Urocleidoides boulengerellae, de Freitas & Bezerra & Meneses & Justo & Viana & Cohen, 2021

de Freitas, Álvaro J. B., Bezerra, Carine A. M., Meneses, Yuri C., Justo, Marcia Cristina N., Viana, Diego C. & Cohen, Simone C., 2021, Three new species of Urocleidoides (Monogenoidea: Dactylogyridae) parasitizing characiforms (Actinopterygii: Characiformes) in Tocantins River, states of Tocantins and Maranhão, and new record for U. triangulus in Guandu River, state of Rio de Janeiro, Brazil, Zoologia (e 65001) 38, pp. 1-11 : 3

Urocleidoides boulengerellae sp. nov.

Figs 4–11, 31, 32

http://zoobank.org/ 3E609A35-9326-4217-83FF-37D5C33435D5

Type host. Boulengerella cuvieri (Spix & Agassiz) ( Ctenoluciidae ).

Type locality. Tocantins River (8°22’55.9’ S; 48° 07’ 04.4’ W), near the municipality of Tupiratins, state of Tocantins, Brazil .

Other localities. Arraias River (12°37’52.3’ S; 47°08’11.2’ W), close to the municipality of Babaçulândia, state of Tocantins; Tocantins River (6°32’24.53’ S; 47° 27’ 0.75’ W), close to the municipalities of Aguiarnópolis and Estreito; at the mouth of the Itaueiras River (6°29’58.73’ S; 47°25’ 27.48’ W), in the municipality of Estreito, state of Maranhão, Brazil .

Infestation parameters. Total number of hosts: 32; prevalence: 91%; total number of parasites: 876; mean intensity: 30.2±26.5; range of intensity: 2–113.

Deposited material. Holotype: CHIOC: 39560, paratypes: CHIOC 39561 , 39562 a-c, 39563a-b, 39564a-b, 39565, 39566; INPA 833 , 834 .

Description. Based on 137 specimens: 9 mounted in Gomori’s trichrome and 128 mounted in Hoyers’ medium: Body fusiform, delicate, 310–530 (363; n = 24) long, 63–140 (102; n = 27) wide. Tegument smooth. Cephalic region with 2 lateral lobes and 2 anterolateral slightly developed; four bilateral pairs of head organs. Eyespots absent; accessory chromatic granules present in cephalic area, Mouth subterminal, midventral; Pharynx muscular, spherical; esophagus short; two intestinal caeca, posteriorly confluent to gonads, lacking diverticula. Haptor sub-hexagonal, presenting ventral anchors connected by ventral bar and dorsal anchors connected by dorsal bar, 62–112 (94; n = 13) wide ( Fig. 4). Ventral anchor with well-developed roots: protruding superficial root, rectangular in shape, deep root distally round, straight shaft and acute point, 26–44 (35; n = 43) long, base 13–26 (17; n = 31) ( Fig. 8); dorsal anchor with developed roots, straight shaft and long point, 23–30 (28; n = 33) long, base 10–21 (12; n = 30) ( Fig. 9). Ventral bar straight and robust, with anteromedian groove and slight protuberances at the end, 35–45 (39; n = 27) long ( Fig. 10). Dorsal bar recurved, 32–40 (37; n = 14) long, with a long posteromedian projection, 9–15 (12; n = 24) long ( Fig. 11). Seven pairs of marginal hooks present, ancyrocephaline distribution, five pairs ventral and two dorsal. Hooks similar in shape; pairs 1 and 5 slightly smaller than other pairs: each with protruded thumb, curved point, straight shank, and very short filamentous hook loop about 1/6 shank length ( Fig. 7). Pair 1, 10–22 (16; n = 15) long, pair 2, 18–30 (23; n = 24) long, pair 3, 19–38 (24; n = 37) long, pair 4, 16–36 (24; n = 38) long, pair 5, 15–25 (19; n = 9) long, pair 6, 20–33 (29; n = 23) long, pair 7, 16–27 (18; n = 10) long. Copulatory complex comprising male copulatory organ (MCO) and non-articulated accessory piece. MCO with 2–3 counterclockwise rings, base with flange, 61–131 (95; n = 17). Accessory piece comprising a robust Y-shaped unit and a sheath-like unit ( Figs 6, 31). Testes dorsal to germarium; seminal vesicle a distal dilation of vas deferens; single prostatic reservoir present. Germarium elongated ( Fig. 4). Vaginal canal a highly sclerotized tube, which coils around vaginal sclerite, connected with seminal receptacle, located anteriorly to germarium; vaginal opening ventrolateral, sinistral; vaginal sclerite present, robust, sinistral, composed of straight rod distally hooked, with a short subterminal projection, 38–50 (41; n = 11) ( Figs 5, 32). Eggs, Mehlis’ glands and ootype not observed. Vitellaria present, distributed throughout the body, except in area of reproductive organs ( Fig. 4).

Etymology. the specific name refers to the scientific name of the host.

Remarks. The new species is allocated in Urocleidoides by the presence of vaginal sclerite, MCO with counterclockwise rings and pairs 1 and 5 reduced in size. Urocleidoides boulengerellae sp. nov. can be differentiated from all other species of the genus mainly by the morphology of the copulatory complex and through the highly sclerotized vaginal canal. Urocleidoides boulengerellae sp. nov. is most similar to Urocleidoides neotropicalis Mendoza-Franco & Reina, 2008 and Urocelidoides piriatiu Mendoza-Franco & Reina, 2008 , by the long posteromedian projection in the dorsal bar. However, the new species differs from U. neotropicalis by the morphology of the male copulatory organ (2–3 rings in U. boulengerellae sp. nov. and a coil of about 5½ counterclockwise rings in U. neotropicalis ), while it differs from U. piriatiu by the shape of the subunits of the accessory piece (an Y-shaped, robust and a sheath-like unit in U. boulengerellae sp. nov. and dextral subunit terminally acute; sinistral subunit bottle-shaped in U. piriatiu ).