Dactylogyrids (Platyhelminthes: Monogenoidea) from the gills of Hassar gabiru and Hassar orestis (Siluriformes: Doradidae) from the Xingu Basin, Brazil Author Soares, Geusivam Barbosa Laboratório de Sistemática e Coevolução, Instituto de Estudos Costeiros, Universidade Federal do Pará. Alameda Leandro Ribeiro, 68600 - 000 Bragança, PA, Brazil. & Programa de Pós-Graduação em Biodiversidade e Conservação, Universidade Federal do Pará. Rua Coronel José Porfírio 2515, 68372 - 040 Altamira, PA, Brazil. Author Neto, João Flor dos Santos Laboratório de Sistemática e Coevolução, Instituto de Estudos Costeiros, Universidade Federal do Pará. Alameda Leandro Ribeiro, 68600 - 000 Bragança, PA, Brazil. & Programa de Pós-Graduação em Biologia Ambiental, Universidade Federal do Pará. Alameda Leandro Ribeiro, 68600 - 000 Bragança, PA, Brazil. mvdomingues@ufpa.br Author Domingues, Marcus Vinicius Laboratório de Sistemática e Coevolução, Instituto de Estudos Costeiros, Universidade Federal do Pará. Alameda Leandro Ribeiro, 68600 - 000 Bragança, PA, Brazil. & Programa de Pós-Graduação em Biologia Ambiental, Universidade Federal do Pará. Alameda Leandro Ribeiro, 68600 - 000 Bragança, PA, Brazil. & Programa de Pós-Graduação em Biodiversidade e Conservação, Universidade Federal do Pará. Rua Coronel José Porfírio 2515, 68372 - 040 Altamira, PA, Brazil. text Zoologia 2018 e 23917 2018-06-29 35 1 19 http://dx.doi.org/10.3897/zoologia.35.e23917 journal article 10.3897/zoologia.35.e23917 1984-4689 13175562 D9131C5F-DEF6-49DF-9876-CFA578CFAA9A Cosmetocleithrum akuanduba sp. nov. http://zoobank.org/ 14BE47EB-2B58-4854-BDA2-907115610047 Figs 15–22 Type host. Hassar gabiru Birindelli, Fayal & Wosiacki, 2011 , Doradidae Site of infection. Gill filaments. Type locality. Ilha grande, Xingu River , municipality of Altamira , Pará ( 03°35’50.2”S , 52°21’22.5”W ) . Prevalence. 52% of 19 hosts examined. Mean intensity. 3 parasites per infected host. Mean abundance. 1.6 parasites per host. Other records. Hassar gabiru (Prevalence: 100% of 2 hosts; Mean intensity: 2.5; Mean abundance: 2.5) Iriri River , municipality of Altamira , Pará ( 03°49’06.4”S , 52°41’25.8”W ) ; Hassar gabiru (Prevalence: 60% of 15 hosts; Mean intensity: 3.8; Mean abundance: 2.3) Bacajá River , municipality of Altamira , Pará ( 03°33’47.1”S , 51°36’50.3”W ) ; Hassar orestis (Prevalence: 62% of 24 hosts; Mean intensity: 2.3; Mean abundance: 1.5), Xingu River , Belo Monte Community , municipality of Vitória do Xingu , Pará ( 03°05’52.5”S , 51°43’18.0”W ; 02°47’27.1”S , 51°59’50.0”W ) . Specimens deposited. Holotype , CHIOC 39045 a, and 6 paratypes , CHIOC 39045 b-e, INPA 776 , MPEG 0141 ; 8 vouchers, CHIOC 39046 a–b, 39047 a–c, INPA 777 , MPEG 0142 . Description (based on 7 type specimens, 1 mounted in Hoyer, 6 stained with Gomori’s trichrome): Body fusiform, total length including haptor 451 (360–517; n = 5) long, 110 (92–130; n = 5) wide at level of germarium. Tegument smooth ( Fig. 15 ). Cephalic margin broad; cephalic lobes poorly differentiated; 4 bilateral pairs of head organs with rod-shaped secretion; cephalic glands unicellular, posterolateral to pharynx. Eyes, pigment granules (eye-spots), absent. Mouth subterminal; pharynx muscular, spherical, 32 (30–35; n = 5) long, 28 (25–30; n = 5) wide; esophagus short; two intestinal ceca, confluent posteriorly,lacking diverticula. Haptor globose 90 (75–117; n = 5) wide. Anchors similar. Ventral anchor, superficial root narrow subtriangular, well developed; deep root inconspicuous; slightly curved shaft and point, forming angle of approximately 75°, point extending just past level of tip of superficial root, outer 27(25–29; n = 7) long, inner 30 (25–41; n = 7) long, base 19 (17–20; n = 7) ( Fig. 21 ). Dorsal anchor, superficial root subtriangular; deep root inconspicuous; slightly curved shaft and point forming angle of approximately 70°, point extending just past level of tip of superficial root, outer 25 (22–29; n = 5) long, inner 30 (29–32; n = 5) long, base 19 (17–20; n = 5) ( Fig. 22 ). Ventral bar, variable ( Figs 18–19 ) 41 (30–57; n = 7) long, 6 (4–10; n = 7) wide, broadly U-shaped or straight with inflated or rounded ends. Dorsal bar ( Fig. 20 ) 41 (31–56; n = 7) long, 5 (4–6; n = 7) wide, V-shaped with rounded ends, two submedial projections posteriorly directed. Hooks similar ( Fig. 17 ), 13 (13–14; n = 7) long, with upright truncate thumb; slightly curved shaft, short; non-dilated shank; filamentous hook about shank length. Genital pore opening midventral, anterior to copulatory complex; muscular genital atrium. Testis post-germarial (observed on paratypes ), dorsal to germarium, ovoid, 56 (51–64; n = 3) long, 40 (32–47; n = 3) wide. Vas deferens looping left of intestinal cecum; seminal vesicle a dilatation of vas deferens; long prostatic reservoir with medial constriction. Copulatory complex comprising MCO, accessory piece ( Fig. 16 ). MCO with tubular coiled shaft of less than one counterclockwise ring, frequently appearing J shaped, 68 (54–76; n = 4) long, with tapered distal region; base sclerotized, bulbous. Accessory piece 23 (18–30; n = 5) long, non-articulated with MCO, comprising straight rod, with tapered distal region, distal portion with a small gutter guarding distal portion of shaft of MCO. Germarium 51 (47–55; n = 5) long, 42 (35–52; n = 5) wide, oval. Uterus delicate, ventral. Eggs, Mehlis’ gland and ootype not observed. Vagina heavily sclerotized, vaginal pore sinistral, marginal or submarginal, vaginal canal slightly sclerotized, proximal region “S”-shaped, distal region expanded; seminal receptacle, spherical. Vitelline follicles dense, coextensive with ceca. Figures 15–22. Cosmetocleithrum akuanduba sp.nov. :(15) holotype whole-mount,ventral;(16) copulatory complex;(17) hook; (18–19) ventral bar; (20) dorsal bar; (21) ventral anchor; (22) dorsal anchor. Scale bars: 15 = 100 Μm; 16, 18–22 = 25 Μm; 17 = 10 Μm. Table 6. Comparative measurements (Μm) of specimens of Cosmetocleithrum bifurcum from the gills of Hassar orestis and H. gabiru from Brazil and H. orestis from Peru. BR = Brazil, PE = Peru.

* H. orestis (BR)	N	** H. orestis (PE)	N	* H. gabiru (BR)	N
Body
Length	292(197–405)	8	(322–420)	17	244(150–325)	8
Width	80(65–107)	8	(51–80)	16	65(52–82)	8
Haptor
Length	59(52–65)	8	(35–40)	14	43(35–62)	6
Width	44(37–55)	8	(47–59)	14	48(37–55)	6
Pharynx
Length	22(19–28)	9	(21–25)	17	22(17–27)	8
Width	25(15–31)	9	–	–	20(16–24)	8
MCO length	38(33–44)	7	(31–50)	13	31(30–33)	7
Accessory piece
Length	21(20–25)	4	(20–23)	15	16(13–20)	4
Ventral Bar
Length	46(37–55)	6	(33–40)	14	32(26–39)	10
Width	4(3–4)	7	–	–	2(2–3)	11
Dorsal Bar
Length	31(20–50)	5	(31–38)	14	30(22–40)	8
Width	3(3)	7	–	–	2(2–3)	9
Ventral Anchor
Outer	29(25–31)	8	27	1	28(25–31)	9
Inner	23(21–25)	8	19	1	21(19–24)	9
Base	14(12–16)	8	(11–12)	25	12(9–17)	9
Dorsal Anchor
Outer	27(25–33)	7	23	1	24(17–30)	8
Inner	20(18–23)	7	18	1	21(18–29)	8
Base	13(11–17)	7	(10–12)	24	11(9–12)	8
Germarium
Length	28(46–55)	9	(55–63)	3	42(36–49)	5
Width	22(17–31)	9	(23–40)	3	19(17–24)	5
Testis
Length	49(41–60)	8	(83–99)	3	41(32–47)	5
Width	24(19–31)	8	(30–47)	3	24(19–30)	5
Hooks	15 (15–16)	6	15	37	14(13–15)	7

Comparative measurements. Table 5 . Etymology. The name akuanduba refers to a divinity called “Akuanduba ” of the Arara native people from the Xingu Basin in Pará . According Arara mythic narratives, Akuanduba played his flute to bring order to the world. One day, because of human disobedience, they were thrown into the water. The few survivors had to learn from scratch how to give continuity to life. Remarks. Cosmetocleithrum akuanduba sp. nov. resembles Cosmetocleithrum parvum Kritsky, Thatcher & Boeger, 1986 and Cosmetocleithrum sobrinus Kritsky, Thatcher & Boeger, 1986 by having a “J” -shaped MCO (see Kritsky et al. 1986 ). However, the new species differs from these two species by possessing an elongate accessory piece, with sharp distal region, distal tip with a small gutter (accessory piece with proximal arm, hollow bulbous portion distally in C. parvum , and accessory piece large, globose, and apparently hollow in C. sobrinus ). Also C. akuanduba has a dorsal anchor with a broad subtriangular superficial root, undeveloped deep root, evenly curved shaft with angle of approximately 70°; (narrow, subrectangular superficial root; developed deep root; evenly curved shaft with angle of approximately 70° and 80° in C. parvum and C. sobrinus , respectively). The morphological variations in the ventral bar of C. akuanduba ( Figs 18–19 ) reported from different hosts and localities (i.e., H. orestis collected below the Volta Grande and H. gabiru collected above the Volta Grande rapids) were considered intraspecific variations.