In the tropics, vertebrates play an important role as pollinators in many ecosystems. Rodents, birds, and bats are the best-known vertebrate pollinators in tropical regions (Nabhan and Buchmann, 1997). Apart from these, many lizard species have been documented to feed on flowers and potentially act as a pollinator (Godínez-Álvarez, 2004). Yet, lizard pollination remains understudied since the beginning of the 20th century (Olesen and Valido, 2003). At present, there are 34 species of lizards known to feed on nectar and flowers of 97 known plant species (Godínez-Álvarez, 2004). Presumably, lizards feeding on nectar are effective pollinators because they transport pollen grains from one flower to another (Godínez-Álvarez, 2004). There are several examples of lizard species which are known to transport pollen such as Podarcis lilfordi (Günther, 1874) which was observed to carry pollen grains of Euphorbia dendroides L. (Traveset and Saez, 1997) and Crithmum maritimum L. (Perez-Mellado and Casas, 1997). Geckos of the genus Hoplodactylus collect large amounts of pollen on their throats and transport it up to at least 50 m for 12 hours to another flower (Whitaker, 1987).

The calabash tree (Crescentia cujete L., 1753) is a perennial species, native to tropical America and widely

introduced across Asia (Burger and Gentry, 2000; Arango-Ulloa et al., 2009). It usually grows in lowland and semi-evergreen tropical forests (Gentry, 1980, 1992) and is cultivated in many gardens for aesthetic purposes and natural fences and medicines (Heinrich et al., 1998; Reyes and Rosado, 2000; Das et al., 2014). The Long-Nosed Bat, Glossophaga soricina (Pallas, 1766) has been reported as a pollinator of C. cujete in the Neotropics (Lemke, 1984; Lemke, 1985). In the Paleotropics, the pollinators of this species remain understudied, but the Dagger-toothed Nectar Bat Macroglossus minimus (É. Geoffroy, 1810) was observed by the first author to visit the flowers of C. cujete. In May 2016, we discovered that the introduced gecko Gehyra mutilata (Wiegmann, 1834) visits the flowers of C. cujete during the evening, and we subsequently documented this behaviour over a period of seven months.

Photo and video documentation of the gecko-plant interaction was conducted between mid-2016 to early-2017 in the lowland rural area at Bagumbayan, Tulunan, North Cotabato, Philippines (6.8444°N, 124.8788°E). We recorded the habit and behavior of G. mutilata to determine if the observed behaviour was opportunistic or a regular interaction between the plant and the gecko (see supplementary file for full video documentation). A single flowering C. cujete tree with a height of approximately 6 m was regularly monitored from 1900–0000 h. Individuals of G. mutilata started their activity at around 2000 h when the flowers of C. cujete were fully open and started to emit a pungent sulphurous odour.

The feeding activity of the geckos started by locating a fully-opened, cauliflorous flower (Fig. 1A,B). After an individual gecko had located a target flower, it moved to the outer part of the flower (Fig. 1C–E), presumably to check the presence of available nectar.

Herpetology Notes, volume 10: 493-496 (2017) (published online on 14 September 2017)

First evidence of nectarivory by four-clawed gecko, Gehyra mutilata (Wiegmann, 1834) (Squamata: Gekkonidae) on a bat-

pollinated Calabash tree (Crescentia cujete L.) (Bignoniaceae) in Southcentral Mindanao, Philippines

Krizler Cejuela Tanalgo1,2,* and Alice Catherine Hughes1

1 Landscape Ecology Group, Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, 666909 Yunnan, People’s Republic of China

2 Department of Biological Sciences, College of Arts and Sciences, University of Southern Mindanao, Kabacan, 9407 North Cotabato, The Philippines

