Gyrodactylus polyadenus Vianna & Boeger 2019, n. sp.
Creators: name: Vianna, Rogério T.
name: Boeger, Walter A.
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Platyhelminthes
Monogenea
Gyrodactylidea
Gyrodactylidae
Gyrodactylus
Gyrodactylus polyadenus

description: 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).
description: Published as part of 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, pp. 87-93 in Zootaxa 4551 (1) on page 90, DOI: 10.11646/zootaxa.4551.1.6, http://zenodo.org/record/2622619