HYLIDAE, Rafinesque, 1815

Candioti, M. Florencia Vera, 2007, Anatomy of anuran tadpoles from lentic water bodies: systematic relevance and correlation with feeding habits, Zootaxa 1600, pp. 1-175 : 43-95

HYLIDAE

Dendropsophus microcephalus . Previous literature for this species includes descriptions of cartilaginous skeleton, part of the musculature, and oral apparatus ( Duellman & Fouquette, 1968; Duellman 1970; Wassersug & Hoff 1979; Wassersug & Rosenberg 1979; Satel & Wassersug 1981; Haas 1996a). The results in this study complete the information on musculature, buccopharyngeal cavity and gut content.

Chondrocranium and hyobranchial skeleton (N = 5, stages 25 and 28. Fig. 23). The chondrocranium of these larvae represents 47% of the body length. Maximum widths are at the level of the muscular process of the palatoquadrate and the otic capsules. The suprarostral cartilage is a single, crescent-shaped structure that articulates syndesmotically with the trabecular horns. The trabecular horns are proportionately short (17% of the total length of the chondrocranium) and acuminate. The cranial floor is lightly chondrified, with thin cartilage in the central area. The carotid foramen is visible at the posterior region; the craniopalatine foramen is not clearly identifiable. In the posterior margin of the cranial floor, the notochordal canal extends 22% of the chondrocranium length. The lateral walls of the chondrocranium are formed by the orbital cartilages. The chondrocranium is dorsally open through the frontoparietal fenestra lined by the taeniae tecti marginales. The otic capsules are quadrangular and dorsally joined by the tectum synoticum; they reach 28% of the chondrocranium length. In the palatoquadrate, the articular process is long and thin. The muscular process is large, qua- drangular, wide and convex, and its dorsal margin contacts the lamina orbitonasalis. The subocular bar is very thin, with a smooth margin. The palatoquadrate attaches to the braincase via three points: the quadratocranial commissure, the ascending process, and the larval otic process. The quadratocranial commissure is wide and devoid of processes. The ascending process is attached to cranial floor. The lower jaw includes the Meckel’s and infrarostral cartilages joined by a cartilaginous intermandibular commissure. Meckel’s cartilages are sigmoid and articulate with the articular process via the retroarticular process. The infrarostral cartilages are short and posteriorly joined. In the hyobranchial skeleton, the ceratohyals are triangular and robust, and have a wide, rounded anterior process, a scarcely evident anterolateral process, a rounded lateral process, and a wide and robust posterior process; the articular condyle is very robust. The basihyal is absent and the basibranchial is long and devoid of urobranchial process. The pars reuniens has no definite limits and it is almost vestigial, making the ceratohyals appear contiguous. The branchial basket is reduced. The hypobranchials are well-developed, quadrangular, and medially articulated, leaving a small, triangular posterior gap. The ceratobranchials are bar-like, and lack lateral projections; terminal commissures connect the ceratobranchials I, II and III, whereas the fourth one remains free. The spicules are absent.

Musculature (N = 5, stages 25 and 28. Table 7 and Fig. 24). Thirty-one muscles appear in this species.

Oral apparatus and buccopharyngeal cavity (N = 2, stages 25 and 28. Fig. 25). The oral disc is modified in an oral tube whose width reaches 13% of the body length. It is devoid of marginal papillae and keratodonts, and the rostrodonts are finely serrated. Gape width is very small (11% of the body length). In the buccal roof, the prenarial arena shows no distinct features. The choanae are small, oriented at an angle of about 52º from the transversal line, and lack narial valve. The postnarial arena has one pair of small pustules in the medial region. The lateral ridge papillae are short, flat, slightly wider at the base, and have pustulate tips. The median ridge is low and with an uneven margin; some pustules scatter between the ridge and the dorsal velum. The buccal roof arena is not defined; buccal roof arena papillae are absent. The dorsal velum is very short and smooth, and no secretory pits are observed with light microscope. In the buccal floor, the infralabial papillae are globose, well-developed, with uneven margins. The tongue anlage is comparatively large, devoid of lingual papillae; some pustules appear near its margins. The buccal floor arena is not defined and numerous pustules are distributed on the central region. The buccal pockets are small, shallow, unperforated, transversally oriented, and they locate far posteriorly on the buccal floor. The ventral velum is not supported by spicules, and it has a semicircular, smooth margin; in the median region there appears a small median notch, and the glandular epithelium on the ventral surface of the velum is absent.

Gut content (N = 9, stages 25–28. Tables 21 and 22). The gut content of the dissected specimens was composed mainly by whole and fragmented oligochaetes of the genus Dero with sizes between 20–90% of the tadpole body length.

Dendropsophus nanus . Morphological features and gut content of this species were described by Lavilla (1990), Fabrezi and Lavilla (1992), Lajmanovich (1998), Vera Candioti and Haas (2004), Vera Candioti et al. (2004). Regarding Vera Candioti and Haas (2004), the disposition of the m. tympanopharyngeus is corrected.

Chondrocranium and hyobranchial skeleton (N = 5, stage 31. Fig. 26). The chondrocranium of these larvae represents 32% of the body length. The maximum width is at the plane of the muscular process and the otic capsules. The suprarostral cartilage is a single, crescent-shaped structure that articulates syndesmotically with the trabecular horns. The trabecular horns are proportionately short (13% of the total length of the chondrocranium) and acuminate. The cranial floor is lightly chondrified, with thin cartilage in the central area. The craniopalatine and carotid foramina are clearly identifiable. In the posterior margin of the cranial floor, the notochordal canal extends 21% of the chondrocranium length. The lateral walls of the chondrocranium are formed by the orbital cartilages. The chondrocranium is open dorsally, and the frontoparietal fenestra is bordered by the taeniae tecti marginales. The otic capsules are quadrangular and small, and are dorsally joined by the tectum synoticum. In the palatoquadrate, the articular process is long and thin. The muscular process is quadrangular, wide, convex, and its dorsal margin contacts the lamina orbitonasalis. The subocular bar has a smooth margin. The palatoquadrate attaches to the braincase via three points: the quadratocranial commissure, the ascending process, and the larval otic process. The quadratocranial commissure is wide and devoid of processes. The ascending process is attached to the cranial floor. The lower jaw includes the Meckel’s and infrarostral cartilages joined by a cartilaginous intermandibular commissure. Meckel’s cartilages are sigmoid and articulate with the articular process via the retroarticular process. The infrarostral cartilages are short and independent. In the hyobranchial skeleton, the ceratohyals are triangular and robust, and have rounded anterior process, scarcely visible anterolateral process, wide and rounded lateral process, and robust posterior process; the articular condyle is rounded and robust. The basihyal is absent and the basibranchial is long and devoid of urobranchial process. The pars reuniens has no definite limits and it is almost vestigial, making the ceratohyals appear contiguous. The branchial basket is reduced. The hypobranchials are well-developed, quadrangular, and medially articulated, leaving a small, triangular posterior gap. The ceratobranchials lack lateral projections and have terminal commissures connecting the ceratobranchials I, II and III; the fourth remains free in some specimens. The spicules are absent.

