First Data on the Helminth Community of the Smallest Living Mammal on Earth, the Etruscan Pygmy Shrew, Suncus etruscus (Savi, 1822) (Eulipotyphla: Soricidae)

SIMPLE SUMMARY: The Etruscan shrew, Suncus etruscus, is the smallest living mammal on Earth. Its minute size (most adults weigh 1.8–3 g with a body length of 35–48 mm) makes it extremely difficult to catch in small mammal traps. The French scientist Dr Roger Fons (1946–2016) developed a particular trapping method which allowed him to assemble the largest collection of S. etruscus in the world. We had the unique opportunity of studying, for the first time, the helminth community of a total of 166 individuals of the Etruscan shrew. We found six cestode species, specifically, two extraintestinal larvae, and four intestinal adult tapeworms, as well as one adult nematode species in the stomach and several nematode larvae. Neither trematode nor acanthocephalan species were detected. Approximately 50% of the individuals harbored tapeworms presenting a two-host life cycle with arthropods as intermediate hosts, a fact that is consistent with its insectivorous diet. The adult helminth community found is highly specific of this shrew whose numerous physiological adaptations due to its small size have probably influenced its helminth spectrum as well as its helminth specificity. ABSTRACT: Suncus etruscus is the smallest living mammal on Earth by mass. Most adults weigh 1.8–3 g with a body length of 35–48 mm. Catching it in small mammal traps in nature is extremely difficult due to its minute size, and therefore special trapping methods must be used. We had the unique opportunity of studying, for the first time, the helminth parasites of 166 individuals of S. etruscus, part of the largest collection in the world, which belonged to the French scientist Dr Roger Fons (1942–2016). A total of 150 individuals were captured in the Banyuls-Cerbère area (France) and 16 in the island of Corsica (France). We found seven helminth species, specifically, the cestodes Joyeuxiella pasqualei larvae, Mesocestoides sp. larvae, Staphylocystis claudevaucheri, S. banyulsensis, S. cerberensis, and Pseudhymenolepis sp., and the nematodes Aonchotheca sp. and Nematoda gen. sp. larvae. Neither trematodes nor acanthocephalans were detected. We provide prevalences, infracommunity compositions, and helminth associations. The adult helminth community of S. etruscus seems to be highly specific, i.e., oioxenous, and linked to its insectivore diet. Due to its small size, S. etruscus has undergone numerous physiological adaptations that have probably influenced its helminth spectrum as well as its helminth specificity.