A Recently Introduced and Unwelcome New Species of Frog in Hong Kong

Only by chance I found that Hong Kong has had a relatively recent addition to its list of amphibian species—and it is one that is there because it has been introduced accidentally.

The first author of a paper published in 2016 found the then mystery frog in a container yard in what was the New Territories of Hong Kong in 2000. Up to 2015 the same frog had been found at 18 locations throughout much of Hong Kong and, furthermore, to be breeding.

Using DNA barcoding the frog was identified as Eleutherodactylus planirostris originally native to the Caribbean (Bahamas, Cayman Islands and Cuba). However, it has been accidentally introduced to a number of other countries in the tropics and subtropics, including mainland USA, several in Central and South America, Hawaii, Guam, Singapore and the Philippines. The first clue to how it has spread so easily is in its common name of Greenhouse Frog. The second is that the frog develops entirely within the egg case, from egg to tadpole and to metamorphosed froglet. Eggs were found in Hong Kong on wet leaf litter. All the indications are that the eggs are spread as part of the trade in live, cultivated plants.

Greenhouse Frog, Eleutherodactylus planirostris
Photograpg by Pierre Fidenci
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The authors wrote (references omitted):

Large volume of live plants was imported to Hong Kong from continental United States of America in early 2000s when E. planirostris was first detected in Hong Kong. This was supported by one frog being found in a potted Tillandsia cyanea plant bought from the flower market in Mong Kok in urban Kowloon in 2011 and another frog found in an apartment on Ap Lei Chau in 2015 that was likely to arrive together with an indoor plant. In addition, we made observations of high densities of frogs (> 30 in 200 m2) near newly renovated slopes where nursery plants were planted on. Due to the extensive trade of live plants in the region, it seems it is a matter of time that E. planirostris will spread to other places that import plants from Hong Kong. In 2015, Hong Kong exported or re-exported over 100,000 kg of plants or parts of plants to tropical or subtropical countries/cities, including Australia, China, Macau, Malaysia, Singapore, Thailand, Taiwan and Vietnam, where the climate may be favorable to the colonization of E. planirostris.

Greenhouse Frogs, although producing a relatively small number of eggs at each spawning, are prolific. There is concern in Hong Kong that this introduced species could compete with another small frog, the endemic Romer’s Frog, Liuixalus romeri, for food. This concern spreads to the possible effects of carrying the frog to other countries and regions which buy plants from Hong Kong. The authors suggested the screening of all plants for adults and eggs leaving Hong Kong. The problem with closing that stable door is that the horse may have already bolted.

I have seen no further information on the status of this introduced species in Hong Kong since the paper was published in 2016. 

Lee WH, Lau MW-N, Lau, A, Rao DQ, Sung Y-H. 2016. Introduction of Eleutherodactylus planirostris (Amphibia, Anura, Eleutherodactylidae) to Hong Kong. Acta Herpetologica 11,85-89. DOI: 10.13128/Acta_Herpetol-16491