Musculature (N = 5, stages 31 and 36. Table 8 and Fig. 27). Thirty-one muscles appear in this species.

Muscle Insertions Comments

Suspensorioangularis ventral margin of the muscular process – retroarticular the site of origin is concealed by the process of Meckel’s cartilage m. orbitohyoideus

Quadratoangularis ventral surface of the palatoquadrate – retroarticular it is completely covered by the m. process of Meckel’s cartilage hyoangularis

Hyoangularis anterior surface of the edge of the ceratohyal –

retroarticular process of Meckel’s cartilage

Interhyoideus ventral surface of the ceratohyal, near the lateral edge

– median aponeurosis

Interhyoideus posterior + I could not find these muscles; since they are both present in a related species ( Dendropsophus Diaphragmatopraecordialis ebraccatus – Haas, 2003), but very hard to detect, it would be necessary to apply histological techniques to confirm their presence

Geniohyoideus posterior, ventral surface of the infrarostral –

hypobranchial plates, near the anterior edge

Levator arcuum branchialium I lateral margin of the subocular bar – ceratobranchial I it is the widest of the mm. l. a. branchialium; its insertion onto the

ceratobranchial occupies a large

surface

Levator arcuum branchialium II larval otic process – terminal commissure I and it is separated of the former muscle by ceratobranchial II a narrow gap, less evident at the

insertion on the palatoquadrate

Levator arcuum branchialium III lateral part of the otic capsule – ceratobranchial III

Levator arcuum branchialium posterolateral part of the otic capsule – it has two slips, the medial one well- IV ceratobranchial IV and hypobranchial plate developed, and inserted on part of the ceratobranchial IV and the

hypobranchial plate

Tympanopharyngeus lateral part of the otic capsule – connective tissue it is formed of a group of fibers that anterior to the glottis diverge from the medial slip of the m.

l. a. b. IV, and contact with those of

the opposite muscle, anteriorly to the

glottis

Dilatator laryngis posterolateral surface of the otic capsule – arytenoid

cartilage

Constrictor branchialis II branchial process II – terminal commissure I

Constrictor branchialis III branchial process II – terminal commissure II

Constrictor branchialis IV fibers are continuous with those of the anterior part of the m. subarcualis rectus II-IV; they insert on the terminal commissure II and the distal part of the ceratobranchial III

Subarcualis rectus I two slips: lateral part of the posterior process of the the dorsal slip is less developed, and ceratohyal – proximal, lateral part of the its fibers adopt an oblique orientation

ceratobranchial I (dorsal slip) and branchial process

III (ventral slip)

Subarcualis rectus II-IV two slips: anterolateral part of the ceratobranchial I – some fibers of the anterior slip are branchial process III (anterior slip) and branchial continuous with those of the m.

process III – ventromedial part of the ceratobranchial subarcualis rectus II-IV and those of

IV (posterior slip) the m. constrictor branchialis IV

Subarcualis obliquus posterior edge of the basibranchial – branchial process

II and III

Diaphragmatobranchialis peritoneum – distal edge of the ceratobranchial III

Rectus cervicis peritoneum – branchial process III

Rectus abdominis peritoneum – pelvic griddle it is well-developed; it originates almost at the level of the branchial

basket

Oral apparatus and buccopharyngeal cavity (N = 2, stages 31 and 36. Figs. 28 and 29). The oral disc is modified in an oral tube (13% of the body length). It is devoid of marginal papillae and keratodonts, and the rostrodonts are finely serrated. Gape width is very small (11% of the body length). In the buccal roof, the choanae are small, arranged at an angle of 57º from the transversal line, and lack narial valve. There are no other distinct structures on the buccal roof, excepting some few pustules. The posterior margin is pigmented and devoid of secretory epithelium, and the dorsal velum is very short. In the buccal floor, the infralabial papillae are paired and globose. The tongue anlage is comparatively large, devoid of lingual papillae, and it shows some pustules on the posterior region. The buccal floor arena is not defined, and a few pustules are scattered on the medial surface of the ceratohyals. The buccal pockets are small, shallow, unperforated, and far caudally located. The ventral velum is semicircular and smooth, with a small median notch; it lacks spicular support, marginal projections and secretory pits on the ventral surface.

Gut content (N = 10, stages 31– 37. Tables 21 and 22). The most conspicuous items were oligochaetes belonging to 10 neustonic and pleustonic species. Individuals were found intact inside the manicotto glandulare. Smaller items only accumulate 0.04% of the digestive content. The size of the oligochaetes represents 90–130% of the tadpole body length.

Hypsiboas rosenbergi . The cartilaginous skeleton and part of the musculature has been previously studied by Haas (1996a). The oral apparatus was described by Duellman (1970). Remaining data are unpublished.

