Urocleidoides tenuis Zago, Yamada, Yamada, Franceschini, Bongiovani & Silva, 2020

Oliveira, Glaucya Silva De, Silva, Reinaldo José Da, Vieira, Fernando Emmanuel Gonçalves & Acosta, Aline Angelina, 2021, Urocleidoides spp. (Monogenea: Dactylogyridae) from the gills of Parodon nasus (Characiformes: Parodontidae) from a Brazilian stream with descriptions of two new species, Zootaxa 5081 (4), pp. 535-550 : 537-538

Urocleidoides tenuis Zago, Yamada, Yamada, Franceschini, Bongiovani & Silva, 2020

( Fig. 1A–I ; 2G–I )

Material studied. 2 vouchers from Zago et al. (2020) ( CHIBB 600L, 601L); 15 specimens from Parodon nasus from the Indiana stream .

Type host. Apareiodon piracicabae (Eigenmann) ( Characiformes : Parodontidae ).

Type locality. Streams of the Middle Paranapanema River (23°9’40.8’’S, 48°53’7.3’’W), Upper Paraná River basin, state of São Paulo, Brazil .

Additional host. Apareiodon affinis (Steindachner) and Parodon nasus Kner ( Characiformes : Parodontidae ).

Site of infestation. Gills

Infestation rate. prevalence of 100% (N=118); minimum mean intensity of infestation and minimum mean abundance of 14.05 ± 1.8 (5–40) [present study].

Specimens deposited. 5 vouchers ( CHIOC 39716a–c; 39717 a–b); 5 vouchers ( INPA 840a–e).

Representative DNA sequence. 1,384 bp long of partial sequence of the 28S rDNA (D1–D3 region). Genbank accession number OK465455 ; paragenophore INPA (840f).

Morphological observations (measurements provided in Table 1 ). Urocleidoides tenuis was described by Zago et al. (2020) for specimens found on the gills and body surface of the parodontid hosts A. piracicabae and A. affinis from streams of the Middle Paranapanema River, Brazil. The specimens found in the present study on the gills of P. nasus were identified as U. tenuis based on the original description and comparison with paratypes ( CHIBB 600L, 601L). Subtle differences were found between some measurements of the specimens from the present study and Zago et al. (2020) ( Table 1 ). In the original description, U. tenuis presents a lateral expansion around the base of the male copulatory organ ( MCO), whereas the specimens of the present study have a base surrounded by sheath-like sclerotizations as two lateral expansions ( Fig. 1C ; 2G ). The vaginal sclerite of the specimens from the present study presented greater length compared to Zago et al. (2020) ( Table 1 ); additionally, it was possible to better visualize the distal hook of the vaginal sclerite (as stated in the original description), in the specimens of the present study (see Fig. 1I ; Fig. 2H ). In the original description of U. tenuis , hook pair 7 appears as having the same size as pairs 2, 3, 4, and 6. However, in the specimens of the present study, it was observed that hook pair 7 is smaller than pairs 2, 3, 4, and 6, presenting size similar to hook pairs 1 and 5 (see Table 1 ; Figure 1G ; 2I ). This study is the second record of U. tenuis also from a parondontid host.

Figures

FIGURE 1. Sclerotized structures of Urocleidoides tenuis from Indiana stream (Capivara River, Tietê River, Upper Paraná River basin), municipality of Botucatu, São Paulo State, Brazil. A—ventral anchor; B—ventral bar; C—male copulatory complex (ventral view); D—dorsal bar; E—dorsal anchor; F—hook pairs 1 and 5; G—hook pair 7; H—hook pairs 2, 3, 4, and 6; I—vaginal sclerite. Scale bar: 10 μm.

FIGURE 2. Phase contrast photomicrographs of Urocleidoides indianensis n. sp.: A—male copulatory complex; B—vaginal sclerite and vaginal tube; C—haptor. Urocleidoides parodoni n. sp.: D—male copulatory complex; E—vaginal sclerite and vaginal tube; F—haptor. Urocleidoides tenuis: G—male copulatory complex (ventral view); H—vaginal sclerite and vaginal tube (arrow); I—haptor. Scale bar: 10 μm.