Acleotrema nenue Dominques & Boeger 2007
Creators: name: Santillan, Angel L.
name: Cruces, Celso L.
name: Mondragón-Martínez, Aarón
name: Rojas, Rosa Martínez-
name: Chero, Jhon D.
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Platyhelminthes
Monogenea
Dactylogyridea
Diplectanidae
Acleotrema
Acleotrema nenue

description: Acleotrema nenue (Yamaguti, 1968) Dominques & Boeger, 2007
Syn. Diplectanum nenue Yamaguti, 1968
Heteroplectanum nenue (Yamaguti, 1968) Rakotofiringa, Oliver & Lambert, 1987
Figs 3A–H, 6C
Host. Kyphosus vaigiensis (Quoy & Gaimard, 1825) (Centrarchiformes: Kyphosidae), brassy chub and Kyphosus elegans (Peters, 1869) (Centrarchiformes: Kyphosidae), Cortez sea chub.
Locality. Off Puerto Santa Rosa (6°52’S, 79°55’W), Lambayeque, Peru, South America.
Deposited material. 10 voucher specimens (MUSM 5515a–j) from K. vaigiensis and 2 (MUSM 5516a–b) from K. elegans.
Site in host. Gill filaments.
Redescription. Based on 11 specimens: 8 mounted in Gomori’s trichrome 3 mounted in Hoyer’s medium: Body elongate, fusiform, 620–789 (705; n = 11) µ long; greatest wide 98–152 (126; n = 11) usually at level of ovary. Tegument scaled in posterior area of trunk and peduncle, scales effortlessly lost in fixed specimens (Fig. 3A). Cephalic region slightly broad, with one terminal and 2 bilateral moderately developed cephalic lobes; 3 bilateral pairs of conspicuous head organs; bilateral pair of inconspicuous unicellular cephalic glands anterior to pharynx. Two pairs of eye-spots present, equidistant; accessory chromatic granules absent (Fig. 3A). Mouth subterminal; pharynx spherical, 27–35 (31; n = 8) 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, 36–92 (58; n = 11) long, 128–224 (167; n = 11) wide. Anchors dissimilar, with fine conspicuous alae (Fig. 3B–C). Ventral anchor 30–40 (34; n = 11); with elongate, slightly broad superficial root; deep root larger than superficial root, elongate with quadrangular distal end; curved shaft with two lateral knob at base; and recurved point; point not surpassing level of tip of superficial root; 3–5 (4; n = 11) wide. Dorsal anchor 21–24 (22; n = 3) long, with inconspicuous superficial root; short, bilobulated, broad deep root; broad shaft, with hatchet-shaped distal extension; and recurved point, surpassing level of tip of superficial root; base 6–7 (7; n = 3) wide. Ventral bar 104–167 (124; n = 11) long, elongate, broad, with mid-ventral longitudinal groove, tapered ends (Fig. 3D). Dorsal bars 48–80 (59; n = 11) long, curved, with posterolateral projection, conspicuous knob at medial end (Fig. 3E). Fourteen similar hooks, 8–10 (9; n = 10) 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 shaft, others submarginal pairs on lateral haptoral lobes (Fig. 3F). Squamodiscs, similar, each 33–72 (51; n = 10) long; 53–84 (72; n = 10) wide, with 23–27 (25; n = 8) concentric rows; dumbbell-shaped rodlets (Fig. 3G). Genital atrium sclerotized, reticulated. MCO dagger-shaped, 39–52 (45; n = 11) long; MCO base ring-shaped; MCO surrounded by weakly sclerotized hamper-shaped sac armed with numerous small plates and distal end with many foliaceous terminations (Fig. 3H). Ejaculatory bulb strongly muscular, sturdy, oval with elongate sclerotized internal tube (Fig. 3H). Testis ovate, 59–104 (82; n = 8) long, 38–88 (68; n = 8) wide; vas deferens not looping left intestinal caeca, dilating to form elongate sinuous seminal vesicle in left side of trunk, lateral to ovary; prostatic reservoir well-elongate and narrow, dorsal to ejaculatory bulb; prostatic glands not observed. Ovary elongate, pyriform, 40–60 (51; n = 8) long, 42–64 (51; n = 8) wide, looping dorsoventrally right intestinal caeca; uterus elongate, in right side of trunk; oviduct, oötype not observed. Vagina tubular; seminal receptacle well developed. Vitelline follicles dense, extending from posterior level of pharynx to posterior end of trunk, absent in regions of reproductive organs. Eggs not observed.
Remarks. This species was described by Yamaguti (1968) as Diplectanum nenue Yamaguti, 1968 from the gills of Kyphosus cinerascens (Forsskål, 7175) in Hawaii. The main morphological characteristic of this species is the presence of numerous foliaceous terminations associated with the distal end of the sclerotized sac that surrounds the MCO. However, this feature has also been reported for Acleotrema nenuoides (Rakotofiringa, Oliver & Lambert, 1987) Domingues & Boeger, 2007, a species described by Rakotofiringa et al. (1987) as Heteroplectanum nenuoides Rakotofiringa, Oliver & Lambert, 1987 from the gills of two sparid fish, Rhabdosargus sarba (Forsskål, 1775) and P. gibbosum, in Tamatave (Madagascar). One of the differences between both species is the presence of a distal extension on the shaft of the dorsal anchor, which is present in A. nenuoides but apparently absent in A. nenue. However, Rakotofiringa et al. (1987) studied the type material of A. nenue and mentioned the presence of a distal extension on the shaft of its dorsal anchor. According to Rakotofiringa et al. (1987), both species are differentiated in terms of the shape of the prostatic reservoir (oval in A. nenue and well-elongate in A. nenuoides), and the host (K. cinerascens of the Kyphosidae for A. nenue and R. sarba and P. gibbosum of the Sparidae for A. nenuoides). Regarding the shape of the prostatic reservoir, our specimens showed an elongated prostatic reservoir, as occurs in A. nenuoides. The examination of the type material A. nenue (USNM 1359367) and photographs and videos provided by Dr. Marcus V. Domingues of a voucher specimen (USNPC 6366302), enabled us to observe a wellelongated prostatic reservoir in A. nenue. Considering that both species, A. nenue and A. nenuoides, are similar in terms of MCO shape, number of rows of squamodisc, prostatic reservoir shape, and dorsal anchor morphology, we propose that A. nenuoides be considered a junior synonym of A. nenue.
description: Published as part of Santillan, Angel L., Cruces, Celso L., Mondragón-Martínez, Aarón, Rojas, Rosa Martínez- & Chero, Jhon D., 2025, New and previously described Acleotrema species (Monogenea, Diplectanidae) parasitizing sea chubs (Centrarchiformes: Kyphosidae) in the Southeastern Pacific Ocean, pp. 533-548 in Zootaxa 5570 (3) on pages 537-538, DOI: 10.11646/zootaxa.5570.3.5, http://zenodo.org/record/14745333