Chondrocranium and hyobranchial skeleton (N = 2, stages 33 and 34. Fig. 30). The chondrocranium of these larvae represents 53% of the body length. The maximum width is at the level of posterior part of the subocular bar, and the anterolateral process of the otic capsule. The suprarostral cartilage has a single, V-shaped corpus that is dorsally articulated to the alae. The alae are well-defined, ventrally rounded, and bear developed processus dorsalis anterior and posterior. The trabecular horns are long (25% of the total length of the chondrocranium) and diverge from the ethmoid plate. The lamina orbitonasalis are formed in the stages analyzed. The cranial floor is lightly chondrified, with thin cartilage in the central area. The carotid foramen is visible on the posterior region, and the craniopalatine foramen is not clearly identifiable, because of the light chondrification of the intertrabecular plate. In the posterior margin of the cranial floor, the notochordal canal extends 19% of the chondrocranium length. The orbital cartilages are not formed. The chondrocranium is open dor- sally, and the frontoparietal fenestra is lined by the taeniae tecti marginales. The otic capsules are quadrangular, and bear an acute and long anterolateral process that nearly reaches the subocular bar. A large fenestra ovalis (50% of the capsule length) is located ventrolaterally on each otic capsule. The otic capsules are joined dorsally by the tectum synoticum. The palatoquadrate is long and relatively narrow. It has a long articular process and a high, triangular muscular process. The subocular bar has a smooth margin and it is posterolaterally rounded. The palatoquadrate attaches to the braincase via two points: the quadratocranial commissure and the ascending process. The quadratocranial commissure is thin and devoid of processes. The lower jaw includes the Meckel’s and infrarostral cartilages joined by a cartilaginous intermandibular commissure. Meckel’s cartilages are L-shaped with three processes, dorsomedialis, ventromedialis and retroarticular. The infrarostral cartilages are short, rectangular and independent. In the hyobranchial skeleton, the ceratohyals are long and have a triangular anterior process, a tall, tin and acute anterolateral process, a rounded lateral process, and a wide posterior process; the articular condyle is a rounded, robust protuberance on the dorsal surface. The ceratohyals are joined medially by the pars reuniens, longer than wide. The basihyal is absent and the basibranchial is twice as long as the pars reuniens, and bears a relatively long urobranchial process (30% of the basibranchial length). The hypobranchial plates are flat and subquadrangular, and they articulate medially leaving a posterior, narrow gap. The ceratobranchials are long, thin, and have numerous, long lateral projections. They are distally joined by terminal commissures. Three spicules are well-developed, and the fourth one is scarcely visible.

Musculature (N = 2, stage 35. Table 9 and Fig. 31). Thirty-three muscles are present on the species.

Muscle Insertions Comments

Suspensoriohyoideus posterior descending margin of the muscular process –

posterior surface of the lateral process of the ceratohyal

Orbitohyoideus anterior and dorsal margins of the muscular process –

lateral edge of the ceratohyal

Suspensorioangularis inferior, lateral part of the descending margin of the fibers occupy approximately the muscular process – retroarticular process of Meckel’s lower half of the muscular process

cartilage

Quadratoangularis ventral surface of the palatoquadrate – retroarticular it is completely covered by the process of Meckel’s cartilage mm. hyoangularis and

suspensorioangularis

Hyoangularis dorsal surface of the ceratohyal, anterior to the articular

condyle – retroarticular process of Meckel’s cartilage

Interhyoideus ventral surface of the ceratohyal, near the lateral edge –

median aponeurosis

Interhyoideus posterior fibers loosely disposed ventral to the peribranchial

chamber, in the region of the anterior ceratobranchials

Diaphragmatopraecordialis connective tissue near the insertion of the fibers of the m.

interhyoideus posterior – connective tissue dorsal to the

pericardium

Geniohyoideus posterior, ventral surface of the infrarostral –

hypobranchial plates

Levator arcuum branchialium I lateral margin of the subocular bar – ceratobranchial I

Levator arcuum branchialium II anterolateral process of the otic capsule – terminal

commissure I

Levator arcuum branchialium III lateroventral part of the otic capsule – terminal

commissure II

Levator arcuum branchialium posterolateral part of the otic capsule – medial margin of it has two slips of similar

IV the ceratobranchial IV configuration

Tympanopharyngeus posterolateral surface of the otic capsule – connective fibers diverge from the medial slip tissue anterior to the glottis of the m. l. a. b. IV, and insert near

the fibers of the opposite muscle

Dilatator laryngis posterolateral surface of the otic capsule – arytenoid

cartilage

Constrictor branchialis II branchial process II – terminal commissure I it is disposed on the ceratobranchial I

Constrictor branchialis III branchial process II – terminal commissure II it is disposed on the ceratobranchial II

Constrictor branchialis IV branchial process II – terminal commissure II it is disposed on the ceratobranchial III

Subarcualis rectus I two slips: lateral base of the posterior process of the

ceratohyal – proximal part of the ceratobranchial I

(dorsal slip), and branchial process II (ventral slip)

Subarcualis rectus II-IV branchial process II – branchial process III and proximal

part of the ceratobranchial IV

Subarcualis obliquus urobranchial process – branchial process II and III the slips diverge near the insertion on the urobranchial process

Diaphragmatobranchialis peritoneum – distal edge of the ceratobranchial III

Rectus cervicis peritoneum – branchial process III and connective tissue

near the ceratobranchial IV

Rectus abdominis peritoneum – pelvic griddle

Oral apparatus and buccopharyngeal cavity (N = 2, stages 33 and 35. Figs. 32 and 33). The oral disc represents nearly 30% of the body length and it is anteroventrally located. Gape width reaches 22% of the body length. The oral disc is completely surrounded by a simple papillar margin, double in part of the upper and lower lips. The dorsal gap is narrow. The rostrodonts have wide serrations. The keratodonts are arranged in a 2(2)/4(1) LTRF. The rows P2 and P3 are the longest, and P4 may appear complete or divided into several fragments and it is shorter than the remaining rows. The keratodonts have a scarcely marked body, and the head is slightly convex, with 12–14 cusps. The keratodonts of the lowest row are slightly shorter than in the other rows. The buccal roof is well-pigmented, mainly in the posterior region. The prenarial arena shows small pustules, and a low, pustulate, rectangular ridge. The choanae are large, very ornate, and obliquely arranged at an angle of about 33º from the transversal line; in the anterior margin, small pustules and prenarial papillae are aligned, and in the posterior margin, the narial valve is well-developed, pustulate and thick. The postnarial arena shows two pairs of conical, low and thin postnarial papillae, and several pustules. The lateral ridge papillae are flat, well-developed, and with pustulate margin. The median ridge is pentagonal, with a free pustulate margin. The buccal roof arena is not defined, and the central region shows numerous pustules uniformly arranged. The glandular zone shows large secretory pits. The dorsal velum is relatively long and smooth. In the buccal floor, posterior to the infrarostrodonts, there are three pairs of infralabial papillae: the two anterior pairs include small, conical papillae; the third pair, located on the Meckel’s cartilage, consists of tall, pustulate and multifid papillae that overlap to each other in the middle line. On the tongue anlage, there is one pair of simple lingual papillae accompanied by pustules. The buccal floor arena is delimited by 6 pairs of tall, bilaterally arranged papillae. The two papillae medial to the buccal pockets are wide, flat and multifid; the remaining ones are conical, of varied sizes. In the entire region posterior to the tongue anlage, including the prepocket region, pustules and small papillae are distributed. The buccal pockets are narrow and transversally arranged. The ventral velum is supported by spicules, and it shows three pronounced marginal projections on the filter plates; the median notch is absent, and secretory pits appear on the posterior ventral surface of the velum.

