Haematoloechus mexicanus, León-Règagnon & Topan, 2018

León-Règagnon, Virginia & Topan, Janet, 2018, Taxonomic revision of species of Haematoloechus Looss, 1899 (Digenea: Plagiorchioidea), with molecular phylogenetic analysis and the description of three new species from Mexico, Zootaxa 4526 (3), pp. 251-302 : 269-272

Haematoloechus mexicanus n. sp.

( Figs. 10 & 11 )

Type host: Montezuma leopard frog Rana montezumae (=Northern leopard frog R. pipiens Schreber and R. montezumae of Caballero 1941).

Type locality: Ciénaga de Lerma, Estado de Mexico, Mexico.

Site of infection: Lungs

Holotype: CNHE 10489

Paratypes: CNHE 10490 , 10491 , 10492 .

Etymology: Species name refers to Estado de Mexico, the province of the type locality.

Other hosts and localities: Mexico: Montezuma leopard frog Rana montezumae, Xochimilco , Mexico City ( Caballero, 1941, as H. medioplexus ); Patzcuaro leopard frog R. dunni, Pátzcuaro , Michoacán ( León-Règagnon et al. 1999, as H. coloradensis ); Transverse Volcanic leopard frog R. neovolcanica, Cointzio , Michoacán (this study).

Description: Based on 17 mature specimens: Body slender, with thinner anterior region; 4.8–8.3 (7.0) mm long, 0.7–1.3 (1.0) mm of maximum width at testicular region. Tegument covered with abundant thin spines, easily lost during fixation; 7.5–12.5 (9.8) long. Oral sucker subterminal, round, 203–350 (284) long, 180–380 (278) wide. Pharynx oval, 140–280 (206) long, 122–220 (183) wide; oral sucker/pharynx ratio 1: 0.74–0.90 (0.83). Anterior border of pharynx and esophagus surrounded by gland cells. Esophagus 41–200 (129) long. Ceca bifurcated at 390–770 (609) from anterior extremity. Ceca terminate blindly near posterior extremity. Ventral sucker small, weakly developed, frequently obscured by uterus, 52–125 (82) long, 57–130 (84) wide, at 1.5–3.0 (2.4) mm (31%– 41% (37%) of BL) from anterior extremity. Sucker length ratio 1:0.28–0.38 (0.33). Testes 2, elliptical, elongate, oblique, posterior to ovary; distance between ovary and anterior testis 350–825 (548). Anterior testis opposite to ovary, 365–1,080 (778) long, 243–600 (451) wide. Posterior testis 422–1200 (863) long, 260–830 (495) wide. Cirrus sac reaches anterior border of ventral sucker, mostly obscured by ascending uterus; internal seminal vesicle, elongate, slightly coiled. Ejaculatory duct weakly muscular, 150–160 (155) long, surrounded by prostatic gland cells. Ovary kidney shaped, lobed, 320–840 (623) long, 162–500 (342) wide; at 1.8–4.3 (2.8) mm (35%–57% (40%) of BL) from anterior extremity. Seminal receptacle posterior, partially overlapped with ovary; 300–1000 (644) long, 250–590 (410) wide. Mehlis gland dorsal to seminal receptacle. Laurer’s canal not observed. Vitellaria in clusters of oval, well defined follicles, distributed laterally, dorsally invade space between ceca in anterior region of ovary and sometimes in post-testicular region. Anterior limit of distribution 982–3200 (1766) (19%–49% (25%) of BL) from anterior end. Follicles extend asymmetrically, to anterior region of posterior testis on ovarian side of body, and halfway between posterior testis and posterior end of body on side opposite to ovary. Uterine loops fill intra- and extracecal space, partially overlap testes and ovary. Descending part of uterus form several diagonal loops that frequently bend anteriorly or posteriorly and form short longitudinal extracecal loops on ovarian side of body. Uterus forms two longitudinal uterine loops on each side of posterior end of body that reach halfway between posterior end and posterior testis; one loop is frequently shorter. Ascending part of uterus forms diagonal loops on side opposite to ovary, frequently bends anteriorly or posteriorly to form longitudinal extracecal loops. Descending and ascending parts of uterus in two lateral fields rarely invade each other. Distal uterus fills intracecal preovarian region with diagonal loops. Genital pore median, ventral to middle region of pharynx. Eggs dark brown, 22–26 (24) long, 14–20 (17) wide. Excretory vesicle not observed. Excretory pore terminal.

