Synlophe structure in Pseudomarshallagia elongata (Nematoda: Trichostrongyloidea), abomasal parasites among Ethiopian ungulates, with consideration of other morphological attributes and differentiation within the Ostertagiinae.

The independence of Pseudomarshallagia and its placement among the medium stomach worms of ungulates, Ostertagiinae, is confirmed based on comparative morphological studies of the synlophe and genital attributes among male and female specimens. An emended description of Pseudomarshallagia elongata is presented based on a series of specimens in sheep from northern Ethiopia. Pseudomarshallagia elongata is retained among the 15 genera of the Ostertagiinae based on presence of a prominent esophageal-intestinal valve, paired "0" papillae, a modified accessory bursal membrane containing the paired "7" papillae, and configuration of the copulatory bursa. The structure of the synlophe in males and females is also typical and within the range of variation demonstrated for Type II and Type A cervical patterns among other ostertagiines. We emphasize the importance of continued survey and inventory of parasite faunas to establish the limits of diversity on local, regional, and global scales. Consequently we strongly encourage routine deposition of voucher specimens from all survey activities designed to explore faunal diversity. Although this is particularly important in regions that remain poorly known, such as Africa, the principle certainly applies more broadly.