti trapped in a pitfall near Jena, Germany.

Pheidole symbiotica

These nemotodes are known from a variety of ants. Borowiec and Salata (2015) found that the workers of the previously described species Pheidole symbiotica were simply workers of Pheidole pallidula that were infested with mermithid nematodes.

Sommimyrma symbiotica

Csosz (2012) - Bolton (1988) reported that the holotype of Sommimyrma symbiotica might have been a developmentally abnormal specimen, avoiding any further speculations. According to the images (Figs. 1a, b) probably two or three nematode worms (confirmed by nematologists, Gábor Majoros and George Poinar) nearly completely fill in the gaster of the type individual. The worms are not completely developed; these parasites apparently did not attain the preadult stage. In general characteristics of external morphology the symbiotica holotype specimen is reminiscent of the workers or mermithogenic phenotypes of Myrmica scabrinodis, hence I conducted a PCA based morphometric comparison of the type with both infested and uninfected classes of M. scabrinodis. Results demonstrate that M. symbiotica holotype is nested in the cluster of infested M. scabrinodis individuals (Fig. 2). Based on these results I propose new junior synonymy with M. scabrinodis.

Known Ant Hosts

Ant	Nematode	Locality	Source	Notes
Azteca alpha	Formicodiplogaster myrmenema	Dominican amber	Poinar, 2011	Dominican amber
Camponotus aethiops	Camponotimermis bifidus		Ipateva et al., 1990
Camponotus aethiops	Comanimermis clujensis		Coman, 1953
Camponotus herculeanus	Oscheius dolichurus	Ontario	Nickle & Ayre, 1966
Camponotus vicinus	Formicitylenchus oregonensis	Oregon, USA	Poinar, 2003
Cephalotes atratus	Myrmeconema neotropicum	Peru, Panama	Poinar, 2007
Cephalotes minutus	Agamomermis cephaloti		Poinar et al., 2006
Cephalotes serratus	Palaeoallantonema cephalotae	Dominican amber	Poinar, 2011	Dominican amber
Eciton burchellii	Agamomermis ecitoni		Poinar et al., 2006
Ectatomma ruidum	Meximermis ectatommi		Poinar et al., 2006
Formica	Diploscapter lycostoma		Wahab, 1962
Formica fusca	Comanimermis clujensis		Coman, 1953
Formica rufa	Oscheius dolichurus		Janet, 1893; Wahab, 1962
Formica rufa	Pristionchus lheritieri		Wahab, 1962
Lasius	Diploscapter lycostoma		Wahab, 1962
Lasius	Koerneria histophora		Wahab, 1962
Lasius	Pheromermis myrmecophila		Crawley & Baylis, 1921
Lasius	Pristionchus lheritieri		Wahab, 1962
Lasius brunneus	Diplogasteroides spengelii		Kohler, 2012
Lasius brunneus	Diploscapter sp.		Kohler, 2012
Lasius brunneus	Halicephalobus similigaster		Kohler, 2012
Lasius brunneus	Koerneria histophora		Kohler, 2012
Lasius brunneus	Oscheius dolichurus		Kohler, 2012
Lasius claviger	Oscheius dolichurus		Nickle & Ayre, 1966
Lasius flavus	Oscheius dolichurus		Janet, 1893; Wahab, 1962
Lasius flavus	Pheromermis villosa		Kaiser, 1986
Lasius niger	Pheromermis lasiusi		Rubstov, 1970
Lasius niger	Pheromermis villosa		Kaiser, 1986
Linepithema	Heydenius myrmecophila	Dominican amber	Poinar et al., 2006	Dominican amber fossil
Linepithema humile	Diploscapter lycostoma		Markin & McCoy, 1968
Myrmica rugulosa	Diploscapter lycostoma		Wahab, 1962
Myrmica scabrinodis	unidentified nematode		Csosz, 2012	infected ant described as ''Sommimyrma symbiotica'', now ''Myrmica scabrinodis''
Odontomachus hastatus	Agamomermis costaricensis		Poinar et al., 2006
Pogonomyrmex barbatus	Skrjabinoptera phrynosoma		Lee, 1957
Prenolepis henschei	Heydenius formicinus	Baltic amber	Poinar, 2002	Baltic amber fossil
Prolasius advena	Diploscapter formicidae	New Zealand	Zhao et al., 2013
Solenopsis invicta	Allomermis solenopsi	Argentina	Poinar et al., 2007
Solenopsis invicta	Steinernema carpocapsae		Poinar, 2012
Solenopsis invicta	Tetradonema solenopsis	Brazil	Nickle & Jouvenaz, 1987
Solenopsis richteri	Tetradonema solenopsis		Jouvenaz & Wojcik, 1990
Tetramorium caespitum	Oscheius dolichurus		Wahab, 1962

References

• Borowiec, L. & Salata, S. 2015. Pheidole symbiotica Wasmann, 1909, an enigmatic supposed social parasite, is a nematode infested form of Pheidole pallidula (Nylander, 1849) (Hymenoptera: Formicidae: Myrmicinae). Sociobiology, 62, 181-186 (doi:10.13102/sociobiology.v62i2.181-186).
• Csősz, S. 2012. Nematode infection as significant source of unjustified taxonomic descriptions in ants (Hymenoptera: Formicidae). Myrmecological News, 17, 27-31.
• Poinar, G., Jr. 2012. Nematode parasites and associates of ants: Past and present. Psyche, 2012, Article ID 192017, 13 pages (DOI 10.1155/2012/192017).
• Steiner, F.M., Kohler, G., Seifert, B., Arthofer, W., Schlick-Steiner, B.C., Buschinger, A. 2019. A worker-like female of Myrmica sabuleti Meinert, 1861 (Hymenoptera: Formicidae: Myrmicinae) in a pitfall trap with five mermithids (Nematoda: Mermithidae) protruding from the gaster. Sociobiology 66(3): 400-407 (doi:10.13102/sociobiology.v66i3.4338).