Cicindis horni Bruch 1908

Habitat

MACROHABITAT: Margins of large salt flats near vernal pools. MICROHABITAT: Adults occur on wet to inundated clay mixed with salt where polygons form when the clay dries out and with no vegetation cover. 

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Cicindis horni habitat, Salinas Grandes, Argentina.

Seasonality

Adults are found in December-March; copulating pairs observed in March; teneral adults in February.

Behavior

This heretofore very rare species was recently found to be markedly unusual among carabid beetles because adults surface-swim and dive in search of their prey, an anostracan fairy shrimp, possibly a species of Thamnocephalus Cohen. Adult beetles do not run along the shore at the margin of the ponds that are formed in the great salt flats like most carabid in this type of habitat elsewhere. However, they do rest in small burrows during the day away from the water's edge, and emerge before nightfall (crepuscular behavior). They then spend the night in search of food or mates swimming on the water surface of markedly alkaline water bodies (17% salinity).

Tibial natatorial setae, tarsal setal fringes, ventral vestiture, and genal/pronotal planing surfaces plus decumbent and very sharply pointed mandibles are specific adaptations that permit this species to behave as a swimming superspecialist predator. Subsequent studies have shown that adults also run on very wet and sticky mud at the edge of vernal pools in search of mates. 

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Specimens of Cicindis horni at night in their habitat at Salinas Grandes, Argentina.

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Cicindis horni.

Mating can take place on the water surface, or on adjacent mud. Adults are best collected by net at night over the pool, by hand when they are running on the mud adjacent to the pool, or at UV and Mercury Vapor lights; and they sometimes can be obtained in pitfall traps placed very near the water's edge. Immature stages and hibernation site unknown.

Dispersal Potential

Adults are fully winged and fly readily at night; adults also are swimmers and divers in vernal pools with 17% salinity.

Geographic Distribution

Native, New World. ARGENTINA - Catamarca, Córdoba Provinces.

Other Names for Cicindis horni Bruch 1908

• Horn’s Fairy Shrimp Hunting Beetle

References

Bruch, C. (1908) Eine neue Carabidendengattung aus Argentinien. Cicindis horni (Col.). Deutsche Entomologische Zeitschrift, 1908, 497-500.

Erwin T.L. & Aschero, V. (2004b) Cicindis horni Bruch (Coleoptera: Carabidae, Cicindini): The Fairy Shrimp Hunting Beetle, its way of life on the Salinas Grandes of Argentina. Zootaxa, 553, 1-16.

Kavanaugh, D.H. & Erwin, T.L. (1991) The tribe Cicindini Bänninger (Coleoptera: Carabidae): Comparative morphology, natural history, and reclassification. Proceeding of the Entomological Society of Washington, 93(2), 356-389.