A new species of Foleyellides (Nematoda: Onchocercidae) parasite of Lithobates spp. (Amphibia: Ranidae) from Mexico with a key for the species of the genus Author Romero-Mayén, Angeles R. Author León-Règagnon, Virginia text Zootaxa 2016 4170 3 581 586 journal article 10.11646/zootaxa.4170.3.10 b480d973-3100-4438-84d3-739d1258866c 1175-5326 268226 7D4EAC7A-4811-4D9D-82EF-99102950FE42 Foleyellides mayenae n. sp. ( Figs. 1 , 2 ) Females more than three times longer than males. Body with anterior and posterior extremities round ( Fig. 1 A, B). Maximum width at the esophagus-intestine junction level. Mouth small, oval, 2 parastomal structures present. Cephalic plate with 4 pairs of papillae,,two on each lateral lobe; external papillae larger than internal; amphids between papillae ( Fig. 2 A). Lateral and caudal alae present in both sexes ( Fig. 1 C, 2B, C). Esophagus long and divided in anterior muscular and posterior glandular parts. Glandular esophagus longer and thicker ( Fig. 1 A). MALES (based on 23 specimens). Body length 18.2-28.8 (21.44) mm. Maximum width at level of glandular esophagus 200–410 (310), width at nerve ring 110–210 (150), at muscular/glandular esophagus junction 110–210 (160), at esophagus—intestine junction 160–290 (260). Esophagus 830–1,460 (1,120), muscular region length 160–270 (210), width 30–49 (40); glandular region length 660–1,210 (900), width 69–130 (91). Nerve ring, anterior to esophagus division, at 120–210 (179) from anterior end. Five pairs of caudal papillae, sessile, mamiliform: 1 pair pre-anal, 1 adanal and 3 post-anal ( Fig. 2 C, D). Their size decreasing towards posterior end. Preanal plaque absent. Spicules unequal in size, left larger than right, 280–440 (380) and 130–180 (150), respectively. Tail length 47–71 (60). Caudal alae reaching tail tip, only the posteriormost papillae; thinner at this level ( Fig. 1 C). FEMALES (based on 17 specimens). Body 41.5–93.8 (68.31) mm, maximum width at the anterior part of the intestine 410–850 (620). Width at nerve ring 140–240 (170), muscular/glandular esophagus junction 150–240 (180), at esophagus-intestine junction 260–530 (360), at vulva 240–470 (330). Esophagus 920–1,850 (1,380), muscular region length 180–350 (240) width 33–58 (40); glandular region length 830–1,630 (1,150), width 71–140 (100). Nerve ring at 130–240 (170) from the anterior end. Vulva anterior to junction of esophagus and intestine, 1,020–1,490 (1,024) from anterior extremity ( Fig. 1 A). Tail length 110–260 (180) (n=19). Lateral alae present and reaching the end of the tail ( Fig. 2 B).