Gut content (N = 6, stages 31–34. Tables 21 and 22). The animal fraction was well-represented, with about 50% of crustaceans and 16% of ciliates. The prey sizes with highest values range between 1–6% of the tadpole body size. Additionally, in the gut contents appeared an unusual number of keratodonts and serrations of the rostrodonts probably ingested by the tadpole itself (keratodonts ≅ 15; serrations of the rostrodonts ≅ 6; values are averages per drop of gut content analyzed).

Lysapsus limellum . Morphological characters of this species were described by Kehr and Basso (1990), Vera Candioti (2004), and Alcalde and Barg (2006). Qualitative composition of the diet was analyzed by Lajmanovich (1998). Regarding Vera Candioti (2004), the disposition of the m. tympanopharyngeus is corrected.

Chondrocranium and hyobranchial skeleton (N = 5, stages 31–35. Fig. 34). The chondrocranium of these larvae represents 60% of the body length. The maximum width is at the plane of the middle part of the subocular bar. The suprarostral cartilage has a single corpus with a dorsal, deep, V-shaped notch. The corpus is dorsally fused to the alae, which are still distinguishable and bear dorsalis anterior and posterior processes. The trabecular horns correspond to 24% of the total length of the chondrocranium and are anteriorly wider. They articulate with the suprarostral through a thickened surface. The cranial floor is not completely cartilaginous, the central zone is occupied by a large basicranial fenestra that includes the craniopalatine foramina. The carotid foramen is visible. In the posterior margin of the cranial floor, the notochordal canal extends 17% of the chondrocranium length. The orbital cartilages are represented by a posterior chondrification (pila metoptica, according to Lavilla & De Sá, 1999). The taeniae tecti marginales are outlined in the posterolateral region of what would constitute the frontoparietal fenestra. The otic capsules are quadrangular and occupy nearly 29% of the chondrocranium total length. The fenestra ovalis reaches 41% of the capsule length and it is located ventrolaterally on each otic capsule. The otic capsules are dorsally joined by a thin tectum synoticum. The palatoquadrate has a thin articular process, a tall, triangular, and medially curved muscular process. The subocular bar is very wide at the middle portion, forming a flat, triangular projection. The palatoquadrate attaches to the braincase via three points: the quadratocranial commissure, the ascending process, and the larval otic process. The quadratocranial commissure is thin and bears a quadratoethmoid process and a small pseudopterygoid process. The ascending process attaches to the braincase floor (ultralow attachment). In the lower jaw, Meckel’s and infrarostral cartilages are joined by a cartilaginous intermandibular commissure. Meckel’s cartilages are sigmoid and bear rounded retroarticular and ventromedial processes. The infrarostral cartilages are short, rectangular and curved, and are joined by an intramandibular commissure. In the hyobranchial skeleton, the ceratohyals are long and have a triangular anterior process, a small, pointed anterolateral process, a rounded lateral process, and a tall, triangular posterior process; the articular condyle is a rounded projection visible from a dorsal view. The ceratohyals are joined medially by the pars reuniens, shorter than the basibranchial. The basihyal is absent and the basibranchial bears a short urobranchial process (17% of the basibranchial length). The hypobranchial plates are triangular, and they articulate medially leaving a posterior long gap. The ceratobranchials are long, thin, and have numerous lateral projections. They are distally joined by terminal commissures. Dorsally, there appear two well-defined spicules, corresponding to ceratobranchials I and II. The third and fourth spicules fuse forming a quadrangular, scarcely chondrified plate, continuous with the hypobranchial plate.

Musculature (N = 5, stages 34 and 35. Table 10 and Fig. 35). Thirty-three muscles appear in this species.

Oral apparatus and buccopharyngeal cavity (N = 2, stages 31 and 35. Fig. 36). The oral disc represents nearly 20% of the body length, and gape width reaches 15% of the body length. The papillar margin is simple, interrupted in a wide dorsal gap, and it is accompanied by scarce submarginal papillae in the commissural regions. The rostrodonts are serrated, well-developed and keratinized. The keratodonts are arranged in five rows, two upper (anterior) and three lower (posterior) resulting in a LTRF 2(2)/3. The row P3 is the shortest one, with a length nearly 1/3 of A1. In the buccal roof, the prenarial arena shows a medial group of pustules. The choanae are transversely arranged and have small prenarial papillae on the anterior margin and a welldeveloped narial valve. The postnarial arena shows two pairs of long, conical papillae and several pustules. The lateral ridge papillae are long and conical. The median ridge is trapezoid with a pustulate free margin. The buccal roof arena is not well-defined, and it shows two pairs of conical, short papillae, and scarce pustules. The glandular zone shows small secretory pits. The dorsal velum is thin and short. In the buccal floor, poste- rior to the infrarostrodonts, there are groups of pustules transversely aligned on both sides of the longitudinal axis. Posteriorly, there are three pairs of infralabial papillae: the most anterior pair consists of short, bifid papillae; the second pair includes small, conical papillae; and the third pair, located on the Meckel’s cartilage, includes tall, flat, multifid papillae that converge toward the middle axis. On the tongue anlage, there is one pair of conical lingual papillae. The buccal floor arena is delimited by 7 pairs of conical, symmetrically arranged papillae. The two anterior pairs are the smaller and locate posteriorly to the tongue anlage, anteroposteriorly aligned. The four following pairs are located at the level of the buccal pockets, and the remaining pair locates far caudally. Several pustules scatter among the papillae. The buccal pockets are deep and transversely oriented. The ventral velum is semicircular and has a V-shaped median notch; marginal projections are absent, and a secretory epithelium develops on the posterior ventral surface.

