Parapharyngodon tikuinii, Garduno-Montes de Oca, Edgar Uriel, Mata-Lopez, Rosario & Leon-Regagnon, Virginia, 2016

Garduno-Montes de Oca, Edgar Uriel, Mata-Lopez, Rosario & Leon-Regagnon, Virginia, 2016, Two new species of Parapharyngodon parasites of Sceloporuspyrocephalus, with a key to the species found in Mexico (Nematoda, Pharyngodonidae), ZooKeys 559, pp. 1-16 : 6-10

Taxon classification Animalia Oxyurida Pharyngodonidae

Parapharyngodon tikuinii sp. n. Figs 3 A–D; 4 A–F

Type material.

Holotype, male, CNHE 9439. Allotype, female, CNHE 9440. Paratypes (8 males, 6 females), CNHE 9441-9447.

Etymology.

The species is named after the Purepecha word “tikuini” which means lizard, referring to the host ( Lathrop 1973).

Diagnosis.

Fusiform and robust nematodes, males smaller than females. Cuticle with thin transverse striations constant in width along the whole body except tail. Triangular oral opening surrounded by three lips simple in males and bilobed in females, in both sexes ventrolateral lips with an amphid each one. Within buccal cavity, both sexes have three transverse plates, bilobed in males and complete in females. Esophageal bulb with sclerotized apparatus. Excretory pore evident, it is located posterior to esophageal bulb-intestine junction. A vesicular body surrounds excretory duct. Males with lateral alae covering almost of body length, females lacking lateral alae. Males without caudal alae. Four pairs of caudal papillae. Caudal filament subterminal and directed dorsally in males. Females with a conical posterior end. Vulva located at middle region. Eggs without alae with punctuated shell and a subpolar operculum, embryo in early stage of cleavage.

Description of male.

Truncated at posterior end (Fig. 3D), total body length 1.9-3.575 (2.62 ± 0.5, n = 9) and maximum width 0.237-0.475 (0.326 ± 0.09, n = 6) at excretory pore level. Cuticle with transverse striae 0.015-0.03 (0.02 ± 0.005, n = 7) maximum width at esophageal bulb level. Triangular oral opening surrounded by three simple lips, at whose internal bases are located three transverse bilobed plates, ventrolateral lips with one amphid each one (Fig. 4A). Esophagus total length 0.342-0.53 (0.416 ± 0.056, n = 8) and maximum width 0.022-0.04 (0.0325 ± 0.006, n = 8), esophagus bulb length 0.075-0.105 (0.09 ± 0.01, n = 8) and width 0.08-0.11 (0.09 ± 0.012, n = 8). Nerve ring and excretory pore at 0.1-0.19 (0.147 ± 0.038, n = 6) and 0.71-1.02 (0.857 ± 0.11, n = 6) from anterior end, respectively. Testis extends from middle body region to level of anterior end of intestine. Hyaline lateral alae start at anterior region between nerve ring and excretory pore at 0.25-0.45 (0.334 ± 0.07, n = 6) from anterior end, with a maximum width of 0.06-0.075 (0.065 ± 0.008, n = 7) and extending to posterior end of body terminating abruptly before cloacal region at 0.12-0.435 (0.263 ± 0.11, n = 7) from the base of corresponding paracloacal papillae (Figs 3D; 4D). Four pairs of caudal rosette papillae as follows: one ventral precloacal pedunculated, one lateral postcloacal pedunculated, one postcloacal mammilliform on the posterior base of postcloacal lip, and one mammilliform on the caudal filament (Figs 3B; 4C). Anterior cloacal lip echinate, with symmetrical ornamentation consisting of a smooth outgrowth with V-form at each side of cloacal opening, in the middle of the lip are located small equidistant simple finger-like outgrowths which vary in number (Figs 3B; 4C). Thick and smooth posterior cloacal lip, with a cuticular outgrowth at its base. This structure has two papillae at the top. Phasmids located at caudal filament base, whose length is 0.045-0.0775 (0.064 ± 0.013, n = 7). Spicule length 0.07-0.11 (0.093 ± 0.014, n = 7), 3.287% of total body length, proximal end wider than distal obtuse tip (Fig. 3E).

Description of female.

Round anterior end, conical posterior end (Fig. 3A). Total body length 4.47-7.57 (6 ± 1.213, n = 7) and maximum width 1.04-1.3 (1.18 ± 0.09, n = 7) at middle body level. Cuticle with transverse striae 0.05-0.08 (0.06 ± 0.01, n = 7) maximum width. Triangular oral opening surrounded by three bilobed lips with an amphid located at dorsal lobe of each ventrolateral lip, at whose internal bases are located three transverse complete plates (Fig. 4B). Esophagus length 1.25-1.56 (1.367 ± 0.134, n = 4) and maximum width 0.07-0.085 (0.075 ± 0.005, n = 6), esophageal bulb length 0.187-0.257 (0.219 ± 0.029, n = 4) by 0.21-0.25 (0.236 ± 0.02, n = 4) width. Nerve ring and excretory pore at 0.15-0.28 (0.21 ± 0.065, n = 3) and 1.17-1.97 (1.658 ± 0.31, n = 5) from anterior end, respectively. Sclerotized vulva at 1.33-3.32 (2.61 ± 0.716, n = 7) from anterior end. Vagina transversely directed and posteriorly flexed to posterior region of body (Fig. 3A). Didelphic, prodelphic, ovaries reach esophagus region coiling around prebulbar esophagus. Uterus reaching caudal region in gravid individuals. Anus 0.44-0.64 (0.566 ± 0.065, n = 6) from posterior end. Phasmids 0.09-0.28 (0.182 ± 0.095, n = 3) from posterior end (Fig. 4E), located laterally at the base of the conical tail. Tail 0.182-0.285 (0.232 ± 0.04, n = 7) length. Eggs containing embryo in early stage of cleavage, oval, without alae, asymmetric, slightly flattened on one side and convex on the other side in lateral view, 0.067-0.087 (0.078 ± 0.006, n = 13) length by 0.02-0.05 (0.04 ± 0.008, n = 12) width, shell egg with pores that cross the uppermost layer, radial striations in lateral view, subpolar operculum smooth without pores (Figs 3C; 4F).

Distribution.

Gabriel Zamora, Michoacán, Mexico (19°10'35"N, 102°03'48"W, elevation 752 m).

Biology.

Nematode species parasite of the intestine of Sceloporus pyrocephalus Cope, collected on June 21, 2004.