Anacanthorus circumspatulatus, Santos Neto & Muriel-Cunha & Domingues, 2019

Santos Neto, João F., Muriel-Cunha, Janice & Domingues, Marcus V., 2019, New species of Anacanthorus (Dactylogyridae: Anacanthorinae) from the gills of Hoplerythrinus unitaeniatus and Erythrinus erythrinus (Characiformes: Erythrinidae) of the coastal drainage in the Eastern Amazon, Brazil, Zootaxa 4615 (2), pp. 303-320 : 315-317

Anacanthorus circumspatulatus sp. n.

( Figs. 26–28 )

Type-host: Erythrinus erythrinus (Bloch & Schneider) , Erythrinidae .

Site of infection: Gills.

Type-locality: Igarapé Cururutuia—Caeté River, municipality of Bragança, Pará State, Brazil (1°4’44.55”S 46°44’18.54”W).

Prevalence: 100% of one host examined.

Mean intensity: 2 parasites per host infected.

Other localities: Erythrinus erythrinus (Prevalence: 14% of seven hosts examined; Mean intensity: two parasites per host infected), Igarapé Maratininga—Moju River, Tailândia, Pará State (02º27’55.7”S 048º53’27.6”W).

Specimens deposited: Holotype: CHIOC no. 40028 a. 1 paratype: CHIOC no. 40028 b. 2 vouchers: CHIOC nos. 40029 a–b.

ZooBank registration: The Life Science Identifier (LSID) urn:lsid:zoobank.org:act:37327D29-D790-4145-8086-35543E65EE71 .

Etymology: The specific epithet derives from the Latin (circum = around + spatula = small blades), and refers to the ornament in the form of small blades distributed around the MCO.

Comparative measurements: Table 6 .

Description: (Based on two specimens, mounted in Hoyer’s). Body fusiform 314 (283–346; n=2) long, excluding the haptor, 108 (100–116; n=2) wide at the height of germarium. Cephalic lobes developed; three groups of developed head organs; cephalic glands not observed. Two pairs of ocelli; anterior pair smaller than posterior pair; accessory granules ellipsoids, present or absent. Pharynx spherical 30 (28–32; n=2) long, 34 (32–36; n=2) wide. Esophagus not observed. Two intestinal caeca, confluent, posteriorly. Genital pore not observed. MCO 104 (101– 107; n=2) long, sclerotized, tubular, moderately long, with ornaments in the form of pointed and small interleaved blades distributed helically around the MCO, extending from the medial region to the distal region of the MCO ( Fig. 26 ); accessory piece absent ( Fig. 26 ). Seminal vesicle, prostatic reservoir, and gonads not observed. Peduncle short. Haptor sub-hexagonal 42 (30–54; n=2) long, 74 (56–93; n=2) wide. Similar 4A hooks 9 (n=1) long, with proximal portion dilated, comprising 1/3 of the hook length ( Fig. 27 ). Seven pairs of similar hooks, blade slightly curved and robust 28 (n=1) long; shank with proximal dilatation comprising approximately ½ of its length; point short and curved; thumb slightly depressed and robust ( Fig. 28 ). Hook filament delicate, extending proximally to the shank dilatation ( Fig. 28 ).

Remarks: Based on the MCO morphology, Anacanthorus circumspatulatus sp. n. is similar to Anacanthorus ataidei sp. n., since both species share the presence of a tubular and elongated MCO, with ornaments around it. However, they differ from each other by the hook morphology. Anacanthorus circumspatulatus sp. n. has the shank of hooks with a proximal dilatation comprising approximately ½ of the total shank length, a characteristic that is not observed in Anacanthorus ataidei sp. n., which has the shank of the hook without a proximal dilatation.

Figures

FIGURES 20–28. Anacanthorus cururutuiensis sp. n. 20. Male copulatory organ (MCO); 21. 4A hooks; 22. Hook; Anacanthorus acrophallus sp. n. 23. MCO; 24. 4A hooks; 25. Hook; Anacanthorus circumspatulatus sp. n. 26. MCO; 27. 4A hooks; 28. Hook. Fig. 20 scale of 25µm; Figs. 21–22 scale of 10µm; Figs. 23–25 scale of 10µm; Fig. 26 scale of 25µm; Figs. 27–28 scale of 10µm.