Ambystoma taylori Brandon, Maruska and Rumph 1982 is a micro-endemic neotenic mole salamander found only in the hyposaline Maar lake Laguna Alchichica, in Puebla State, Mexico (19°24’49.02” N, 97°24’10.48” W). The species is considered Critically Endangered by the IUCN due to its small area of occupancy and decline in its habitat quality, which is increasingly affected by desiccation, pollution and fishing (Shaffer et al., 2010). Due to its evolutionary distinctiveness (Shaffer, 1984 a; b) and level of endangerment, A. taylori ranks joint seventh on the Zoological Society of London’s (ZSL) Evolutionarily Distinct and Globally Endangered (EDGE; Isaac et al., 2012) list of amphibian conservation priorities.

As part of a two year EDGE Fellowship programme, we sampled for A. taylori at Laguna Alchichica on the May 16th-20th and the 27th June 2015, under permit from the Mexican government (permit number SGPA/DGVS/07294/15). One component of the programme

included nocturnal visual encounter surveys at the lake margins. On May 16th, at c. 22:00 local time (well after sunset) we captured two salamanders at night on the northerly shore of the lake on silty patches of substrate under c. 60cm of water, between stromatolite rocks. Both animals were emaciated (Fig. 1A). Gills were pale, small and ragged (Fig. 1A) and the tissue surrounding gill arches had been entirely catabolised, leaving large openings between the pharynx and the environment (Fig 1C). One animal weighed 15.0g and measured 8.75cm (mass/SVL = 1.71), the other weighed 8.0g and measured 7.29cm (mass/SVL = 1.19). For comparison, visually healthy salamanders (e.g. Fig. 1B) of similar length had a mass/SVL value of 2.90 ± 0.36 (n = 7). Both animals were transferred to small aquaria containing water from the lake and maintained at temperatures similar to those measured in the vicinity of the animals (19-21oC) using a HI98127 Waterproof thermometer and pH meter (Hanna Instruments). Salamanders were offered small dead fish, which probably form part of the natural diet of the species, and both attempted to feed, but only the larger individual was able to swallow food. However, it regurgitated all food swallowed within three hours and within 12 hours both animals had died. Post mortem examinations were performed immediately after death (Fig. 1D), confirming extremely poor body condition and revealing enlarged, dark, granular liver with a plethoric gall bladder. This pathology is indicative of starvation through inanition. The mucosa of the stomach and upper small intestine of both salamanders was irritated and hyperaemic and both organs were densely packed with nematodes (Fig. 1E). Infection had apparently become so high that the digestive tract was partially obstructed, physically compromising animals’ feeding and proper

Herpetology Notes, volume 9: 43-46 (2016) (published online on 17 February 2016)

Fatal parasitosis caused by Hedruris siredonis (Nematoda) Baird, 1858 in the Alchichica salamander Ambystoma taylori Brandon,

Maruska and Rumph 1982

Christopher John Michaels1,*,#, José Alfredo Hernández Díaz2*, María del Carmen Carmona Muciño2, Claudia Muñoz-García3, David Osorio-Sarabia4, Laura Acebes, Olivia Couchman1, Nisha Owen1 and Carly Waterman1

1 Zoological Society of London, Regent’s Park, London, NW1 4RY

2 Africam Safari, Puebla - Mexico3 Departamento de Producción Agrícola y Animal, Universidad

Autónoma Metropolitana - Xochimilco, Mexico City, Mexico

4 Laboratorio de Helmintología, Instituto de Biología, Universidad Nacional Autónoma de México. Mexico City, Mexico

* These authors contributed equally to this work# Corresponding author e-mail: christopher.michaels@zsl.org

Christopher John Michaels et al.44

nutrient absorption as well as competing for nutrients. A further animal was found freshly dead on the 27th

June at the eastern shore of the lake. Body condition was visually adequate, but the animal showed ventral dermatitis which could be indicative of septicaemia (Fig. 2-A). Cause of death for this specimen could not be established, but post mortem examination revealed focal fibrinoid coelomitis involving the stomach and upper small intestine which contained abundant nematodes immersed in dense mucus. Diffusely, the digestive tract was severely congested to haemorrhagic (Fig. 2-B). All three salamander specimens were fixed in 10% neutral buffered formalin. Nematodes were fixed separately

in absolute ethanol and were identified as Hedruris siredonis.

H. siredonis has been reported from the gastro-intestinal tract of A. taylori by Dyer (1984), and Dyer and Brandon (1973), as well as from A. velasci in freshwater lakes (Atexcac, Quechulac and Las Minas) geographically close to Laguna Alchichica (Dyer, 1988), but none of these authors report emaciation or death caused by these parasites. Parasitoses can also be a complication associated with other immune challenges, such as chytridiomycoses or ranavirus (Wright and Whitaker, 2001). All animals were dermally swabbed for archive according to standard methodology for amphibian

Figure 1. A. Emaciated Ambystoma taylori collected alive on the June 16th. Note the prominent bones visible through the soft tissue and the small, pale grey and ragged external gills. B. Healthy individual of similar size; note the large, branching, red gills and plump body. C. The animal pictured in panel A, dead, with abnormal apertures into pharynx between gill arches exposed. These are likely due to catabolism of soft tissues in the final stages of starvation. D. Internal organs of parasitized salamander, viewed ventrally, with the plethoric gallbladder (left) and dark, granular, enlarged liver (right) indicated with white arrows. There are no fat bodies, usually present as large yellow-white pads. The fine black speckling on the inside of the body wall is normal pigmentation. E. Resected stomach showing hyperaemic lining and a large ball of nematodes.

chytrid fungus detection (Lips, 2007). However the salinity of Laguna Alchichica (7.1-8.5ppt; Kazmierczak et al., 2011 and literature cited therein) is much higher than levels (1-4ppt) shown to prevent growth of the chytrid fungus Batrachochytrium dendrobatidis (Bd) (Stockwell et al., 2012; 2015a; b), which is likely to also kill the other amphibian chytrid, B. salamandrivorans (Bsal). Moreover, all exposed Ambystoma species have shown to be entirely resistant to Bsal and furthermore no instances of the disease have been reported from the New World (Martel et al., 2014). It is therefore unlikely that these animals were affected by chytridiomycoses. The salamanders reported here did not show any typical symptoms of ranavirus; however this pathogen is difficult to accurately detect in small samples (Gray et al., 2009), and in any case such assays are beyond the scope of the present project.

