Urocleidoides parodoni, Oliveira & Silva & Vieira & Acosta, 2021

Oliveira, Glaucya Silva De, Silva, Reinaldo José Da, Vieira, Fernando Emmanuel Gonçalves & Acosta, Aline Angelina, 2021, Urocleidoides spp. (Monogenea: Dactylogyridae) from the gills of Parodon nasus (Characiformes: Parodontidae) from a Brazilian stream with descriptions of two new species, Zootaxa 5081 (4), pp. 535-550 : 542-544

Urocleidoides parodoni n. sp.

( Fig. 4A–I ; 2D–F ; 5 )

Type host. Parodon nasus Kner ( Characiformes : Parodontidae ).

Site of infestation. Gills.

Type locality. Indiana stream ( Capivara River , Tietê River , Upper Paraná River basin), municipality of Botucatu, São Paulo State, Brazil (22°53’57.4’’S, 48°23’11.3’’W) .

Infestation rate. Prevalence 35%; mean intensity of infestation 5.5 ± 2.4 (1–20); mean abundance 1.9±1 (0– 20).

Specimens deposited. Holotype ( CHIOC39714 a); 3 paratypes CHIOC (39714b–c; 39715); 3 paratypes INPA (842a–c).

Representative DNA sequence. 1,375 bp long of partial sequence of the 28S rDNA (D1–D3 region). Genbank accession number OK485867; 1 paragenophore INPA (842d).

Etymology. The specific name refers to the generic name of its host species.

Description. Based on 8 specimens fixed in Gray and Wess’ medium: Body fusiform 919–1,113 (1,037; n = 7) long; greatest width 165–197 (182; n = 7) near mid-length. Cephalic lobes poorly developed; 3 bilateral pairs of head organs. Few subspherical granules scattered from cephalic lobes to level of male copulatory organ present or absent. Pharynx spherical, 43–54 (47; n = 5) long, 39–46 (43; n = 5) wide; esophagus moderately long; intestinal ceca confluent posterior to testis. Peduncle short; haptor subhexagonal, 90–118 (105; n = 7) long, 120–146 (132; n = 7) wide. Ventral anchor 32–37 (35; n = 8) long, base 21–25 (23; n = 8) wide; well-developed roots, deep root conspicuous, rounded end, superficial root longer, robust base, shaft short evenly curved, elongate point not exceeding base width; anchor filament double ( Fig. 4B ). Dorsal anchor 29–33 (30; n = 8) long, base 17–21 (19; n = 8); well-developed roots, deep root conspicuous, rounded end, superficial root slightly longer, broad base, shaft short evenly curved, elongate point slightly exceeding base width, anchor filament double ( Fig. 4E ). Ventral bar 27–34 (31; n = 8) long, bowed, with expanded ends, with a slightly sclerotized piece on its anterior surface ( Fig. 4C ). Dorsal bar 29–35 (43; n = 16) long, open V-shaped, with rounded ends and conspicuous medial projection on posterior margin present ( Fig. 4D ). Hooks similar in shape, with protruding thumb, delicate shaft and point, point slightly curved, slender shank slightly enlarged at base, round and weakly sclerotized subunit at base present ( Figs. 4F ). Hook pairs 1 and 5, 10–11 (10; n = 8) long, pairs 2, 3, 4, 6 and 7, 13–14 (13; n = 8) long, FH loop about ¼ of shank length ( Fig. 4F ). MCO not articulated to accessory piece, 50–89 (76; n = 8) long, a coiled thin delicate tube of about 7 ½ counterclockwise rings, having broad base surrounded by sheath-like sclerotizations ( Fig. 4G, I ; 2D ). Accessory piece 19–24 (20; n = 8) long, composed of two subunits, one robust, lobate with a small hook-like projection, presenting variations in shape according to the angle of visualization on the slide ( Fig. 5 ), the other subunit is small, rod-shaped, presenting a small bifurcation on distal end, and overlapping the bigger subunit ( Fig. 4G, I ; 2D ; Fig. 5 ). Gonads overlapping. Testis dorsal to ovary, slightly visible at posterior end of germarium; seminal vesicle a dilation of vas deferens; prostatic reservoir not observed. Vas deferens looping left intestinal caecum. Oviduct, ootype, uterus, and egg not observed. Vaginal aperture sinistrolateral, vaginal tube sclerotized, convoluted tube emptying seminal receptacle, goblet-shaped sclerotized atrium present ( Figs. 4I ; 2E ). Vaginal sclerite 24–28 (26; n = 8) long, rod shape, slightly curved with thumb-like subterminal projection ( Figs. 4H ; 2E ). Vitelline follicles scattered throughout trunk, except in regions of reproductive organs.

