Jainus peruensis Cruces & Santillán & Silvera & Morey & Rubin & Chero 2024, n. sp.
Creators: name: Cruces, Celso L.
name: Santillán, Luis A.
name: Silvera, Jordan F.
name: Morey, Germán Augusto Murrieta
name: Rubin, Veronica
name: Chero, Jhon D.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Platyhelminthes
Monogenea
Dactylogyridea
Ancyrocephalidae
Jainus
Jainus peruensis

description: Jainus peruensis n. sp.
(Fig. 2A–G)
Type-host: Brycon amazonicus (Spix & Agassiz) (Characiformes: Bryconidae).
Site on host: Gill filaments.
Type locality: Madre de Dios River (12°35’S, 69°10’W), Puerto Maldonado City, Madre de Dios region, Peru.
Type material: Holotype, MUSM-HEL 5392; 9 paratypes, MUSM-HEL 5393 a-i.
Etymology: The specific epithet refers to the country where the species was found.
Description: Based on 10 specimens. Body robust, fusiform (Fig. 2A), 311–758 (649; n = 10) long; greatest width 144–292 (226; n = 10) usually near mid-length. One terminal, 2 bilateral cephalic lobes poorly developed. Three bilateral pairs of conspicuous head organs. Eyes present. Pharynx spherical, 20–23 (21; n = 10) in diameter. Group of well-developed secretory gland-cells lying on peduncle. Haptor sub-quadrangular (Fig. 2A), poorly differentiated from body proper, 58–85 (67; n = 10) long; 72–137 (91; n = 10) wide.Anchors dissimilar in shape and size (Fig. 2B, C). Ventral anchor 20–23 (21; n = 10) long, base 7–9 (8; n = 10) wide, rodlike deep root, superficial root bearing irregular sclerotized ornamentation, blade-like shaft and point. Dorsal anchor 40–43 (42; n = 10) long, base 7–8 (7; n = 8) wide, inconspicuous deep root, well-developed superficial root, straight shaft and recurved point. Ventral bar delicate, rod-shaped, with medial projection and slightly curved ends (Fig. 2D), 20–27 (24; n = 7) long. Dorsal bar robust, almost V-shaped, grooved (Fig. 2E), 27–37 (33; n = 6) long. Hooks similar in shape and size, 11– 13 (12; n = 8) long, each with upright thumb, slender and straight shank, and short and recurved point; filamentous hook (FH) about ¾ length (Fig. 2F). MCO 41–49 (46; n = 10) long, slender tube, with crenulated base, forming counterclockwise loop at proximal end (Fig. 2G). Accessory piece unarticulated to MCO base, sinuous proximally, well expanded distally, with scythe-shaped distal end (Fig. 2G), 18–29 (27; n = 6) long. Testis subspherical, wide; prostatic reservoir and prostatic glands not observed. Ovary elongate, 112–172 (142; n = 2) long, 36–37 (37; n = 2) wide; oviduct, oötype, uterus, vagina and seminal receptacle not observed. Eggs not observed.
Remarks: The new species is clearly a member of Jainus, characterized by its ventral anchor whit elongate rodlike deep root, and an accessory piece that is non-articulated to MCO (Mizelle et al. 1968). Jainus peruensis n. sp. can be distinguished from other congeners by the morphology of the MCO. The accessory piece (hook-shaped distally) and ventral bar (rod-shaped with a medial projection) morphology suggests a closer resemblance to Jainus iocensis Cohen, Kohn & Boeger, 2012. Nonetheless, J. peruensis n. sp. differs from J. iocensis by the morphology of the MCO base (with a crenulated base in the new species vs without crenulated base in J. iocensis), dorsal bar (V-shaped and grooved in J. peruensis n. sp. vs rod-shaped with slightly enlarged ends in J. iocensis), and by the superficial root of the dorsal anchor (less expanded in the new species vs well-expanded in J. iocensis). Furthermore, the species differ in the hook morphology, characterized by a proximal shank enlargement that is subcircular in J. iocensis, whereas absent in the new species. Finally, both species, J. peruensis n. sp. and J. iocensis, differ in the morphology of the accessory piece. In J. peruensis n. sp., it is more robust distally and lacks an oval-shaped projection halfway along its length, whereas in J. iocensis, it is less robust distally and exhibits an oval-shaped projection halfway along its length.
Jainus peruensis n. sp. is the eleventh species described in the genus, but it is the first species of the genus described in Peru (Kritsky et al. 1980; Karling et al. 2011; Abdallah et al. 2012; Cohen et al. 2012; Yamada et al. 2023). One known species of Jainus has been previously registered in Peru, infecting a bryconid host (Mathews et al. 2014). Additionally, three undescribed species of Jainus have also been reported (Rengifo-Chota et al. 2022), suggesting that Peruvian Amazon fishes could harbor an exceptionally diverse array of Jainus species.
description: Published as part of Cruces, Celso L., Santillán, Luis A., Silvera, Jordan F., Morey, Germán Augusto Murrieta, Rubin, Veronica & Chero, Jhon D., 2024, Two new dactylogyrid species (Dactylogyroidea: Dactylogyridae), gill parasites of freshwater fishes from the Peruvian Amazon, including the proposal of Peruanella n. gen., pp. 591-600 in Zootaxa 5443 (4) on pages 594-597, DOI: 10.11646/zootaxa.5443.4.7, http://zenodo.org/record/11064545