Pronoprymna petrowi ( Layman, 1930 ) Bray & Gibson, 1980

Sokolov, S. G., Shchenkov, S. V. & Gordeev, I. I., 2021, A phylogenetic assessment of Pronoprymna spp. (Digenea: Faustulidae) and Pacific and Antarctic representatives of the genus Steringophorus Odhner, 1905 (Digenea: Fellodistomidae), with description of a new species, Journal of Natural History 55 (13 - 14), pp. 867-887 : 873-874

Pronoprymna petrowi ( Layman, 1930) Bray & Gibson, 1980 ( Figure 1 (b))

Host. Clupea pallasii pallasii .

Site of infection. Intestine.

Locality. Off eastern shore of Kamchatka Peninsula (59°15ʹ6 N & 163°43ʹ9E) at a depth of 80 m .

Prevalence. 15 of 30 host specimens (50%).

Intensity of infection. 1–120 worms per host specimen.

Deposited material. Two paragenophores (IPEE RAS 14295).

Representative DNA sequences. A partial 28S rRNA gene sequence was deposited in Genbank (NCBI) as MT872204 .

Description (based on a slightly macerated paragenophore). Body fusiform, length 1,018, maximum width 217 at level of ventral sucker, 21.3% of length. Tegument unarmed. Oral sucker cup-shaped, 98 × 126, length 9.6% of body length; oral opening subterminal. Ventral sucker 112 × 112, length 10.9% of body length. Sucker width ratio 1:0.89. Forebody 25.4% of body length. Prepharynx not detected. Pharynx 45 × 39, length 4.5% of body length. Oral sucker to pharynx width ratio 1:0.31. Oesophagus 87, 8.6% of body length. Intestinal bifurcation in posterior quarter of forebody. Caeca terminating at level of testes; post-caecal distance 43.9% of body length.

Testes two, entire, opposite, in anterior third of hindbody, separated from ventral sucker; left 116 × 70, length 11.3% of body length; right 105 × 63, length 10.3% of body length. Post-testicular region length 43.9% of body length. Cirrus-sac clavate, thin-walled, extending posteriorly slightly beyond ventral sucker, enclosing bipartite seminal vesicle, very small vesicular pars prostatica, and ejaculatory duct, 126 × 35, length 12.4% of body length. Genital atrium tubular. Genital pore median, anterior to ventral sucker.

Ovary trilobed, median, post-testicular, 126 × 88, length 12.4% of body length. Laurer’s canal not detected. Mehlis’ gland anterior to ovary. Uterus filling most of hindbody. Eggs 31 × 17. Vitellarium from two lateral compact oval masses, posterior to ventral sucker, left 91 × 49, length 8.9% of body length, right 70 × 45, length 6.9% of body length. Vitelline ducts wide, running towards median line of body, ventral to testes.

Excretory vesicle almost V-shaped; excretory pore terminal.

Remarks. Layman (1930) originally described Pr. petrowi under the name ‘ Monorcheides (?) petrowi ’ basing on specimens found in Osmerus dentex Steindachner & Kner, 1870 (Osmeridae) caught in the Peter the Great Bay ( Japan Sea). The genus affiliation of this species has been repeatedly discussed by various authors (see reviews of Margolis and Ching 1965; Shimazu 2018). Combination with the generic name Pronoprymna was proposed by Bray and Gibson (1980). Sucker-ratio 1:0.89, oral sucker cup-shaped and the cirrus-sac extending beyond the posterior edge of the ventral sucker, as well as the general morphology of the cirrus-sac, position of the testes, the shape and arrangement of the ovary and the vitellarium indicate that our specimens belong to Pr. petrowi (compare with Margolis and Ching 1965; Shimazu 2018).

Figures

Figure 1. Paragenophores of Pronoprymna spp. (a) Pronoprymna ventricosa, ventral view; (b) Pronoprymna petrowi, ventral view. Scales: (a) 400 µm; (b) 200 µm.