ISSN 1827-9635 (print) © Firenze University Press ISSN 1827-9643 (online) www.fupress.com/ah Acta Herpetologica 9(1): 15-23, 2014 DOI: 10.13128/Acta_Herpetol-12931 The tadpole of Odontophrynus barrioi Cei, Ruiz, and Beçak, 1982 (Anura: Odontophrynidae): a comparison with the other tadpoles of the genus Exequiel González1, Guillermina Galvani1, Eduardo Sanabria2,*, Diego A. Barrasso3, Leandro Alcalde4, Lorena Quiroga1 1 Departamento de Biología, Facultad de Ciencias Exactas Físicas y Naturales, Universidad Nacional de San Juan. Av. José Ignacio de la Rosa y Meglioli, CP5400 San Juan, Argentina 2 CONICET. 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. CP: 5400. * Corresponding author. E-mail, sanabria.eduardoa@gmail.com 3 Centro Nacional Patagónico (CENPAT-CONICET). Blvd. Brown 2915 (U9120ACD), Puerto Madryn, Chubut, Argentina 4 Área Sistemática, Sección Herpetología, Instituto de Limnología ‘‘Dr. Raúl A. Ringuelet’’ (ILPLA-CONICET), 120 Y 62 (CP1900), La Plata, Buenos Aires, Argentina Submitted on 2013, 2nd September; revised on 2014, 7th January; accepted on 2014, 20th February Abstract. We describe the tadpole of Odontophrynus barrioi including external larval features, chondrocranial and cranial musculature, and compare it with the other species of the genus. Tadpoles of O. barrioi at stages 31–37 are about 52.46 mm long. The body is slightly depressed in lateral view and ovoid in dorsal view. Oral disc is emarginate laterally, anteroventral and small with a single row of marginal papillae, a single large dorsal gap, and labial tooth row formula 2(2)/3(1). Despite small interspecific variations, like different labial tooth row formulae, the general aspect of species is quite similar. Although poorly-known yet, the chondrocranium and cranial musculature display some varia- tions within the genus. Keywords. Chondrocranium, Cranial muscles, External morphology, Odontophrynidae, Odontophrynus barrioi, Tadpole. INTRODUCTION The genus Odontophrynus Reinhardt and Lütken (1862) is distributed in southern and eastern South Amer- ica. It is composed of 11 species (Frost, 2014), that are divided into three species groups (Savage & Cei, 1965; Cei, 1987; Caramaschi, 1996; Amaro et al., 2009). The O. occidentalis Group includes Odontophrynus barrioi Cei, Ruiz, and Beçak, 1982, O. occidentalis (Berg, 1896), and O. achalensis Di Tada, Barla, Martori, and Cei, 1984. The spe- cies under study is associated with arid and semiarid envi- ronments of central and western Argentina in the Chaco Seco eco-region (Torrella and Adamolí, 2005). The O. occidentalis Group is characterized by possessing enlarged postorbital, temporal, and parotoid glands, and other glands on the tibia (Savage and Cei, 1965). The adults of O. barrioi distinguish from the other species of the group by the following combination of characters: presence of irregularly arranged rounded dorsal glands; lack of a light vertebral stripe; presence of a great number of closely arranged post-orbital, temporal, and parotoid glands; absence of keratinous spines; presence of a well-developed gland between the eye and the maxilla; light brown back- ground with dark brown spots; among others (for more details see Rosset et al., 2007). The tadpole of O. barrioi was described only synthetically by Cei et al. (1982) and compared in some morphometrical measurements with the tadpole of O. occidentalis by Cei and Crespo (1982). The aim of this work is to provide a detailed descrip- tion of the external larval features, chondrocranial and 16 E. González et alii cranial musculature of the tadpole of Odontophrynus bar- rioi and to compare these characteristics with the avail- able information for other species of the genus. MATERIALS AND METHODS All specimens studied for the present work are housed at the amphibian collection of the Museo de La Plata (Buenos Aires, Argentina). Odontophrynus barrioi tadpoles were col- lected on 27 January 2011 in Las Tumanas stream (30º86’083”S, 67º32’628”W; 920 m a.s.l. – MLP 5690), La Mesada stream (30º99’132”S, 67º29’694”W; 784 m a.s.l. – MLP 5691), Astica stream (30º93’822”S, 67º34’055”W; 916 m a.s.l. – MLP 5692), and Agua de las Totoras (30º08’18”S, 67º 53’17.7”W; 1311 m a.s.l. – MLP 5693), Valle Fértil Department, San Juan, Argen- tina. The Valle Fértil Department is located in the Chaco Seco eco-region (Torrella and Adamolí, 2005). The vegetation