Gut content (N = 6, stages 29–31. Tables 21 and 22). The gut content was mainly composed of crustaceans and diatoms, and the more represented sizes were those smaller to 6% of the tadpole size. Filamentous chlorophytes were abundant.

Phyllomedusa hypochondrialis . Ulloa Kreisel (2003) described the buccopharyngeal cavity of this species. Recently, Alcalde (2005) described cranial musculature. Remaining morphological data presented are unpublished. Lajmanovich (1998) and Vera Candioti and Lajmanovich (1998) studied qualitative composition of the diet.

Chondrocranium and hyobranchial skeleton (N = 5, stages 31–34. Fig. 37). The chondrocranium of these larvae represents 74% of the body length. The maximum width is at the plane of the posterior part of the subocular bar and the larval otic process. The suprarostral cartilage has a single, U-shaped corpus that is dorsally fused to the alae. These are well-defined, ventrally rounded, and bear well-defined dorsalis anterior and posterior processes. The trabecular horns correspond approximately to 19% of the total length of the chondrocranium and diverge from the ethmoid plate. The cranial floor is completely cartilaginous. The carotid and craniopalatine foramina are visible. In the posterior margin of the cranial floor, the notochordal canal extends 17% of the chondrocranium length. The lateral walls of the chondrocranium are formed by the orbital cartilages. The chondrocranium is open dorsally, and the frontoparietal fenestra is bordered by the taeniae tecti marginales. The otic capsules are ovoid and occupy nearly 28% of the chondrocranium total length. The fenestra ovalis reaches 47% of the capsule length. The otic capsules are dorsally joined by the tectum synoticum. The palatoquadrate has a wide articular process, a triangular muscular process, and a subocular bar with three lateral, triangular, flat projections. The palatoquadrate attaches to the braincase via three points: the quadratocranial commissure, bearing a quadratoethmoid process; the ascending process, joined to the braincase floor; and the larval otic process. In the lower jaw, Meckel’s cartilages are long, with conspicuous ventromedial and retroarticular processes. The infrarostral cartilages are short, rectangular and independent. In the hyobranchial apparatus, the ceratohyals are long and have a rounded anterior process, a small anterolateral process, an acute lateral process, and a tall and wide posterior process; the articular condyle is a rounded, robust protuberance on the dorsal surface. The ceratohyals are joined medially by a pars reuniens shorter than the basibranchial. The basihyal is very small and the basibranchial is long and bears a long urobranchial process (about 50% of the basibranchial length). The hypobranchial plates are small, subquadrangular and flat, and they articulate medially leaving a posterior ovoid gap. The ceratobranchials are long, thin, and have numerous lateral projections. They are distally joined by terminal commissures. Four long cartilaginous spicules arise dorsally from each ceratobranchial.

Musculature (N = 5, stages 31–34. Table 11 and Fig. 38). Thirty-three muscles are present in this species.

Oral apparatus and buccopharyngeal cavity (N = 2, stage 33. Fig. 39). The oral disc represents 21% of the body length, and gape width reaches 18% of the body length. The oral disc is not emarginate. Marginal papillae are arranged in a simple margin on the upper lip and commissures, and a double margin on the lower lip; the dorsal gap is as long as the suprarostrodont length. Several submarginal papillae appear in the commissural region. The rostrodonts are well-developed and keratinized. The keratodonts are arranged in five rows, two upper (anterior) and three lower (posterior), resulting in a LTRF 2(2)/3(1). The row A2 is interrupted by a wide, median gap; P1 is discontinuous as well, but the sections are very close to each other. The row P3 is very short and in some specimens has a median gap. In the buccal roof, the prenarial arena shows a well-developed ridge with two crescent-shaped, crenulate portions. The choanae are transversely arranged; the anterior margin has small prenarial papillae, and the narial valves are scarcely developed. In the postnarial arena there is one pair of bifid, medially oriented papillae. The lateral ridge papillae are flat and bifid. The median ridge is low, slightly semicircular, and with an irregular free margin. The buccal roof arena is not defined; the central region of the buccal roof has numerous pustules and few small papillae. The glandular region appears as a posterior, V-shaped array with secretory pits. The dorsal velum is relatively long, curled, and medially interrupted in a wide gap. In the buccal floor, there is a pair of bifurcate infralabial papillae medially directed. The tongue anlage shows two short, conical lingual papillae. The buccal floor arena is delimited on both sides by two pairs of tall peripheral papillae, the anterior pair, bifid and flat, and the posterior pair, conical and shorter. Among them, and on the lateral portion of the ceratohyals, there appear numerous pustules. The buccal pockets are elongate and transversally oriented. The ventral velum is long and supported by spicules; it has three pronounced marginal projections on the filer plates, and a triangular median notch surrounded by a couple of acute projections. Secretory pits appear on the posterior ventral surface of the velum.

Gut content (N = 7, stages 31–34. Tables 21 and 22). The gut content was mainly composed of diatoms and rotifers with sizes mostly smaller to 2% of the tadpole size. Numerous filamentous chlorophytes and debris, considered non-quantifiable, also appeared in the samples.

Phyllomedusa sauvagii . Previous literature for this species includes the studies by Fabrezi and Lavilla (1992) and Fabrezi and Vera (1997).

