An important question in many parasitological studies is the assessment of differences in parasite numbers between samples of hosts. This is not always an easy problem with which to deal. While almost everyone will agree that the main task consists in deciding whether the values in one sample tend to be higher than the values of another sample, there is considerable disagreement about what higher (or lower) should mean. In most cases, dissimilarity measures are differences between mean values, medians, geometric means, prevalence rates, relative effects, and more. In general, different measures can lead to different conclusions. However, a debate as to which measure is superior is fruitless; it depends on goals and circumstances of the respective study. In our opinion, it is more important to identify situations in which most of the above measures coincide, and, hence, one can confidently claim that the values in one sample are higher than in another. This is the case when one sample is stochastically larger than a second. Roughly speaking, a random variable X is stochastically larger than a second random variable Y , when X assumes large values with a higher probability than Y . In this paper, we review this concept using distributional and data examples, and we propose the use of graphical tools for detecting stochastic dominance. Our method provides a relatively easy, visual way of fully justifying general statements that the number of parasites in one sample is larger than in another.

A new species of parasitic nematode, Procamallanus ( Procamallanus ) pacificus n. sp., is described from the stomach of the Pacific shortfinned eel, Anguilla obscura (type host), and from the speckled longfin eel, Anguilla reinhardtii , from northern New Caledonia (Melanesia, South Pacific); from Anguilla sp. (cf. obscura ) from the Fiji Islands (Melanesia, South Pacific); and from the giant mottled eel Anguilla marmorata from Futuna Island (Wallis and Futuna Islands, Polynesia). Although a total of 450 nematodes were collected, all specimens were females; this suggests either an extremely rare occurrence of males or parthenogenetic reproduction in this species. Procamallanus pacificus differs markedly from all congeners from fish hosts in possessing a greater number (4–9) of caudal mucrons in the female and by other morphological features. This parasite might become a serious pathogen of cultured eels in the region of the South Pacific. Batrachocamallanus Jackson and Tinsley, 1995 is considered a junior synonym of Procamallanus Baylis, 1923, to which 2 species are transferred as Procamallanus occidentalis ( Jackson and Tinsley, 1995 ) n. comb. and Procamallanus siluranae ( Jackson and Tinsley, 1995 ) n. comb. One third-stage larva of Procamallanus ( Spirocamallanus ) sp. was also recorded from Anguilla sp. (cf. obscura ) from the Fiji Islands.

A new seuratoid nematode of the family Quimperiidae, Paraquimperia africana n. sp., is described from the small intestine of the longfin eel, Anguilla mossambica Peters, from the Eastern Cape Province, South Africa. The new species is characterized mainly by the presence of a ventral sucker in mature males, short spicules (147–171 μm), the number and arrangement of caudal papillae, the postesophageal position of the excretory pore, and by the slender female tail. In this new species, a variability in the number (3–5 pairs) of subventral preanal papillae was observed. Paraquimperia africana is the first representative of the genus in Africa. In view of recent reports, Paraquimperia aditum ( Mueller, 1934 ) is considered a junior synonym of Paraquimperia tenerrima ( Linstow, 1878 ). Paraquimperia xenentodonia Gupta and Bakshi, 1984 is considered a species inquirenda.