Neotetraonchus proops ( Zambrano & Añez, 1993 ) Zambrano & Anez, 1993

Domingues, Marcus V., Soares, Geusivam B. & Watanabe, Alana, 2016, Monogenoidea (Polyonchoinea: Dactylogyridae) parasitizing the gills of marine catfish (Siluriformes: Ariidae) inhabiting the Atlantic Amazon Coast of Brazil, Zootaxa 4127 (2), pp. 301-326 : 321-324

Neotetraonchus proops ( Zambrano & Añez, 1993) n. comb.

( Figures 47–56 )

Syn. Neomurraytrematoides proops Zambrano & Añez, 1993

Neomurraytrematoides proops: Zambrano & Añez (1993) : 10 –12, fig. 1 (descr); Kohn and Paiva (2000): 35 (citat); Kohn et al. (2013): 55, 135, fig. 245 (citat).

Type-host: Sciades proops (Valenciennes)

Site of infection: Secondary lamellae of the gills

Type-locality: Enseada de La Guardia, Ilha de Margarita, Venezuela. Other records: Sciades passany, Fish market, Municipality of Bragança, State of Pará, Brazil. Specimens studied: 5 Vouchers, CHIOC 38281–38282, INPA 687. Prevalence of infection: 3 of 13(23 %) of S. passany .

Redescription: Based on 5 adult specimens; 4 mounted in Gomori’s trichrome, 1 mounted in Hoyer’ medium. Body fusiform, total length excluding haptor 2552 (2305–2800; n=2) long, fusiform, 700 (n = 2) wide, usually at level of germarium. Tegument smooth. Cephalic margin tapered; moderately developed terminal lobes; three bilateral pairs of head organs with rod-shaped secretion; cephalic glands unicellular, posterolateral to pharynx. Eyes 4, equidistant; members of posterior pair of eyes larger than anterior pair; accessory granules absent. Mouth subterminal, midventral; pharynx subspherical, 102 (90–111; n = 2) long, 105(69–122; n=4) wide; oesophagus short; intestinal caeca, nonconfluent, lacking diverticula. Genital pore opening midventral, anterior to copulatory complex; genital atrium muscular. Gonads tandem; testis dorsal to germarium. Testis elongate, fusiform, 140 (n=1) long, 55 (n=1) wide. Vas deferens looping left intestinal cecum; seminal vesicle a dilatation of vas deferens. Prostatic reservoir spherical. Copulatory complex comprising male copulatory organ accessory piece ( Fig. 48 ); male copulatory organ, sclerotized elongate tube with small base covered by sclerotized cap, proximal shaft directed posteriorly and reaching level of vaginal sclerotization, then recurving anteriorly to genital pore, terminal portion twisted. Accessory piece sclerotized, non-articulated with male copulatory organ comprising variable sheath along distal shaft of male copulatory organ. Germarium 74 (71–76; n=2) long, 150 (n=1) wide, ovate. Vaginal aperture marginal with dextroventral opening; vaginal vestibule with soft tissue at proximal portion; distal portion of vaginal vestibule comprising two portions: (1) a blind pouch containing a heavily sclerotized piece comprising a base with five projections directed to proximal portion of vaginal vestibule, three projections (two anterior, one posterior) armed with spines ( Fig. 47 ); (2) vaginal canal sclerotized, elongate connected to seminal receptacle. Seminal receptacle medial, immediately pregermarial. Mehlis’ gland large, dorsal, anterior to seminal receptacle, bilateral to ootype; uterus delicate, midventral. Vitellaria dense; bilateral vitelline ducts extending from lateral bands toward midline anterior to seminal receptacle, joining to form common vitelline duct. Egg not observed. Peduncle elongate. Haptor subtrapezoidal, 147 (136–158; n = 2) long, 142(n = 1) wide. Onchium (sensu Kritsky et al., 2009) inverted “Y-shape, ventral in haptor, associated with hook pair 1 ( Fig. 54 ). Anchors dissimilar. Ventral anchor ( Fig. 55 ) 55 (55–56; n = 3) long, base 31 (30–34; n = 3) long, robust, with broad base, subequal divergent roots covered with sclerotized cap; shaft slightly recurved, point short with undulation; point extending beyond of tip of superficial root. Dorsal anchor ( Fig. 56 ) 45 (45–46; n = 3) long, base 13 (12–15; n = 3) long, with depressed superficial root, subtriangular, short to inconspicuous deep root, margin covered with sclerotized cap; evenly curved shaft and point; union of point and shaft forming angle of approximately 65°. Ventral bar ( Fig. 49 ), 43 (34–57; n = 3) long, 54 (50–61; n = 4) wide, subtriangular, with anteromedial projection; small protuberances at each end for articulation with ventral anchor. Dorsal bar ( Fig. 50 ) 5 (4–16; n = 3) long, 34 (31–37; n = 3) wide, broadly U-shaped, robust, with thumb-like projections in anterior direction, rounded ends. Hooks ( Figs. 51–53 ) dissimilar, with ancyrocephalin distribution; hook pair 5 with erect thumb, lightly curved shaft, short point, uniform shank, filamentous hook loop extending to entire shank length ( Fig. 51 ); other hook pairs with flattened thumb, short shaft, elongate point, having shanks comprised of 2 variably expanded subunits, filamentous hook loop extending to near beginning of shank dilation ( Figs. 52–53 ). Hook pair 1 52 (50–53; n = 3) long, hook pairs 2– 4, 6 –7 39 (34–41; n = 5) long, hook pair 5 13 (14–15; n = 3) long.