of the area is diverse; predominantly tree species such as Prosopis spp. (Algarrobos), Aspidosperma quebracho-blanco (Quebracho blan- co), Ziziphus mistol (Mistol) and shrub of Larrea spp. (Jarillas) are present, among others. The other anurans inhabiting in the area were tadpoles and adults of Rhinella arenarum (Bufonidae), Leptodactylus latrans, L. bufonius (Leptodactylidae), and Phyl- lomedusa sauvagii (Hylidae) (Sanabria and Quiroga, 2008). The average annual temperature is 17 ºC, annual mean minimum is 10.2 ºC and annual mean maximum 25.2 ºC, with rainfall concentrated in summer, with an annual average of 225 mm (Cabrera, 1976). The tadpoles were anesthetized (2.5 ml of 2% xylo- caine and 2% lidocaine HCl, AstraZeneca Labs, Buenos Aires, Argentina) after capture and immediately fixed in 10% buff- ered formalin. Seven tadpoles of Odontophrynus barrioi (MLP 5694) were employed for the external morphology descriptions at Stages 31–37 (Gosner, 1960), also attaching morphological measurements at Stages 26–30 and 38–41. To clearly visualize oral disc papillae, it was stained with 1% of Giemsa solution, for 10 min. Three Stage 37–38 tadpoles of O. barrioi (MLP 5695) were double stained following the technique of Taylor and Van Dyke (1985) to study the chondrocranium and associated mus- cles. Muscles were observed before the clearing of specimens, after which the chondrocranium was studied. Measurements were taken under a Lancet stereomicroscope (10–40x) with an Essex digital caliper (accuracy 0.01 mm). Terminology follows Haas (1995), and d’Heursel and de Sá (1999) for chondrocra- nium; Alcalde and Rosset (2003) for chondrocranial measure- ments; Haas (2001) for mandibular muscles; Haas and Richards (1998) and Haas (2003) for hyobranchial muscles; Schlosser and Roth (1995) for innervations; Altig and McDiarmid (1999), Lannoo (1999), and Grenat et al. (2009) for external morpholo- gy; Altig and McDiarmid (1999) for oral disc morphology; and Altig and Johnston (1989) for tadpole ecomorphological types. We measured 17 morphological variables: Total length (TL), Body length (BL), Tail length (TAL), Body height (BH), Maximum tail height (MTH), Tail muscle height (TMH), Dor- sal fin height (DFH), Ventral fin height (VFH), Maximum body width (MBW), Body width at nares (BWN), Tail muscle width (TMW), Eye diameter (ED), Interorbital distance (IOD), Inter- narial distance (IND), Eye-narial distance (END), Snout-narial distance (SND), Oral disc width (ODW). Measurements follow Lavilla and Scrocchi (1986), Altig and McDiarmid (1999), and Grenat et al. (2009). The morphological measurements are in millimeters (mm) and are reported as mean ± standard error. The identification of the tadpole was based in the fact that Odontophrynus barrioi is the only species of this genus inhab- iting at the Valle Fértil Department (San Juan, Argentina: see Rosset et al., 2007). RESULTS External morphology Description: Tadpoles at stages 31–37 are 52.46 ± 6.96 mm of TL. Body is slightly depressed in lat- eral view and ovoid in dorsal view (BH/MBW = 0.86 ± 0.05), shorter than half of total length (BL/TL = 0.38 ± 0.004). The snout is rounded in dorsal view, and abrupt and blunt in lateral view. The nostrils are dorsal, directed anterodorsally, scarcely visible laterally, and positioned closer to the eyes than the tip of the snout (SND/END = 1.49 ± 0.13). The nostrils are elliptical, kidney-shaped, with a rounded and thin rim all around. Rounded eyes, small and in dorsal position, directed dorsolaterally, vis- Table 1. Morphometric measurements (mm, Mean ± SE) for tad- poles of Odontophrynus barrioi. 40 larvae at Stage: 26–30, 7 larvae at Stage 31–37 and 10 larvae at Stage 38–41 from Valle Fértil, San Juan, Argentina. Character Mean ± SE 26–30 31–37 38–41 Total lenght TL 32.21 ± 4.17 52.46 ± 6.96 76.76 ± 7.64 Body lenght BL 12.65 ± 1.61 20.15 ± 2.95 28.85 ± 2.80 Tail lenght TAL 20.40 ± 3.23 34.12 ± 3.92 48.10 ± 5.35 Body height BH 5.69 ± 1.03 9.12 ± 2.32 13.52 ± 2.58 Maximum tail height MTH 6.39 ± 0.93 9.49 ± 0.89 9.97 ± 3.58 Tail Muscle height TMH 3.16 ± 0.72 5.30 ± 0.80 8.22 ± 1.27 Dorsal Fin height DFH 2.90 ± 0.50 4.52 ± 0.58 8.08 ± 0.67 Ventral Fin height VFH 2.65 ± 0.58 4.36 ± 0.52 6.50 ± 1.44 Maximum body width MBW 6.77 ± 1.04 11.24 ± 1.72 17.48 ± 4.89 Body width at nares BWN 4.92 ± 0.88 7.35 ± 1.84 11.55 ± 2.62 Tail muscule width TMW 1.87 ± 0.47 