Gyrodactylus polyadenus, Vianna & Boeger, 2019

Vianna, Rogério T. & Boeger, Walter A., 2019, Neotropical Monogenoidea. 60. Two new species of Gyrodactylus (Monogenoidea: Gyrodactylidae) from the armored-catfish, Pareiorhaphis parmula Pereira (Loricariidae) and from the cascarudo, Callichthys callichthys (Linnaeus) (Callichthyidae) from Brazil, Zootaxa 4551 (1), pp. 87-93 : 90

Gyrodactylus polyadenus n. sp.

( Figs. 6–10 )

Type host: Callichthys callichthys (Linnaeus, 1758) (Callichthyidae) .

Site of infection. Body surface.

Type locality. Córrego dos Macacos stream (22° 06′ 35, 2″S, 47° 49′ 12, 5″W), São Carlos, São Paulo, Brazil, May 2005 .

Specimens studied. holotype—MZUSP 7966; 14 paratypes—MZUSP 7967a–n.

Etymology. The specific name originates from Greek and refers to the several follicle masses near the testis and glands in the peduncle region (poly = several, very; adenos = gland).

Description. Body fusiform, elongate, 570 (460–659, n = 15) long, greatest width in the midlength, at level of gonads, 89 (66–110, n = 15) wide. Unicellular cephalic glands, head organ conspicuous. Proximal pharyngeal bulb 28 (22–33, n = 9) diameter, glandular; distal pharyngeal bulb 24 (19–27, n = 9) in diameter, muscular. MCO 14 (13–17, n = 6) in diameter, bulbous, armed with a spine, and 6–8 spinelets disposed in a single row. Seminal vesicle, ovate, connected to the MCO by a short duct. Two bilateral prostatic glands connected to MCO by short ducts. Testis 34 (28–42, n = 7) long, 27 (21–37, n = 7) wide, ovate, ventral. Germarium 25 (18–38, n = 8) long, 20 (12–37, n = 8) wide, ovate. Uterus with up to two generations of embryos. Polynucleated follicle mass antero- and post-testis. Peduncular mononucleated cells, apparently glandular. Haptor 70 (69–71, n = 3) long, 67 (59–73, n = 3) wide. Anchor 49 (47–50, n = 4) long; shaft and point straight. Superficial bar 13 (10–14, n = 5) long, 9 (8–9, n = 5) wide, subrectangular, with short anterolateral projections. Superficial bar shield is present, rounded, and inconspicuous under standard light microscopy. Deep bar 9 (7–13, n = 5) long, 3 (2–4, n = 5) wide, with a small indentation near the midlength tapering near the attachment to the anchors. Hook shank 14 (12–15, n = 3) long; hooklet 6 (4–7, n = 3) long; point slightly curved; shaft straight; shelf convex; toe triangular; heel subrectangular, elongate.

Remarks. Seven species of Gyrodactylus parasites from species of Callichthyidae were described in the Neotropical Region: G. anisopharynx , G. bueni , G. corydori , G. major , G. scleromystaci , G. samirae , and G. superbus . These species all present a conspicuous shield on the superficial bar, a hooklet with rounded heel and slightly curved point, delicate deep bar, and a double row of spinelets on the MCO ( Popazoglo & Boeger 2000; Bueno-Silva & Boeger 2009; 2014). Exceptions occur in G. pimelodellus , which presents an MCO with one row of spinelets, and a hooklet with a toe and rounded heel ( An et al. 1991).

Gyrodactylus polyadenus n. sp. can be distinguished from these species by presenting a hooklet with a subrectangular heel and triangular toe, continuous to the slightly concave base, with a relatively wide, deep bar with tapering extremities, and a single row of spinelets (6–8 spinelets).

Figures

FIGURES 6–10. Gyrodactylus polyadenus n. sp. (Gyrodactylidae, Monogenoidea) on the body surface of Callichthys callichthys (Callichthyidae), holotype. 6. Whole body, ventral view. 7. Hook. 8. MCO and seminal vesicle. 9. Complex of anchors, superficial and deep bars, shield. 10. Anchor.