Acleotrema oliveri (León-Régagnon, Pérez-Ponce de León & Garcia Prieto, 1997) Domingues & Boeger, 2007

Acleotrema oliveri (León-Régagnon, Pérez-Ponce de León & Garcia Prieto, 1997) Domingues & Boeger, 2007 View in CoL

Syn. Heteroplectanum oliveri Leon-Regagnon, Pérez-Ponce de León & Garcia-Prieto, 1997

Figs 4A–H View FIGURE 4 , 6D View FIGURE 6

Host. Kyphosus elegans (Peters, 1869) and K. vaigiensis (Quoy & Gaimard, 1825) .

Locality. Off Puerto Santa Rosa (6°52’S, 79°55’W), Lambayeque, Peru, South America GoogleMaps .

Deposited material. 13 voucher specimens (MUSM 5513a–m) from K. elegans and 1 (MUSM 5514) from K. vaigiensis .

Site in host. Gill filaments.

Redescription. Based on 14 specimens: 8 mounted in Gomori’s trichrome and 6 mounted in Hoyer’s medium: Body elongate, fusiform, 0.83–1.40 (1.18; n = 14) mm long; greatest width 130–436 (233; n = 14) usually at level of gonads. Tegument scaled in posterior area of trunk and peduncle, scales effortlessly lost in fixed specimens ( Fig. 4A View FIGURE 4 ). Cephalic region narrow, with one terminal and 2 bilateral poorly developed cephalic lobes; 3 bilateral pairs of conspicuous head organs; bilateral pair of unicellular cephalic glands lateral to pharynx. Two pairs of eye-spots present, equidistant; accessory chromatic granules absent ( Fig. 4A View FIGURE 4 ). Mouth subterminal; pharynx spherical, 34–57 (48; n = 9) in diameter; esophagus short to absent; intestinal caeca unbranched, extending from anterior to near posterior end of trunk, not confluent posteriorly. Haptor differentiated from body proper, laterally expanded, 49–108 (73; n = 9) long, 274–432 (341; n = 9) wide. Anchors dissimilar, with fine conspicuous alae ( Fig. 4B–C View FIGURE 4 ). Ventral anchor 61–78 (71; n = 14) long; with elongate superficial root; well-elongate deep root twice as long as superficial root, medially expanded; curved shaft; and recurved point; point not surpassing level of tip of superficial root; base 3–4 (4; n = 14) wide. Dorsal anchor 31–43 (37; n = 13) long, with inconspicuous superficial root, short and subquadrangular deep root, evenly curved shaft, and short point; point surpassing level of tip of superficial root; base with surface striate 9–11 (10; n = 13) wide. Ventral bar 236–482 (327; n = 14) long, elongate, broadly V-shaped, with mid-ventral longitudinal groove, tapered ends ( Fig. 4D View FIGURE 4 ). Dorsal bars 64–125 (90; n = 14) long, almost bludgeon-shaped, with spatulate medial end ( Fig. 4E View FIGURE 4 ). Fourteen similar hooks, 9–11 (10; n = 13) long, each with depressed obtuse thumb, slender and slightly curved shank, and short point; filamentous hook (FH) loop about shank length; hook pair 1 at level of ventral bar; hook pair 5 at level of ventral anchor base, others submarginal pairs on lateral haptoral lobes ( Fig. 4F View FIGURE 4 ). Squamodiscs, similar, each 35–171 (70; n = 11) long; 173–333 (235; n = 8) wide, with 59–61 (60; n = 2) concentric rows; dumbbell-shaped rodlets with three lateral projections ( Fig. 4G View FIGURE 4 ). Genital atrium sclerotized, corrugated with fingerprint-shaped. MCO sclerotized, almost club-shaped, composed of two nested tubes (external and internal tube), 129–206 (161; n = 14) long; external tube with cone-shaped, strongly corrugated with triangular expansion in distal end; spined internal tube with five large spines in middle region, distal portion of internal tube uncovered by external tube but covered by strong muscular bulb ( Fig. 4H View FIGURE 4 ). Testis ovate, lobulated, 113–253 (187; n = 9) long, 73–165 (111; n = 9) long; vas deferens not looping left intestinal caeca, dilating to form small reniform seminal vesicle in left side of trunk, posterior to MCO; prostatic reservoir, prostatic glands not observed. Ovary elongate, pyriform, 35–57 (43; n = 7) long, 99–133 (119; n = 7) wide, looping dorsoventrally right intestinal caeca; oviduct, oötype, uterus not observed. Vagina, seminal receptacle not observed. Vitelline follicles dense, extending from posterior level of pharynx to posterior end of trunk, absent in regions of reproductive organs. Eggs not observed.

Remarks. Acleotrema oliveri (León-Régagnon, Pérez-Ponce de León & Garcia Prieto, 1997) Domingues & Boeger, 2007 was proposed by León-Régagnon et al. (1997) as Heteroplectanum oliveri León-Régagnon, Pérez-Ponce de León & Garcia Prieto, 1997 parasitizing K. elegans in Chamela bay, Jalisco, Mexico. León-Régagnon et al. (1997) described and illustrated the MCO of A. oliveri as a tube proximally spined. However, our observation of the type material (CNHE 2728–2729, holotype and paratype) and the newly collected specimens revealed that the MCO is club-shaped, composed of two nested tubes (external and internal tube). The external tube exhibits a cone-shaped, is strongly corrugated, and has a triangular expansion at the distal end, while the internal tube is spined along its entire length, with five large spines in the middle region. In newly collected specimens of A. oliveri , we confirmed the presence of a medially expanded deep root of the ventral anchors and a lobulated testis, which were not mentioned in the original description of A. oliveri . Additionally, tegument scaling in the posterior area of the trunk and peduncle were also observed. The redescription presented herein supplements the original description with details of the internal anatomy, sclerotized structures (MCO, anchors and bars) and provided new whole-mount drawing of A. oliveri , as well as morphometric data. Domingues & Boeger (2007) analyzed specimens of Acleotrema sp. , deposited in the Queensland Museum (QM no. GL 13653–13657), obtained from the gills of K. vaigiensis off Green Island, Queensland, Australia, and noted their conspecificity with A. oliveri . However, certain characteristics, such as the elongate sac associated with the MCO, were not observed due the poor condition of specimens. Considering that A. lamothei and A. serrulopenis also exhibit a spined MCO, the identification of these specimens requires verification. Consequently, the presence of A. oliveri on K. vaigiensis confirms the observations made by Domingues & Boeger (2007). Moreover, the presence of A. oliveri in the Southeastern Pacific Ocean off Peru represents a new geographical record.