Chauhanellus susamlimae, Domingues, Marcus V., Soares, Geusivam B. & Watanabe, Alana, 2016

Domingues, Marcus V., Soares, Geusivam B. & Watanabe, Alana, 2016, Monogenoidea (Polyonchoinea: Dactylogyridae) parasitizing the gills of marine catfish (Siluriformes: Ariidae) inhabiting the Atlantic Amazon Coast of Brazil, Zootaxa 4127 (2), pp. 301-326 : 308-311

Chauhanellus susamlimae n. sp.

( Figs. 15–21 )

Type-host: Sciades herzbergii (Bloch) .

Site of infection: Secondary lamellae of the gills.

Type locality: Fishing village of Ajuruteua, Municipality of Bragança, State of Pará, Brazil (0°49’31”N, 46°36'29"W).

Other records: Sciades herzbergii, Bombom Village, Municipality of Viseu, State of Pará, Brazil (01°11’48”N, 46°08’24”W); S. herzbergii, Fish market, Municipality of Bragança, State of Pará, Brazil; S. herzbergii, Furo da Ostra (0°38’ 59”S, 47°53’22,89917”W) municipality of Curuça, State of Pará, Brazil; S. herzbergii, Japerica Village (0°51’28”S, 47º10’ 41,69”W), municipality of São João de Pirabas, State of Pará, Brazil; Sciades passany (Valenciennes) , Fish market, Municipality of Bragança, State of Pará, Brazil.

Prevalence of infection: 12 of 13 (92%).

Specimens deposited: Holotype, CHIOC 38251a; 13 paratypes, CHIOC 38251b–h, INPA 684, MPEG 073– 074; 26 vouchers, CHIOC 38252–38260, INPA 685–686, MPEG 075–079.

Etymology: the species is dedicated to Prof. L.H.S. Lim in recognition for her work on monogenoids from Ariidae .

Comparative measurements: Table 3 .

Description: Based on 15 adult specimens; 4 mounted in Gomori’s trichrome, 11 mounted in Hoyer’ medium. Body fusiform ( Fig. 15 ), total length excluding haptor 435(330–520; n=4) long, 85 (70–90; n=4) wide at level of germarium. Tegument smooth. Cephalic margin tapered; moderately developed terminal lobes; three bilateral pairs of head organs with rod-shaped secretion; cephalic glands unicellular, lateral to pharynx. Eyes 4, posterior pair closer than anterior pair; accessory granules absent or few in cephalic area, spherical. Mouth subterminal, midventral; pharynx ovate, 68 (62–75; n=4) long, 46 (34–54; n=4) wide; oesophagus, intestinal ceca obscured by vitellaria. Genital pore opening ventral, moved to lateral margin of the body, lateral to copulatory complex; genital atrium muscular. Testis post-germarial; testis dorsal to germarium. Testis saccate, 100 (79–117; n=4) long, 44 (40– 48; n=4) wide. Vas deferens apparently looping left of intestinal cecum, seminal vesicle a dilatation of vas deferens, sigmoid. One prostatic reservoir, pyriform, lying ventral lateral to copulatory complex. Copulatory complex comprising male copulatory organ, accessory piece; male copulatory organ, sclerotized tube, sigmoid 47 (43–55; n=6) long, distal aperture acute. Accessory piece sclerotized, non-articulated with male copulatory organ comprising an elongated sheath ( Fig. 16 ). Germarium 66 (63–74; n=4) long, 35 (24–41; n=4) wide, subspherical. Vagina comprising vaginal aperture with dextroventral opening; vaginal vestibule with soft tissue; vaginal canal short, muscular, sigmoid. Seminal receptacle saccate, distal end ascendant; Mehlis’ glands bilateral to ootype, some portions of Mehlis’ glands obscured by transverse vitelline commissures and seminal vesicle. Vitellaria dense throughout trunk, except in region of reproductive organs. Eggs not observed. Peduncle elongate. Haptor digitate, 116 (100–145; n=4) long, 124 (95–175; n=4) wide. Anchors dissimilar. Ventral anchor ( Fig. 20 ), base 14 (10–19; n=11) long, with divergent roots, truncate superficial root, 28 (25–32; n=11) long, expanded deep root, 23 (25–32; n=11) long; evenly curved shaft, point; point extending at level of tip of superficial root. Dorsal anchor ( Fig. 21 ) 37 (35–40; n=9) long, base 12 (11–14; n=9) long, robust, with inconspicuous roots, slightly curved shaft, elongated point extending well past level of tip of inner base; anchor spine blunt. Ventral bar ( Fig. 19 ) 6 (5–8; n=9) long, 40 (35–44; n=8) wide, broadly U-shaped, with short protuberances at each end for articulation with ventral anchor, anterior protuberance smaller than posterior protuberance. Dorsal bar ( Fig. 18 ) 7 (6–8; n=8) long, 42 (38–48; n=8) wide, V-shaped, with bifurcation on both ends, acute anterior protuberance, rounded posterior protuberance; blunt posteromedial process. Hooks similar in shape ( Fig. 17 ), 13 (12–15; n = 6) long, shank without inflation, erect thumb, lightly curved long shaft, delicate point, filamentous hook loop not observed.

Remarks: The new species seems to be closely related to Chauhanellus boegeri Domingues & Fehlauer, 2006 and Chauhanellus neotropicalis Domingues & Fehlauer, 2006 by having dorsal bar with posteromedial process, hooks not proximally inflated, and a muscular vagina (unsclerotized). However, Chauhanellus susamlimae n. sp. can be easily distinguished from these species because it possesses a haptor with digitations, ventral bar with short posterior protuberances (posterior protuberances foot-like in C. boegeri and C. neotropicalis ), and dorsal bar with bifurcation on both ends (non-bifurcated in C. boegeri and C. neotropicalis ).

Figures

FIGURES 15 – 21. Chauhanellus susamlimae n. sp. 15. Holotype, whole-mount (ventral). 16. Copulatory complex. 17. Hook. 18. Dorsal bar. 19. Ventral bar. 20. Ventral anchor. 21. Dorsal anchor. Fig. 15 scale of 100 µm; Figs. 16 – 21 scale of 25 µm.

Tables

TABLE 3. Comparative measurements (in µm) of specimens of Chauhanellus susamlimae n. sp. from the gills of Sciades herbergii and S. passany. MCO = male copulatory organ.

S. herbergii	N	S. passany	N
Body
Length 435(330–520)	4	648(497–913)	5
Width 85(70–90)	4	115(95–153)	4
Haptor
Length 116(100–145)	4	135(132–138)	2
Width 124(95–175)	4	86(79–94)	2
Pharynx
Length 68(62–75)	4	51	1
Width 46(34–54)	4	40	1
MCO length 47(43–55)	6	28	1
Ventral Bar
Length 6(5–8)	9	5(2–7)	6
Width 40(35–44)	8	40(36–49)	6
Dorsal Bar
Length 7(6–8)	8	5(5–7)	7
Width 42(38–48)	8	39(29–50)	6
Ventral Anchor
Inner 23(22–24)	11	23(22–25)	5
Outer 28(25–32)	11	30(28–33)	4
Base 14(10–19)	11	13(12–16)	4
Dorsal Anchor
Inner 37 (35–40)	9	35(33–37)	5
Outer 35 (35–38)	9	35(34–37)	5
Base 12(11–14)	9	11(10–14)	5
Hooks 13(12–15)	6	12(12–13)	5
Germarium
Length 66(63–74)	4	76	1
Width 35(24–41)	4	64	1
Testis
Length 100(79–117)	4	116(91–142)	2
Width 44(40–48)	4	59(55–64)	2