Sciadicleithrum anapurusensis, Silva & Ottoni & Viana & Saraiva & Justo & Cohen, 2025

Silva, Marciara L., Ottoni, Felipe P., Viana, Diego C., Saraiva, Dennisiane J., Justo, Marcia Cristina N. & Cohen, Simone C., 2025, Sciadicleithrum spp. (Dactylogyridae, Monopisthocotyla) parasitizing Saxatilia brasiliensis (Cichlidae, Cichliformes) from the Munim River Basin, northeastern Brazil, with a description of a new species, Zoosystematics and Evolution 101 (4), pp. 2161-2169 : 2161-2169

Sciadicleithrum anapurusensis sp. nov.

Fig. 2

Host.

Saxatilia brasiliensis (Bloch, 1792) ( Cichlidae , Cichliformes )

Type-locality.

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

Other localities.

Stream Feio, San José village , rural zone of the municipality of Chapadinha, Munim River Basin, Maranhão State, Brazil ( 03°51'18.1"S, 043°17'14.0"W)

Etymology.

The epithet specific refers to the host’s location, the municipality of Anapurus, Maranhão State, Brazil.

Specimens deposited.

Holotype ( CHIOC 40480 ) , Paratypes ( CHIOC: 40481 a, b; 40482; 40483; 40484; 40485; 40486 a, b; 40487)

Number of examined hosts.

64.

Number of parasites.

274.

Prevalence.

64.1 %.

Range of intensity.

1–27 parasites per fish.

Mean intensity.

6.7 parasites per infected fish.

Mean abundance.

4.3 parasites per analyzed fish.

Description.

(Based on 27 specimens mounted in Hoyer’s medium): Body elongated, fusiform, 363 (256–470, n = 27) long, including haptor, by 138 (108–195, n = 27) wide at level of ovary; tegument smooth; three developed cephalic lobes, two lateral and one terminal; four pairs of head organs; cephalic glands indistinct; accessory granules sparse in cephalic area; four equidistant eyespots, eye granules elongate ovate. Pharynx 32 (28–38, n = 5) in diameter; esophagus short; caeca confluent posterior to testis, without diverticula (Fig. 2 A ). Copulatory complex comprises male copulatory organ (MCO) and accessory piece. MCO 111 (92–123, n = 16) long and 18 (15–22, n = 15) wide, composed of 2 clockwise rings; accessory piece 40 (27–50, n = 22) long, 12 (10–14, n = 19) wide, non-articulated to MCO base, bifurcated, with unequal branches at distal portion, the longest widens to distal region, with a subterminal thin projection and terminal end hook-shaped (Fig. 2 B ). Gonads slightly overlapping. Testis dorsal to germarium; vas deferens looping left intestinal cecum; seminal vesicle elongated and single rounded prostatic reservoir. Germarium pretesticular; seminal receptacle, Mehlis’ glands, ootype, eggs, and uterus not observed (Fig. 2 A ). Vagina weakly sclerotized, opening ventrally, forming a bulb near the aperture, vaginal canal long, thin (Fig. 2 C ). Vitellaria distributed throughout the trunk (Fig. 2 A ). Peduncle broad; haptor subhexagonal 97 (75–133, n = 25) wide. Ventral anchor 17 (13–20, n = 26) long, straight, with short deep root, superficial root developed presenting a little hump between the superficial and deep roots, base 14 (11–16, n = 26) wide (Fig. 2 D ); dorsal anchor 31 (23–37, n = 27), long, with differentiated roots, well-developed superficial root, and short and developed deep root, base 19 (14–22, n = 24) (Fig. 2 E ). Ventral bar 27 (22–35, n = 26) long, yoke-shaped, with enlarged extremities and delicate postero-medial umbiliform membrane (Fig. 2 F, G ); dorsal bar 19 (15–22, n = 25) long, straight, with extremities directed posteriorly (Fig. 2 H ). Hook pairs similar in shape and dissimilar in size, pairs 1 and 5 slightly smaller: Pair 1, 11 (11–12, n = 10); pair 2, 12 (12–13, n = 10); pair 3, 13 (12–13, n = 10); pair 4, 13 (13, n = 10); pair 5, 11 (10–12, n = 9); pair 6, 13 (12–13, n = 9); pair 7, 12 (12–13, n = 9) with Ancyrocephalinae distribution, straight shank with protuberant thumb, recurved shaft, point; FH loop about ¾ shaft length.

Remarks.

Sciadicleithrum anapurusensis sp. nov. was allocated in Sciadicleithrum by the diagnostic characters of the genus, such as the male copulatory organ that consists of a spiral tube comprising one to several clockwise rings, gonads overlapping, testis dorsal to ovary, and hooks of similar shape and size and not dilated shank ( Kritsky et al. 1989). Species of the genus were characterized as presenting two variably developed umbeliform membranes on the anterior bar margin, but this character is no longer considered differential, as some species that do not exhibit these characteristics were included in the genus. The new species differs from all congeneric species in the general morphology of the sclerotized structures (anchors, bars, vagina, accessory piece, and the number of MCO rings). The new species is closely related to Sciadicleithrum satanopercae Yamada, Takemoto, Bellay & Pavanelli, 2009 , Sciadicleithrum araguariensis Paschoal, Tavares-Dias, Scholz & Luque, 2016 , Sciadicleithrum edgari Paschoal, Tavares-Dias, Scholz & Luque, 2016 , and Sciadicleithrum amazoniensis Morey, Dávila, Arimuya, Sousa, Cruces & Chero, 2024 by the bifurcated accessory piece, but differs by the presence of postero-medial umbiliform membranes in the ventral bar.

Figures

Figure 2. Sciadicleithrum anapurusensis sp. nov. A. Total, ventral; B. Copulatory complex; C. Vagina; D. Ventral anchor; E. Dorsal anchor; F, G. Ventral bar; H. Dorsal bar; I. Hook. Scale bars: 100 µm (A); 20 µm (B, D – H); 40 µm (C); 5 µm (I).