Unilatus luciarappae, Branches & Muriel-Cunha & Domingues, 2021

Branches, Bárbara, Muriel-Cunha, Janice & Domingues, Marcus Vinícius, 2021, Two new species of monogenoidean parasites (Platyhelminthes: Neodermata) of ornamental fish of Loricariidae (Siluriformes) from the Xingu River, Brazilian Amazon, Zoologia (e 65471) 38, pp. 1-10 : 5-6

Unilatus luciarappae sp. nov.

http://zoobank.org/ 53487FBA-2F56-4430-A36F-5CEC198A16CC

Figs 11–19

Description. Based on 13 specimens, 11 mounted in Hoyer’s medium, two mounted in Gomori´s trichrome. Body fusiform, 279 (175–385; n = 6) long, excluding haptor, 76 (50–100; n = 7) wide at level of germarium; tegument smooth ( Fig. 11). Cephalic area with terminal lobes, poorly developed or absent; bilateral head organs present, three pairs, with rod-shaped secretion; cephalic glands not observed in studied specimens. Eyespots, accessory chromatic granules absent. Mouth subterminal, midventral; pharynx muscular, spherical, 19 (17–22; n = 9) in diameter; esophagus elongated; two intestinal ceca, confluent posteriorly to gonads, lacking diverticula. Genital pore, opening dextroventral, near median line of body at level of cecal bifurcation; genital atrium muscular. Intercecal gonads apparently overlapping, testis not observed. Vas deferens looping left intestinal cecum; seminal vesicle representing a dilation of vas deferens, distal portion looping posteriorly before entering base of MCO. Copulatory complex comprising sclerotized MCO, accessory piece. MCO spiral, 103 (89–120; n = 11) long, counterclockwise, with approximately 18–19 coils, non-articulated to accessory piece, base with sclerotized edge, median distal portion bulbous, final distal portion tapered ( Fig. 12). Accessory piece 72 (43–100; n = 6) long, straight or slightly sinuous rod, comprising approximately 2/3 of MCO length; distal portion of accessory piece with subterminal two small flaps, guiding distal portion of MCO. Single prostatic reservoir, saccate, anterior to base of MCO, 22 (n = 1) largest diameter, 13 (n = 1) smallest diameter. Germarium fusiform, 37 (n = 1) long, 15 (n = 1) wide. Mehlis’ glands, ootype not observed. Vagina single, opening ventrally (dextral) at level of vitelline commissure; vaginal vestibule muscular; vaginal canal heavily sclerotized, sigmoid, with a loop in distal portion. Seminal receptacle subspherical, at level of anterior margin of germarium, ventral. Vitelline follicles dense. Egg ovate elongate, 62 (55–68; n = 4) long excluding filament, 29 (25–33; n = 4) wide ( Fig. 13). Egg filament comprising twice the size of the egg. Haptor trapezoidal, 77 (55–105; n = 4) long, 49 (25–75; n = 5) wide. Anchors dissimilar, in tandem, (both) on dorsal side of haptor. Anterior anchor, 30 (30–32; n = 11) long, anchor base, 19 (16–20; n = 11) long ( Fig. 16), with superficial root straight, elongate, distal portion round; inconspicuous or reduced deep root; slightly curved shaft; point elongate, extending to level of superficial root, tapered; filament of anterior anchor extends from deep root to median portion of shaft. Accessory structures (one pair) associated with anterior anchor ( Fig. 11). Posterior anchor 37 (35–40; n = 9) long, anchor base 13 (12–14; n = 9) long ( Figs 18–19) with superficial, deep roots not differentiated; anchor base covered with sclerotized layer with a small protuberance for articulation of posterior bar; shaft, point uniformly curved, point extending beyond level of tip of superficial root; filament of posterior anchor in anterior portion of shaft. Anterior bar open-V shaped, 33 (27–41; n = 8) long, 4 (3–5; n = 8) wide, with round ends ( Fig. 15); posterior bar open-V shaped, 71 (61–81; n = 7) long, 8 (7–10; n = 8) wide, with tapered, rounded ends ( Fig. 14). Hooks similar in shape, 11 (10–12; n = 11) long, with erect thumb, short, slightly curved shaft, shank divided into two subunits; hook filament not observed ( Fig. 17).

Type host. Panaque armbrusteri ( Loricariidae : Hypostominae ).

Site of infection. Gill filaments.

Type locality. Volta Grande , Xingu River ( Amazon Basin ; Amazonas, Xingu , Iriri , Paru Sub-basin), municipality of Altamira, Pará, Brazil (03°21’15,7”S; 52°11’47,5”W) .

Prevalence. 67% of three hosts examined.

Mean intensity. 20 parasites per infected host.

Specimens deposited. Holotype, MPEG 00322 ; 12 Paratypes, MPEG 00323–00334 .

Etymology. The species is named in honor of Dra Lucia Rapp of the Instituto Nacional de Pesquisas da Amazônia (INPA), Brazil, in recognition of her contribution to the knowledge of loricariid diversity.

Remarks. Unilatus luciarappae sp. nov. resembles U. brittani by to the morphology of the anterior anchor/bar complex. However, U. luciarappae sp. nov. is distinguished by having a posterior anchor with shaft and uniformly recurved point, and posterior bar with tapered ends, while U. brittani has a posterior anchor with a slightly curved shaft and long and straight point, as well as a posterior bar with expanded and rounded ends. These species can also be differentiated by the ratio of the distance from the proximal portion of the MCO to the dilation of the MCO and the distance from the dilation of the MCO to the distal end of the MCO ( Unilatus luciarappae sp. nov. 1:2; U. brittani 1:1).