A New Species of Aplectana (Nematoda: Cosmocercidae
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Zootaxa 4247 (2): 121–130 ISSN 1175-5326 (print edition) http://www.mapress.com/j/zt/ Article ZOOTAXA Copyright © 2017 Magnolia Press ISSN 1175-5334 (online edition) https://doi.org/10.11646/zootaxa.4247.2.3 http://zoobank.org/urn:lsid:zoobank.org:pub:1E7A7589-FC54-405D-A46B-835C8B1E69FF A new species of Aplectana (Nematoda: Cosmocercidae) parasite of Pleurodema nebulosum (Anura: Leptodactylidae) from the Monte desert, Argentina, with a key to Neotropical species of the genus Aplectana MAURICIO D. PIÑEIRO GOMEZ1, CYNTHYA E. GONZÁLEZ 2,4 & EDUARDO A. SANABRIA3, 4 1Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de San Juan. Av. Ignacio de la Roza 590 (O), Rivadavia, San Juan, Argentina, C.P. 5400. E-mail: mauridpg@gmail.com 2Centro de Ecología Aplicada del Litoral, Ruta Provincial Número 5, km 2,5, Corrientes, Argentina, C.P. 3400. E-mail: cynthyaelizabethg@hotmail.com 3 Instituto de Ciencias Básicas, Facultad de Filosofía Humanidades y Artes, Universidad Nacional de San Juan. Av. José Ignacio de la Roza 230 (O), Capital, San Juan, Argentina C.P. 5400. E-mail: sanabria.eduardoa@gmail.com 4 Consejo Nacional de Investigaciones Científicas y Técnicas Abstract Here we describe a new cosmocercid nematode, Aplectana nebulosa sp. nov., from the small and large intestines of Pleu- rodema nebulosum (Anura: Leptodactylidae), from the Monte desert of San Juan, Argentina. The new species belongs to the Aplectana group that possesses a gubernaculum and unpaired adcloacal papilla anteriorly to cloaca. It resembles A. membranosa, A. paraelenae and A. travassosi by the presence of four adcloacal papillae, but differs from those species by the following characters: number and arrangement of precloacal papillae; number and arrangement of postcloacal pa- pillae; shape and size of spicules and gubernaculum, and by the presence of lateral alae in caudal region of males. The description of the new species is based on light microscopy and scanning electron microscopy (SEM) and we also provide a key to Neotropical species of Aplectana. Key words: Nematode parasite, Amphibians, San Juan Province, Argentina Introduction The frog genus Pleurodema Tschudi (Leiuperinae) includes 13 valid species widely distributed from Panama to southern South America (Frost 2016), nine of which are present in Argentina (Ferraro and Casagranda, 2009). Pleurodema nebulosum and Pleurodema guayapae are the species that constitute the P. nebulosum clade (Faivovich et al., 2012), and within this clade, Pleurodema guayapae inhabits the ‘Chaco Seco’ ecoregion in Argentina, while P. nebulosum occurs in the ecoregions ‘Chaco Seco’, ‘Monte de Sierras and Bolsones’, ‘Monte de Llanuras and Mesetas’, and ‘Espinal’ and its distributional limits reach the ‘Pampa’, ‘Puna’, and ‘Estepa’ regions. In Argentina, P. nebulosum is the species of this genus with widest altitude range (Ferraro and Casagranda, 2009), and is a common frog in the Monte desert. The information available on metazoan parasites of the herpetofauna from the Monte desert in Argentina mostly refers to helminth species found in reptiles (Ramallo and Díaz, 1998; Ramallo et al., 2002a; 2002b; 2016a; 2017; Goldberg et al., 2004). Regarding helminths found in amphibians, González et al. (2013a) described the nematode Falcaustra sanjuanensis González, Sanabria and Quiroga, 2013 from the large intestine of Odontophrynus cf. barrioi and González et al. (2013b) reported the nematode Aplectana hylambatis (Baylis, 1927) Travassos, 1931 from the large intestine of Rhinella arenarum Hensel, 1867. González et al. (2014) reported the presence of the nematodes F. sanjuanensis and Contracaecum sp. (larvae), from the large intestine and stomach of Lithobates catesbeianus (Shaw, 1802). Finally, F. sanjuanensis was also reported by Ramallo et al. (2016b) from Leptodactylus latrans (Steffen, 1815). However, no helminths have been described for Pleurodema nebulosum from Argentina until now. Thus, here Accepted by R. Carreno: 9 Feb. 2017; published: 27 Mar. 2017 121 we describe a new cosmocercid species belonging to the genus Aplectana Railliet and Henry, 1916. This species was found as parasites of the digestive tract of P. nebul osum from Matagusanos, Ullúm Department, San Juan province. We also provide a key of identification for the Aplectana species found in the Neotropical Realm. Materials and methods Study area: The Matagusanos barreal is located 55 km east of San Juan city, in Ullúm Department (31.11250 S, 68.63587 W, elevation: 600 m). The dominant vegetation in the area includes Larrea cuneifolia and Larrea divaricata (jarillas), Prosopis sp. (algarrobos), and Capparis atamisquea (matagusanos). This region is part of the Monte desert, characterized by its arid climate with a mean annual temperature of 17.3 ºC, a mean maximum temperature of 25.7 ºC, and a mean minimum temperature of 10.4 ºC, with a mean annual