Morphological and molecular (28 S rRNA) data of monogeneans (Platyhelminthes) infecting the gill lamellae of marine fishes in the Campeche Bank, southwest Gulf of Mexico Mendoza-Franco, Edgar F. Tun, Mariela del Carmen Rosado Anchevida, Allan de Jesus Duarte Rodriguez, Rodolfo E. del Rio ZooKeys 2018 783 125 161 7NSS8 sp. 1 Monogenea Diclidophoridae Choricotyle CoL Animalia Choricotyle Mazocraeidea 0 125 Platyhelminthes genus  Present study.  Haemulon plumieri(new host)  Locality/prevalence, abundance and intensity of infection. San Francisco: 53 fish (mean TL 28.8 cm; range 22-34) infected of 90 examined (58.9 %); abundance, 1; intensity of infection, 1-4 worms. Seyba Playa: 59 fish (TL 28.9; 21.5-31.3) infected of 90 examined (65.5%); abundance, 3; intensity of infection, 1-6. Champoton: 53 fish (TL 28.8; 19.3-33.3) infected of 90 examined (58.9%); abundance, 3; intensity of infection, 2-7.  Measurements (based on nine specimens). Body, 2,260 (1,580-3050; 8) long. Maximum width 514 (400-635; 5) at germarium level. Two oral suckers 56 (45-60; 8) long by 40-44 width. Opisthaptor with eight narrow peduncles. Clamps 214 (150-362; 24) long, 191 (130-325; 20) wide, with 6-7 concentric arcs of small skeletal rods in dorsal fields of clamp and an apparent sucker on internal quadrant on clamp (see Ca and Sc in Figure 7A). Terminal lappet on slight posterior protrusion between third and fourth clamp with one pair (at least) of hooks, each 30 (27-33; 3) long, base 7 (6-7; 3) wide, with short filament (see Fi in Figure 7F) connecting shank and base. Genital atrium 39 (30-45; 6) long, 37 (30-45; 8) wide, armed with ten spines in a single concentric row (see Figure 7B). Number of testes 12, each subspherical, 101 (80-145; 4) long, 109 (80-140; 4) wide. Vas deferens, Ootype and Mehli'sgland, seminal receptacle, genito-intestinal canal and oviduct not observed. Eggs, 125-150 long, 65-70 wide, each with two polar filaments.  Figure 7. Choricotylespp. from Haemulon plumierifrom Campeche Bank, Mexico: Choricotylesp. 1. (A), clamp (B), genital atrium (F), hook. Choricotylesp. 2. (C), clamp (D), genital atrium (G), hook. Choricotylesp. 3. (E), clamp. Scale bars: 100 µmand 20 µmfor all figures, except E 50 µmand F, G 10 µm. Abbreviations: Ca = concentric arcs; Sc = sucker; Fi = filament; Mp = posterior portion of the medial sclerite; sh = shank.  Comments. Placement of present specimens in Choricotyleis based on examination of original descriptions of other species allocated or currently assigned to the genus in Fujii (1944), Hargis (1955b), Kritsky and Bilqees (1973), Oliva (1987), Lamothe-Argumedo et al. (1998), Oliva et al. (2009), and Cohen et al. (2011). While the eight specimens of Choricotylesp. 1 were unsatisfactory to clarify details of internal organs for species identification, they appear to represent an undescribed species based on the general morphology of the haptor and genital atrium. Choricotylesp. 1 resembles C. anisotremiOliva, 1987 on Anisotremus scapularis(Tschudi, 1846) from Chile; C. aspinorchaHargis, 1955b on Orthopristis chrysopterus[now Orthopristis chrysopteraLinnaeus, (1766)] from Beaufort, North Carolina, USA; and C. hysteroncha(Fujii, 1944) Sproston, 1946 on Bathystoma striatum[now Haemulon striatumLinnaeus, (1758)] (type host), Brachygenys chrysargyreus[now Haemulon chrysargyreus( Guenther, 1859)] and Haemulon flavolineatum(Desmarest, 1823) from Tortugas, Florida USA. All these monogeneans share the following features: presence of a sucker on internal quadrant on clamp (present in Choricotylesp. 1 and C. anisotremi), relatively similar morphometry of clamps (i.e., 150-362 long x130-325 vs. 152-219 in diameter in C. aspinorcha), number of spines of the genital atrium (10 spines in Choricotylesp. 1 and C. aspinorcha), and a lappet with one pair of hooks, each with 27-33 long (one pair, each with 28 long in C. hysteroncha). Choricotylesp. 1 differs from these three latter monogenean species by number of testes (12 vs. 90 in C. anisotremi, 42-88 in C. aspinorcha, and 6-7 in C. hysteroncha). The finding of Choricotylesp. 1 constitutes the second record (the first being that of Choricotyle leonilavazquezaeLamothe-Argumedo, Aranda-Cruz & Perez-Poncede Leon, 1998, that occurs on the Pacific coast of Mexico) of a species of Choricotylein Mexico and the first record on H. plumieri. In the present study, three species of Choricotyle(i.e., Choricotylesp. 1, Choricotylesp. 2 and Choricotylesp. 3) were identified on this latter host species (see below) based on morphological features of the genital atrium, clamps and hooks on terminal lappets (when present), if they actually represent different species since variability in these diclidophorids might exhibit intraspecific differences in the shape or size of these structures above mentioned (see Yang et al. 2007).  Molecular data. The present study also provided the firstmolecular data on species of Choricotylein Mexico; both sequences of Choricotylesp. 1 included into the present analyses revealed that this species forms a sister lineage to that containing C. anisotremi(see Figure 6) which occurs on A. scapularis( Pomadasyidae) from Chile ( Oliva 1987).  Specimens deposited. Nine reference specimens, CNHE (10618). Other two slides, each containing a haptor of a specimen of Choricotylesp. 1 used to amplify its DNA are deposited in the CNHE (10624 and 10625).  Representative DNA sequence. GenBank accession number MG586865, MG586866.