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Almost thirty years ago Jackie Poole provided an article for our magazine about the Tobusch Fishhook Cactus, pointing out the threat of illegal collecting as a concern for the species’ survival. While the threat of illegal collecting has waned since then and the status of the species is currently trending positively, there are still plenty of reasons to remain aware of this gem of the South Texas landscape.
(Sclerocactus brevihamatus ssp. tobuschii)
Originally listed as endangered in 1979, the Tobusch Fishhook Cactus (Sclerocactus brevihamatus ssp. tobuschii) is a small, inconspicuous cactus of the western Edwards Plateau. The Tobusch Fishhook Cactus is generally solitary and typically ranges from one to six inches tall. Flowers are yellow to greenish yellow; the primary blooming period is late January to mid-March. The cactus is found in sparsely vegetated, gravelly openings set within oak-juniper woodlands. While it typically occurs on flat to gently sloping hilltops, it can also be found on the steps of steeper rocky slopes and in rocky floodplains.
At the time of its listing, the Tobusch Fishhook Cactus was considered a distinct species (Ancistrocactus tobuschii) albeit closely related to a similar-looking cactus (A. brevihamatus.) However the classification of these two species remains unsettled. The two are now considered by some authors to be subspecies of Sclerocactus brevihamatus, with the former A. brevihamatus now known as Shorthook Fishhook Cactus (Sclerocactus brevihamatus ssp. brevihamatus) and the former A. tobuschii keeping its common name, Tobusch Fishhook Cactus, and being reclassified as Sclerocactus brevihamatus ssp. tobuschii. The two species are typically separated based on flower color (yellow to yellowish-green for the Tobusch Fishhook Cactus and dusky rose to yellowish-pink for the Shorthook Fishhook Cactus) and the number of radial and central spines. While some debate remains, the US Fish and Wildlife Service has accepted S. brevihamatus ssp. tobuschii as a sub-species, and it is recognized here as such.
Photos by Arron Tuggle
When the species was listed in 1979, there were approximately 200 known individuals in Bandera and Kerr counties. The main threats to the species were illegal collecting, habitat modification and loss due to real estate development, livestock damage and other natural factors. Today more than 3,000 individuals are known on ten protected sites in eight counties (Bandera, Edwards, Kerr, Kimble, Kinney, Real, Uvalde and Val Verde.) Because legally propagated individuals of the Tobusch Fishhook Cactus are now available, the threat of illegal collecting has been greatly reduced. Studies have also found that livestock trampling and herbivory are not significant threats to survival and little urban or industrial development has occurred in the species range.
Studies have identified another threat to Tobusch Fishhook Cactus populations, the Tobusch Weevil. The cactus is the preferred host plant for this undescribed species of weevil (Gerstaeckeria sp.) whose larvae feeds upon the cactus. While studies remain ongoing, some data suggests this weevil may have reduced some of the largest known cactus populations over the course of a few years.
However it’s too soon to know exactly what the impact of the Tobusch Weevil is until we better understand that organism as well. What confounds the issue is that the weevil only lays its eggs in the cactus, making it as rare as the cactus itself. Only long-term studies will shed light on this ecological conundrum. Further information on the weevil’s life-cycle and ecological relationship with the cactus are needed to better understand its impact.
While the uncertainty of the weevils’ threat to the cactus remains, it is only the trend of subdividing large ranches in Texas that remains a possible threat for the species survival. The primary threats identified in 1979 have been greatly reduced and the distribution and abundance of the cactus has increased. Consequently it was recommended in 2013 that the Tobusch Fishhook Cactus be re-classified as threatened and no longer listed as endangered. While the final decision has not yet been made, we should be encouraged that since we originally presented the case of the Tobusch Fishhook Cactus in our newsletter some twenty-seven years ago, the populations have increased considerably. As populations continue to trend positively, we still have much to learn about the species and cannot relax our efforts to ensure its ongoing protection.
Further Information:
United States Fish & Wildlife Service – http://ecos.fws.gov/speciesProfile/profile/speciesProfile.action?spcode=Q1SV
Texas Parks & Wildlife Department – http://tpwd.texas.gov/huntwild/wild/species/tobusch/
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**ARCHIVED POST AUTHOR: kjanni