Remarks: Haematoloechus mexicanus n. sp. resembles those species of the genus possessing short longitudinal or diagonal uterine loops not reaching the posterior testis, namely H. aubriae , H. caballeroi , H. danbrooksi , H. fuelleborni , H. humboldtensis , H. illimis , H. kernensis , H. occidentalis n. sp., H. pukinensis , and H. veracruzanus n. sp. It also resembles those species with a ventral sucker less than half the size of the oral sucker, namely H. combesi Batchvarov & Bourgat, 1974 , H. danbrooksi , H. darcheni Combes & Knoepffler, 1967 , H. floedae , H. leonensis ( Williams & Coker, 1967) , H. medioplexus , H. meridionalis , H. nicolasi , H. ocellati Gassmann, 1975 and H. parviplexus ( Table 2). This new species differs from H. caballeroi , H. fuelleborni , H. humboldtensis , H. illimis , H. kernensis , H. occidentalis n. sp., H. pukinensis , and H. veracruzanus n. sp. in the size of the ventral sucker compared to the oral sucker, which is smaller in H. mexicanus n. sp. (1: 0.5–1.0 in the other species vs 1: 0.33 in H. mexicanus n. sp.), and it differs from H. aubriae in the presence of ventral sucker, which is absent in that species. It also differs from H. aubriae , H. caballeroi , H. fuelleborni , H. humboldtensis , H. kernensis , H. occidentalis n. sp., H. pukinensis , and H. veracruzanus n. sp. in the shape of ovary and testes, which are oval in those species, while in H. mexicanus n. sp. the ovary is lobed and testes are elliptical or elongate. Haematoloechus mexicanus n. sp. differs from H. combesi , H. darcheni , H. floedae , H. leonensis , H. medioplexus , H. meridionalis , H. nicolasi , H. ocellati and H. parviplexus in the arrangement of the uterine loops. Haematoloechus medioplexus and H. meridionalis lack uterine longitudinal loops ( Stafford, 1902; León-Regagnon et al. 2001), in H. combesi , H. floedae and H. leonensis they reach the level of the ovary ( Williams & Coker 1967; Batchvarov & Bourgat 1974; León-Règagnon et al. 2005), in H. darcheni and H. ocellati they reach the level of the anterior testis ( Combes & Knoepffler 1967; Gassmann 1975), in H. nicolasi and H. parviplexus they reach the level of the posterior testis ( Irwin 1929; León-Règagnon 2017), while in H. mexicanus n. sp. they reach halfway between the posterior testis and the posterior end. In this new species there are frequently several short longitudinal uterine loops in the posttesticular region and at the level of testes, which are absent in the other species. Haematoloechus mexicanus n. sp. most closely resembles H. danbrooksi in the size of the ventral sucker and the presence of short diagonal or longitudinal uterine loops in the posterior end of body, but differs from that species in the shape of the ovary, which is oval or slightly bi-lobed in some specimens ( León-Règagnon & Paredes-Calderón 2002) and deeply lobed in H. mexicanus n. sp. The arrangement of the uterus also differentiates these two species; while in H. danbrooksi the descending and ascending uterine loops often invade both sides of the body, in H. mexicanus n. sp. descending and ascending uterine loops form two lateral fields and rarely invade one another. Finally, the longitudinal uterine loops in the posterior end of the body are shorter in H. danbrooksi .

Figures

FIGURE 10. Haematoloechus mexicanus n. sp., from the Montezuma leopard frog, Rana montezumae from Estado de Mexico, Mexico. Ventral view; AU = ascending uterus, DU = descending uterus, GP = genital pore, OS = oral sucker, IC = intestinal ceca, OV = ovary, PH = pharynx, SR = seminal receptacle, T = testes, VF = vitelline follicles, VS = ventral sucker. Scale bar = 1 mm.

FIGURE 11. Haematoloechus mexicanus n. sp., from the Montezuma leopard frog, Rana montezumae from Estado de Mexico, Mexico. Male terminal genitalia; female proximal genialia. Ventral view; AU = ascending uterus, DU = descending uterus, GP = genital pore, ED = ejaculatory duct, MG = Mehlis gland, OS = oral sucker, OV = ovary, PH = pharynx, SR = seminal receptacle, SV = seminal vesicle, VD = vitelline ducts, VS = ventral sucker. Scale bar = 0.5 mm.