4.19 ± 1.07 7.15 ± 0.93 Eye diameter ED 1.28 ± 0.23 2.03 ± 0.31 2.60 ± 0.32 Interorbital distance IOD 2.92 ± 0.43 4.32 ± 1.28 7.20 ± 0.68 Internarial distance IND 1.54 ± 0.23 2.15 ± 0.51 2.47 ± 0.38 Eye-nares distance END 1.87 ± 0.36 2.98 ± 0.61 4.40 ± 0.39 Snout-narial distance SND 2.73 ± 0.47 4.14 ± 0.70 5.27 ± 0.52 Oral disc width ODW 2.45 ± 0.46 3.5 ± 1.15 4.61 ± 1.01 17The tadpole of Odontophrynus barrioi ible in dorsal and lateral views. The spiracle is single, short, sinistral, lateroventrally positioned, spiracle open- ing oval, posterodorsally directed and with the inner wall of the opercular tube absent, visible in lateral, dor- sal and ventral views. Neuromasts of posterior supraor- bital, supraorbital, infraorbital angular and posterior infraorbital are noticeable. The tail is large (TAL/TL = 0.65 ± 0.01), with its maximum tail height similar to the body height (MTH/BH = 1.19 ± 0.13) and its end por- tion rounded. Myomeres are more evident in the anterior portion of the tail, with the musculature almost reaching the tip of the tail. The dorsal fin height is slightly higher than ventral fin height (DFH/VFH = 1.16 ± 0.09) and originates at body-tail junction. The vent tube is medial, attached to ventral fin, opening dextrally. Oral disc: The oral disc is anteroventral, small (OD/ MBW = 0.37 ± 0.03), laterally emarginated with absent papillae in the emarginated edges (Fig. 1 D). It has a single row of marginal papillae, conical, with pointed tip, of variable sizes. A single large dorsal gap is present (approximately 85% of ODW), without ventral gap. Single or paired submarginal papillae are present in the supra- and infraangular zone, more common and numerous in the later. Labial teeth single, with one cusp, and posterior ridges curved. Labial tooth row formula 2(2)/3(1). Jaw sheaths keratinized, with upper jaw totally pigmented, and lower jaw pigmented on its upper half; serrated edges in both jaws; upper jaw sheath smooth arch-shaped with lat- eral processes and lower jaw sheath V-shaped. Color in preservative: The body is black pale in the abdominal region and light brown in the anterior body region, with perinarial region darker. The ventral region is pale and transparent allowing the visualization of the visceral system. Tail musculature is yellow pale, slightly darker at the junction of the dorsal fin with the body, and it shows grouped chromatophores forming a dense retic- ulate. Fins are opalescent, in some cases finely reticulated and with irregular dark blotches. Chondrocranium and cranial muscles Neurocranium oval (width/length = 0.87) and depressed (height/width = 0.46), with greatest width at level of the arcus subocularis. The tetrapartite cartilago suprarostralis has the pars corpora medially joined by ligament (Fig. 2 D). A proximal bridge connects the pars corpora with the respective pars alaris at each side. The par alaris bears processus anterior dorsalis and proces- sus posterior dorsalis. Spherical and small adrostral car- tilages present. The cornu trabeculae diverges anterolater- ally from the planum ethmoidale and comprises 27% of chondrocranial length. They are uniformly wide and bear a well-developed processus lateralis trabeculae. Both the lamina orbitonasalis and the septum nasi are present at the studied stages. The fenestra frontoparietalis is lim- ited posteriorly by the tectum synoticum, laterally by the taenia tecti marginalis, and anteriorly by the taenia tecti ethmoidalis. The taenia tecti transversalis divides the fenestra in two parts, the frontal and parietal ones, being the later subdivided in left and right parietal fenestrae by the taenia tecti medialis. The cartilaginous lateral walls formed by the cartilagines orbitalis are open at level of the optic, metoptic, and trochlear foramina, and fisura prootica. At the studied stages, the basi cranii is com- pletely closed. The capsula auditiva comprises 30% of the chondrocranial length and its anterior copula is slightly overlapped with the dorsum of the processus ascendens. The larval crista parotica with processus anterolateralis and posterolateralis well developed. The medial wall of the capsula auditiva is Alcian-blue negative and its open- ings could not be observed. The superior perilymphatic foramen opens in the posterior wall of the capsule. The operculum is present. The palatoquadrate bears processus articularis