Alloglyptus Byrd, 1950

Karar, Yasser F. M., Blend, Charles K., Dronen, Norman O. & Adel, Asmaa, 2023, Towards resolving the problematic status of the digenean genus Astiotrema Looss 1900: Taxa excluded from Astiotrema (sensu stricto) with special reference to plagiorchioid genera closely related to the restricted concept of Astiotrema, Zootaxa 5284 (3), pp. 445-495 : 485

Genus Alloglyptus Byrd, 1950

( Fig. 30 )

Byrd (1950) erected Alloglyptus within the Plagiorchiidae (syn. Plagiorchiinae Pratt, 1902 ) for its type species, Alloglyptus crenshawi Byrd, 1950 , collected from the small intestine of the green or North American green anole, Anolis carolinensis Voigt ( Squamata : Dactyloidae ), in Baker County, Georgia, USA ( Byrd 1950). Based on possessing a plump to elongate body without sleeve-like lateral expansions posterior to the ventral sucker, an I-shaped excretory vesicle, and a hermaphroditic duct as well as the absence of an external seminal vesicle, Yamaguti (1958) differentiated and separated Alloglyptus into its own subfamily, Alloglyptinae Yamaguti, 1958, within the Plagiorchiidae . Tkach (2008) synonymized the Alloglyptinae with the Plagiorchiidae and retained Alloglyptus in the Plagiorchiidae .

We find that Alloglyptus exhibits a high morphological similarity to Astiotrema (sensu stricto) and its closely related group of genera ( Homeoastiotrema , Ichthyastiotrema , Longigula , Kalipharynx and Plesioastiotrema ) particularly in possessing a unipartite, saccate seminal vesicle. Otherwise, Alloglyptus can be differentiated from the earlier genera by a tegument completely devoid of spines, a weakly muscular cirrus pouch containing a slightly indented seminal vesicle, the distal portion of the male and female ducts fuse together to form a short hermaphroditic duct before opening to the outside through the genital pore, and members of Alloglyptus possess an I-shaped excretory vesicle terminating near the level of the testes ( Byrd 1950, figs. 1, 2).

In a comparison with other plagiorchiid genera, Alloglyptus can be distinguished by its naked tegument, Ishaped excretory vesicle and hermaphroditic duct which, in turn, reflect a convergence of Alloglyptus with both the Opisthorchioidea (see Bray 2008b) and the Apocreadioidea Skrjabin, 1942 (i.e., Megaperidae Manter, 1934 or Apocreadiidae Skrjabin, 1942 [Note: family name currently under consideration by the ICZN (see Blend et al. 2019)]) (see Bray 2005; Cribb 2005; Blend et al. 2017). However, the Apocreadioidea and the Opisthorchioidea lack a cirrus pouch, which is observed in Alloglyptus . Moreover, we find Alloglyptus exhibits a great resemblance with the Gorgoderoidea (syn. Allocreadioidea Looss, 1902 ), specifically members of the Allocreadiidae , in all morphological features and host group(s) except the former possesses a hermaphroditic duct (see Caira & Bogea 2005; Cribb 2005).

With a very small cirrus-pouch relative to body size (see Byrd 1950, fig. 1) as well as the absence of a detailed morphological illustration of the genital system, specifically the distal parts of the male and female ducts, it is possible that Byrd (1950) may have erred in his acknowledgement and description of the short hermaphroditic duct. It may be that the distal parts of the male and female ducts near the genital pore become closer and overlap each other, thus superficially appearing to fuse together into a common duct.

From the foregoing, we conclude that if it is true that there is a short hermaphroditic duct in Alloglyptus , we feel it is not of significant importance to create a severe conflict regarding its affiliation with any of the aforementioned families. Consequently, based on the current understanding of the morphology of Alloglyptus and adopted digenean keys, we conclude that the Allocreadiidae represents the most appropriate taxonomic position for Alloglyptus .

Figures

FIGURE 30. Alloglyptus crenshawi Byrd, 1950, ventral view, redrawn from Byrd (1950, figs. 1 & 2). Abbreviations: Ce, cecum; CP, cirrus-pouch; EA, excretory arm; EP, excretory pore; Es, esophagus; EV, excretory vesicle; GP, genital pore; HD, hermaphroditic duct; LT, left testis; Me, metraterm; MG, Mehlis’ gland; OS, oral sucker; Ov, ovary; Ph, pharynx; PP, pars prostatica; RT, right testis; SR, seminal receptacle; SV, seminal vesicle; Ut, uterus; VD, vitelline duct; VF, vitelline follicle; VR, vitelline reservoir; VS, ventral sucker. Scale bar: Fig. 30 = 1,000 µm.