In the early 1970s, D. Fish conducted an extensive study of the aquatic invertebrate fauna of the phytotelmata in the leaf axils of native bromeliads from central Florida south to the Everglades, but not the Florida Keys. Meanwhile, J. H. Frank was conducting an intensive ecological and ethological study of the mosquito genus Wyeomyia, whose immature stages inhabit bromeliad leaf axils in southern Florida. The Ph.D. dissertation of Fish (Fish 1976) reported several species for which specialist taxonomists were unable at that time to provide species-level identifications. The two investigators collaborated on chapters of a book. Fish (1983) wrote about phytotelmata in general. Frank (1983) wrote about bromeliad phytotelmata; included was a review of the knowledge of the way of life of southern Florida’s Wyeomyia mosquitoes; included also was a catalog of aquatic organisms from bromeliad phytotelmata worldwide with bibliography; this catalog included records provided by Fish (1976).

In the late 1980s G. F. O’Meara (Florida Medical Entomology Laboratory) began studies on mosquito larvae in imported, ornamental bromeliads. Frank et al. (2004) reported on the total (not just aquatic) macro-invertebrate fauna of a small sample of native bromeliads in Sarasota County, collected in 1997 by S. Sreenivasan, an intern at the Marie Selby Botanical Gardens. Then, L. J. Hribar (Florida Keys Mosquito Control District) reported new finds of bromeliad-inhabiting aquatic invertebrates from this limited area (Wagner & Hribar 2005; Grogan & Hribar 2006; Reid & Hribar 2006).

In 1989, an invasive weevil, Metamasius callizona (Chevrolat), was detected in Broward County, destroying native Florida bromeliads. Its larvae mine the meristematic tissue and kill the plants (Frank & Thomas 1994). By 2005, its populations had spread to most southern Florida counties, it threatened the survival of 12 of the 16 species (Table 1) of native Florida bromeliads, including all those species that provide phytotelmata, and a biological control campaign had been started to attempt to limit the destruction (Frank & Cave 2005). Several native bromeliads had already been declared to be threatened or endangered, and attrition by the weevil caused 2 more to be placed on the list of endangered species (Florida Administrative Code 1998). Natural bromeliad populations suffer losses due to natural causes such as wind and breakage of tree branches, but M. callizona has increased those losses to an unsustainable level. Death of Tillandsia utriculata and T. fasciculata from natural populations was monitored in the Myakka River State Park (Sarasota County for 49 mo.), Loxahatchee National Wildlife Reserve (Palm Beach County, for 28 mo.), Highlands Hammock State Park (Highlands County for 33 mo.), and St. Sebastian River Preserve State Park (Indian River County for 17 mo.) ending in Jun 2005. The percentage deaths due to M. callizona ranged from 71% to 82%, far exceeding the deaths due to other causes (Cooper 2006).

The fate of all specialist aquatic organisms inhabiting phytotelmata in Florida’s native bromeliads may now depend upon the success of this biological control campaign. It is now urgent to catalog the invertebrates that depend upon these plants as habitat. This paper is an attempt to describe what may be lost if the weevil is not controlled. Although vertebrates in Florida may use bromeliads as food, concealment, hunting grounds, or water sources (the free water in the axils), no vertebrates depend upon bromeliads in Florida as habitat for reproduction; it is the invertebrate fauna that will be most affected.

We present an annotated list of the specialist aquatic bromeliad-inhabiting organisms in Florida. Species that seem to be occasional inhabitants are mentioned in passing. We attempt to distinguish the precinctive species (those that have been detected only in Florida, often called “endemic”, but see Frank & McCoy 1990) from species with a wider distribution. For those species with a wider distribution, we attempt to distinguish those that have been present for a long time (probably pre-Columbian) from those that may have arrived very recently as contaminants of imported, ornamental bromeliads or other imported materials. We start with the viewpoint that the ancestors of Florida’s native bromeliads arrived as wind-dispersed seed (see e.g., Luther 1993). The bromeliads established, dispersed, and began to diverge. One result of their evolution in Florida was the precinctive species Tillandsia simulata. Other results included increasing genetic diversity of Florida’s native bromeliads and the evolution of natural hybrids which may be incipient species. Once the bromeliads had colonized southern Florida, they in turn were subject to colonization by wind-blown invertebrates especially from the Greater Antilles and Mexico’s Yucatan peninsula. Then, the invertebrates began to evolve. It must not be supposed that arrival of the bromeliads or the invertebrates was a single event; instead, there probably is continual natural arrival (immigration) of propagules (Luther 1993), but it has recently been complicated by inadvertent effects of international trade (human activities) in allowing the arrival of additional invertebrate species as contaminants of imported bromeliads.