quad- rati, processus muscularis quadrati, commissura quadra- to-cranialis anterior, commissura quadrato-orbitalis, long processus pseudopterygoideus, and processus ascendens. The processus ascendens meets the pila antotica just pos- terior to the oculomotor foramen (intermediate union) forming a straight angle with the cranial floor. The lower jaw is composed by cartilagines infraros- trales and cartilago meckeli. The later with processus ret- roarticularis, processus dorsomedialis and processus ven- tromedialis well developed. The commissura intraman- dibularis is Alcian-blue negative (Fig. 2D, E). Fig. 1. External morphology of the tadpole of Odontophrynus bar- rioi at Stage 38 (MLP.A-5695). (A) Dorsal, (B) Lateral, and (C) Ven- tral views (scale bar = 10 mm); (D) Oral disc (scale bar = 1 mm). Drawer: Gonzalez E. 18 E. González et alii The hyobranchial apparatus lacks copula I. All cera- tohyale processes (anterohyal lateral, anterohyal, postero- hyal and articular) are well developed. The ceratohyalia is medially joined by the pars reuniens. The copula II bears a short processus urobranchialis. The ceratobranchiales I, II, and IV are continuous to the planum hypobranchiale; the third joins the planum by a smooth connection. The commissura proximalis is absent in all ceratobranchiales and all them are distally joined by a double distal com- missure. The processus branchialis is closed and the fourth spiculae are well developed. The exoccipital, fron- toparietal, and parasphenoid are the only ossification cen- tres present at the studied stages (not drawings in Fig. 2). Respect to the cranial muscles, the ramus mandibu- laris of the nervus trigeminus runs laterally to all mm. levatorae mandibulae. In the Table 2 are detailed the ori- gin and insertion of each muscle. DISCUSSION External morphology The comparison of the larval external morphol- ogy of Odontophrynus barrioi with the available lar- val descriptions for other species of the genus allow us to propose the following tadpole characterization of Odontophrynus with small variations characteristic of each species: (1) small to medium sized tadpoles (TL = 30–75 mm, stages 31–39), (2) globose/ovoid in dor- sal view and somewhat depressed or flattened below in lateral view, (3) rounded snout in dorsal view, (4) sin- gle and sinistral spiracle, directed dorsolaterally, (5) medial vent tube, (6) dorsal nostrils, (7) medium-sized tail, being always larger than 1/2 TL with robust mus- culature, (9) anteroventral oral disc, laterally emargin- ated (except in O. cultripes and O. salvatori), with a large dorsal gap and a single row of marginal papillae. Submarginal papillae occur in the species O. barrioi, O. lavillai, O. cordobae, and O. maisuma only, (10) the most common LTRF for the genus is 2(2)/3(1) (O. bar- rioi, O. occidentalis, O. americanus, O. lavillai, O. cor- dobae, O. maisuma, O. cultripes, and O. salvatori), but 2/3(1) (O. maisuma and O. carvalhoi), 2/3 (O. maisu- ma), and 2(2)/3 (O. cultripes) are also present (see Table 3), and (11) exotrophic, lentic and benthic tadpoles. Regarding the Odontophrynus occidentalis Group to which O. barrioi belongs alongside O. occidentalis and O. achalensis, they are externally similar; the only difference that can be highlighted is that O. barrioi has the tip of the tail rounded contrary to O. occidentalis and O. acha- lensis in which the tip of the tail is acute. Selected exter- nal morphological characters of Odontophrynus tadpole Fig. 2. Chondrocranium of Odontophrynus barrioi at stage 38. (A) Dorsal view, (B) Ventral view of hyobranchial apparatus (scale bar = 3 mm), (C) Frontal view of cartilago suprarostralis (scale bar = 1 mm). References: ac: adrostral cartilage, as: arcus subocularis, ca: capsula auditiva, cb: ceratobranchiales, ch: ceratohyale, cot: com- missura terminalis, cp: copula posterior and processus urobranchia- lis, cqo: commissura quadrato-orbitalis, ct: cornua trabeculae, h: hypobranchiale, pa: pars alaris, pab: processus anterior branchialis, pad: processus anterior dorsalis, pah: processus anterior hyalis, pal: processus anterolateralis hyalis, par: processus articularis, pas: pro- cessus ascendens, pc: pars corporis, plh: processus lateralis hyalis, pmq: processus muscularis quadrati, pp: processus pseudoptery- goideus, ppd: processus posterior dorsalis, pph: processus posterior hyalis, pq: processus quadrato-ethmoidalis, pr: pars reuniens, pra: processus anterolateralis, s: spiculae I–II, sn: septum nasi, tm: taenia tecti marginalis, ts: tectum synoticum, ttm:taenia tecti medialis, ttt: taenia tecti transversalis. 