Anacanthorus acrophallus, 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

Anacanthorus acrophallus sp. n.

( Figs. 23–25 )

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).

Prevalence: 66% of three hosts examined.

Mean intensity: 1,5 parasites per host examined.

Specimens deposited: Holotype: CHIOC no. 40024. 2 paratypes: CHIOC nos. 40025 a–b.

ZooBank registration: The Life Science Identifier (LSID) urn:lsid:zoobank.org:act:DFCCF79B-0944-4AC9-A9DB-4391828B8C1B .

Etymology: The specific epithet derives from the Greek (acro = point + phallus = penis) and refers to the MCO morphology, based on the presence of a pointed flap in its distal portion.

Description: (Based on three specimens mounted in Hoyer’s). Body fusiform 468 (425–512; n=2) long, excluding the haptor, 117 (115–120; n=2) wide at the height of germarium. Four cephalic lobes developed; three groups of head organs; cephalic glands not observed. Two pairs of ocelli, posterior pair slightly bigger than the anterior pair; accessory granules not observed. Pharynx oval 45 (36–60; n=3) long; 34 (27–47; n=3) wide; oesophagus moderately elongated. Two intestinal caeca confluent and posterior to the gonads. Genital pore not observed. MCO 27 (26–29; n=3) long, 10 (9–11; n=3) wide, sclerotized and short, with a small pointed sinistral flap (ventral view) ( Fig. 23 ); accessory piece absent ( Fig. 23 ). Seminal vesicle, germarium, prostatic reservoir and testicles not observed. Uterus with anterior portion slightly sclerotized. Haptor 57 (50–65; n=3) long, 74 (47–95; n=3) wide. Peduncle short or elongated. Similar 4A hooks with portion posterior slightly dilated 14 (n=1) long ( Fig. 24 ). Seven pairs of similar hooks 23 (22–24; n=3) long; blade relatively long and recurved, point short and curved, shank with proximal dilatation 6 (6–7; n=3) long, comprising 1/3 of the total shank length, thumb robust and depressed ( Fig. 25 ). Hook filament delicate, extending until the half of the shank, proximal to the dilatation ( Fig. 25 ).

Remarks: Anacanthorus acrophallus sp. n. is similar to Anacanthorus scyphophallus sp. n. and A. brevicirrus due to the presence of a short and tubular MCO. However, Anacanthorus acrophallus sp. n. differs from Anacanthorus scyphophallus sp. n. mainly by the hook morphology since Anacanthorus acrophallus sp. n. has hooks with shank showing a proximal and robust dilatation, comprising 1/3 of the shank length, and a short, extended and slightly depressed thumb. On the other hand, Anacanthorus scyphophallus sp. n. has hooks shank with shank showing a proximal dilatation comprising ½ of the shank length, and a rounded and short thumb. Anacanthorus brevicirrus differs from Anacanthorus acrophallus sp. n. also by the hook morphology since it has a small bulb with a translucid spot in the proximal portion of the shank, which is not found in Anacanthorus acrophallus sp. n.

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.