Diaphorocleidus kritskyi, Justo & Silva & Ottoni & Mendonça & Nigris & Cohen, 2025

Justo, Marcia Cristina Nascimento, Silva, Marciara Lopes, Ottoni, Felipe Polivanov, Mendonça, Gabriela Cristina De França, Nigris, Giovanna Oliveira De & Cohen, Simone Chinicz, 2025, New species of Diaphorocleidus and Urocleidoides with a redescription of Curvianchoratus hexacleidus (Monopisthocotyla: Dactylogyridae) parasitizing characiform fishes from the Munim River Basin, northeastern Brazil, Zootaxa 5729 (1), pp. 135-150 : 140

Diaphorocleidus kritskyi sp. nov.

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( Figure 3 , Figure 6C, D )

Type-host: Knodus guajajara Aguiar, Brito, Ottoni & Guimarães, 2022 ( Characiformes , Stevardiidae)

Type-Locality: Estrela Stream , balneary of Anapurus , urban zone of the municipality of Anapurus , Munim River Basin , Maranhão State, northeastern Brazil ( 03°40'15.6"S 043°7'9.7"W) .

Parasitological indices: Total number of hosts examined: 53; number of infested hosts: 1; total number of specimens: 4.

Etymology: The specific epithet honors Dr. Delane C. Kritsky of Idaho State University in recognition of his outstanding contributions to the taxonomy and systematics of dactylogyrid parasites.

Specimens deposited: Holotype CHIOC 40868 a ; Paratypes CHIOC 40868 b-d

Description: (Based on 4 specimens mounted in Hoyer’s medium). Body robust, flattened dorsoventrally, 318 (250–370; n = 4) long by 166 (80–200, n = 4) greatest width. Tegument thin and smooth. Cephalic lobes moderately developed; three bilateral pairs of head organs; cephalic glands indistinct. Two pairs of eyes, equidistant, anterior pair smaller than posterior. Pharynx spherical 40 in diameter; oesophagus short; two intestinal caeca, confluent posteriorly to gonads, without diverticula. Gonads overlapping, intercaecal; testis, posterior to germarium. Vaginal aperture sinistral; vagina consisting of a sclerotized tube with wide opening; seminal small receptacle with irregular edges ( Fig. 3B ). Vitelline follicles distributed throughout the trunk, absent in the regions surrounding the reproductive organs. Mehlis’ gland and oötype not observed. Copulatory complex comprising male copulatory organ (MCO) and accessory piece. Male copulatory organ as a coiled sclerotized tube, counterclockwise, with 1½ rings 80 (62–91, n = 4) in total length; first ring 18 (17–20, n = 4) in diameter; base tubular with subdivided flange. Accessory piece consisting of two large subunits: anterior subunit curved, with a hook-shaped distal part, where it apparently articulates with the other subunit; second subunit robust as Y-shaped, with irregular base, serves as a guide for the MCO, 24 (20–29, n = 4) long ( Figs. 3A , 6D ). Peduncle short. Haptor sub hexagonal 98 (70–162; n = 4) wide, with anchor/bar complex, 14 pairs of hooks. Anchors dissimilar in size. Ventral anchor with well-developed superficial and deep roots; superficial root elongated, sub rectangular shape, deep root pointed, round, slightly straight shaft, point, 22 (19–26, n = 8) long, base 14 (12–16, n = 8) wide ( Figs. 3C , 6C ); dorsal anchor with straight superficial root, pointed deep root, short shaft and straight elongated point, 16 (14–20, n = 8) long, base 11 (9–12, n = 8) wide ( Figs. 3D , 6C ). Ventral bar V-shaped 26 (25–27, n = 4) long ( Figs. 3E , 6C ); Dorsal bar straight, 33 (28–35, n = 4) long ( Figs. 3F , 6C ). Hooks dissimilar in shape and size. Pairs 1 and 5, 13 (12–15, n = 6) long with straight shank, straight thumb, delicate shaft and tip; FH loop not observed ( Fig. 3G ); pair 2, 3, 4, 6 and 7, 16 (15–20, n = 25) long, shaft composed of two subunits: robust distal subunit with constriction in the medial region; proximal subunit very short, representing about 10% of the total shaft size. Filamentous hook loop approximately 0.2 of the shank length ( Figs. 3H , 6C ).

Remarks: The new species presented the characteristics typical of the genus. Considering the number of rings of the MCO, approximately 1½ - 2 counterclockwise, and the accessory piece divided into two subunits, the new species is similar to Diaphorocleidus affinis (Mizelle, Kritsky & Crane, 1968) , Diaphorocleidus forficata Santos-Neto, Paixão &Domingues, 2024 , Diaphorocleidus guajajara sp. nov., Diaphorocleidus magnus Zago, Franceschini, Abdallah, Müller, Azevedo & Silva, 2021 , D. munimensis , D. neotropicalis , and D. petrosusi . However, D. kritskyi sp. nov. can be easily distinguished from all previously cited species mainly by the unique morphology of the hooks, which possess a robust shaft with a pronounced constriction in the medial region, not observed in any other species of the genus to date.

Figures

FIGURE 3. Diaphorocleidus kritskyi sp. nov.: (A) Copulatory complex (dorsal); (B) Vagina; (C) Ventral anchor; (D) Dorsal anchor; (E) Ventral bar; (F) Dorsal bar; (G) Hook pairs 1, 5; (H) Hook pairs 2, 3, 4, 6, and 7. Scale bars: (A, B).20 µm. (C, D, E, F). 15 µm. (G, H).5 µm.

FIGURE 6. Photomicrographs Diaphorocleidus guajajara sp. nov.: (A) Haptoral structures (dorsal); (B) Copulatory complex (dorsal); Diaphorocleidus kritskyi sp. nov.: (C) Haptoral structures (dorsal); (D) Copulatory complex (dorsal); Urocleidoides mizellei sp. nov.: (E) Haptoral structures (ventral); (F) Copulatory complex (ventral); Curvianchoratus hexacleidus: (G) Haptoral structures (ventral); (H) Dorsal subunit; (I) Copulatory complex (ventral). Scale bars: (A, B, D, G, I). 20 µm. (C). 30 µm. (E). 25 µm, (F). 10 µm. (H) 15 µm.