Echinorhynchus baeri Kostylew, 1928

Amin, Omar M., Heckmann, Richard A., Evans, R. Paul & Tepe, Yahya, 2016, A description of Echinorhynchus baeri Kostylew, 1928 (Acanthocephala: Echinorhynchidae) from Salmo trutta in Turkey, with notes on synonymy, geographical origins, geological history, molecular profile, and X-ray microanalysis, Parasite (Paris, France) 23, pp. 1-14 : 4-6

Echinorhynchus baeri Kostylew, 1928

Family Echinorhynchidae Yamaguti, 1935 Genus Echinorhynchus Zoega in Müller, 1776

Host: Brown trout, Salmo trutta Linn. ( Salmonidae ).

Other host: Sevan trout, Salmo ischchan Kessler

( Salmonidae ) [ 8, 9].

Site in host: Intestine.

Specimens: Six slides of whole-mounted male and female specimens were deposited in the parasite collection of the Harold W. Manter Laboratory ( HWML) collection no. 101,847 at the University of Nebraska State Museum, Lincoln, NE, USA.

Locality: Kilise Stream, Murat River near Erzurum, Turkey (40°5 0 47.57 00 N, 41°11 0 26.18 00 E).

Other locality: Lake Sevan, Armenia [ 8, 9].

Comments : Considering the absence/loss of any type material of this species, the present material from Turkey is designated as neotype .

Description ( Figs. 3–22 )

General. With characters of the genus Echinorhynchus . Shared structures invariably larger in females than in males. Trunk cylindrical, widest in anterior third, and gradually tapering posteriorly; females with slightly expanded rounded posterior end ( Figs. 3, 4 ). Body wall with numerous multinucleated amoeboid to round elongate cells, oriented laterally, and micropores with diverse diameter and distribution in all trunk regions ( Fig. 18 ) including the female genital orifice and the bursa. Base of proboscis with sensory pores but no micropores ( Fig. 17 ). Proboscis cylindrical, plump, rounded anteriorly, and widest at middle ( Fig. 11 ), often tilted ventrad ( Fig. 3 ), with three or more large uninucleated round cells mostly in posterior half ( Fig. 6 , arrow) and apical rootless uncalcified hooks with multiple perforations ( Figs. 13, 14 , 24 ). Proboscis with 18–24 rows with 8–10 alternating hooks each (rarely 11 in 1 male) with normal levels of structural minerals ( Fig. 23 ). Occasionally, whole range of 8–10 hooks per row on individual proboscides. Hooks more robust and slightly longer ventrally than dorsally and transition from small anteriorly to largest at middle (hooks 3–6 from anterior) then smallest basally. Anterior hooks with indentations near base ( Fig. 12 , arrow). Anterior and middle hooks with simple roots, about as long as blades, directed posteriorly. Posterior hook roots (nos. 6–10 from anterior) with manubria varying from small (no. 6) to prominent (no. 10) with gradually decreasing size of roots posteriorly ( Fig. 8 ). Neck marked. Proboscis receptacle double-walled with cephalic ganglion at middle and with two sets of prominent retractor muscles attached to midtrunk ( Fig. 3 ). Lemnisci usually subequal, digitiform, invariably and markedly longer than receptacle, widening posteriorly, with at least three large, multinucleated, lobulated giant nuclei each (arrow), and with posterior fibrous connective. Gonopores terminal in both sexes.

Male (based on 21 whole mounted mature adults with sperm, and 5 specimens studied by SEM). Measurements and counts in Tables 1 and 2 . Testes ovoid-elongate, almost equal, close or contiguous, equatorial or slightly postequatorial. Cement glands clustered to paired, contiguous with posterior testis or occasionally overlapping it ( Fig. 3 ). Anterior cement glands larger than posterior glands emptying into cement ducts in two groups surrounding common sperm duct and joining posteriorly. Saefftigen’s pouch prominent, overlapping cement ducts ( Fig. 4 ). Bursa muscular, thick walled, directed ventrad, with one ring of sensory structures ( Figs. 21, 22 ).

Female (based on 26 whole mounted mostly gravid adults, and 5 specimens studied by SEM). Measurements and counts in Tables 1 and 2 . Reproductive system about 1/4 trunk length. Uterus unusually long and slender compared to rest of the reproductive system ( Fig. 5 ); its length proportional to trunk length. Vagina without prominent sphincters. Proximal end of uterine bell with few laterally projecting nucleated cells ( Fig. 5 , top arrow) and basal expansion ( Fig. 5 , bottom arrow). Gonopore terminal with plain non-specialized orifice ( Fig. 19 ). Eggs elliptoid elongate, non-ornate, with marked polar prolongation of fertilization membrane ( Figs. 7 , 20 ).

Figures

Figure 23. The printout of the elemental scan (EDXA) for the common large hooks for E. baeri. Note height of calcium and phosphorus peaks.

Figure 24. The printout for the elemental scan (EDXA) for the miniature apical hook at the apex of the E. baeri proboscis. Note the drop in calcium and phosphorus peaks compared to that of normal hooks (Fig. 23).

Figures 3–10. Specimens of Echinorhynchus baeri collected from Salmo trutta in Turkey and proboscis hook rows of specimens of E. sevani and E. baeri, respectively, collected from Salmo ischchan in Lake Sevan, Armenia. 3. A male specimen. Note the unique amoeboid, lobulated giant nuclei in the long lemnisci (arrow), the prominent retractor muscles, and the near contiguous ovoid-elongate testes. Proboscis is usually bent ventrad. 4. A gravid female with typically long lemnisci. The reproductive system is obscured by eggs. 5. The female reproductive system. Note the very long and slender uterus and the longitudinal bulge near its distal end (upper arrow). Also note the laterally extending uterine glands at the base of the uterine bell (lower arrow). 6. The proboscis of the male specimens in Fig. 3. Note the uninucleated round cells (arrow). 7. A ripe egg with prominent polar prolongation of the fertilization membrane. 8. A ventral row of proboscis hooks from a male specimen. Note the lack of root manubria anteriorly and the gradual development of manubria with decreasing size of roots posteriorly. 9. Lateral view of hooks of E. sevani after Dinnik (1932) showing variable manubriation in all hook roots ‘‘A = first two hooks. B & C = middle hooks, D & E = last two hooks of the vertical row.’’ Measurement bars were not provided. 10. Lateral view of hooks of E. baeri after Kostylew (1928) showing the absence of manubria in all hook roots and the virtual absence of roots of the basal hook; measurement bars were not provided.

Figures 11–16. SEM of mature specimens of Echinorhynchus baeri from S. trutta in Turkey. 11. Proboscis of a female specimen. Note variation in hook size; smaller hooks at base 12. Anterior hooks. Note indentation at the base of the hooks (arrow). 13. Double miniature hooks at apical end of proboscis (arrow); occasionally one miniature apical hook present. 14. Higher magnification of an apical hook; note perforations. This hook has a low Ca reading (see EDAX data). 15. A gallium cut normal hook from the mid-proboscis. Note prominent calcified root. 16. A gallium cut miniature apical hook. Note the hollow base and absence of roots.

Figures 17–22. SEM of mature specimens of Echinorhynchus baeri from S. trutta in Turkey. 17. Sensory pore (arrow) at the base of the proboscis. No micropores here. 18. Epidermal micropores at midtrunk. 19. The posterior end of a female specimen showing terminal gonopore. 20. Egg mass from a dissected female specimen. 21. Bursa of a male specimen. 22. The opening of the bursa showing one ring of sensory knobs (arrow).