Anacanthorus douradensis, Cohen, Simone Chinicz, Kohn, Anna & Boeger, Walter A., 2012

Cohen, Simone Chinicz, Kohn, Anna & Boeger, Walter A., 2012, Neotropical Monogenoidea. 57. Nine new species of Dactylogyridae (Monogenoidea) from the gill of Salminus brasiliensis (Characidae, Characiformes) from the Paraná River, State of Paraná, Brazil, Zootaxa 3149, pp. 57-68 : 61-62

Anacanthorus douradensis sp. n.

( Figs. 7, 8 )

Type locality. Paraná River below and above of the reservoir of Itaipu Hydroelectric Power Station in the locality of Guaira (24º04’48’’S, 54º15’21’’W), State of Paraná, Brazil

Prevalence. 19.2% (5 out of 26 fishes examined)

Specimens studied. Holotype, CHIOC 37594; 8 paratypes, CHIOC 37584, 37599a–b, 37610–37611, 37616, 37654, 37679.

Etymology. The specific name refers to the common regional name of the host (“dourado”).

Description. (Based on 14 specimens). Body fusiform, 1,204 (850–1,500; n=12) long, 342 (180–420; n=12) wide. Tegument with subcircular scales distributed from peduncle to level of MCO. Cephalic lobes well developed. Eyes 4, posterior pair slightly farther than anterior pair; accessory granules spread in cephalic region. Pharynx spherical, 81 (56–110; n=11) long, 68 (44–90; n=11) wide. Haptor 140–162 (n=2) wide, slightly bilobed, with concave posterior border, 7 pairs of hooks with anacanthorine distribution (4 ventral, 3 dorsal pairs of hooks) and 2 pairs (1 dorsal, 1 ventral) of 4A’s. Anchors, bars absent. Hooks 16–23 (19; n=16), similar in shape and size, with depressed thumb, curved shaft, short recurved point, shank proximally expanded with indented circular foramen; FH loop well developed, extending to distal subunit. MCO 187 (178–227; n=12) long, a loose spiral with funnelshaped base, distal end flattened, expanded, lateral to longitudinal axis of MCO. Accessory piece 178 (125–200; n=11) long, articulated to MCO base by proximal process, composed of single rod-shape section that bifurcates into two branches at about 1/5 of its length; short branch rod shape, with blunt distal end; longer branch proximally bent on itself, with expanded distal end. Testis postgermarial, 138 (108–175; n=5) long; seminal vesicle elongate, a dilation of vas deferens; two prostatic reservoirs lying beneath (dorsal to) MCO; vas deferens looping left intestinal cecum. Germarium 70 (40–110; n=4) long, 78 (68–90; n=4) wide, subovate. Vitellaria in two bilateral fields of trunk, from pharynx to the posterior region of testes, coextensive with intestinal ceca. Egg 56 long, 32 wide, oval, lacking filament. Oviduct, ootype not observed. Metraterm with delicate wall, non-sclerotized.

Remarks. Anacanthorus douradensis n. sp. appears closely related to Anacanthorus colombianus Kritsky & Thatcher, 1974 from the gills of S. affinis Steindachner from Colombia mainly by sharing a MCO composed of a loosely spiraled tube. Further similarities that suggest their phylogenetic proximity are related to the presence of an articulated and bifurcated accessory piece, with one of the rami presenting a thumb-like structure, and the expanded distal end of the MCO. The two species may be differentiated by 1) the bifurcation of the accessory piece, which in A. colombianus is located in the mid-length of the accessory piece while in A. douradensis sp. n. it occur close to the proximal portion of the structure; 2) the rami of the accessory piece of the new species are subequal with a long expanded and a short blunt ramus (about the same length and pointed in A. colombianus ); and 3) based on the original illustrations of A. colombianus ( Fig. 4 , Kritsky & Thatcher 1974), the MCO of the new species appears to have more coils (about 6 coils in the new species and 3 coils in the MCO of A. colombianus ).

Figures

FIGURES 1 – 10. Sclerotized parts of Anacanthorus spp. from the dourado, Salminus brasiliensis, from Paraná River, Brazil. Figs. 1 – 2. Anacanthorus bicuspidatus 1. Copulatory complex (dorsal view). 2. Hook. Figs. 3 – 4. Anacanthorus contortus sp. n 3. Copulatory complex (dorsal view). 4. Hook. Figs. 5 – 6. Anacanthorus daulometrus sp. n. 5. Copulatory complex (ventral view). 6. Hook. Figs. 7 – 8. Anacanthorus douradensis sp. n.. 7. Copulatory complex (dorsal view). 8. Hook. Figs. 9 – 10. Anacanthorus kruidenieri sp. n. 9. Copulatory complex (dorsal view). 10. Hook. Fig. 7 is presented to the 50 µm scale; Figs. 2, 4, 6, 8 and 10 to the 10 µm scale; Figs. 1, 3, 5 and 9 to the 30 µm scale.