Anacanthorus lacinimentulatus sp. n.

(Figs. 16–19)

Type-host: Hoplerythrinus unitaeniatus (Spix & Agassiz), Erythrinidae .

Site of infection. Gills.

Type-locality: Igarapé Arinandeua—Guamá River, municipality of São Miguel do Guamá, State of Pará, Brazil (1°37’42.50”S 47°29’45.06”W).

Other localities: Hoplerythrinus unitaeniatus (Prevalence: 16% of six hosts examined; Mean intensity: two parasites per host infected), Igarapé Maratininga—Moju River, municipality of Tailândia, Pará State (02º27’55.7”S 048º53’27.6”W).

Prevalence: 33% of three hosts examined.

Mean intensity: 1 parasite per host infected.

Specimens deposited: Holotype: CHIOC no. 40031 a. 2 paratypes: CHIOC nos. 40031 b–c. 2 vouchers: CH- IOC nos. 40031 a–b.

ZooBank registration: The Life Science Identifier (LSID) urn: lsid:zoobank.org:act: CEE15CB2-A8F7-44E8- 8743-BC2FBC98CF65.

Etymology: The specific epithet derives from the Latin (lacini = flap + mentul = penis), and refers to the flap morphology in the distal region of the MCO.

Comparative measurements: Table 4.

Description: (Based on three specimens, two mounted in Gomori trichrome and one mounted in Hoyer’s). Body fusiform 380 (337–410; n=3) long, excluding the haptor, 66 (52–85; n=3) wide at the height of germarium (Fig. 16). Four cephalic lobes developed; three groups of head organs; cephalic glands not observed (Fig. 16). Two pairs of ocelli, anterior pair smaller than the posterior pair; accessory granules absent (Fig. 16). Pharynx oval or subspherical 29 (28–30; n=3) long, 24 (20–28; n=3) wide; oesophagus elongated (Fig. 16). Two intestinal caeca confluent, posterior to the gonads (Fig. 16). Genital pore not observed. MCO 32 (24–38; n=3) long, 8 (6–9; n=3) wide, sclerotized, simple and tubular, with extrovert flap skirting the distal region of the MCO (Fig. 17); accessory piece absent (Fig. 17). Seminal vesicle long, ascending from the vas deferens and looping the intestinal caecum near the testis (Fig. 16). Gonads not overlapping; germarium 43 (36–49; n=2) long, 21 (15–26; n=2) wide; testis posterior to germarium, oval 45 (44–46; n=2) long, 24 (22–25; n=2) wide (Fig. 16). Prostatic reservoir not observed. Peduncle elongated (Fig 16). Haptor bilobed 34 (27–42; n=3) long, 52 (45–60; n=3) wide (Fig. 16). Similar 4A hooks, with a proximal region, dilated, comprising ¼ of the hook length (Fig. 18). Seven pairs of similar hooks 27 (n=1) long; blade slightly curved, point short and curved, shank with proximal dilatation 12 (n=1) long, comprising approximately ½ of the total shank length; thumb erect and short (Fig. 19). Hook filament delicate, extending until near the shank dilatation (Fig. 19).

Remarks: Anacanthorus lacinimentulatus sp. n. differs from the other Anacanthorus species for having MCO with extrovert flap skirting its distal region and the absence of accessory piece. The hooks have a shank with proximal dilatation comprising approximately ½ of the total shank length.