Curvianchoratus psectrogasteri Bezerra, Cohen, Meneses & Justo, 2023

Bezerra, Carine Almeida Miranda, Cohen, Simone Chinicz, de Meneses, Yuri Costa, Neres, Helyab Gabriel Chaves, Viana, Diego Carvalho & Justo, Marcia Cristina Nascimento, 2023, Two new species of Curvianchoratus (Monogenoidea, Dactylogyridae) parasitizing Psectrogaster amazonica (Characiformes, Curimatidae) and a new record for Curvianchoratus singularis in the Tocantins River, Maranhao, Brazil, ZooKeys 1172, pp. 101-116 : 101

Curvianchoratus psectrogasteri Bezerra, Cohen, Meneses & Justo sp. nov.

Figs 3A-H , 5A, B, E

Type host.

Psectrogaster amazonica Eigenmann & Eigenmann, 1889 ( Curimatidae ).

Type locality.

Embiral, rural zone (5°27'50"S, 47°33'48"W), municipality of Imperatriz, Maranhão State.

Infestation parameters.

22.06% prevalence; 68 total number of parasites; 2.27 ± 1.75 mean intensity; 1-15 range of intensity.

Deposited material.

Holotype: CHIOC 39977a; paratypes: CHIOC 39977 b-d, 39978 a, b, 39979, 39980, 39981, 39982.

Etymology.

The specific name of the species is derived from the generic name of the host.

Description.

Based on 43 specimens: 21 mounted in Gomori’s trichrome and 22 mounted in Hoyer’s medium: Body elongated, 425-883 (665; N = 30) long, 135-520 (308; N = 30) wide. Tegument smooth. Cephalic region with poorly-developed cephalic lobes; five pairs of head organs; cephalic glands lateral to pharynx. Eyes 4; anterior pair smaller than posterior. Pharynx round, muscular, 32-75 (50; N = 18) long, 32-87 (50; N = 18) wide; esophagus short. Peduncle inconspicuous, followed by a small haptor compared to body size, 125-292 (225; N = 21) wide. Ventral bar absent. Ventral anchor with inconspicuous deep root and elongated superficial root, long and slightly curved shaft; straight tip, not passing from the level of the tip of the superficial root, 21-30 (24; N = 43) long, base, 10-13 (12; N = 43) wide. Dorsal anchor complex heavily modified, composed by 2 subunits: dorsal-median and dorsal. Dorsal-median subunit strongly curved, 52-87 (64; N = 34) long and base, 41-63 (49; N = 48), with the robust shaft, 63-92 (78; N = 34) long, subdivided into two pieces, one anterior, with sclerotized ridges, and one posterior, lightly sclerotized, point sickle-shaped, articulated with the dorsal subunit, 4-7 (6; N = 36) long; deep and superficial roots well developed, crested-shaped, 12-27 (16; N = 46) long and 10-20 (14; N = 37) long, respectively. Dorsal subunit large, irregular, 40-65 (48; N = 15) long well-developed deep root 19-22 (20; N = 17), superficial root absent, and median region expands to form a rounded structure, 32-57 (40; N = 23) wide. Hooks similar in shape, pairs 1 and 5 smaller than others, 11-14 (12; N = 27) long, pairs 2-4,6,7 with erected thumb, curved shaft, short point, shank with dilated bulb at distal end, 13-18 (16; N = 95). Copulatory complex comprising male copulatory organ (MCO) and articulated accessory piece. Male copulatory organ composed by a tubular sclerotized cirrus that makes a short turn on itself near the base and spirals halfway towards the tip of the cirrus, with sclerotized base possessing delicate membrane, 47-60 (53; N = 5) in total length. Accessory piece, 25-30 (26; N = 5) long, claw-shaped, with dissimilar tip sizes, the smaller tip serves as guide to MCO, hinged by a ligament to the base of the cirrus. Testis oval, dorsal to germarium; seminal vesicle a distal enlargement of vas deferens; prostatic reservoir single, posterior to MCO. Germarium pretesticular, 62-122 (102; N = 7). Vaginal aperture midway between ovary and copulatory complex, sinistro-ventral, with vaginal canal slightly sclerotized, followed by rounded seminal receptacle, anterior to germarium. Oviduct, ootype, uterus not observed. Vitellaria dense, extends over the entire body, except in the region of the reproductive organs and haptor. Eggs operculated, 72-87 (82; N = 3) long by 60-70 (64; N = 3) wide.

Remarks.

Curvianchoratus psectrogasteri sp. nov. is allocated in the genus mainly by the morphology of the copulatory complex, composed by a tubular cirrus and a pincer-shaped accessory piece, connected to the base of the cirrus by a ligament and by the presence of the greatly modified dorsal anchor, composed by two subunits: dorsal-median and dorsal. The new species differs from the two known species by the absence of the ventral bar and by the morphology of the dorsal-median subunit (strongly curved, with the shank and tip visibly separated; a robust shank ornamented with a thorn at the base and crested-shaped deep and superficial roots in the new species vs. a stickle shaped end inserted in the cavity of the shaft in C. hexacleidus and C. singularis ) and by the morphology of the dorsal subunit (elongated, with a broadly circular central region in the new species vs. elongated, with deep root in C. singularis and without in C. hexacleidus ).

Figures

Figure 3. Curvianchoratus psectrogasteri sp. nov. from Psectrogaster amazonica from Tocantins River A whole specimen, ventral view B copulatory complex, ventral view C vagina D egg E ventral anchor F hook G dorsal-median subunit H dorsal subunit. Scale bars: 100 μm (A); 10 μm (B, C, E, F); 30 μm (D, G, H).

Figure 5. Light photomicrographs of Curvianchoratus spp. A, B, E Curvianchoratus psectrogasteri sp. nov. A total, ventral view B copulatory complex, ventral view E haptor C, D, F Curvianchoratus dominguesi sp. nov. C copulatory complex, ventral view D total, ventral view F haptor. Scale bars: 100 μm (A); 20 μm (B); 30 μm (C, F); 100 μm (D); 40 μm (E).