More work is required to understand the prevalence of this parasite in the A. taylori population and its effect on mortality, morbidity and population trends of salamanders, as well as any association with other diseases. Increased infection by nematodes and trematodes has been linked to pollution of water bodies in other amphibians (Gendron et al., 2003; Rohr et al., 2008; Koprivnikar et al., 2012). Laguna Alchichica is surrounded by agricultural land, subject to water extraction and desiccation and polluted by domestic refuse (pers. Obs. C. Michaels and J. Hernández; Alcocer et al., 2004). Increased parasitosis and instances

of lethal levels of infection may therefore be the first indicators of negative effects of anthropogenic changes to the lake on the salamander. Further monitoring of changes in water quality, prevalence of parasitosis and the proportion of infections resulting in morbidity and mortality is warranted.

Acknowledgements. Fieldwork was conducted thanks to an EDGE Fellowship for José Alfredo Hernández Díaz from the Zoological Society of London. The authors would like to thank Frank Carlos Camacho, Africam Safari CEO, for supporting the project and Benjamin Tapley (ZSL) for comments on the manuscript.

References

Gendron, A.D., Marcogliese, D.J., Barbeau, S., Christin, M. S., Brousseau, P., Ruby, S., Fournier, M (2003): Exposure of leopard frogs to a pesticide mixture affects life history characteristics of the lungworm Rhabdias ranae. Oecologia 135: 469-476.

Gray, M.J., Miller, D.L., Hoverman, J.T. (2009): Ecology and pathology of amphibian ranaviruses. Diseases of Aquatic Organisms 87: 243-266.

Isaac, N.J., Redding, D.W., Meredith, H.M., Safi, K. (2012): Phylogenetically-informed priorities for amphibian conservation. PLoS ONE 7: e43912. doi:10.1371/journal.pone.0043912.

Kaźmierczak, J., Kempe, S., Kremer, B., López-García, P., Moreira, D., Tavera, R. (2011): Hydrochemistry and microbialites of the alkaline crater lake Alchichica, Mexico. Facies 57: 543-570.

Koprivnikar, J., Marcogliese, D.J., Rohr, J.R., Orlofske, S.A., Raffel, T.R., Johnson, P.T. (2012): Macroparasite infections of amphibians: what can they tell us?. EcoHealth 9: 342-360.

Fatal parasitosis caused by Hedruris siredonis in Ambystoma taylori 45

Figure 2. Dead A. taylori individual collected on the 27th June. A. Ventral view of the body, showing dermatitis. B. Open stomach containing H. siredonis nematodes (white arrow) and congested to haemorrhagic digestive tract partially covered with fibrinoid exudate.

Martel, A., Blooi, M., Adriaensen, C., Van Rooij, P., Beukema, W., Fisher, M.C., Farrer, R.A., Schmidt, B.R., Tobler, U., Goka, K., Lips, K.R., Muletz, C., Zamudio, K.R., Bosch, J., Lötters, S., Wombwell, E., Garner, T.W.J., Cunningham, A.A., Spitzen-van der Sluijs, A., Salvidio, S., Ducatelle, R., Nishikawa, K., Nguyen, T.T., Kolby, J.E., Van Bocxlaer, I., Bossuyt, F., Pasmans, F. (2014): Recent introduction of a chytrid fungus endangers Western Palearctic salamanders. Science 346 : 630-631.

Rohr, J.R., Schotthoefer, A.M., Raffel, T.R., Carrick, H.J., Halstead, N., Hoverman, J. T, Beasley, V.R. (2008): Agrochemicals increase trematode infections in a declining amphibian species. Nature 455: 1235-1239.

Shaffer, B., Parra-Olea, G., Wake, D., Burkhardt, T. (2010): Ambystoma taylori. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 25 July 2015.

Shaffer, H.B. (1984a): Evolution in a paedomorphic lineage. I. An electrophoretic analysis of the Mexican ambystomatid salamanders. Evolution 38: 1194-1206.

Shaffer, H.B. (1984b): Evolution in a paedomorphic lineage. II. Allometry and form in the Mexican ambystomatid salamanders. Evolution 38: 1207-1218.

Stockwell, M.P., Clulow , J., Mahony, M.J. (2012): Sodium chloride inhibits the growth and infective capacity of the amphibian chytrid fungus and increases host survival rates. PLoS ONE 7: e36942. doi:10.1371/journal.pone.0036942

Stockwell, M.P., Clulow, J., Mahony, M.J. (2015b): Evidence of a salt refuge: chytrid infection loads are suppressed in hosts exposed to salt. Oecologia 177: 901-910.

Stockwell, M.P., Storrie, L.J., Pollard, C.J., Clulow, J., Mahony, M.J. (2015a): Effects of pond salinization on survival rate of amphibian hosts infected with the chytrid fungus. Conservation Biology 29: 391–399.

Christopher Michaels et al.46

Accepted by Benjamin Tapley