Thubunaea leonregagnonae, Oca, Edgar Uriel Garduno-Montes de, Lopez-Caballero, Jorge D. & Mata-Lopez, Rosario, 2017

Oca, Edgar Uriel Garduno-Montes de, Lopez-Caballero, Jorge D. & Mata-Lopez, Rosario, 2017, New records of helminths of Sceloporuspyrocephalus Cope (Squamata, Phrynosomatidae) from Guerrero and Michoacan, Mexico, with the description of a new species of Thubunaea Seurat, 1914 (Nematoda, Physalopteridae), ZooKeys 716, pp. 43-62 : 43-45

Thubunaea leonregagnonae sp. n. Figs 1 A–H; 2 A–F

Type host.

Sceloporus pyrocephalus Cope ( Squamata : Phrynosomatidae ).

Symbiotype.

MZFC-HE 18345

Type locality.

Los Pocitos, La Huacana, Michoacán, Mexico (18°40'24.2"N, 101°59'42.5"W). Collected on July 7, 2005.

Site in host.

Stomach.

Prevalence and intensity of infection.

23% (14 of 61 hosts examined), with a mean intensity of 11 (7-67).

Type specimens.

Holotype: CNHE 9426 (1 male); allotype: CNHE 9427 (1 female); paratypes CNHE 9428, 9429, 9430 and 9431 (9 females and 7 males).

Etymology.

This species is named in honour of Virginia León-Règagnon (Instituto de Biología, UNAM), who was the mentor of the authors of this paper, and for her valuable contribution to our knowledge of helminth parasites in Mexico.

General description.

Medium-sized nematodes, filiform body, cuticle with fine transverse striations along entire body. Males smaller than females. Round cephal ic plate in both sexes (Figs 1B, 2B). Deirids symmetrical, simple with rounded tip (Fig. 2A, C), located immediately posterior to nerve ring. Mouth with two round and simple lateral lips, each with three small teeth on its internal surface; each lip bears a lateral amphid, and a pair of sub-median papillae (Figs 1B, 2B). Pharynx short, cylindrical, opening into oesophagus. Oesophagus divided into anterior muscular portion and posterior glandular portion. Excretory pore in anterior region of body, posterior to nerve ring and located at level of division of muscular and glandular oesophagus. Posterior end conical and rounded in both sexes (Figs 1F, H, 2D, F).

Description of male (based on eight specimens; the number of measurements, where different from eight, is given in parentheses): Total body length (MTBL) 4.85-8.03 mm (6.19), width at mid-body 200-300 (243). Deirids 150-185 (166; n = 7) from anterior end. Nerve ring and excretory pore 100-168 (125) and 125-295 (179, n = 6) from anterior end, respectively. Pharynx length 23-45 (33). Oesophagus total length 613-1038 (800, n = 7), muscular portion length 108-170 (128, n = 7), glandular portion length 488-913 (671, n = 7). Ratio oesophagus total length: MTBL 0.1-0.16 (0.13, n = 7). Testis elongated, distributed in zigzag from anterior intestinal portion to posterior region, near cloaca. Caudal alae well developed, bearing ventrally numerous papilliform plates. Cloaca surrounded by numerous papillae (24-28), 11-14 sessile papillae and 10-16 pedunculate papillae distributed asymmetrically in the following arrangement: ventrolateral: 4-8 pedunculate on right, 6-9 pedunculate on left side; ventral, sessile: 5-8 on right and 4-8 on left side (Figs 1F, 2E, F). Number and disposition of papillae variable with respect to cloaca, thus, precloacal, paracloacal, and postcloacal positions not established. Spicules and gubernaculum absent. Tail 50-67 (59, n = 6) long.

Description of female (based on ten gravid specimens; the number of measurements, where different from ten, is given in parentheses): Total body length (FTBL) 8.72-21.46 mm (14.61), width at mid-body 270-440 (349). Deirids 125-250 (173, n = 8) from anterior end. Nerve ring and excretory pore 100-188 (147, n = 8) and 193-343 (256, n = 6) from anterior end, respectively. Pharynx length 30-58 (41, n = 9). Oesophagus total length 853-1500 (1227, n = 7); muscular portion length 125-325 (220, n = 8), glandular portion length 703-1220 (996, n = 7); ratio oesophagus total length:FTBL 0.1-0.16 (0.14, n = 7). Didelphic, opisthodelphic, ovaries distributed in posterior region of body, uteri extended parallel along almost entire body. Vagina muscular, directed posteriorly, located in anterior region of body close to anterior end of intestine, vulva at 1130-2570 (1770) from anterior end (Fig. 1C). Ratio distance vulva to anterior end of body: FTBL 0.11-0.13 (0.12). Tail 25-30 (27, n = 8) long. Embryonated eggs occupying almost entire uterus, thick shelled with smooth surface, 39-44 (41, n = 15) long by 29-33 (31, n = 15) wide (Fig. 1D); larvated eggs located near vulva, 45-50 (48, n = 15) long by 38-40 (39, n = 15) wide (Fig. 1E).

