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Further observations on the emergence composition and phenology of crane flies (Diptera: Tipulidae) from a tropical rain forest stream at El Verde, Puerto Rico.

1993; Kansas (Central States) Entomological Society; Volume: 66; Issue: 4 Linguagem: Inglês

1937-2353

Mary E. Livingston, Jon K. Gelhaus,

Forensic Entomology and Diptera Studies

This paper represents a continued study of the emergence phenology of adult crane flies from a small stream in northeastern Puerto Rico. Twenty-two species were collected by an emergence trap from February 1991 through April 1992 at Quebrada Prieta, a second-order stream in the Luquillo Mountains. Four species of Limonia comprised 53% of the individuals and one species alone, Limonia (Geranomyia) virescens (Loew) comprised 22%. These additional fifteen months of emergence data confirm the pronounced seasonality in the crane fly emergence phenology reported by Gelhaus et al. (1993), with most emergence occurring during November through April, and little or no emergence from June through September. Decline in the individuals of the dominant species, L. virescens, and in numbers of total Tipulidae overall, may be related to the canopy re-growth following the destruction by Hurricane Hugo in 1989, and the resulting decline in light levels and benthic algal levels. Grazers on benthic algae included 48% of the crane fly individuals. Limonia (Discobola) gowdeyi Alexander and L. (Neolimonia) caribaea Alexander are recorded from Puerto Rico for the first time. Although many studies have examined emergence phenology or adult activity periods for crane flies in north temperate regions, Gelhaus et al. (1993) presented the first study of emergence phenology for Tipulidae in a tropical environment, specifically a small stream in a relatively non-seasonal, mountainous region of Puerto Rico. Surprisingly, the results of that study showed crane fly emergence at that site to be distinctly seasonal, although that result was taken to be prelim inary as it was based on a single year of emergence data. This paper represents a study of the succeeding fifteen months of emergence data from the same site and examines the earlier conclusions in light of this additional information. Materials and Methods Methods are outlined in detail by Masteller and Buzby (1993). The traps were maintained and samples sorted to family level by Buzby and Masteller. The trap was not operated in October 1991. All identifications to species were made by Livingston and Gelhaus. Verifications of most species determinations were made by reference to type specimens and other determined material in the Alexander Collection, Smithsonian Institution, Washington, D.C. Specimens are preserved in 80% ethanol and deposited in the collection of the Academy of Natural Sciences, Philadelphia.