Remarks: Zambrano and Añez (1993) proposed the monotypic genus Neomurraytrematoides Zambrano & Añez, 1993 to receive their new species, N. proops Zambrano & Añez 1993 , from the gills of Arius proops (Valenciennes) [now Sciades proops (Valenciennes) ] from the Bay of La Guardia, Margarita Island, Venezuela. The genus was characterized mainly by the possession of three separate bars, two of them associated with ventral/dorsal anchors, one bar associated with an atypical pair of larval hooks, and a sclerotized structure associated with the vagina.

Specimens collected from Sciades passany during the present study are fundamentally similar to Neomurraytrematoides proops based on the morphology of the haptoral and reproductive structures. However, we detected some misinterpretations in the morphological description of the haptoral structures of N. proops by Zambrano & Añez (1993). These authors reported 12 haptoral hooks for N. proops . However, our study of available specimens confirms the presence of 14 hooks, similar in distribution to the other ancyrocephalines. They also erroneously identified a haptoral structure associated with hook pair 1 as the proximal bar. We identify this structure as an onchium, typically found in species of Neotetraonchus . Although museum specimens of N. proops were not available, it is clearly evident that this species shares internal and haptoral features that are fundamentally similar to those of Neotetraonchus . This suggests that Neomurraytrematoides proops is congener with species of Neotetraonchus .

However, Neotetraonchus has temporal priority and, consequently, Neomurraytrematoides should be considered as its subjective junior synonym. Hence, the species of that latter genus are hereby transferred to Neotetraonchus as N. proops ( Zambrano & Añez, 1993) n. comb.

Neotetraonchus proops ( Zambrano & Añez, 1993) n. comb. appears to be closely related to N. felis ( Hargis, 1955) Paperna, 1977 based on the general morphology of the copulatory complex, anchors/bars complex and hooks. Both species also share the presence of a large vaginal vestibule with a vaginal duct originating from the proximal end of the vestibule. However, it can be easily differentiated from this and other species of the genus by the presence of a heavily sclerotized piece associated with the distal portion of the vaginal vestibule.

Figures

FIGURES 47 – 56. Neotetraonchus proops (Zambrano & Añez, 1993) n. comb. 47. Vaginal sclerotization. 48. Copulatory complex. 49. Ventral bar. 50. Dorsal bar. 51. Hook pair 5. 51. Hook pair 1. 53. hook pairs 2 – 4, 6 – 7. 54. Onchium. 55. Ventral anchor. 56. Dorsal anchor. Fig. 47 scale of 50 µm; Figs. 48 – 56 scale of 25 µm.