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 Author Soares, Geusivam B. Author Magalhães, Keila X. Author Silva, Ana Carolina Author Carneiro, Jânio S. Author Barbosa, Lucineia L. Author Costa, Nayna G. S. Author Domingues, Marcus V. text Zootaxa 2019 2019-11-19 4700 2 229 245 journal article 24864 10.11646/zootaxa.4700.2.3 99c5e241-0bc7-41eb-bf28-5dc9adbd660d 1175-5326 3548428 C10998AB-822A-4B17-8FE1-596DC44C7D6A Mymarothecioides Soares and Domingues n. gen. Type species: Mymarothecioides xinguensis n. sp. from 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 . Other species: Mymarothecioides altamirensis n. sp. ; Mymarothecioides ararai n. sp. ; Mymarothecioides germanoi n. sp. ; Mymarothecioides whittingtoni ( Kritsky, Boeger & Jégu, 1996 ) n. comb. Etymology: The generic name indicates the similarity of this genus to Mymarothecium . Zoobank Life Science Identifier: (LSID) for Mymarothecioides n. gen. is urn:lsid:zoobank.org:act: D3889C11- 8D48-4F05-86D8-55BD6AAE6EBB Diagnosis: Body divisible into cephalic region, trunk, peduncle, haptor. Tegument thin, smooth. Cephalic region with terminal ventral cephalic lobe; bilateral pairs of head organs opening subterminal to tip of cephalic lobes; cephalic glands lateral or postero-lateral to pharynx. Eyes absent; accessory chromatic granules present or absent. Mouth subterminal, midventral; pharynx muscular, glandular; esophagus short; two intestinal ceca, confluent posteriorly to gonads, lacking diverticula. Genital pore opening midventral, anterior to copulatory complex; genital atrium of soft tissue. Gonads tandem. One testis, dorsal to germarium; vas deferens looping left intestinal cecum; seminal vesicle sigmoid. One prostatic reservoir. Copulatory complex comprising articulated MCO, accessory piece; MCO sclerotized, tubular usually arcuate, small grooves at edges of distal opening present or absent; accessory piece sclerotized, distal end with hook-shaped process. Vagina single, dilated, nonsclerotized, opening on midventral or ventro-marginal surface near the midlength of trunk; vaginal vestibule muscular; vaginal canal non-sclerotized, sigmoid; seminal receptacle present, anterior to germarium. Vitellaria well developed, coextensive with ceca. Haptor globose or subhexagonal, with 14 hooks (8 marginal, 2 central, 4 dorsal); 2 pairs of anchors (1 ventral, 1 dorsal); 2 (1 ventral, 1 dorsal) haptoral bars. Ventral bar with anteromedial projection. Parasites of gills of characiform fishes. Remarks: Mymarothecioides n. gen. resembles Mymarothecium Kritsky, Boeger & Jegú 1996 , mainly by including species with broad arcuate MCO, articulated with the accessory piece; the accessory piece with a subterminal hooked process; an anteromedial process on the ventral bar. The genera are distinguished by Mymarothecioides n. gen. having a dextro, midventral vaginal opening (middorsal or dextro-dorsal in Mymarothecium ) and by lacking eyespots (four eyespots in Mymarothecium ). These combined characters support the transfer of Mymarothecium whittingtoni Kritsky, Boeger & Jégu, 1996 to Mymarothecioides n. gen. as Mymarothecioides whittingtoni ( Kritsky, Boeger & Jégu, 1996 ) n. comb.