19The tadpole of Odontophrynus barrioi Table 2. Origin and insertion of the cranial muscles on tadpoles of Odontophrynus barrioi at Stages 37–38. Muscle Origin Insertion Nervus trigeminus (cranial nerve V), mandibular musculature Levator mandibulae internus Processus ascendens Cartilago meckeli Levator mandibulae longus superficialis Arcus subocularis Cartilago meckeli Levator mandibulae longus profundus Arcus subocularis Both muscles insert together in the pars alaris by a common tendon Levator mandibulae externus profundus Processus muscularis Levator mandibulae externus superficialis Processus muscularis Pars alaris Levator mandibulae articularis Processus muscularis Cartilago meckeli Levator mandibulae lateralis Processus retroarticularis Pars alaris Submentalis Cartilago infrarostrale Median raphe Intermandibularis Cartilago meckeli Median raphe Mandibulolabialis inferior Cartilago meckeli Oral disc Mandibulolabialis superior Absent Nervus facialis, (cranial nerve VII), hyoid musculature Suspensoriohyoideus Processus muscularis and arcus subocularis Ceratohyale Suspensorioangularis Processus muscularis Processus retroarticularis Orbitohyodeus Processus muscularis Ceratohyale Quadratoangularis Anteroventral on palatoquadrate Processus retroarticularis Hyoangularis lateralis Ceratohyale Cartilago meckeli, retroarticular Hyoangularis medialis Absent Interhyoideus Ceratohyale Median raphe Interhyoideus posterior Ventral wall on branchial chamber Diaphragmatopraecordialis Median endof m. interhyoideus posterior Septum transversus Nervus glossopharyngeus (cranial nerve IX), branchial musculature Levator arcuum branchialium I Arcus subocularis Commissura terminalis I Subarcualis rectus I Dorsal head on ceratobranchiale I. Ventral heads on ceratobranchiales II and III Ceratohyale Constrictor branchialis I Absent Nervus vagus (cranial nerve X), branchial musculature Constrictor branchialis II Ceratobranchiale II Commissura terminalis I Constrictor branchialis III Ceratobranchiale II Commissura terminalis II Constrictor branchialis IV Ceratobranchiale III Commissura terminalis III Diaphragmatobranchialis Peritoneal wall Commissura terminalis III Levator arcuum branchialium II Anterolateral on capsula auditiva and posterior arcus subocularis Commissura terminalis II Levator arcuum branchialium III Posterolateral on capsula auditiva Commissura terminalis III Levator arcuum branchialium IV Posteroventral on capsula auditiva Ceratobranchiale IV Subarcualis obliquus II Ceratobranchiales II–III Processus urobranchialis Subarcualis rectus II–IV Ceratobranchiale IV Ceratobranchiale I Tympanopharyngeus M. levator arcuum branchialium IV Pericardium Dilatator laryngis Posteroventral on capsula auditiva Constrictor laryngis Constrictor laryngis Forms an annulus rounding the larynx Transversus ventralis IV Absent Nervus hypoglossus (spinal nerve II), hypobranchial musculature Geniohyoideus Hypobranchial at level of ceratobranchiale III Cartilago infarostrale Rectus cervicis Peritoneal wall Ceratobranchiale III 20 E. González et alii Table 3. Main morphological features of the tadpoles of Odontophrynus. Abbreviations: DG (dorsal gap), DV (dorsal view), LTRF (labial tooth row formula), LV (lateral view), S (sinistral), TOT (tip of tail). With asterisks (*) are marked the characters inferred from illustrations. (**)O. salvatori was transferred to Proceratophrys, should be remarked that possible this species also pertain to this genus, but provisionally is considered as a species of Odontophrynus not assigned to anygroup. The tadpole of Odontophrynus monachus was not included because it remains unknown (Caramaschi and Napoli, 2012). Species Reference Body Shape Oral disc LTRF Spiracle Vent Tube Nostrils Tail Eyes occidentalis group O. barrioi Present Study Ovoid in DV, depressed in LV Laterally emarginated, DG present 2(2)/3(1) S, opening posterodorsally directed Medial, dextral opening Dorsal, elliptical Large, TOT rounded Small, dorsal, directed dorsolaterally O. barrioi Cei et al. 1982; Cei and Crespo 1982; Cei 1987 — — — S, opening dorsolaterally directed — — TOT rounded — O. occidentalis Savage and Cei 1965; Cei 