Sciadicleithrum araguariensis Paschoal, Scholz, Tavares-Dias & Luque, 2016

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 araguariensis Paschoal, Scholz, Tavares-Dias & Luque, 2016

Fig. 3

Type host and locality.

Saxatilia labrina (Spix & Agassiz, 1831) [= Crenicichla labrina (Spix & Agassiz, 1831) ] ( Cichlidae , Cichliformes ), Araguari River in Ferreira Gomes ( 0°52'N, 51°12'W), Amapá State, Brazil .

Other host.

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

Other localities.

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

Specimens deposited.

Voucher ( CHIOC 40488 ; 40489; 40490; 40491 a-d) .

Number of examined hosts.

64.

Number of parasites.

83.

Prevalence.

50 %.

Range of intensity.

1–6 parasites per fish.

Mean intensity.

2.6 parasites per infected fish.

Mean abundance.

1.3 parasites per analyzed fish.

Redescription.

(based on 20 specimens mounted in Hoyer’s medium; original measurements are presented in brackets): Body elongated, fusiform, 342 (250–397, n = 15) [412–430 (419; n = 8)] long, 141 (71–198, n = 17) [95 (90–102; n = 6)], width at the region near vagina; tegument smooth; three cephalic lobes, two lateral and one terminal; four well-developed eye spots, posterior pair larger than anterior; pharynx spherical, 35 (32–41, n = 6) [22 (21–24; n = 4)] in diameter (Fig. 3 A ). Copulatory complex comprises male copulatory organ (MCO) and accessory piece. MCO tubular, thin, with 1.5 to 2 clockwise rings, 97 (75–110; n = 9) [100 (92–104; n = 4)] long. Accessory piece 29 (21–38; n = 7) [40 (38–42; n = 5)] long by 12 (8–15; n = 9) wide, non-articulated to the MCO base, formed by a bifurcated tube at mid-region and a slightly sclerotized cap at distal region (Fig. 3 B ). Vagina strongly sclerotized, vaginal aperture bulbous-shaped, and vaginal canal long (Fig. 3 C ). Egg 60 (n = 1) in diameter. Haptor 101 (81–128, n = 17) [43 (40–48; n = 8)] wide (Fig. 3 A ); ventral anchor 18 (15–22, n = 17) [26 (24–28; n = 7)] long, base 12 (11–16, n = 17) [22 (21–24; n = 7)], superficial root elongated and short deep root, presenting a little hump between the roots, straight shaft and recurved point (Fig. 3 D ); dorsal anchor 27 (23–30, n = 16) [34 (31–39; n = 7)] long, base, 13 (11–18, n = 16) [32 (30–34; n = 6)] base, slightly elongated superficial root, inconspicuous deep root (Fig. 3 E ); ventral bar 30 (24–34, n = 20) [31 (29–34; n = 4)] long, yoke-shaped, with expanded ends and delicate umbelliform membrane (Fig. 3 F ); dorsal bar 22 (18–26, n = 14) [22 (21–25; n = 5)] long, straight, with expanded ends directed posteriorly and postero-medial umbelliform membrane (Fig. 3 G ). Hooks of similar shape and size: Pair 1, 11 (10–12, n = 12); pair 2, 12 (11–12, n = 12); pair 3, 13 (12–13, n = 12); pair 4, 13 (12–13, n = 11); pair 5, 11 (10–11, n = 6); pair 6, 12 (12–13, n = 9); pair 7, 12 (12–13, n = 11) [14 (12–16; n = 9)] with ancyrocephaline distribution, straight shaft, prominent thumb, recurved point; FH loop about ¾ shaft length (Fig. 3 H ).

Remarks.

Sciadicleithrum araguariensis was originally described from specimens of Crenicichla labrina (now recognized as Saxatilia labrina ) collected from the Araguari River in Ferreira Gomes, Amapá State, Brazil. The species is now reported in S. brasiliensis from Maranhão State. The specimens analyzed in this study are morphologically similar to those described originally, except for the presence of a cap at the distal portion of the accessory piece. While the original description characterized the accessory piece as Y-shaped and proximally bent, it did not mention the structure observed in the current specimens. Upon re-examining the holotype and paratypes, the cap was observed by the authors of this study.

Figures

Figure 3. Sciadicleithrum araguariensis. A. Total, ventral; B. Copulatory complex; C. Vagina; D. Ventral anchor; E. Dorsal anchor; F. Ventral bar; G. Dorsal bar; H. Hook. Scale bars: 100 µm (A); 20 µm (B, D – G); 40 µm (C); 5 µm (I).