* Corresponding Author. E-mail: tkrizler@gmail.com

Krizler Cejuela Tanalgo & Alice Catherine Hughes494

In some observations, individual G. mutilata moved on to another flower without feeding on the first one. After the individual gecko found a target flower, it moved at least a third of its body inside it and started feeding (Fig. 1G,H). Gehyra mutilata are good climbers and

easily reached cauliflorous flowers laying on stems or hanging down from different heights. The feeding on an individual flower usually lasted a few minutes, after which a gecko moved along the branches to look for another flower. Flowers were not visited by more than

Figure 1. Nectarivory of Gehyra mutilata on flowers of Crescentia cujete in south-central Mindanao, the Philippines. (A,B) Images demonstrating the ‘locating’ behaviour stage of the Gehyra mutilata-plant interaction. During this stage, one or two G. mutilata locate and move towards C. cujete flowers, selecting the potential flower to feed on, and observing potential competitors. (C–E) An individual G. mutilata is shown as it tests a flower of C. cujete. (F–H) Images showing the last stage of nectarivory, the ‘foraging’ activity. An individual of G. mutilata enters the flower to at least one third of its body length to reach the nectar. (I) Gehyra mutilata carrying pollen grains on its throat after consuming the nectar of C. cujete. Photos by K.C. Tanalgo.

one individual G. mutilata at the same time. Geckos remained active until 0100 h when flowers started to close their petals.

This is the first documented evidence of G. mutilata feeding on C. cujete, a species that is otherwise known to be pollinated by bats. Gehyra mutilata is widely distributed throughout Southeast Asia and other tropical regions (e.g., Fisher, 1997; Devan-Song and Brown, 2012). It is a nocturnal predator of small insects and common in urbanized areas (Devan-Song and Brown, 2012). A recent comprehensive diet analysis revealed that G. mutilata mainly consumes arthropods, particularly Diptera (Nematocera), and has never been recorded to feed on nectar (Barragán-Ramírez et al., 2015). In the family Gekkonidae, the genera Hoplodactylus, Naultinus, and Phelsuma have been recorded and are known as nectar feeders and potential pollinators (Whitaker, 1987; Nyhagen et al., 2001). The day gecko Phelsuma mutabilis (Grandidier, 1869) was observed to feed on the nectar of the mangrove tree Sonneratia alba Smith, 1816 from southwest Madagascar (Taylor and Gardner, 2014), and Phelsuma borbonica Mertens, 1966 was reported to feed on the nectar of the orchid Angraecum cadetii Bosser, 1988 (Bègue et al., 2014).

On this occasion, we did not examine the pollination role of G. mutilata but observed that pollen sticking to the gecko’s snout and body came in contact with the flowers’ stigmata (Fig. 1F,G) which indicates that G. mutilata is a potential pollinator of C. cujete. Additionally, we observed few G. mutilata individuals carrying pollen grains of C. cujete on their throats (Fig. 1I), similar to other nectarivorous gecko. The capacity of the gecko to transfer pollen from the anther to the stigma remains to be studied in further investigations. Nonetheless, similar observations of the gekkonid species Hoplodactylus duvauceli (Duméril and Bibron, 1836), Woodworthia maculata (Gray, 1845), and Phelsuma ornata Gray, 1825 found that these species deposit on their throats a considerable amount of pollen grains of the flowers they visit (Sáez and Traveset, 1995; Godinez-Alvarez, 2004). We hope that our observation will encourage ecologists to further explore this previously undocumented plant-animal interaction. The only known pollinator of C. cujete is a nectarivorous bat from the Neotropics and it will be interesting to investigate how the Calabash Tree is pollinated in the absence of its natural pollinators.

Acknowledgement. The authors are grateful to Richard T. Corlett, (Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences) for

his insightful comments on the early findings of this study. We are also grateful to C. Tanalgo and I. Tanalgo for the assistance during the field observations.

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Supplementary Video

A supplementary video documentation of the nectarivory of Gehyra mutilata on C. cujete tree was deposited and accessible from here: https://doi.org/10.6084/m9.figshare.5285995.v1.

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Accepted by Maximilian Dehling