1980; Cei 1987 Depressed in LV Laterally emarginated, DG present 2(2)/3(1) S Medial, dextral opening Dorsal Large, TOT rounded Dorsal, directed upwards O. achalensis Di Tada et al. 1984; Cei 1987 Short Laterally emarginated, DG present* 2(2)/3(1)* S — Dorsal Large, TOT acute Dorsolaterally americanus group O. americanus Savage and Cei 1965; Cei 1980 Ovoid in DV Laterally emarginated, DG present 2(2)/3(1) S Medial Dorsal Large, TOT acute Dorsal, directed laterally O. lavillai Lavilla and Scrocchi 1991; Fabrezi and Vera 1997 Ovoid in DV, depressed in LV Laterally emarginated, DG present 2(2)/3(1) S Medial, dextral opening Dorsolaterally, elliptical Large, TOT acute Large, lateral O. cordobae Grenat et al. 2009 Ovoid in DV, depressed in LV Laterally emarginated, DG present 2(2)/3(1) S Medial, dextral opening Dorsal, elliptical Large, TOT acute Small, directed dorsolaterally O. maisuma Borteiro et al. 2010 Ovoid in DV, depressed in LV Laterally emarginated, DG present 2(2)/3(1), 2/3(1) and 2/3 sometimes S, opening posterodorsally directed Medial, dextral opening Dorsal, rounded Large, TOT rounded Large, dorsal, directed laterally cultripes group O. cultripes Savage and Cei 1965; Cei 1980 Ovoid in DV, depressed in LV Not laterally emarginated, DG present 2(2)/3, 2(2)/3(1) S, opening posterodorsally directed* Medial, dextral opening Dorsal Large, TOT acute Dorsal, directed laterally O. carvalhoi Caramaschi 1979 Ovoid in DV, triangular elongated in LV laterally emarginated, DG present 2/3(1) S Medial, dextral opening Dorsal TOT acute Large, dorsal, directed laterally No group O. salvatori** Brandão and Batista 2000 Ovoid in DV, depressed in LV Not laterally emarginated, DG present 2(2)/3(1) S, opening posterodorsally directed Medial, dextral opening Dorsal, rounded TOT rounded Large, dorsal, directed laterally 21The tadpole of Odontophrynus barrioi known to date are summarized in Table 3 complementing the table done by Do Nascimento et al. (2013). Chondrocranium and cranial muscles The cranial morphology of the Odontophrynus occi- dentalis Group is known only for O. achalensis (Haas, 1997; 2003). The chondrocranium of this species was illus- trated and its cranial muscles and chondrocranial charac- ters were described in the context of a broad phylogenetic analysis of anurans. In addition, only chondrocranial fea- tures (lacking muscle descriptions) are available for three species of the O. americanus Group (O. americanus, O. lavillai, O. maisuma; Fabrezi and Vera, 1997; Do Nas- cimento et al., 2013) and two species of the O. cultripes Group (O. carvalhoi, O. cultripes; Do Nascimento et al., 2013). The chondrocranial features were described for five species of Proceratophrys (Dos Santos Dias et al., 2013) but not for the other genus that composed Odontophrynidae (Macrogenioglottus). Do Nascimento et al. (2013) provided a chondrocranial characterization of Odontophrynus based on the following combination of characters: (1) tetrapar- tite suprarostral cartilage, (2) processus lateralis trabeculae present, (3) crista parotica distinct, (4) processus pseu- dopterygoideus present, (5) low attachment of the proces- sus ascendens, (6) commissural quadratoorbitalis present, (7) processus lateralis hyalis present, (8) tectum parietale present, (9) open processus branchialis, and (10) fourth spicule modified into a small plate. There is a notable vari- ation in the character (1) of this characterization within Odontophrynus and Proceratophrys: although always tetra- partite, both corpora may be either free or distally joined by cartilage, the corpus – ala union may be absent, proxi- mally present, or both proximally and distally present. The same condition of the characters 3, 4, 6, and 9 are present in species of Proceratophrys with available chondrocranial descriptions (see Dos Santos Dias et al., 2013), whereas the characters 2, 7, and 10 were not clearly described by Dos Santos Dias et al. (2013) for the Proceratophrys they studied. The characters 5 and 8 are variable within Odon- tophrynus since they have a different condition in O. bar- rioi (intermediate union of the processus ascendens and absence of tectum parietale at advanced stages of devel- opment). Furthermore, we have verified both characters in a sequence of larval stages of a tetraploid population of O. americanus (from Buenos Aires province, Argentina) housed at the