The Antarctic gastropod Dickdellia labioflecta (Dell, 1990) (originally described as Laevilittorina (Corneolittorina) labioflecta) is an obligate parasite of pycnogonids, which exploits their body fluids through the cuticular gland holes (Lehmann et al. 2007) and lays its eggs on the pycnogonid’s legs where embryos complete their life cycle (Hedgpeth 1964, Sirenko 2000, Lehmann et al. 2007). The
ecology of D. labioflecta appears to be unique, as no other examples of such a specialized parasitic behaviour on pycnogonids are known. This life-style and the related anatomical specializations (gut and digestive gland morphology), prompted the erection of a new genus, Dickdellia Ware´n & Hain, 1996 provisionally included in the family Zerotulidae (Ware´n & Hain 1996). Although
information is quite scant, to date, two pycnogonid host species are known for Dickdellia: Colossendeis megalonyx
megalonyx Fry & Hedgpeth, 1969 (Lehmann et al. 2007) and Nymphon isabellae Turpaeva, 2000 (Sirenko 2000).
Dickdellia labioflecta had recently been considered to be endemic to the Weddell Sea (Linse et al. 2006), probably
due to its type locality (off Elephant Island, South Shetland Islands: Eltanin station 410). However, the paratypes
(Eltanin stations 1870 and 1871, both from Cape Adare, and Eltanin station 1907 [figured at http://acsmith.si.edu/,
cat. No. 886103] from McMurdo Sound) were collected in the Ross Sea. We report here new findings from the Ross Sea,
originating both from recent cruises and from the reexamination of historical collections, which enlarge the host spectrum and the bathymetric distribution of this peculiar parasitic gastropod.