Chondrocranium and hyobranchial skeleton (N = 5, stages 31–36. Fig. 40). The chondrocranium of these larvae represents 45% of the body length. The maximum width is at the plane of the posterior part of the subocular bar and the larval otic process. The suprarostral cartilage has a single, U-shaped corpus dorsally fused to the alae. These are well-defined, ventrally rounded, and bear developed dorsalis anterior and posterior processes. The trabecular horns correspond approximately to 22% of the total length of the chondrocranium and diverge from the ethmoid plate. They show an irregular anterior margin, and on the lateroventral margin, the processus lateralis trabeculae is slightly outlined. The cranial floor is completely cartilaginous. The carotid and craniopalatine foramina are clearly identifiable. In the posterior margin of the cranial floor, the notochordal canal extends 18% of the chondrocranium length. The lateral walls of the chondrocranium are formed by the orbital cartilages. Three foramina are observed: the optic foramen, posteroinferiorly located, the oculomotor foramen, nearly 1/5 of the former foramen, and the trochlear foramen, very small and dorsally placed. The chondrocranium is open dorsally through a frontoparietal fenestra lined by the taeniae tecti marginales. The otic capsules are ovoid and occupy nearly 33% of the chondrocranium total length. The fenestra ovalis represents 33% of the capsule length. The otic capsules are dorsally joined by the tectum synoticum; in the anterior margin of the tectum, the taenia tecti medialis is outlined. The palatoquadrate is relatively narrow. It shows a long and thin articular process, a high, triangular muscular process, and a subocular bar with three long, triangular lateral projections. The palatoquadrate attaches to the braincase via three points: the quadratocranial commissure, which bears a quadratoethmoid process, the ascending process attached to the braincase floor, and the larval otic process. In the lower jaw, Meckel’s cartilages are long and bear rounded ventromedial and retroarticular processes. The infrarostral cartilages are short, rectangular and independent. In the hyobranchial skeleton, the ceratohyals are long and have a tall and rounded anterior process, a small anterolateral process, a rounded posterior process, and a wide and tall posterior process; the articular condyle is robust, visible from a dorsal view. The ceratohyals are joined medially by a pars reuniens shorter than the basibranchial. The basihyal is very small and the basibranchial is long and bears a long urobranchial process (30% of the basibranchial length). The hypobranchial plates are triangular and articulate medially leaving a posterior ovoid gap. The ceratobranchials are long, thin, and have numerous lateral projections. They are distally joined by terminal commissures. Four long cartilaginous spicules arise dorsally from each ceratobranchial.

Musculature (N = 5, stages 31–36. Table 12 and Fig. 41). Thirty-three muscles are present in this species.

Oral apparatus and buccopharyngeal cavity (N = 2, stages 33 and 36. Fig. 42). The oral disc represents 20% of the body length and gape width reaches 19% of the body length. The marginal papillae are large, arranged in a simple margin, and interrupted in a dorsal gap. Several submarginal papillae appear in the commissural region. The rostrodonts are well-developed and keratinized. The keratodonts are arranged in five rows, two upper (anterior) and three lower (posterior), resulting in a LTRF 2(2)/3(1). The row A2 is interrupted by a wide, median gap; the row P1 is also discontinuous, but sections are very close to each other. The P3 is very short, approximately half the P2. In the buccal roof, the prenarial arena shows a well-developed ridge, with two crescent-shaped portions with irregular margin. The choanae are transversely arranged; the anterior margin has small prenarial papillae, and the narial valve is scarcely developed. In the postnarial arena there is one pair of bifid papillae, medially oriented. The lateral ridge papillae are flat and wide, with three short tips. The median ridge is low, slightly triangular, and with a pustulate free margin. The buccal roof arena is defined by three pairs of conical papillae; numerous pustules scatter on the central region. The glandular region is a posterior, V-shaped array with secretory pits. The dorsal velum is long and curled, and interrupts medially in a wide gap. Posteriorly, near the oesophagic funnel, there is a set of large pre-oesophagic papillae. In the buccal floor, there is one pair of tall, multifid, non-overlapping infralabial papillae. The tongue anlage has two tall, bifurcate lingual papillae. The buccal floor arena is delimited by 6 pairs of peripheral, tall, conical papillae. Among them, and on the lateral portion of the ceratohyals, numerous pustules there appear. The buccal pockets are elongate and obliquely oriented. The ventral velum is long and supported by spicules; it shows three pronounced marginal projections on the filter plates, and a median notch surrounded by two rounded projections; secretory pits appear on the posterior ventral surface of the velum.

Gut content (N = 6, stages 31–36. Tables 21 and 22). The gut content was almost completely composed of small euglenoids with sizes smaller than 1% of the tadpole size.

Pseudis paradoxus . Characters of the chondrocranium and musculature of this species were described in Haas (2003) and Alcalde and Barg (2006). The oral apparatus and buccopharyngeal cavity were described in Rada and Bello (1988) and Ulloa Kreisel (2003). An analysis of the qualitative composition of the diet appeared in Arias et al. (2002).

Chondrocranium and hyobranchial skeleton (N = 2, stages 31 and 35. Fig. 43). The chondrocranium of these larvae represents 37% of the body length. The maximum width is at the plane of the middle portion of the subocular bar. The suprarostral cartilage has a single corpus with a deep, narrow dorsal notch; the corpus is completely fused to the alae. These bear developed dorsalis anterior and posterior processes. The trabecular horns correspond approximately 21% of the total length of the chondrocranium and diverge from the ethmoid plate. They show relatively straight anterior margins and are slightly wider anteriorly. The nasal septum and small antorbital processes are developed. On the lateroventral margin, the processus lateralis trabeculae is slightly outlined. The cranial floor is completely cartilaginous. The dermal primordium of the parasphenoid is present and has an elongate, triangular shape. The carotid foramina are visible on both sides of the parasphenoid. In the posterior margin of the cranial floor, the notochordal canal extends 16% of the chondrocranium length. The orbital cartilages are represented by a posterior chondrification (pila metoptica, according to Lavilla & De Sá, 1999). The cranial roof is closed in the most posterior region, and the taeniae tecti marginales are well-developed. The otic capsules are small, quadrangular, and occupy nearly 19% of the chondrocranium total length. The fenestra ovalis reaches 55% of the capsule length and it is located ventrolaterally on each otic capsule. The palatoquadrate has a thin and long articular process and a low, triangular, medially curved muscular process. The subocular bar is very wide at the middle portion, forming a flat, triangular projection. The palatoquadrate attaches to the braincase via three points: the quadratocranial commissure, the ascending process, and the larval otic process. The quadratocranial commissure is thin and bears a well-developed quadratoethmoid process and a large pseudopterygoid process. The ascending process attaches to the braincase floor (ultralow attachment). In the lower jaw, Meckel’s and infrarostral cartilages are joined by a cartilaginous intermandibular commissure. Meckel’s cartilages are sigmoid in shape and bear rounded retroarticular and ventromedial processes. The infrarostral cartilages are short, rectangular, curved, and are joined by an intramandibular commissure. In the hyobranchial skeleton, the ceratohyals are long and have a triangular, medially directed anterior process, a small and pointed anterolateral process, a rounded lateral process, and a wide posterior process; the articular condyle is a rounded protuberance on the dorsal surface. The ceratohyals are joined medially by a pars reuniens shorter than the basibranchial. The basihyal is absent and the basibranchial bears a rounded urobranchial process (30% of the basibranchial length). The hypobranchial plates are quadrangular and medially continuous, excepting a small posterior gap. The ceratobranchials are long, thin, and with numerous lateral projections. They are distally joined by terminal commissures. The ceratobranchials II and III are joined by a conspicuous branchial bridge. Dorsally, there appear two well-defined spicules corresponding to ceratobranchials I and II. The third and fourth spicules fuse to the posterior part of the hypobranchial plates forming a quadrangular, scarcely chondrified plate.

