Odontomachus clarus Roger (Hymenoptera: Formicidae) Reported in Kisatchie National Forest, Louisiana [pdf]

Adams, B. J.1, X. Chen1 and L. M. Hooper-Bùi2,3

1Louisiana State University, Department of Entomology, Baton Rouge, La 70803
2Louisiana State University Agricultural Center, Department of Entomology, Baton Rouge, La 70803
3To whom correspondence should be addressed

Received: 15-VII-2010 Accepted: 23-VII-2010



The genus Odontomachus is easily identified due its large size, distinctive head features, and elongated linear mandibles (Wheeler 1910, Brown 1976, Deyrup et al. 1985). Four native species of Odontomachus are recorded within the United States: O. brunneus (Patton), O. ruginodis Smith, O. relictus Deyrup & Cover, and O. clarus Roger. Though the range of Odontomachus clarus Roger (Hymenoptera: Formicidae: Ponerinae) is reported to extend into the western part of Louisiana (Smith 1939), none have been collected within the state in recent surveys.
            O. clarus (shown in Figure 1) has been reported in Mexico, Arizona, New Mexico, and Texas (Deyrup and Cover 2004). The species was first described in 1861 by Rogers. Junior synonyms include O. texana Buckley, O. coninodis Wheeler, O. desertorum Wheeler, and O. clarionensis Wheeler(Brown 1976). Nests are often found under rocks or in grasses associated with both arid and mesic habitats. They have also been located under downed trees in fine sand and gravel soils (Smith 1939, Cokendolpher & Francke 1990, Deyrup and Cover 2004).


Figure 1

Figure 1. Profile of Odontomachus clarus worker

Results and Discussion

On 11 August 2009 two head capsules were collected in the midden pile of a colony of Dorymyrmex flavus McCookon the road near the Corral Camp area of the Kisatchie National Forest in Central Louisiana (31°31.774’N 093°03.510’W Elev. 323’). The head capsules were missing the recognizable jaws but the converging dorsal furrows on the capsules matched the characters of Odontomachus (Deyrup et al. 1985, Brown 1976). Coloration and head size indicated a species other than the non-native O. haematodus (Linnaeus), already known to exist in southeastern Louisiana. Presence of the capsules within the midden pile indicate possible predation of Odontomachus by Dorymyrmex. Aggressive interaction between Dorymyrmex bureni (Trager) and O. brunneus has previously been reported by Wild (in Deyrup and Cover 2004).An Odontomachus colony was located on 26 March 2010 in the Kisatchie district of Kisatchie National Forest on the Long Leaf Vista trail (31°28.576’N 092°59.683’W Elev. 238’). Three workers were collected under a rock in sandy soil at the base of a rock bluff. Workers were hand collected and stored in ethanol. Another colony was located on 18 June 2010 near Corral Camp (31°32.105’N 093°03.403’W Elev. 270’) under a large rock next to a rotting stump near the road. The entire colony was collected, including workers and male and female alates. Vouchers are deposited in the Louisiana State Arthropod Museum.
            Specimens of O. clarus were identified by using the key of Deyrup and Cover (2004) based on workers and male alates. The following characters distinguished O. clarus from other species. Workers: fine appressed hairs distributed at least ½ their own length on the first gastral tergite; pronotum striated transversely on the posterior; petiole slightly rugose basally on sides while smooth on back; inner side of hind femur glabrous at base; reddish brown with a black gaster; and a smooth basalar lobe. Males: ocelli smaller than the space between lateral ocelli and eye; a finely striated pronotum and a dark brown head and body. (Deyrup et al. 1985, Deyrup and Cover 2004). The other species differ in the density of hair on the gaster, the smoothness of the posterior side of the petiole, and smoothness of the basalar lobe in workers. The identification of the ants was confirmed by Dr. Mark Deyrup (Archbold Biological Station, Lake Placid, Florida).



We thank Mark Deyrup for species identification and advice, Rachel Strecker for technical assistance, Ashley Miller for editorial assistance, Crystal Mayer from Louisiana State University Arthropod Museum for photographic assistance, and Louisiana State University A&M College and the LSU Agricultural Center. We also thank Gregg Henderson and Chris Carlton for review of the manuscript.



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Cokendolpher, J. C., and O. F. Francke. 1990. The Ants (Hymenoptera, Formicidae) of Western Texas. Part II. Subfamilies Ecitoninae, Ponerinae, Pseudomyrmecinae, Dolichoderinae, and Formicinae. Museum of Texas Tech University Special Publication 30: 3-76.

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