Herpetological Collection of the Museo de La Plata (MLP. 5111). These specimens have an interme- diate union of the processus ascendens and lack the tec- tum parietale (at least at stage 42) as we found here for O. barrioi. The fenestra frontoparietalis may be posteriorly closed by the formation of a tectum parietal (O. achalensis at least at Stage 40); other condition is the presence of two fenestrae parietales limited by the tectum synoticum and the taenia tecti transversalis et medialis (O. barrioi at Stage 38); and the fenestra frontoparietalis remains widely opened by the existence of a tectum synoticum only (O. americanus and O. lavillai at Stages between 31–37). How- ever, these features are clearly due to the heterochronic development observed at different developmental stages across the species. Finally, we wish to make a brief com- ment about the presence/absence of adrostral cartilages in the species of Odontophrynus. Odontophrynus barrioi is the unique species of the genus in which the adrostrals seem invariable present. In other species they may be either pre- sent or absent as in O. americanus (absent in the speci- mens studied by Do Nascimento et al., 2013; but present in those studied by Fabrezi and Vera, 1997) and O. achalensis (see Haas, 2003); or merely present as adrostral tissue mass (not chondrified, O carvalhoi, O. maisuma). The comparison of the cranial muscles of O. acha- lensis (Haas, 1997, 2003), with the muscles we described for O. barrioi shows a single variable feature between both species: the insertion site of the m. rectus cervicis (ceratobranchiale III in O. barrioi, ceratobranchiale III and IV in O. achalensis). In summary, the external morphology of the tadpole of Odontophrynus barrioi is similar to the other species of the genus with small variations between them, and the internal larval features are controversial (e.g. morphology of the adrostral cartilages) to diagnose the species groups of Odontophrynus. ACKNOWLEDGMENTS We thank E. Espejo for providing housing and T. Gonza- lez and R. Aguilar for helping with the English. Authorities of San Juan fauna office provide permits (SA y DS nº 1300-4736- 2011). We special thank to P. Pastor, A. Navas, M. Herrera, D. Moreno, A. Cataldo for the field work assistance and two anon- ymous reviewers that greatly contributed to ameliorate the man- uscript. This work was partially supported by a postdoctoral fel- lowship from CONICET, awarded to EAS. REFERENCES Alcalde, L., Rosset, S.D. (2003): Descripción y compar- ación del condrocráneo en larvas de Hyla raniceps (Cope, 1862), Scinax granulatus (Peters, 1871) y Sci- nax squalirostris (A. Lutz, 1925) (Anura: Hylidae). Cuad. Herpetol. 17: 35-51. Altig, R., Johnston, G.F. (1989): Guilds of anuran larvae: relationships among developmental modes, morphol- ogies, and habitats. Herpetol. Monogr. 3: 81-109. 22 E. González et alii Altig, R., McDiarmid, R.W. (1999): Body Plan: Develop- ment and Morphology. In: Tadpoles: The Biology of Anuran Larvae, pp. 24-51. McDiarmid, R.W., Altig, R, Eds., University of Chicago Press, Chicago. Amaro, R.C., Pavan, D., Rodrigues, M.T (2009): On the generic identity of Odontophrynus moratoi Jim & Caramaschi, 1980 (Anura, Cycloramphidae). Zootaxa 2071: 61-68. Borteiro, C., Kolenc, F., Pereyra, M.O., Rosset, S., Baldo, D. (2010): A diploid surrounded by polyploids: tad- pole description, natural history and cytogenetics of Odontophrynus maisuma Rosset from Uruguay (Anu- ra: Cycloramphidae). Zootaxa. 2611: 1-15. Brandão, R.A., Batista, C.G. (2000): Descrição do girino de Odontophrynus salvatori (Anura, Leptodactylidae). Iheringia, Ser. Zool. 89: 165-170. Cabrera, A.L. (1976): Regiones fitogeográficas de la República Argentina, Enciclopedia Argentina de Agri- cultura y Jardinería, Buenos Aires. Caramaschi, U. (1979): O Girino de Odontophrynus car- valhoi Savage & Cei, 1965 (Amphibia, Anura, Cera- tophrydidae). Rev. Bras. Biol. 39: 1691-71. Caramaschi, U., Napoli, M.F. (2012): Taxonomic revision of the Odontophrynus cultripes species group, with description of a new related species (Anura, Cyclo- ramphidae). Zootaxa. 3155: 1-20. Cei, J.M. (1980): Amphibians of Argentina. Monit. Zool. It. (NS), Monografie II, Italy. Cei, J.M. (1987): Additional notes to “Amphibians of Argentina”: an update, 1980–1986. Monit. Zool. It., N.S., Monografia, 21: 209-272. Cei, J.M., Crespo, E.G. (1982): Differences in larval mor- phology of allopatric isolated populations of the Odontophrynus occidentalis Group from Western Argentina. Arq. Mus. Bocage. 