Species: Amblyomma maculatum Koch
Family: Ixodidae (Acari)
Description: A small to medium sized tick, body 3-7 mm long and 2-4 mm wide, with females reaching 18 x 13 mm dimensions at full engorgement. Dorsum of unfed female ticks is reddish-brown; scutum is longer than wide and ornate, with reddish-brown markings over a pale cream background. Bodies of male Gulf Coast ticks are oval in shape, and pale in color with elongated reddish-brown mottling.
Distribution: The range of the Gulf Coast is historically described as a region approximately 100-150 miles inland along the Gulf of Mexico and southern Atlantic coast, extending from Texas to South Carolina. Resident populations of Gulf Coast ticks are established in Oklahoma, Kansas, and Arkansas, where their distributions appear to be expanding. Incidental introductions of these ticks beyond endemic regions occurs with increasing frequency; likely due to the feeding of immature ticks on migrating birds, and the transportation of tick infested livestock and wildlife onto new areas.
Hosts: Larvae and nymphs feed on small mammals and ground-frequenting birds including quail, meadowlarks and field sparrows. However, there is increasing evidence indicating that nymphs may also attach to large animals (e.g. cattle). Adult ticks attach and feed on cattle, horses, deer, sheep, feral swine, coyotes, dogs, cats, and other carnivores.
Biology: Gulf Coast ticks normally inhabit grassland prairies and the edges of wooded areas where the shade of canopy cover provides the microclimate for optimal optimize off-host survival. A three-host tick, the Gulf Coast tick is an arthropod of veterinary and medical importance throughout its range. Adult ticks attach and concentrate feeding primarily in the ears of their hosts. This clustered feeding habit concentrates tissue damage and can cause “gotch ear” in young calves, a condition that negatively effects their sale value at market. Seasonal activity of Gulf Coast ticks varies among lifestage and population locality. Adults in coastal and south Texas regions become active early in spring, and peaks during August and September. Inland populations of adult ticks from Oklahoma and Kansas are active as early as late winter with activity peaking in April and extending into July. Larvae and nymphs from coastal populations are generally active from Fall through early Spring, while immature stages from inland populations are active from Spring to early Fall.
Associated Disease Pathogens: The Gulf Coast tick is an arthropod of increasing medical and veterinary importance. These ticks transmit the pathogen Rickettsia parkeri rickettsiosis, a type of spotted fever to humans, with recent studies reporting infection rates of >20%. Gulf Coast ticks are responsible for transmitting Hepatozoon americanum, a protozoal agent that causes American canine hepatozoonosis in wild and domestic canines in the U.S. This species has also been shown to experimentally transmit Ehrlichia ruminatium, causal agent of heartwater, a disease fatal to >80% of wild and domestic ruminants.
Similar Tick Species: Unfed male and female Gulf Coast ticks look similar to the American dog tick, Dermacentor variabilis at first glance, but the length and shape of the mouthparts are longer and more narrow. Gulf Coast ticks are nearly identical in appearance to the Neotropical tick, Amblyomma triste. However, the known distribution of A. triste in the U.S. is limited to southern Arizona and the Trans-Pecos region of west Texas, and there is no evidence todate that the range of these two species is sympatric in Texas.