Remarks.

The family Physalopteridae is composed of three subfamilies: Thubunaeinae Sobolev, 1949, Proleptinae Schulz, 1927 and Physalopterinae Railliet, 1893 ( Chabaud 1975). Thubunaeinae comprises two genera Thubunaea and Physalopteroides Wu & Liu, 1940, both of which are parasites of reptiles and are characterized by the absence of a cephalic ring, the presence of numerous caudal papillae, and an ornamented cuticle forming papillary plates distributed on the surface of the cauda in males ( Chabaud 1975). These two genera differ from each other mainly by the symmetry of their cephalic structures; in Thubunaea these structures are symmetrical, while they are asymmetrical in Physalopteroides ( Chabaud 1975). Some authors, for example Moravec et al. (1997), considered that the morphological features of Thubunaea and Physalopteroides have rarely been analysed using techniques such as SEM, and that these observations could provide detailed information to assess the validity of these two genera. However, to the best of our knowledge, SEM studies are still scarce in both genera, being available for only three species of Thubunaea ( Moravec et al. 1997, Pazoki and Rahimian 2014, Ramallo et al. 2016) and two species for Physalopteroides ( Elwasila 1990, Goswami et al. 2016). The specimens described in the present study show a symmetrical cephalic structure, as in Thubunaea .

Currently, 20 species of Thubunaea are considered as valid: one in the Afrotropical region, T. fitzsimonsi Ortlepp, 1931; five in the Nearctic region, T. cnemidophorus Babero & Matthias, 1967, T. ctenosauri Moravec, Salgado-Maldonado & Mayen-Peña, 1997, T. iguanae Telford, 1965, T. intestinalis Bursey & Goldberg, 1991 and T. leiolopismae Harwood, 1932; two in the Neotropics, T. parkeri Baylis, 1926, and T. eleodori Ramallo, Goldberg, Bursey, Castillo & Acosta, 2016; six in the Oriental region, T. aurangabadensis Deshmukh, 1969, T. brooki Deshmukh, 1969, T. hemidactylae Oshmarin & Demshin, 1972, T. mirzai Narayan, 1941, T. singhi Deshmukh, 1969, and T. syedi Deshmukh, 1969; two in the Palearctic region, T. schukurovi Annaev, 1973 and T. smogorzhewskii Sharpilo, 1966; and four species in the Saharo-Arabian region, T. baylisi Akhtar, 1939, T. dessetae Barus & Tenora, 1976, T. mobedii Pazoki & Rahimian, 2014 and T. pudica Chabaud & Golvan, 1957 ( Ramallo et al. 2016).

Six of these species lack spicules, as is the case in T. leonregagnonae sp. n.: T. cnemidophorus , T. eleodori , T. fitzsimonsi , T. mobedii , T. parkeri and T. schukurovi (Table 3). Males of four of these species ( T. eleodori , T. fitzsimonsi , T. parkeri and T. mobedii ) are larger in body length than T. leonregagnonae sp. n. (10.25-11.16, 8.5-9, 10.5, 11.4-15.4 vs 4.85-8.03 mm, respectively). In the number of papillae, pedunculate or sessile, the new species also differs from most of these six species. Thubunaea leonregagnonae sp. n. has 10-16 pedunculate papillae and 11-14 sessile papillae, T. mobedii does not have pedunculate papillae; in contrast, T. fitzsimonsi and T. parkeri lack sessile papillae, and in this latter species the number of caudal papillae is smaller (16-20) than in the present specimens (24-28) (Table 3). Thubunaea leonregagnonae sp. n. is most similar to T. cnemidophorus , T. eleodori and T. schukurovi , however, it can be distinguished from the last two species in the number of sessile papillae: T. eleodori has ten and T. schukurovi has 16, instead of 11-14 in T. leonregagnonae sp. n. Males of T. leonregagnonae sp. n. and T. cnemidophorus can be differentiated mainly by having a different oesophagus length/MTBL ratio (0.1-0.16 vs 0.26) and by the former having a smaller body width (200-300 vs 350-390).