Musculature (N = 2, stages 31 and 35. Table 13 and Fig. 44). Thirty-four muscles appear in this species.

Oral apparatus and buccopharyngeal cavity (N = 1, stage 35. Fig. 45). The oral disc width represents nearly 14% of the body length. Gape width is small, reaching 13% of the body length. The oral disc is lined by a double margin of marginal papillae grouped by pairs in the lower lip. Large submarginal papillae appear in the commissural region. The marginal papillation interrupts in a wide dorsal gap. The rostrodonts are finely serrated. The keratodonts are arranged in five rows, two upper (anterior) and three lower (posterior), resulting in a LTRF 2(2)/3. The row P1 is the shortest one, with a length nearly 1/2 of P2. In the buccal roof, the prenarial arena shows no distinct features. The choanae are arranged at an angle of about 37º from the transversal line, and have small prenarial papillae on the anterior margin and a well-developed narial valve. The postnarial arena shows four pairs of transversely arranged papillae. The lateral papillae are flat and bifurcate, whereas the six medial papillae are low and conical. Some pustules are scattered among these papillae. The lateral ridge papillae are paired, flat and multifid. The median ridge is wide and trapezoid, with a pustulate free margin. The buccal roof arena is defined by 6–7 papillae on both sides; among buccal roof papillae and on the central region, there appear several pustules and short papillae. Secretory pits are present in a broad V-shape array on the posterior region of the buccal roof. The dorsal velum is short, thin and smooth. In the buccal floor, posterior to the infrarostrodonts, there are 3–4 conical or slightly bifid infralabial papillae, on both sides of the middle axis. The tongue anlage has a couple of conical lingual papillae. Seven pairs of symmetrically arranged papilla delimit the buccal floor arena. Several pustules and short papillae scatter laterally on the ceratobranchial and on the posterior region of the arena. The buccal pockets are deep and transversely oriented. Numerous pustules scatter on the lateral surface of the ceratohyals, the prepocket region, and the buccal floor arena. The ventral velum is long, supported by spicules, semicircular, with slight undulations on the posterior margin and a deep median notch. Secretory pits appear on the posterior ventral surface of the velum.

Gut content (N = 2, stage 35. Tables 21 and 22). Nearly 70% of the gut content was composed of insects, followed by a lower percentage of macrophytes. For such a large tadpole, the size of these items only represent up to 20% of the tadpole body size.

Scinax boulengeri . Previous information on this species includes the study by Duellman (1970), on the oral apparatus. The remaining data are unpublished.

Chondrocranium and hyobranchial skeleton (N = 2, stages 29 and 31. Fig. 46). The chondrocranium of these larvae represents 65% of the body length. The shape is quadrangular, with maximum width at the plane of the muscular process and the larval otic process. The suprarostral cartilage is a single U-shaped structure with acute lateral edges corresponding to the alae. The trabecular horns correspond nearly to 22% of the total length of the chondrocranium and they show relatively straight anterior margins. The cranial floor is completely cartilaginous and in the posterior margin, the notochordal canal extends 17% of the chondrocranium length. The carotid foramina are visible. The orbital cartilages are not completely chondrified in the stages analyzed. The chondrocranium is open dorsally through the frontoparietal fenestra, which is lined by the taeniae tecti marginales. The otic capsules are ovoid and occupy nearly 30% of the chondrocranium total length. The large fenestra ovalis reaches 34% of the capsule length and it is located ventrolaterally on each otic capsule. The otic capsules are dorsally joined by the tectum synoticum. The palatoquadrate is relatively narrow. It has a short and wide articular process, a triangular muscular process, and a uniformly wide subocular bar. The palatoquadrate attaches to the braincase via three points: the quadratocranial commissure; the ascending process, attached to the neurocranium above the oculomotor foramen; and the larval otic process. In the lower jaw, Meckel’s cartilages are massive, short, L-shaped and bear three conspicuous processes: dorsomedial, well-developed, tall and acute; ventromedial; and retroarticular, medially oriented. The infrarostral cartilages are short, rectangular and independent. In the hyobranchial apparatus, the ceratohyals are long and have a tall, triangular anterior process, a narrow and acute anterolateral process, a rounded lateral process, and a tall, wide posterior process; the articular condyle is a rounded protuberance visible from a dorsal view. The ceratohyals are joined medially by the pars reuniens, which is shorter than the basibranchial. The basihyal is absent and the basibranchial bears an urobranchial process (29% of the basibranchial length). The basibranchial is fused to the hypobranchial plates. The hypobranchial plates are flat and triangular and they articulate medially leaving a small, triangular posterior gap. The ceratobranchials are long, thin, and have numerous lateral projections. They are distally joined by terminal commissures. Four cartilaginous spicules arise dorsally from each ceratobranchial, the fourth being slightly reduced.

Musculature (N = 2, stages 29 and 31. Table 14 and Fig. 47). Thirty-three muscles appear in this species.

