Cosmetocleithrum leandroi, Soares & Neto & Domingues, 2018

Soares, Geusivam Barbosa, Neto, João Flor dos Santos & Domingues, Marcus Vinicius, 2018, Dactylogyrids (Platyhelminthes: Monogenoidea) from the gills of Hassar gabiru and Hassar orestis (Siluriformes: Doradidae) from the Xingu Basin, Brazil, Zoologia (e 23917) 35, pp. 1-19 : 5-7

Cosmetocleithrum leandroi sp. nov.

http://zoobank.org/ C76094F5-7967-4AD3-BD04-0575F829E30C

Figs 8–14

Type host. Hassar gabiru Birindelli, Fayal & Wosiacki, 2011 , Doradidae Site of infection. Gill filaments. Type locality. Bacajá River, municipality of Altamira, Pará (03°33’47.1”S, 51°36’50.3”W). Prevalence. 100% of 15 hosts examined. Mean intensity. 20 parasites per infected host. Mean abundance. 20 parasites per host. Other records. Hassar gabiru (Prevalence: 100% of 19 hosts; Mean intensity: 15; Mean abundance: 15), Ilha Grande,

Xingu River, municipality of Altamira, Pará (03°35’50.2”S, 52°21’22.5”W); 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) .

Specimens deposited. Holotype, CHIOC 39053 a, and 8 paratypes, CHIOC 39053 b–f, INPA 773 , MPEG 0137 ; 8 vouchers, CHIOC 39054 a–c, INPA 774 , MPEG 0138–0140 .

Description (based on 10 type specimens, 6 mounted in Hoyer, 4 stained with Gomori’s trichrome): Body robust, fusiform, total length including haptor 712 (575–835; n = 8) long, 132 (102–157; n = 8) wide, at level of germarium. Tegument smooth ( Fig. 8). Cephalic margin broad; cephalic lobes poorly differentiated; 4 or 5 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, 39 (33–46; n = 7) long, 36 (30–42; n = 7) wide; esophagus short; two intestinal ceca, confluent posteriorly, lacking diverticula. Haptor subtriangular 89 (65–110; n = 8) wide. Anchors similar, base wide, superficial and deep root poorly developed. Ventral anchor, curved shaft and point, forming angle of approximately 85°, point extending just past level of tip of superficial root, outer 40 (25–45; n = 10) long, inner 45 (28–52; n = 10) long, base 26 (16–30; n = 10) ( Fig. 13). Dorsal anchor, slightly curved shaft and point, forming angle of approximately 110°, point extending just past level of tip of superficial root, outer 35 (30–39; n = 10) long, inner 38 (36–42; n = 10) long, base 20 (15–23; n = 10) ( Fig. 14). Ventral bar ( Fig. 11) 44 (32–57; n = 9) long, 6 (4–9; n = 8) wide, straight with knobbed ends. Dorsal bar ( Fig. 12) 49 (35–65; n = 10) long, 6 (3–8; n = 10) wide, straight with inflated or rounded ends; two submedial projections posteriorly directed. Hooks similar ( Fig. 10), 14 (13–15; n = 8) long, with upright rounded thumb; slightly curved shaft, short; non-dilated shank; filamentous hooket about ½ shank length. Genital pore opening to left of body midline, anterior to copulatory complex; muscular genital atrium. Testis post-germarial, dorsal to germarium, ovoid, 43 (43–44; n = 2) long, 27 (24–30; n = 2) wide. Vas deferens looping left of intestinal cecum; seminal vesicle a dilatation of vas deferens; prostatic reservoir with medial constriction. Copulatory complex comprising MCO, accessory piece ( Fig. 9). MCO, coiled sclerotized tube, 572 (550–637; n = 9) long, with 3 ½ counterclockwise rings, with tapered distal region, base of MCO sclerotized. Accessory piece 121 (110–130; n = 5) long, non-articulated with MCO, comprising sigmoid rod, with cup-shaped distal region. Germarium 85 (65–106; n = 5) long, 49 (39–62; n = 5) wide, pyriform. Eggs, Mehlis’ gland, ootype and uterus not observed. Vagina heavily sclerotized, vaginal pore sinistral, marginal or submarginal, vaginal canal long, convoluted, heavily sclerotized, proximal region looped, distal region sigmoid; seminal receptacle pyriform. Vitelline follicles dense, coextensive with ceca.

Comparative measurements. Table 4.

Etymology. The specific name is in honor of Dr Leandro Melo de Sousa, Universidade Federal do Pará, Brazil, in recognition of his valuable work on the fish diversity of Xingu River, and also because the specific name of the host species, “gabiru ”, is the nickname of Dr de Souza ( Birindelli et al. 2011). Now, Dr de Sousa has the host and parasite named after him.

Remarks. Cosmetocleithrum leandroi sp. nov. resembles Cosmetocleithrum longivaginatum Suriano & Incorvaia, 1995 by the general morphology of the bars and by the presence of a long vaginal canal (see Suriano and Incorvaia 1995). However, the new species differs from C. longivaginatum , mainly by possessing a MCO comprising a coil of about with 3 ½ rings (6 rings in C. longivaginatum ) and a sigmoid accessory piece with the distal portion cup-shaped (straight, non-expanded distal accessory piece in C. longivaginatum ). Also, C. leandroi has hooks with similar size, whereas C. longivaginatum has 2 different sizes of hooks (pairs 2 to 5 are smaller than pairs 1, 6 and 7). Finally, these species differ in the shape of their anchors, i.e., C. longivaginatum has well-defined roots, whereas C. leandroi has poorly differentiated roots.