When a species known only from Brazil has been detected recently in Florida, we suspect that it arrived as a contaminant of imported plants. When a species known from the Greater Antilles has been known in Florida for decades, we suspect that it arrived in pre-Columbian times.

Specialist Macro-invertebrates Detected in Bromeliad Phytotelmata in Florida

Discussion

That many of the invertebrates discussed here exist in no habitat other than bromeliads is supported by the work of Picado (1913). Picado (1913, pp. 264-274) reviewed data of earlier authors as well as his own to argue that many bromeliad-inhabiting invertebrate species are restricted to bromeliads. Frank & Curtis (1981b) reviewed published collection records for 241 mosquito species whose larvae had been reported from bromeliads in the Americas south of the U.S.A., revealing that many had been found only in bromeliad phytotelmata. Some had been collected also in water-impounding leaf axils of other plants; conversely, some had been found mainly in axils of other plants, rarely in bromeliads. Corbet (1983) reviewed the phytotelma-inhabiting Odonata, distinguishing specialists from generalists and showing that some species develop only in bromeliads. These data support the existence of a specialist bromeliad-inhabiting fauna.

Florida law defines the conservation status of Florida’s native biota without regard to extralimital distributions. Seven of the bromeliad species attacked by M. callizona are listed as endangered (two because of attack by M. callizona) and three more as threatened under Florida law (Florida Administrative Code 1998). The only precinctive species among the species under attack, T. simulata, has no protected status (Table 1). None of the specialist invertebrates inhabiting these bromeliads is protected under Florida law. However, protection under Florida law provides no guarantee of funding to achieve protection--it just makes permits necessary for biologists or anyone else to collect or possess them.

U.S. Federal law, under the Endangered Species Act, operates differently. Purportedly, it pays no attention to species that may be at risk in the U.S. while having a large population outside the U.S. It concentrates on species that are precinctive in some part of the USA. Thus, we might expect that T. simulata (and the 5 invertebrates listed as precinctive in Table 2) would be eligible for protection under Federal law. The U.S. Fish and Wildlife Service has not yet accorded them protected status.

Under the Endangered Species Act, funding is available for protection of Florida populations (named as subspecies) of species that have populations elsewhere, even though these extralimital populations may be widespread and thriving. Thus, Florida populations of Felis concolor L. (cougar), Trichechus manatus L. (West Indian manatee), and Heraclides aristodemus Esper (dusky swallowtail) have been given the names of Felis concolor coryi (Bangs) (Florida panther), Trichechus manatus latirostris (Harlan) (Florida manatee), and Heraclides aristodemus ponceanus (Schaus) (Schaus swallowtail). These subspecies have been declared under the law to have protection, and are even called “endangered species.” None of the bromeliads listed in Table 1 or invertebrates listed in Table 2 has had Florida subspecies named; we might argue that this is so because the taxonomists involved have been so stretched to provide species-level identification that they have not had time to provide a finer-meshed classification.

Losses being inflicted by Metamasius callizona on Florida bromeliad populations also affect their aquatic invertebrate fauna. Twenty one native species, consisting of 12 bromeliads and at least 9 (perhaps 19) invertebrates are at risk of extinction in Florida and in the U.S.A. At least 6 of them (1 bromeliad and 5 invertebrates) seem to be precinctive species.

The most important task with the aquatic invertebrates is to get adult specimens into the hands of expert taxonomists who will identify or describe them. This task has not changed since the 1970s. It requires collecting living specimens of the juvenile aquatic organisms and rearing them to the adult stage. The task is now more difficult than it was in the 1970s because of loss of bromeliad populations and because the community of expert taxonomists is reduced by retirements and deaths.

Readers are requested not to send specimens to the authors for identification. Instead, please use the cited works to make your own identifications, and/or contact expert taxonomists. Conceivably, by making your chosen taxonomist aware of this publication (showing the historical background) you may hasten the identification process. If Florida authorities list them as endangered and require permits for their collection, this will only make more difficult the task of description and study. The best way to protect the bromeliad-associated invertebrates is to control M. callizona.

This paper documents, as far as is now possible, the identity of the aquatic invertebrates in native Florida bromeliads in order to highlight the threat caused by M. callizona. It does not include the geographic distributional information or much of the host-plant information or abundance data provided by Fish (1976). Frank & Thomas (2001) include an extensive bibliography of aquatic organisms in bromeliad phytotelmata worldwide.