Oral apparatus and buccopharyngeal cavity (N = 2, stages 31 and 36. Figs. 48 and 49). The oral disc width represents nearly 25% of the body length, and gape width reaches 18% of the body length. The oral disc is lined by a simple papillar margin and submarginal papillae on the commissural region. The papillation interrupts forming dorsal and ventral gaps. The rostrodonts are wide, thick and finely serrated. The serrations have a wide base and an acute tip. The keratodonts are arranged in five rows, two upper (anterior) and three lower (posterior), resulting in a LTRF 2(2)/3. The row P3 is shorter than the remaining rows, nearly 1/3 of the A1, and it is disposed on a “labial arm”. The keratodonts are slightly curve, spike-like, and longer in the lowest row than in the others. In the buccal roof, the prenarial arena lack distinct features. The choanae are large, arranged at an angle of 39º from the transversal line; there are no prenarial papillae, and the narial valve is visible. The postnarial arena shows a couple of short papillae. The lateral ridge papillae are tall, flat and have a pustulate tip. The median ridge is low and wide, with irregular margin. The buccal roof arena is not defined and numerous pustules are distributed in the entire region. Secretory pits appear in a V-shape array, on the posterior region of the buccal roof. The dorsal velum is thin, short and smooth. In the buccal floor, infralabial and lingual papillae are absent. The buccal floor arena is small, delimited by five pairs of papillae and several pustules among them. The most anterior pair includes wide, flat, multifid papillae, and the remaining papillae are bifid. The buccal pockets are elongate and transversally oriented. The ventral velum is supported by spicules, and it is semicircular, with a small V-shaped median notch; marginal projections are absent and secretory pits appear on the posterior ventral surface of the velum.

Gut content (N = 3, stages 27–36. Tables 21 and 22). The gut content was almost completely composed of filamentous chlorophytes. They could be quantified in this case, because they appeared fragmented in the gut contents in sizes that represent up to 30% of the tadpole body size.

Scinax nasicus . Fabrezi and Vera (1997) described the cartilaginous skeleton of this species. Lajmanovich (1998) studied the qualitative composition of the diet. Ulloa Kreisel (2003) presented a description of the buccopharyngeal cavity. Later, Vera Candioti et al. (2004) studied the skeleton, mandibular and hyoid musculature, oral apparatus and buccopharyngeal cavity, digestive tract and gut contents. More recently, Alcalde (2005) described cranial musculature. In the present study, morphology of a new set of larvae is described, and the gut content reanalyzed.

Chondrocranium and hyobranchial skeleton (N = 5, stages 32 and 35. Fig. 50). The chondrocranium of these larvae represents 40% of the body length. The maximum width is at the plane of the otic capsules. The suprarostral cartilage has a simple corpus with a concave dorsal notch, fused to the alae. The alae are still distinguishable and bear a processus dorsalis posterior. The trabecular horns correspond nearly to 18% of the total length of the chondrocranium and they show acuminate anterior margins. The cranial floor is completely cartilaginous, and in the posterior margin, the notochordal canal extends 13% of the chondrocranium length. The carotid and craniopalatine foramina are visible. The orbital cartilages are well-developed and the optic foramen is visible and large. The chondrocranium is open dorsally, and the frontoparietal fenestra is lined by the taeniae tecti marginales. The otic capsules are ovoid and occupy nearly 33% of the chondrocranium total length; they are dorsally joined by the tectum synoticum. The palatoquadrate shows a wide articular process, a tall, triangular muscular process, and a subocular bar slightly wider caudally. The palatoquadrate attaches to the braincase via three points: the quadratocranial commissure, the ascending process, attached to the neurocranium above the oculomotor foramen, and the larval otic process. In the lower jaw, Meckel’s cartilages are Lshaped and bear three conspicuous processes: dorsomedial, ventromedial, and retroarticular. The infrarostral cartilages are short, rectangular and independent. In the hyobranchial apparatus, the ceratohyals are long and have a wide, triangular anterior process, a pointed anterolateral process, an acute lateral process, and a tall, triangular posterior process; the articular condyle is a rounded protuberance visible from a dorsal view. The ceratohyals are joined medially by the pars reuniens, which is slightly shorter than the basibranchial. The basihyal is small and elliptical and the basibranchial bears a short urobranchial process (22% of the basibranchial length). The hypobranchial plates are triangular and medially articulated. The ceratobranchials are long, thin, and with numerous lateral projections. They are distally joined by terminal commissures. Four cartilaginous spicules arise dorsally from each ceratobranchial, being the fourth highly reduced.

Musculature (N = 5, stages 32 and 35. Table 15 and Fig. 51). Thirty-two muscles appear in this species.

Oral apparatus and buccopharyngeal cavity (N = 2, stages 31 and 32. Figs. 52 and 53). The oral disc width represents nearly 18% of the body length, and gape width reaches 22% of the body length. The oral disc is lined by a simple papillar margin interrupted in a dorsal gap; small submarginal papillae appear in the commissures. The rostrodonts are wide and thick, well-developed and keratinized. The keratodonts are arranged in five rows, two upper (anterior) and three lower (posterior), resulting in a LTRF 2(2)/3(1). The row P3 is slightly shorter than the other rows. The keratodonts have three regions, sheath, body and head. The head is convex, slightly spatulate, and with an average of 12 cusps. In the buccal roof, the prenarial arena has some pustules transversally aligned. The choanae are oriented at an angle of 43º from the transversal line. The postnarial arena has a couple of trifurcate papillae and central pustules. The lateral ridge papillae are well-developed, flat and bifid. The median ridge is trapezoid, with a pustulate free margin. Between the postnarial arena and the median ridge, a small, quadrangular premedian ridge there appears. The buccal roof arena is not defined and lacks any papillae. Several pustules distribute on the entire region. Conspicuous secretory pits appear in a V-shaped array, on the posterior region of the buccal roof. The dorsal velum is short and medially interrupted. In the buccal floor, posteriorly to the infrarostrodonts, there is a pair of keratinized spurs, anteromedially oriented. Posteriorly, there appear several pustules transversely arranged. The infralabial papillae are paired, bifid and non-overlapping. The tongue anlage is devoid of lingual papillae. The buccal floor arena is delimited on both sides by four conical or bifid papillae and pustules among them. The buccal pockets are elongate and transversally oriented. The ventral velum is supported by spicules, semicircular, thick, and lacks marginal projections and median notch. A conspicuous secretory epithelium develops on the posterior ventral surface of the velum.

Gut content (N = 10, stages 31–36. Tables 21 and 22). Gut contents were mainly composed of filamentous algae (not quantified) and crustaceans, followed by epiphytic diatoms. The more frequent item-sizes were those between <1–7% of the tadpole body size.