Gyrodactylus anaspidus, 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 : 88-90

Gyrodactylus anaspidus n. sp.

( Figs. 1–5 )

Type host: Pareiorhaphis parmula Pereira, 2005 (Loricariidae) .

Site of infection. Body surface.

Type-locality. Rio dos Patos (25 o 50, 646′S, 49 o 43, 263′W), Lapa, Paraná, Brazil, April 2004.

Specimens studied. holotype—MZUSP 7964, 8 paratypes—MZUSP 7965a–h.

Etymology. The specific epithet originates from Greek and refers to the absence of shield on the superficial bar (an = without, absence; aspidus = shield).

Description. Body fusiform 271 (235–299, n = 7) long, greatest width at level of midlength 66 (42–84, n = 7). Unicellular cephalic glands, head organ conspicuous. Proximal pharyngeal bulb 26 (23–35, n = 7) long, 31 (25–38, n = 7) wide, ovate; distal pharyngeal bulb 22 (17–30, n = 7) long, 25 (18–33, n = 7) wide, ovate. MCO 9 (8–11, n = 3) in diameter, bulbous, armed with spine, one row of spinelets, with 9–11 morphologically different spinelets. Seminal vesicle ovate, connected to the MCO by a short duct. Testis 20 (15–30, n = 5) diameter, rounded, ventral, overlapped to germarium. Germarium 15 (13–17, n = 5) long, 18 (14–25, n = 5) wide, ovate. Uterus with up to two generations of embryos. Follicles, apparently glandular, disposed ventrally in U-shape, posterior to the terminations of the caeca. Haptor 59 (50–74, n = 5) long, 63 (56–70, n = 3) wide. Anchor 43 (41–45, n = 6) long; shaft slightly curved; point straight; superficial root short; deep root knob like. Superficial bar 16 (12–20, n = 4) long, 6 (7–9, n = 4) wide, subrectangular. Shield on the superficial bar absent. Deep bar 11 (10–13, n = 3) long, 1 (1–2, n = 3) wide, ribbon shaped, with small constriction near midlength. Hook shank 16 (14–19, n = 6) long; hooklet 8 (6–10, n = 6) long; point and shaft continuous, evenly curved; shelf concave, toe pointed; heel rounded.

Remarks. Gyrodactylus anaspidus n. sp. has no shield on the superficial bar. The absence of a shield in Gyrodactylus species is not an original observation—it was observed in G. emembranatus Malmberg, 1970 , G. longidactylus Geets, 1998 , G. funduli Hargis, 1955 and Gyrodactylus inesperatus Boeger, Ferreira, Vianna & Patella, 2014 , among others ( Boeger et al. 2014).

Gyrodactylus anaspidus n. sp. possesses a hooklet most similar to G. superbus and has a toe pointed, as described for G. corydori , G. superbus and G. scleromystaci Bueno-Silva & Boeger, 2014 . Moreover, all of these species are different from G. anaspidus n. sp. by presenting a shield on the superficial bar ( Popazoglo & Boeger 2000; Bueno-Silva & Boeger 2009, 2014).

The new species can be differentiated from other Gyrodactylus species described previously by their species of neotropical siluriform hosts and by the armature of the MCO. Double rows of spinelets on the MCO are present in G. anisopharynx , which has 3–4 (internal row) and 2–3 (external row); G. bueni , which has 3–4 and 2–3; G. corydori , which has 4–5 and 2–3; G. major , which has 5–7 and 4–6; G. samirae , which has 3 and 4–6; G. scleromystaci , which has 5–7 and 4–5; and G. superbus , which has 4 and 5. Gyrodactylus pimelodellus exhibits one row of six spinelets while G. anaspidus n. sp. has 9–11 spinelets in one row (see Popazoglo & Boeger 2000; Bueno-Silva & Boeger 2009; 2014).

Gyrodactylus anaspidus n. sp. co-occurs with Aglaiogyrodactylus salebrosus Kritsky, Vianna & Boeger, 2007 , Aglaiogyrodactylus ctenistus Kritsky, Vianna & Boeger, 2007 and A. conei Kritsky, Vianna & Boeger, 2007 , all of which are oviparous gyrodactylids and parasitize P. parmula within the same locality.

Figures

FIGURES 1–5. Gyrodactylus anaspidus n. sp. (Gyrodactylidae, Monogenoidea) on the body surface of Pareiorhaphis parmula (Loricariidae), holotype. 1. Whole body, ventral view. 2. MCO. 3. Hook. 4. Complex of anchors, superficial and deep bars. 5. Anchor.