Proteocephalus midoriensis Shimazu 1990

3.2.2. Proteocephalus midoriensis Shimazu, 1990

Fig. 3

Type host: Lefua echigonia Jordan and Richardson, 1907 (Cypriniformes: Nemacheilidae).

Other host: Lefua costata (Kessler, 1876) (new host record — see Remarks).

Site of infection: Intestine.

Type locality: Midori, Iiyama City, Nagano Prefecture, Japan (36̊53′ N, 138̊21′ E).

Type material: National Museum of Nature and Science, Tsukuba, Ibaraki Prefecture, Japan (formerly National Science Museum, Tokyo; holotype — NSMT-P 1 3658; paratypes – NSMT-P 1 3642 and 3652– 3661).

Distribution: Palaearctic Asia (Japan — Nagano and Shiga Prefectures, Primorsky Region of Russia — new geographical record).

Selected references: Shimazu (1990) [19], Hypša et al. (2005) [10], Scholz et al. (2007) [11].

The species was described by Shimazu [19] from specimens found in L. echigonia from a small river and small irrigation canals in the paddy field at Midori, Iiyama City, Nagano Prefecture, Japan. In the present study, specimens from the type host and type locality were studied, which made it possible to supplement the original description with previously unreported measurements (see Table 2). In addition, the number of proglottids was counted (30–35 in total, with 19–30 immature, only 1 mature and 6–11 pregravid; gravid proglottids, i.e. those with eggs containing fully formed hexacanth larvae, were not observed) and uterine development of type 2 of de Chambrier et al. (2004; see below and [9]) was observed.

As in P. misgurni, which is newly described here from M. anguillicaudatus (see below), the proglottids of P. midoriensis are longer than wide except for the first immature ones — Fig.3 C (versus wider than long or rectangular in P.sagittus and P.demshini, which is newly described here from B. toni [see below]), the cirrus-sac is ovoid to almost spherical — Fig. 3 E (versus pyriform to elongate), and the vitelline follicles form a narrow lateral band composed of few (usually 1 or 2) follicles — Fig. 3 C–E (versus wide bands composed of several follicles at the same level in both species from Barbatula spp.), which may overlap the ovary on its ventral side — Fig. 3 D (only exceptionally some follicles overlap the ovarian lobes in the other species). Unlike P. misgurni, the ovary of P. midoriensis is large, with very wide (high), but short (horizontally) lateral wings, and a considerable part of the ovary (up to its half-length) may be overlapped by the vitelline follicles ventrally (Fig. 3 C, D). The scolex of P. midoriensis is similar to that of P. misgurni (Fig. 5 C), but it is less conspicuously widened at its apical part, and suckers are smaller in relation to the scolex width (Fig. 3 A; Table 2).

Tapeworms from L. costata, collected by the late N.I. Demshin and designated by him as ‘ Proteocephalus sp. n. ’, were found to be indistinguishable from those of P. midoriensis from congeneric fish hosts and are considered conspecific, even though the quality of all specimens is poor due to their post mortem decomposition and improper fixation by strong flattening (Fig. 3 B).