Mymarothecioides ararai Soares and Domingues, 2019

Soares, Geusivam B., Magalhães, Keila X., Silva, Ana Carolina, Carneiro, Jânio S., Barbosa, Lucineia L., Costa, Nayna G. S. & Domingues, Marcus V., 2019, Monogenoids (Polyonchoinea, Dactylogyridae) from Hydrolycus armatus (Characiformes, Cynodontidae) with the description of a new species of Rhinoxenus and the proposal of a new genus from the Xingu River, Pará, Brazil, Zootaxa 4700 (2), pp. 229-245 : 238-240

Mymarothecioides ararai Soares and Domingues n. sp.

( Figs. 27–33 ; 42 )

Type host: Hydrolycus armatus (Jardine & Schomburgk) .

Site: Gills.

Type locality: Volta Grande-Xingu River , municipality of Altamira, Pará State, Brazil (03°21’15,7’’S; 52°11’47,5’’W), collected on June 13, 2015 .

Prevalence: 100% of three hosts examined.

Mean intensity: one parasite per infected host.

Specimens deposited: Holotype, MPEG nº 203; 2 paratypes, MPEG n° 204–205.

Etymology: The specific name honors the Arara native people from the Xingu Basin, Pará, Brazil.

Zoobank Life Science Identifier: (LSID) for Mymarothecioides ararai n. sp. is urn:lsid:zoobank.org:act:85291EFD-9CD5-4746-9A5C-BFBABC761EA5

Comparative measurements: see Table 3 .

Description (based on three specimens, two mounted in Hoyer, one mounted in Gomori’s trichrome): Body robust, fusiform, total length excluding haptor 1,200 (n= 1), total width at level of germarium 300 (n=1) ( Fig. 27 ). Cephalic margin tapered; cephalic lobes poorly developed; three to four bilateral pairs of head organs with rodshaped secretion; cephalic glands not observed. Accessory chromatic granules present in cephalic area. Pharynx spherical, 74 (n= 1) long, 70 (n=1) wide. Testis massive, saccate, 120 (n=1) long, 60 (n=1) wide; prostatic reservoir saculiform, posterior to MCO. MCO, 74 (70–77; n=3) long, robust, with ax-shape at distal portion, small grooves at edges of distal opening; base of MCO with broad sclerotized margin ( Fig. 28 ; 42 ). Accessory piece comprising straight rod, distal portion with subterminal flap with hook, thumb. Germarium bacilliform, 57(n=1) long, 25 (n=1) wide. Eggs, Mehlis’ glands, ootype not observed. Vaginal aperture marginal (dextral), opening at level of vitelline commissure; vaginal vestibule heavily muscular; vaginal canal straight. Seminal receptacle sub-spherical. Uterus delicate. Vitelline follicles dense. Peduncle long, tapered posteriorly; haptor globose, 112 (n=1) long, 137 (n=1) wide. Anchors similar, each with heavily divergent roots covered with sclerotized cap; short slightly curved shaft; elongate point extending to level of tip of superficial root. Ventral anchor, outer 69 (58–79; n=2) long, inner 45 (43–47; n= 2) long, base 55 (47– 62; n= 2) ( Fig. 32 ). Dorsal anchor, outer 61 (52–70; n=2) long, inner 43 (39–47; n= 2) long, base 43 (36–49; n=2) ( Fig. 33 ). Ventral bar, 67 (47–87; n=2) long, 25 (16–35; n=2) wide, slightly curved rod with sigmoid to straight anteromedial projection, rounded ends ( Fig. 30 ). Dorsal bar, 58 (41–74; n=2) long, 12 (8–16; n=2) wide, broadly inverted U-shaped rod with rounded ends ( Fig. 31 ). Hooks similar in shape, 34 (26–40; n=10) long, with upright thumb, rounded, slightly curved shaft and point, shank divided into two units, proximal unit compressed, distal unit inflated, distal unit with 1 ½ size of proximal unit; filamentous hook loop extended near to beginning of distal unit ( Fig. 29 ).

Remarks: Mymarothecioides ararai n. sp. differs from the other congeneric species by possessing a combination of the following features: anchors with heavily divergent roots, short slightly curved shaft, elongate point, an MCO with ax-shape at distal portion, and a massive testis (twice as big than the germarium).

Figures

FIGURES 27–33. Mymarothecioides ararai n. sp. 27. Holotype whole-mount (ventral) (composite). 28. Copulatory complex. 29. Hook. 30. Ventral bar. 31. Dorsal bar. 32. Ventral anchor. 33. Dorsal anchor.

FIGURES 42–45. The copulatory complex of species of Mymarothecioides n. gen. 42. Mymarothecioides ararai n. sp. 43. Mymarothecioides xinguensis n. sp. 44. Mymarothecioides altamirensis n. sp. 45. Mymarothecioides germanoi n. sp.