Remarks. Urocleidoides parodoni n. sp. is also allocated to this genus due to the presence of the characteristics stated in the amended diagnosis proposed by Kritsky et al. (1986) and Zago et al. (2020), i.e., coiled MCO with counterclockwise rings, vaginal sclerite, overlapping gonads, and hook pairs 1 and 5 reduced in size. The new species differs from all congeners, except for U. tenuis , by showing the highest number of counterclockwise rings of MCO (approximately 7 ½). Urocleidoides tenuis also presents MCO with approximately 7 ½ counterclockwise rings but differs from the new species by the morphology of the accessory piece that is pincer-shaped, according to its original description by Zago et al. (2020), versus lobate with a small hook-like projection in the new species ( Fig. 4G ; 2D ). It was also possible to observe in the specimens of U. tenuis from the present study, an small rod-shaped subunit overlapping the bigger subunit in the accessory piece, but presenting thumb-like distal end as opposed to bifurcated in Urocleidoides parodoni n. sp. ( Fig. 1C ; 2G ). The vaginal sclerite in the new species differs in shape from U. tenuis : thumb-like subterminal projection vs. presence of a distal with a distal hook, which is more noticeable in the U. tenuis specimens from the present study ( Fig. 1I ; 2H ); additionaly, the vaginal tube in the new species is conspicuously sclerotized ( Fig. 4I ; 2E ), whereas in U. tenuis is slightly sclerotized ( Zago et al. 2020 and Fig. 2H - arrow). The new species also differs from U. tenuis by having shorter hook pairs 2, 3, 4, 6 and 7, and all hooks with slender shank slightly enlarged at base, with the presence of a weakly sclerotized subunit at base, as opposed to all hooks composed of one subunit and dilated shank in pairs 2, 3, 4, 6 and 7 in U. tenuis . Urocleidoides parodoni n. sp. presents greater range of total length and width compared to U. tenuis from the original description and the present study, respectively: 919–1,113 vs. 317–519 and 307–504 long; 165–197 vs. 55–136 and 65–125 wide. Lastly, the new species can also be differentiated from U. tenuis by the shape of the ventral bar, which is wide V-shaped with anterior undulations versus bowed in the new species, as well as ventral and dorsal anchors that have robust base and short shaft in the new species, whereas U. tenuis present long shaft in both anchors, and considerably less robust base [see Zago et al. (2020) for details on U. tenuis and Fig. 1A, E ; 2I of the present study]. Urocleidoides triangulus (Suriano, 1981) , Urocleidoides aimairai Moreira, Scholz & Luque, 2015 , and Urocleidoides paratriangulus Freitas, Bezerra, Meneses, Justo, Viana, Cohen, 2021 , also present ventral and dorsal anchors with robust base and short shaft, but differ in their shape from the new species; the morphology of the bars, hooks, and male copulatory complex are also different in the new species. The MCO of Urocleidoides triangulus presents 2½ –3 counter-clockwise rings and accessory piece comprising 2 subunits, one internal piece fork-shaped and another external piece curved (Rossim & Timi, 2016); U. aimairai presents MCO with 1½ counterclockwise and accessory piece as a single unit sigmoid in shape ( Moreira et al. 2015); and U. paratriangulus presents MCO of about two counterclockwise rings and single unit accessory piece as a shaft ( Freitas et al. 2021). Urocleioides parodoni n. sp. is the fourth species of the genus described from a parodontid host.

Figures

FIGURE 1. Sclerotized structures of Urocleidoides tenuis from Indiana stream (Capivara River, Tietê River, Upper Paraná River basin), municipality of Botucatu, São Paulo State, Brazil. A—ventral anchor; B—ventral bar; C—male copulatory complex (ventral view); D—dorsal bar; E—dorsal anchor; F—hook pairs 1 and 5; G—hook pair 7; H—hook pairs 2, 3, 4, and 6; I—vaginal sclerite. Scale bar: 10 μm.

FIGURE 2. Phase contrast photomicrographs of Urocleidoides indianensis n. sp.: A—male copulatory complex; B—vaginal sclerite and vaginal tube; C—haptor. Urocleidoides parodoni n. sp.: D—male copulatory complex; E—vaginal sclerite and vaginal tube; F—haptor. Urocleidoides tenuis: G—male copulatory complex (ventral view); H—vaginal sclerite and vaginal tube (arrow); I—haptor. Scale bar: 10 μm.

FIGURE 4. Urocleidoides parodoni n. sp. from Indiana stream (Capivara River, Tietê River, Upper Paraná River basin), municipality of Botucatu, São Paulo State, Brazil. A—whole mount composition (ventral view); B—ventral anchor; C—ventral bar; D—dorsal bar; E—dorsal anchor; F—hook; G, I—male copulatory complex; H—vaginal sclerite; I—vaginal tube. Scale bar: 10 μm unless otherwise stated.

FIGURE 5. Photomicrographs of the male copulatory complex of Urocleidoides parodoni n. sp. showing variations in shape of the accessory piece according to the angle of visualization on the slides.