Peruanella, Cruces & Santillán & Silvera & Morey & Rubin & Chero, 2024

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., Zootaxa 5443 (4), pp. 591-600 : 593

Peruanella n. gen.

Type-species: Peruanella madredediosensis n. gen. n. sp.

Other species: Peruanella aureagarciae n. comb.

Etymology: The genus name refers to the country where the specimens were found. This name is appended to the diminutive (- ella) and should be treated as feminine.

Diagnosis: Dactylogyridae . Body comprising cephalic region, trunk and haptor. Tegument thin, smooth. One inconspicuous terminal and 2 poorly developed cephalic lobes; three or four pairs of bilateral head organs. Cephalic glands unicellular, posterolateral to pharynx. Eyespots absent; accessory granules present or absent. Mouth subterminal, midventral; pharynx muscular, glandular; oesophagus short. Two intestinal caeca, confluent posteriorly to gonads, lacking diverticula. Common genital pore mid-ventral, near level of intestinal bifurcation. Genital atrium muscular. Gonads intercaecal, tandem. Testis dorsal to ovary; seminal vesicle a dilation of vas deferens; one or two prostatic reservoirs. Copulatory complex comprising male copulatory organ (MCO) and accessory piece. MCO sclerotized, J-shaped; accessory piece sclerotized, articulated with the MCO base via a filament. Ovary entire; oviduct, uterus not observed. Vaginal aperture mid-ventral; vaginal vestibule slightly sclerotized; vaginal canal sclerotized, emptying to seminal receptacle. Vitelline follicles dense, coextensive with intestinal caeca. Haptor armed with 2 pairs of anchor-bar complexes and 7 pairs of hooks with ancyrocephalinae-like distribution sensu Mizelle (1936). Anchors equal; each with short roots. Ventral and dorsal bars straight, robust. Hooks similar in shape and size, with undilated shanks and protruded, obtuse, depressed thumb. Parasites of gills of pimelodid fish.

Remarks: Peruanella n. gen. is limited to dactylogyrid species that parasitize the gill filaments of siluriform fishes belonging to the Pimelodidae . These species are characterized by possessing a combination of the following features: (1) tandem gonads, (2) a tubular J-shaped MCO, (3) an accessory piece connected to the base of the MCO via a filament, (4) a midventral vaginal aperture, (5) anchors similar in shape, each with short roots, (6) straight and robust bars, and (7) equal hook, each with undilated shanks and a depressed thumb. Currently, species from the genera Ameloblastella Kritsky, Mendoza-Franco & Scholz, 2000 ; Boegeriella Mendoza-Palmero & Hsiao, 2020 ; Cosmetocleithrum Kritsky, Thatcher & Boeger, 1986 ; Demidospermus Suriano, 1983 ; Nanayella Acosta, Mendoza-Palmero, da Silva & Scholz, 2019 ; Pavanelliella Kritsky & Boeger, 1998 ; Unibarra Suriano & Incorvaia, 1995 ; Urocleidoides Mizelle & Price, 1964 ; and Vancleaveus Kritsky, Thatcher & Boeger, 1986 , have been reported infesting pimelodid fish. Species of the new genus differs from Unibarra spp. by possessing two bars (ventral and dorsal) in the haptor, whereas only a ventral bar is present in Unibarra species. Species of Peruanella n. gen. are easily distinguished from Pavanelliella spp. by the presence of a haptoral bar/anchor complex, which is absent in Pavanelliella spp. The species of the new genus differs from Nanayella spp. and Vancleaveus spp. by possessing straight and robust dorsal and ventral bar (U- or V-shaped bars in Nanayella spp. and Vancleaveus spp. ), and by having a mid-ventral vaginal aperture (vaginal aperture sinistral in Nanayella spp. and Vancleaveus spp. ). Species of Peruanella n. gen. differs from species of Ameloblastella and Boegeriella by the morphology of the MCO (uncoiled in Peruanella spp. vs coiled in Ameloblastella spp. and Boegeriella spp. ), ventral bar (straight without process or projections in Peruanella spp. vs with an antero-medial process in Ameloblastella spp. vs with projections directed anteriorly in Boegeriella spp. ) and the position of the vaginal pore (mid-ventral in Peruanella spp. vs sinistral in Ameloblastella spp. and Boegeriella spp. ). The species of the new genus differs from Cosmetocleithrum spp. by the morphology of the copulatory complex (uncoiled MCO with an accessory piece articulated in its base in Peruanella spp. vs coiled MCO with a non-articulated accessory piece in Cosmetocleithrum spp. ), and dorsal bar (straight without submedial ribbon-like projection in Peruanella spp. vs with two submedial ribbon-like projections on the dorsal bar in Cosmetocleithrum spp. ). The species of Peruanella n. gen differs from Demidospermus spp. by the morphology of the bars (straight and robust in Peruanella spp. vs U-, W- or V-shaped in Demidospermus spp. ), copulatory complex (a tubular J-shaped MCO and an accessory piece connected to the base of the MCO via a filament in Peruanella spp. vs counterclockwise coiled MCO and a sheet-like accessory piece unarticulated to the base of MCO in Demidospermus spp. ), hooks (similar in shape and size in Peruanella spp. vs variable in shape and size in Demidospermus spp. ), and position of the vaginal pore (mid-ventral in Peruanella spp. vs sinistral or dextral in Demidospermus spp. ).

A Demidospermus species, D. aureagarciae Morey, Rojas, Dávila, Chu & De Pina, 2023 from Pseudoplatistoma punctifer (Castelnau) in Peru, has been reported to have a midventral vaginal aperture ( Morey et al., 2024a). Furthermore, this species exhibits straight and robust bars, a tubular J-shaped MCO and with an accessory piece connected to its base via a filament and hooks similar in shape and size. These characteristics align with the diagnosis features of the new genus, suggesting a close phylogenetic relationship. Based on this, D. aureagarciae is now transferred to Peruanella n. gen as P. aureagarciae n. comb.