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 phryctophallus sp. nov. http://zoobank.org/ EB19025E-AC8F-4E74-BCF3-71932680832C Figs 1–7 Type host. Hassar orestis (Steindachner, 1875) , Doradidae Site of infection. Gill filaments. Type locality. Xingu River , Belo Monte Community , municipality of Vitória do Xingu , Pará ( 03°05’52.5”S , 51°43’18.0”W ) . Prevalence. 100% of 16 hosts examined. Mean intensity. 6.5 parasites per infected host. Mean abundance. 6.5 parasites per host. Other records. Hassar orestis (Prevalence: 100% of 8 hosts; Mean intensity: 6; Mean abundance: 6), Xingu River , municipality of Vitória do Xingu , Pará ( 02°47’27.1”S , 51°59’50.0”W ) . Specimens deposited. Holotype 39055 a, and 9 paratypes , CHIOC 39055 b–g, INPA 770 , MPEG 0135 ; 9 vouchers, CHIOC 39056 a–b, 39057 a–c, INPA 771–772 , MPEG 0136 . Description (based on 10 type specimens, 5 mounted in Hoyer, 5 stained with Gomori’s trichrome): Body fusiform, total length including haptor 356 (250–462; n = 10) long, 77 (62–95; n = 10) wide at level of germarium. Tegument smooth. ( Fig. 1 ). Cephalic margin rounded, cephalic lobes inconspicuous; 3 or 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, sub-spherical, 28 (24–33; n = 9) long, 23 (17–25; n = 9) wide; esophagus short, two intestinal ceca, confluent posteriorly; lacking diverticula. Haptor globose 67 (55–85; n = 9) wide. Anchors similar. Ventral anchor, superficial root, narrow triangular, well developed; deep root inconspicuous; slightly curved shaft and point, forming angle of approximately 90°; point extending just past level of tip of superficial root, outer 27 (24–31; n = 10) long, inner 28 (25–32; n = 10) long, base 18 (11–22; n = 10) ( Fig. 6 ). Dorsal anchor, superficial root triangular, large; deep root inconspicuous; slightly curved shaft and point, forming angle of approximately 75°, point extending just past level of tip of superficial root, outer 28 (21–31; n = 8) long, inner 29 (27–31; n = 8) long, base 19 (16–31; n = 7) ( Fig. 7 ). Ventral bar ( Fig. 4 ) 35 (28–45; n = 10) long, 5 (3–7; n = 10 wide, broadly U-shaped with inflated ends, slightly curved in posterior direction. Dorsal bar ( Fig. 5 ) 36 (28–45; n = 10) long, 4 (3–6; n = 10) wide, U-shaped with rounded ends, slightly curved; two submedial projections posteriorly directed. Hooks similar ( Fig. 3 ), 13 (12–17; n = 10) long, with upright rounded thumb; slightly curved shaft, short; non-dilated shank; filamentous hooklet loop about shank length. Genital pore opening midventral, anterior to copulatory complex; muscular genital atrium. Testis post-germarial, dorsal to germarium, elongated 47 (31–69; n = 6) long, 33 (25–39; n = 6) 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. 2 ). MCO, coiled sclerotized tube 236 (201–299; n = 7) long, with 2 ½ counterclockwise rings, with tapered distal region, base MCO, wide sclerotized margin. Accessory piece 36 (31–50; n = 6) long, non-articulated with MCO, comprising straight rod, distal end with elongate torch-shaped blade, guarding termination of MCO. Germarium 44 (31–69; n = 8) long, 23 (17–31; n = 8) wide, pyriform. Eggs, Mehlis’ gland, ootype and uterus not observed. Vagina slightly sclerotized, vaginal pore sinistral, marginal or submarginal, vaginal vestibule cup-shaped, long vaginal canal, sigmoid, slightly sclerotized; seminal receptacle oval. Vitelline follicles dense, coextensive with ceca. Figures 1–7. Cosmetocleithrum phryctophallus sp. nov. : (1) holotype whole-mount, ventral; (2) copulatory complex; (3) hook; (4) ventral bar; (5) dorsal bar; (6) ventral anchor; (7) dorsal anchor. Scale bars: 1 = 100 Μm; 2, 4–7 = 25 Μm; 3 = 10 Μm. Table 3. Comparative measurements (Μm) of specimens of Cosmetocleithrum phryctophallus sp. nov. from the gills of Hassar orestis from two locations. MCO = male copulatory organ.

Belo Monte	N	Vitória do Xingu	N
Body
Length	356 (250–462)	10	350 (245–510)	6
Width	77(62–95)	10	70(62–90)	6
Haptor
Wide	67,5(55–85)	9	60,5(50–85)	7
Pharynx
Length	28(24–33)	9	28(24–33)	6
Width	23(17–25)	9	20(17–23)	7
MCO length	236(201–299)	7	230(201–290)	7
Accessory piece
Length	36 (31–50)	6	34 (31–45)	5
Ventral Bar
Length	35(28–45)	10	38(28–45)	8
Width	5(3–7)	10	4(3–7)	10
Dorsal Bar
Length	46(28–45)	10	35(23–46)	5
Width	4(3–6)	10	4(3–6)	4
Ventral Anchor
Outer	27(24–31)	10	25(24–30)	5
Inner	28(25–32)	10	27(23–35)	3
Base	18(11–22)	10	17(11–18)	8
Dorsal Anchor
Outer	29(27–31)	8	25(21–30)	5
Inner	28(21–31)	8	27(27–30)	8
Base	19(16–21)	7	17(16–20)	7
Germarium
Length	44(31–69)	8	40(31–67)	8
Width	23(17–31)	8	25(17–30)	8
Testis
Length	47(31–79)	6	45(30–79)	6
Width	33(25–39)	6	30(25–39)	6
Hooks	13 (12–17)	10	15 (12–17)	10

Comparative measurements. Table 3 . Etymology. The specific name (a noun) is from Greek ( phryctos = burning torch + phallos = penis) and refers to the unique shape of the accessory piece. Remarks. Cosmetocleithrum phryctophallus sp. nov. resembles Cosmetocleithrum akuanduba sp. nov. by sharing similar morphology of the haptoral structures. However, it can be easily distinguished from C. akuanduba sp. nov. due to the presence of a coiled MCO (J-shaped in C. akuanduba sp. nov. ) and by having a lightly sclerotized vagina with a sigmoid vaginal canal (heavily sclerotized vagina with short, “S”-shaped vaginal canal in C. akuanduba sp. nov. ). The new species also differs from C. akuanduba sp. nov. and all other congeneric species by possessing an accessory piece with an elongate torch-shaped blade.