Prevalence and anatomic site ofCrassicaudasp. infection, and its use in species identification, in kogiid whales from the mid‐Atlantic United States

Abstract

The parasitic nematode Crassicauda sp. was initially described in kogiid whales from specimens collected within cervical tissues, uncommon sites of infection for this parasite. Crassicauda sp. has only been reported in Kogia breviceps to date, but no study has yet investigated a large sample of both kogiid species. A 15 yr record of 104 kogiid strandings (K. sima, n = 40; K. breviceps, n = 64) in North Carolina and Virginia, U.S.A. was used to determine the prevalence of Crassicauda sp. across species, within species across sex, and within sex across length and life history categories. Crassicauda sp. was confirmed to be a species‐specific parasite among kogiids infecting only K. breviceps (prevalence = 45%). Within K. breviceps, prevalence was similar (45%) in both immature and mature males, but increased from 10% in immature to 76% in mature females. This study confirmed the cervico‐thoracic distribution of the parasite, and identified a novel site of infection in a previously undescribed exocrine gland associated with the pigmented “false gill slit.” The species‐specific nature of Crassicauda sp. infection, the exocrine gland, and the distinct features of the false gill slit pigmentation associated with the gland, are all useful characters to identify kogiid species in the field.

High diversity and unique composition of gut microbiomes in pygmy (Kogia breviceps) and dwarf (K. sima) sperm whales

“…Historically, the shared morphological characteristics between these species have confounded taxonomic analyses of the genus Kogia . Current species-level resolution of kogiid whales recognizes two species, based on morphology and molecular evidence 29 – 31 , although at-sea identification remains challenging. In general, K .…”

“…breviceps exhibits greater body size than K . sima , with distinct differences in dorsal fin location, dorsal fin height and external “false gill slit” pigmentation between the two species 28 , 31 , 32 . It has been suggested that K .…”

Biology and ecology of bottlenose dolphins (Tursiops truncatus) stranded and sighted at 25°S in the south-western Atlantic Ocean during 1989–2016

“…The nematode Crassicauda sp. is usually observed in the urogenital system, glands and the cranium pterygoid bone of cetaceans, and has been associated with vascular lesions, reproduction and renal failure and skull erosion (Lambertsen, 1985; Dailey, 2001; Keenan-Bateman & McLellan, 2016). The skull erosions observed here in T .…”

“…truncatus indicate a greater infection of Crassicauda sp. than observed during necropsies of several other species across other areas (Perrin & Powers, 1980; Carvalho et al ., 2010; Keenan-Bateman & McLellan, 2016). Further, such infections remained consistent among juveniles, subadults and adults.…”

“…Controversially, Keenan-Bateman & McLellan (2016) recently noted that Kogia spp. infection was positively related to female TL, and also was greater in females than males.…”