PREVALENCE AND SEVERITY OF SKUNK CRANIAL WORM (SKRJABINGYLUS CHITWOODORUM) DAMAGE INCREASE WITH PRECIPITATION IN SPOTTED SKUNKS (SPILOGALE SPP.)

Eastern and western spotted skunks (Spilogale putorius and Spilogale gracilis) serve as definitive hosts for skunk cranial worm (Skrjabingylus chitwoodorum), a metastrongylid nematode that spends its adult stage inhabiting the frontal sinuses of the host cranium. Skunk cranial worm can cause severe damage to the skull of spotted skunks, and this damage is identifiable in preserved specimens. We visited six mammal collections between 2016 and 2018 and used 578 spotted skunk skull specimens to identify patterns in prevalence and severity of skunk cranial worm damage in spotted skunks. Specimens were collected between 1895 and 1981 from across the US. We assessed effects of host genetic clade, collection year, precipitation, and sex on prevalence and severity rates. We hypothesized that the midwestern genetic clade (plains spotted skunk, Spilogale putorius interrupta), which experienced a range-wide population decline in the mid-1900s, would experience the highest infection and severity rates. We expected precipitation, but not sex to influence infection and severity. Our top models indicated that host genetic clade, precipitation in the year prior to specimen collection, and the year prior to specimen collection best predicted prevalence and severity of skunk cranial worm. We suggest the positive association with precipitation is a result of local availability of gastropods, the intermediate host for skunk cranial worm. There was a negative association between prior year and prevalence, but the severity of damage increased over time for all clades. Given concerns over population declines of spotted skunks as well as observations of increasing damage over the past century, there is a need for further research on the impacts of cranial worm infection on individual-scale behavior, reproduction and survival, and on population-scale demographics.

PREVALENCE AND INTENSITY OF THE SINUS ROUNDWORM ( SKRJABINGYLUS CHITWOODORUM) IN RABIES-NEGATIVE SKUNKS OF TEXAS, USA

:  Estimates of the distribution and prevalence of the sinus roundworm ( Skrjabingylus chitwoodorum) have been based largely on the inspection of skunk (Mephitidae) skulls showing damage from infections. We examined 595 striped skunks ( Mephitis mephitis) and nine hog-nosed skunks ( Conepatus leuconotus) that had tested negative for rabies by the Texas Department of State Health Services (US) between November 2010 and April 2015 to determine species of Skrjabingylus, prevalence and intensity of infection, and distribution of infection in Texas by county. We expected ecoregions with more precipitation to have higher rates of infection than more-arid ecoregions. Prevalence of S. chitwoodorum in striped skunks was 48.7%, with a mean intensity of 19.4 (SD=24.44, range=1-181) nematodes. There was a bias for the left sinus. The prevalence of infection varied among ecoregions of Texas, but it was not correlated with precipitation. Infection intensity did not vary among ecoregions. The prevalence of sinus roundworms in rabies-negative skunks suggested that behavioral changes because of skrjabingylosis might have been responsible for the submission by the public of some skunks for rabies testing.

A new species of Skrjabingylus Petrov, 1927 (Nematoda: Metastrongyloidea) from the frontal sinuses of the hooded skunk, Mephitis macroura (Mustelidae)

Skrjabingylus santaceciliae n. sp. is described based on specimens from the frontal sinuses of a hooded skunk, Mephitis macroura, collected from the Area de Conservación Guanacaste, Costa Rica. Skrjabingylus santaceciliae n. sp. differs from the other 5 species in the genus in having pointed spicule tips that lack a rounded or lobed formation and by lacking a prominent distal projection at the tail tip. Morphometric comparisons show that S. santaceciliae n. sp. is much smaller than the only other valid species from Mephitis, Skrjabingylus chitwoodorum Hill, 1939. Likewise, morphometric comparisons also distinguish S. santaceciliae n. sp. from other described Skrjabingylus species.