The Hidden Diversity of the Enigmatic Archigetes (Cestoda: Caryophyllidea) in North America: Two New Combinations and Description of a New Species from Golden Shiner

Tapeworms of the order Caryophyllidea (Cestoda) are widespread parasites of cypriniform and siluriform fishes. Most species occur in suckers (Catostomidae) in the Nearctic, including 4 species of the enigmatic genus Archigetes Leuckart, 1878. Species of this genus can mature in oligochaetes, i.e., may have a monoxenous (direct) life cycle. In this article, Archigetes notemigoni n. sp. is described from the golden shiner Notemigonus crysoleucas (Mitchill, 1814) (Leuciscidae) in Wisconsin. The new species differs from other Archigetes species in having a small (≤2 mm long), spindle-shaped body with the maximum width at the middle, tapering toward the scolex and posterior end, and a small scolex wider than the neck, with a pair of narrow, deep median loculi on the dorsal and ventral sides and 2 pairs of lateral, very shallow loculi. Phylogenetic analyses suggest that A. notemigoni is closely related to Archigetes sieboldi Leuckart, 1878 and Archigetes vadosus Uhrovič, Oros, Kudlai, Kuchta, & Scholz, 2022. In addition, Hypocaryophyllaeus gilae Fischthal, 1953 from the Utah chub Gila atraria (Girard, 1856) in Wyoming and Biacetabulum oregoni Williams, 1978 from the largescale sucker Catostomus macrocheilus Girard, 1856 in Oregon are placed as new combinations in Archigetes because their morphology, such as the shape of the small body (usually <5 mm in total length), bulboloculate scolex, distribution of vitelline follicles, and shape of the ovary, corresponds to that of Archigetes species. In total, the Nearctic fauna of Archigetes now comprises 7 species: 4 from minnows (Leuciscidae) and 3 from suckers (Catostomidae). In addition, there are 2 undescribed Archigetes morphotypes from Notropis spp. (Leuciscidae) in northern Mexico.