rainfall of 89 mm during the summer months (wet season) (Cabrera, 1976; Warner, 2004). In this area we collected by hand 41 specimens of Pleurodema nebulosum (18 females, 23 males) during the breeding season (January 2012). Analytical procedure: The frogs were examined for nematode parasites using the standard technique. Intestinal nematodes were fixed in 10% formaldehyde solution and preserved in 70% ethanol and cleared with lactophenol for examination under the light microscope. Illustrations were made using a Leica microscope with the aid of a drawing tube. For examination with scanning electron microscope (SEM), the nematodes were postfixed in 1% OsO4, dehydrated through an ethanol and an acetone series and critical point dried . The specimens were coated with gold and examined with a JSM-5800 scanning electron microscope. The measurements along the text are given in micrometers unless otherwise indicated, and are presented as the mean ±1 Standard Deviation with the range in parentheses; measurements of holotype and allotype are shown in brackets. Amphibian taxonomy follows Frost (2016). Nematodes were deposited in the Helminthological Collection of Museo de La Plata, La Plata, Argentina, and the Helminthological Collection of Centro de Ecología Aplicada del Litoral, Corrientes, Argentina. Symbiotypes are stored in the Herpetological Collection of Fundación Miguel Lillo. Results Aplectana nebulosa sp. nov. (Figs. 1–2) General morphology. Small, slender nematodes. Cuticle transversely striated. Slight sexual dimorphism, females larger than males (Fig. 1A, B). Narrow lateral alae present in both sexes, beginning at region of nerve ring and ending at the middle of tail in females and at level of first pair of precloacal papillae in males (Figs. 1E–1K). Numerous small somatic papillae present. Mouth with three lips; dorsal lip with two cephalic papillae and each ventrolateral lip with one cephalic papilla and one large amphid (Fig. 1C). Excretory pore anterior of oesophageal bulb (Fig. 1D). Male (based on holotype and 15 paratypes): Total length 2.9 ± 0.41 mm (2.2–3.5mm) [2.9 mm]; maximum width 136.5 ± 25.4 (100–178) [125]. Pharynx length 40.7 ± 4.2 (35–49.5) [46], width 34.3 ± 5.1 (25–41) [37.7]; oesophagus: corpus length 320.2 ± 31.4 (280–392) [310] width 34.8 ± 5.3 (25–40) [25]; isthmus length 43.7 ± 8.4 (30–56.5) [30], isthmus width 23.8 ± 5.1 (18–35.5) [25]; bulb length 54.2 ± 9 (35.5–68) [60], bulb width 53.3 ± 5.8 (39–61) [55]. Nerve ring 223.0 ± 23.4 (175–255) [240] and excretory pore 331.7 ± 72.9 (191–502.5) [345], from anterior extremity, respectively. Tail length 167.9 ± 31.3 (105–220) [202.2]. Cloacal papillae arranged as follows (Fig. 1E, F): Two rows of 6–7 pairs of precloacal papillae, the last two paris located laterally to the cloaca (Fig. 2A); 2 pairs of adcloacal papillae in anterior margin of cloaca and one middle, large unpaired papilla between the two anterior pairs (Fig. 2B); 5 pairs of postcloacal papillae (first and second pairs ventral, third pair lateral, fourth pair ventral, fifth pair lateral) (Fig. 2C); papillae pattern: 6–7:2:5+1. Spicules slightly equal, length 104.2 ± 12.4 (85–125.9) [110], pointed at distal end and with variably shaped capitulum (Fig. 1G). Gubernaculum length 52.2 ± 9.1 (37.4–62.9) [55], weakly sclerotized, ovate in ventral view (Fig. 1H). Female (based on allotype and 13 paratypes): Total length 4.6 ± 0.28 mm (2.9–5.8 mm) [4.54 mm]; maximum width 200 ± 60.1 (100–298) [235]. Pharynx length 58.2 ± 15 (30–83) [70], pharynx width 49.2 ± 12.5 (28–72) [60]; 122 · Zootaxa 4247 (2) © 2017 Magnolia Press PIÑEIRO GOMEZ ET AL. FIGURE 1. Aplectana nebulosa sp. nov. from P. nebulosum. A. Female, general view. B. Male, General view. C. Male, anterior extremity, apical view. D. Male, anterior extremity, lateral view. E. Male, posterior extremity, ventral view. F. Male, posterior extremity, lateral view. G. Spicule, ventral view. H. Gubernaculum, ventral view. I. Female, vulva and ovejector, ventral view. J. Female, vulva and ovejector, lateral view. K. Female, posterior extremity, lateral view. NEW APLECTANA FROM ARGENTINA Zootaxa 4247 (2) © 2017 Magnolia Press · 123 FIGURE 2. Aplectana nebulosa sp. nov. from P. nebulosum. A. Posterior end of male, detail of precloacal papillae. B. Posterior end of male, detail of adcloacal papillae and spicules. C. Posterior end of male, detail of postcloacal papillae. Abbreviations: ap: adcloacal papillae; up: unpaired papilla. In figure A, closed arrows indicate precloacal papillae; open arrows indicate lateral alae; in figure C, closed arrows indicate postcloacal papillae. oesophagus: corpus length 395.4 ± 65.0 (277–485) [425], width 47.6 ± 13.2 (30–79.1) [60]; isthmus length 48.5 ± 5.3 (41–58) [50], isthmus width 29.5 ± 4.7 (21–38) [40], bulb length 68.4 ± 9.8 (52–84) [80], bulb width 62.9 ± 9.4 (48–75) [70]. Nerve ring 249.4 ± 40.3 (200–325) [285] and excretory pore 417.7 ± 70 (234–506) [450] from anterior extremity, respectively.