1: 335-340. Cei, J.M., Ruiz, I.R.G., Beçak, W. (1982): Odontophrynus barrioi, a new species of Anuran from Argentina. J. Herpetol. 16: 97-102. d’Heursel, A., de Sá, R.O. (1999): Comparing the tadpoles of Hyla geographica and Hyla semilineata. J. Herpetol. 33: 353-361. Di Tada, I.E., Barla, M.J., Martori, R.A., Cei, J.M. (1984): Odontophrynus achalensis una nueva especie de anfibio de la Pampa de Achala (Córdoba, Argentina). Hist. Nat. 17: 149-155. Do Nascimento, F.A.C., Mott, T., Langone, J.A., Davis, C.A., de Sá, R.O. (2013): The genus Odontophry- nus (Anura: Odontophrynidae): a larval perspective. Zootaxa 3700: 140-158. Dos Santos Dias, P.H., Telles de Carvalho-E-Silva, M.D.P., Potsch de Carvalho-E-Silva, S. (2013): Larval chon- drocranium morphology of five species of Procera- tophrys Miranda Ribeiro (Amphibia; Anura; Odon- tophrynidae). Zootaxa 3683: 427-438. Fabrezi, M., Vera R. (1997): Caracterización morfológica de larvas de anuros del Noroeste argentino. Cuad. Herpetol. 11: 37-49. Frost, D.R. (2014): Amphibian Species of the World: an Online Reference, Version 5.6 (09 January 2013). American Museum of Natural History, New York, USA. Available from http://research.amnh.org/vz/her- petology/amphibia/Amphibia/Anura/Odontophryni- dae/Odontophrynus (accesed 18 February 2014). Grenat, P.R., Zavala Gallo, L.M. Salas, N.E., Martino, A.L. (2009): The tadpole of Odontophrynus cordobae Mar- tino & Sinsch, 2002 (Anura: Cycloramphidae) from central Argentina. Zootaxa 2151: 66-68. Gosner, K.L. (1960): A simplified table for staging anuran embryos and larvae with notes on identification. Her- petologica 16: 183-190. Haas, A. (1995): Cranial features of dendrobatid larvae (Amphibia: Anura: Dendrobatidae). J. Herpetol. 224: 241-264. Haas, A. (1997): The larval hyobranchial apparatus of Discoglossoid frogs: Its structure and bearing on the systematics of the Anura (Amphibia : Anura ). J. Zool. Syst. Evol. Res. 35: 179-197. Haas, A. (2001): Mandibular arch musculature of anuran tadpoles, with comments on homologies of amphibian jaw muscles. J. Herpetol. 247: 1-33. Haas, A. (2003): Phylogeny of frogs as inferred from pri- marily larval characters (Amphibia: Anura). Cladistics 19: 23-89. Haas, A., Richards, S.J. (1998): Correlations of cranial morphology, ecology, and evolution in Australian suc- torial tadpoles of the genera Litoria and Nyctimystes (Amphibia: Anura: Hylidae: Pelodryadinae). J. Herpe- tol. 238: 109-141. Lannoo, M.J. (1999): Integration: Nervous and Sensory Systems. In: Tadpoles: The Biology of Anuran Larvae, pp. 149-169. Altig, R., McDiarmid, R.W., Eds., Uni- versity of Chicago Press. Lavilla, E.O., Scrocchi, G.J. (1986): Morfometría larval de los géneros de Telmatobiinae (Anura: Leptodactyli- dae) de Argentina y Chile. Physis 44: 39-43. Lavilla, E.O., Scrocchi, G.J. (1991): Aportes a la herpeto- fauna del Chaco argentino: II- Nuevos datos sobre Odontophrynus lavillai Cei, 1985 (Anura: Leptodac- tylidae). Acta Zool. Lilloana. 40: 33-37. Rosset, S.D., Ferraro, D.P., Alcalde, L., Basso, N.G. (2007): A revision of Odontophrynus barrioi (Anura: Neo- batrachia): Morphology, osteology, vocalizations, and geographic distribution. S. Ame. J. Herpetol. 2: 97-106. 23The tadpole of Odontophrynus barrioi Sanabria, E., Quiroga, L. (2008): Guía Sonora de los anfibios de San Juan. (CD-ROM) Versión Digital 1. ISBN 978–987–05–4623–8, San Juan, Argentina. Savage, J.M., Cei, J.M. (1965): A review of the Leptodac- tylid frog genus Odontophrynus. Herpetologica 21: 178-195. Schlosser, G., Roth, G. (1995): Distribution of cranial and rostral nerves in tadpoles of the frog Discoglossus pic- tus (Discoglossidae). J. Morphol. 226: 189-212. Taylor, W.R., Van Dyke, G.C. (1985): Revised procedures for staining and clearing small fishes and other ver- tebrates for bone and cartilage study. Cybium 9: 107- 119. Torrella, A.T., Adamolí, J. (2005): Situación ambiental en la ecoregión del Chaco Seco. In: La situación ambien- tal de Argentina 2005, pp. 74-100. Brown, A., Ortiz, U., Acerbi, M., Corchera, J. Eds., Fundación Vida Sil- vestre, Buenos Aires, Argentina. Acta Herpetologica Vol. 8, n. 2 - December 2013 Firenze University Press Journal of the Societas Herpetologica Italica ACTA HERPETOLOGICA