Pronoprymna sayori ( Yamaguti, 1942 ) Dronen & Blend & Mohammed & Bannai, 2021

Dronen, Norman O., Blend, Charles K., Mohammed, Essa T. & Bannai, Majid, 2021, Reconsideration of the species assigned to Faustula Poche, 1926 (Digenea: Microphalloidea) with the proposal of five new genera in the Faustulidae Poche, 1926, Zootaxa 5027 (2), pp. 231-253 : 249

Pronoprymna sayori ( Yamaguti, 1942) n. comb.

Faustula sayori (Syn. Orientophorus sayori ) described from the Japanese halfbeak, H. sajori , from Tutiura, Japan is similar to species of Faustula by having suckers that are about the same size; a cirrus sac that dorsally overreaches the ventral sucker and may surpass it posteriorly by a short distance; a posttesticular ovary and a uterus that is largely posttesticular filling most of the hindbody (see fig. 19 of Yamaguti 1942). However, this species is unlike species of Faustula by having a stout body form with a more broadly rounded posterior end; similar-sized, large suckers; a terminal, cup-shaped oral sucker; a cirrus sac that extensively overreaches the ventral sucker posteriorly, invading the intertesticular space to terminate near the level of the posterior margin of the testes; a bipartite seminal vesicle; symmetrical, postacetabular testes located near the midlevel of the body; an ovary that is trilobed; and vitelline fields that are condensed into 2 compact groups and confined to the lateral fields of the second one-fourth of the body. Based on these differences, especially the posttesticular trilobed ovary, the postacetabular placement of the side by side testes, the bipartite vs tubular seminal vesicle and the vitelline follicles being condensed into 2 compact groups that are posterolateral to the ventral sucker, we agree with Bray (2008) and more recently WoRMS (2021a) that F. sayori does not represent a species of Faustula . Bray and Gibson (1980) recommend that F. sayori be reassigned to Pronoprymna and synonymized it with P. petrowi ( Layman, 1930) Bray & Gibson, 1980 (Syn. Monorcheides petrowi Layman, 1930 ). However, P. petrowi as originally described by Layman (1930) (see fig. 35 of Layman 1930) displays a number of characteristics, including the testes being located more posteriorly vs well anterior to the midlevel of the body; the presence of an entire vs a trilobed ovary; the cirrus sac terminating a short distance posterior to the ventral sucker vs extending posteriorly in to the intertesticular space to near the posterior margins of the testes; vitelline fields that are confined from the midlevel of the ventral sucker to the level of the anterior margin of the testes vs terminating more posteriorly about the midlevel of the testes and the presence of a unipartite saccate vs bipartite seminal vesicle that distinguish it from F. sayori (Syn. O. sayori ) as described by Yamaguti (1942, 1958). We therefore recommend that F. sayori be considered a separate species from P. petrowi and be assigned to Pronoprymna as Pronoprymna sayori ( Yamaguti, 1942) n. comb. In addition, Pronoprymna petrowi (Syn. Pentagramma petrowi [ Layman 1930] Margolis & Ching, 1964) as described by Margolis & Ching (1964) and Pronoprymna petrowi as described by Shimazu (2018), for the present, should be maintained in Pronoprymna as P. sayori . However, based on the smaller size of the ventral sucker relative to the oral sucker it is likely that P. petrowi as described by Shimazu (2018) is a separate species from P. sayori . Until additional specimens and information are available concerning these 2 species, we have elected to support their synonymies with P. sayori .