Land leech (Haemadipsa zeylanica) parasitizing Indosylvirana indica (Indian golden-backed frog) in Agumbe, India

From Firenze University Press Journal: Acta Herpetologica

Mahesh Bilaskar, Department of Environmental Sciences, Savitribai Phule Pune University

Surendra Walke, Survey №112/2/2/2, Opposite Hemgiri Apartment, Baner, Pune -411045, Maharashtra, India

Empirical evidence of anuran–leech parasitic asso-ciations suggests that anurans represent a principal host group for leeches (Berven and Boltz, 2001; Merilä and Sterner, 2002). Leeches are extensively documented as ectoparasites of amphibians, exhibiting parasitic interac-tions across multiple life stages, including ovum, embry-onic (Burgin and Schell, 2005), and adult phases (Merilä and Sterner, 2002). These hematophagous organisms not only inflict direct physiological stress through blood-feeding and tissue damage but also play a potential role as mechanical vectors in pathogen transmission. Notably, leeches have been implicated in the dissemination of pro-tozoan and fungal pathogens, including Ichthyophonusspp. and Trypanosoma spp., thereby contributing to the epidemiology of infectious diseases within amphibian populations (Delima et al., 2024).In India, the ecological and parasitic associations between leeches and anurans remain insufficiently inves-tigated and represent a relatively underexplored area of research. Numerous field observations have been report-ed by herpetologists; however, the majority of these accounts remain undocumented in peer-reviewed litera-ture. To date, there are no published accounts documenting leech–anuran interactions involving species of the genus Indosylvirana. Nevertheless, a previously published record reports the presence of leeches affixed to vocaliz-ing male rhacophorid frogs (Raorchestes sp.) within Silent Valley National Park, situated in the Western Ghats of India (Zachariah et al., 2016). Indosylvirana indica, the Indian golden-backed frog, is a species of frog endemic to Western Ghats, north of the Palghat Gap in the states of Karnataka and Kerala (Biju et al., 2014; Frost, 2019). This species was former-ly considered conspecific with Indosylvirana temporalis, but was subsequently recognized as a distinct species based on morphological and molecular evidence (Biju et al., 2014). On 06 June 2024, at 12.43 PM in the Agumbe Forest, Shimoga district, Karnataka, India (13.5087°N, 75.0959°E; elevation 660 m asl), we observed an individual of I. indica being parasitized by a leech. The posterior end of the leech was attached to the frog’s tym-panum and anterior was towards the narrower end of the frog’s mouth. The species of leech was identified as Hae-madipsa zeylanica cochiniana, which is considered a land leech (Fogden and Proctor, 1985). This leech is endemic to India, having type locality Cochin (Chandra, 1982; Mandal, 2004). Land leeches (Haemadipsa spp.), known for biting humans and cattle’s (Chandra, 1982), are wide-ly distributed throughout rainforests from Madagascar and India to Southeast Asia, the western Pacific, and Aus-tralia. During the 1977–1978 joint expedition to Gunung Mulu National Park, Sarawak, conducted by the Sarawak Forest Department and the Royal Geographical Society, researchers studied leech species in the area. Two of the three Haemadipsa species known from Borneo — Hae-madipsa zeylanica and H. picta — were recorded in the park. H. zeylanica was found to be the more abundant and widespread species, primarily occurring at ground level, while the rarer H. picta was often observed climb-ing up to two metres into the undergrowth. Both spe-cies attacked humans, but only a single instance of non-human predation by Haemadipsa species — specifically H. zeylanica Moore and H. picta Moore — on a frog has been reported (Fogden and Proctor, 1985). However, land leeches, particularly species like Batracobdella algira, have been documented parasitiz-ing various amphibians, including the endemic Sardin-ian Speleomantes salamanders (Ben Ahmed et al., 2015; Manenti et al., 2016). These leeches feed on amphib-ians in both aquatic and terrestrial environments, often attaching to their hosts, consuming their blood, and sometimes acting as vectors for micro-parasites such as Trypanosoma and Lankesterella ( Jiménez Sánchez, 1997). Despite the limited number of documented cases, the parasitic relationship between land leeches and amphibians, including potential impacts on body condition, warrants further study, as some reports sug-gest negative effects on the hosts’ health (Elliot and Dobson, 2015). While leech predation on amphibians has generally been seen as opportunistic without caus-ing immediate death, the role of environmental factors, such as stable microclimates in terrestrial habitats, may influence the extent of this parasitism and its long-term consequences for amphibian populations (Rocha et al., 2012). The study performed by Lunghi et al. (2018) also revealed a strong association between environmen-tal features, such as high humidity and water hardness in karst cave systems, and leech prevalence. While B. algira did not significantly reduce the Body Condition Index (BCI) of its salamander hosts overall, individu-als carrying heavier parasite loads exhibited a decline in BCI, suggesting cumulative physiological costs (Lung-hi et al., 2018). This pattern parallels the potential, yet undocumented, fitness effects that H. zeylanica may have on I. indica when attachment duration or infesta-tion intensity is high. These findings together highlight that leech–amphibian associations, though often over-looked, can be influenced by shared ecological variables and may bear sublethal consequences worthy of further investigation. To the best of our knowledge, this repre-sents the first documented instance of ectoparasitism by a land leech in I. indica, thereby expanding our under-standing of host-parasite interactions within this spe-cies. While prior observations have reported mosquitoes (Uranotaenia sp.) engaging in hematophagy on I. indicain the Western Ghats (Kalki et al., 2020), there are no published records detailing leech parasitism in this amphibian. This novel finding underscores the need for further research into the ecological dynamics and potential health implications of such parasitic relationships in amphibian populations.

DOI: https://doi.org/10.36253/a_h-17768

Read Full Text: https://oaj.fupress.net/index.php/ah/article/view/17768