EIMERIA SPECIES FROM CRYPTOTIS SHREWS (INSECTIVORA: SORICIDAE) WITH DESCRIPTION OF A NEW SPECIES

Eimeria longirostris (Apicomplexa: Eimeriidae) from Vagrant Shrew, Sorex vagrans (Mammalia: Eulipotyphla: Soricidae), from Montana, USA

PURPOSE

Nothing is known about the coccidian parasites of vagrant shrews, Sorex vagrans Baird, 1868. Here we report, for the first time, the occurrence of Eimeria longirostris Hertel and Duszynski, 1987 from faecal contents of S. vagrans from Montana, USA.

METHODS

Faecal samples, collected in July and August 2020 from six pitfall-trapped vagrant shrews as well as faeces from two masked shrews, Sorex cinereus Kerr, 1792, and one American pygmy shrew, Sorex hoyi Baird, 1857 from Missoula County, Montana, USA, were examined for coccidian parasites. Samples were placed in individual vials containing aqueous potassium dichromate. They were examined for coccidia after flotation in Sheather's sugar solution, measured, and photographed.

RESULTS

Three (50%) S. vagrans and one (50%) S. cinereus were found to be passing oocysts of Eimeria longirostris Hertel and Duszynski, 1987; the single S. hoyi was negative. Oocysts from S. vagrans were subspheroidal and measured (average L × W) 16.1 × 14.4 µm with an L/W ratio of 1.1. One (typically) to two polar granules was present but a micropyle and oocyst residuum were absent. Sporocysts were ovoidal and measured 9.6 × 6.2 µm with an L/W ratio of 1.6. A Stieda body was present but subStieda and paraStieda bodies were absent. The sporocyst residuum was composed of various sized granules typically scattered between and across the sporozoites but sometimes formed a loose aggregate or compact mass.

CONCLUSION

We document a new host and new geographic record for E. longirostris from S. vagrans and report the coccidian from S. cinereus for the third time but the first report from specimens from Montana. This coccidian has now been reported from at least 12 species of shrews within the genus Sorex in 14 US states and two provinces in Canada.

Biodiversity of the Coccidia (Apicomplexa: Conoidasida) in vertebrates: what we know, what we do not know, and what needs to be done

Over the last two decades my colleagues and I have assembled the literature on a good percentage of most of the coccidians (Conoidasida) known, to date, to parasitise: Amphibia, four major lineages of Reptilia (Amphisbaenia, Chelonia, Crocodylia, Serpentes), and seven major orders in the Mammalia (Carnivora, Chiroptera, Lagomorpha, Insectivora, Marsupialia, Primates, Scandentia). These vertebrates, combined, comprise about 15,225 species; only about 899 (5.8%) of them have been surveyed for coccidia and 1,946 apicomplexan valid species names or other forms are recorded in the literature. Based on these compilations and other factors, I extrapolated that there yet may be an additional 31,381 new apicomplexans still to be discovered in just these 12 vertebrate groups. Extending the concept to all of the other extant vertebrates on Earth; i.e. lizards (6,300 spp.), rodents plus 12 minor orders of mammals (3,180 spp.), birds (10,000 spp.), and fishes (33,000 spp.) and, conservatively assuming only two unique apicomplexan species per each vertebrate host species, I extrapolate and extend my prediction that we may eventually find 135,000 new apicomplexans that still need discovery and to be described in and from those vertebrates that have not yet been examined for them! Even doubling that number is a significant underestimation in my opinion.