Pharyngostomoides, Harkema, 1942

Achatz, Tyler J, Chermak, Taylor P, Martens, Jakson R, Woodyard, Ethan T, Rosser, Thomas G, Pulis, Eric E, Weinstein, Sara B, Mcallister, Chris T, Kinsella, John M & Tkach, Vasyl V, 2022, Molecular phylogeny supports invalidation of Didelphodiplostomum and Pharyngostomoides (Digenea: Diplostomidae) and reveals a Tylodelphys from mammals, Zoological Journal of the Linnean Society 196 (1), pp. 124-136 : 129

STATUS OF PHARYNGOSTOMOIDES

The morphological characteristics of Pharyngostomoides spp. in our material conform to the original descriptions of Ph. procyonis and Ph. ovalis ( Fig. 4E, F ). Beckerdite et al. (1971) considered Ph. ovalis to be a junior synonym of Ph. procyonis . In addition, Beckerdite et al. (1971) redescribed Ph. procyonis and provided an illustration that appears remarkably similar to Ph. ovalis . Our material of Ph. procyonis and Ph. ovalis differ by 0.4% and 10% in partial sequences of 28S and cox1, respectively ( Table 2 ; Supporting Information, Table S1 ). The morphology of Ph. procyonis and Ph. ovalis most obviously differs in general body shape (spatulate in Ph. procyonis vs. oval in Ph. ovalis ), shape of prosoma (anterior end rounded in Ph. procyonis vs. anterior end square shaped in Ph. ovalis ), relative sucker sizes (oral sucker similar in size or smaller than ventral sucker in Ph. procyonis vs. oral sucker usually larger than ventral sucker in Ph. ovalis ) and egg size (egg length 82–93 µm in Ph. procyonis vs. egg length 100–115 µm in Ph. ovalis ). Considering the genetic and morphological differences listed above, we restore Ph. ovalis .

Pharyngostomoides spp. are readily distinguished from Alaria spp. based on the position of the testes (opposite in Pharyngostomoides vs. tandem in Alaria ) ( Niewiadomska, 2002; Fig. 4E, F vs. Fig. 4 B-D, G, H). However, our molecular phylogeny based on 28S ( Fig. 1 ) positioned Ph. procyonis (type species) and Ph. ovalis among Alaria spp. , including the type species A. alata .

Figures

Figure 1. Phylogenetic interrelationships among 54 diplostomoidean taxa based on BI analysis of partial 28S rDNA gene sequences including Didelphodiplostomum and Pharyngostomoides spp. BI posterior probability values lower than 80% are not shown. The new sequences generated in this study are indicated in bold. The scale bar indicates the number of substitutions per site.

Figure 4. Photographs of: A, Tylodelphys variabilis comb. nov.from Didelphis virginiana, Arkansas; B, Alaria arisaemoides from Canis latrans, Oregon; C, Alaria alata from Nyctereutes procyonoides, Ukraine; D, Alaria marcianae from Taxidea taxus, North Dakota; E, Alaria ovalis comb. nov. from Procyon lotor, Mississippi; F, Alaria procyonis comb. nov. from Procyon lotor, Minnesota; G, H, Alaria mustelae from Mephitis mephitis, North Dakota.