HYLIDAE - TREE-FROGS FAUNA PARAGUAY

HYLIDAE - TREE-FROGS

Twenty-eight species in three subfamilies occur in Paraguay. Tree-frogs typically have well-developed digital pads and are adapted to a basically arboreal existence (except Pseudinae). They possess eight free procoelous, holochordal presacral vertebrae. The urostyle is free with two condyles and there are no ribs. The pectoral girdle is arciferal and the sternum and omosternum are cartilaginous. Palatines are usually present and the clavicle does not overlie the scapula. Teeth are present on the maxilla and premaxilla. The astralagus and calcaneum are fused only at the ends. Cartilaginous penultimate intercalary phalanges in each digit. Sartorius muscle separate and distinct. Aquatic larvae. Sperm usually with single filament, but double filament in some species. 2n=22 to 34 (most commonly 24).
The characteristics of the three subfamilies are detailled below:

Subfamily Hylinae - Tree-frogs - Rafinesque 1815
Generalised tree-frogs. Mandibularis not differentiated in most cases, but where differentiated lacks an apical element. Pupil horizontal. Sperm with single tail filament, except for in Scinax. 2n=24 or 30. Worldwide distribution. Subfamily as it stands probably does not represent a monophyletic unit. The majority of the members of the subfamily Hylinae were formerly placed in the genus Hyla. This genus is now applied only to Old World species, the New World "Hyla" being placed in two separate genera Hypsiboas (for larger species) and Dendropsophus (for smaller species). The generic change necessitated nomenclatural adjustments in some cases.

Subfamily Phyllomedusinae - Leaf Frogs - Günther 1815
Mandibularis not differentiated and lacking distinct intermandibularis. Pupil vertically elliptical. Thumb opposable. Arboreal egg deposition and aquatic larvae. Sperm with two unequal tail filaments. Dermis of skull sometimes co-ossified. 2n=26. Confined to New World.

Subfamily Pseudinae - Paradox Frogs - Fitzinger 1843
Bony intercalcary phalanges. Eggs and larvae aquatic, larvae extremely large - larger than adult form - creating the "paradox" of the common name. Adults semi-aquatic with fully-webbed toes. 2n=24. Confined to New World.

REFERENCES
Cei JM 1980 - Amphibians of Argentina - Monitore Zoologico Italiano Monografia 2.
Fouquette MJ (undated) - Synopsis of Recent Amphibians to Genus - Arizona University.
Whitfield P Ed.1984 - Longman Illustrated Animal Encyclopedia - Guild Publishing, London.

Key to the Adults of Paraguayan Species of Hylidae

1a Highly aquatic, with hind limbs greatly enlarged and paddle like. Eyes protruding, set high on the head and pointing upwards - 2
1b Not as above - 3

2a Medium sized, SVL>35mm. Thin dark lines on snout forming a V-shaped when viewed frontally. Skin smooth. Tips of digits pointed or slightly swollen - Pseudis paradoxus
2b Small, SVL<25mm. No dark markings on snout. Skin rough, densely granular. Tips of digits expanded into terminal disks - Lysapus limellum

3a Medium to large in size SVL 30-70mm. Dorsal skin smooth and green. Hindlimbs greatly elongated and slender. Eyes large with vertical pupil. Movements slow and purposeful. Interdigital membranes greatly reduced. Prominent disks on terminal digits. - 4
3b Not as above - 6

4a Medium-sized SVL up to 40mm. Parotid gland small and barely visible. Tympanum small and inconspicuous. Flash colours orange with vertical black bars - Phyllomedusa azurea
4b Large SVL>55mm. Parotid gland large and prominent. Tympanum large and conspicuous. - 5

5a - Ventral surface unmarked white, sharply demarcated from dorsal colouration. Orange colouration present on the limbs and groin, reticulated with brown and lilac. In humid forest in southern Oriental region. - Phyllomedusa tetraploidea
5b - Ventral surface green and blotched with white, separated from dorsal colouration by a white lateral line extending from the lips to the groin. Limbs and groin blotched with white, orange colouration usually absent (present only in very rare cases) but when present lacking any darker markings. In arid environments in the Chaco and northern Oriental region. - Phyllomedusa sauvagii

6a - Large (SVL>45mm) tree-frogs - 7
6b - Small or medium-sized tree-frogs (SVL<45mm) - 12

7a - Slender tree-frogs with very long, thin, almost skeletal hindlegs that extend well beyond the snout when adpressed. Head triangular in dorsal view - 8
7b Not as above - 9

8a - Snout rounded in lateral view. Groin, armpits and posterior surface of thigh lilac with transverse dark bars - Hypisboas raniceps
8b - Snout triangular in lateral view. Groin, armpits and posterior surface of thighs dark blackish-purple with irregular yellow blotches - Hypsiboas albopunctatus

9a Very large tree-frog with rounded, flattened head. Dorsal pattern relatively uniform brownish (or with slight darker marbling), usually with thin vertebral line beginning at the snout and often slightly broken in postocular region. Ventrally orange-yellow. Lateral skin smooth. Posterior surface of thighs strongly yellow, vertically banded darker. Terminal disks of toes concolorous with rest of foot. Conspicuous pollex and protrusible spine at base of first finger of males. Single large medial gular sac. - Hypsiboas faber
9b Not as above. Males with paired lateral vocal sacs that open posteriorly - 10

10a - Coppery-brown dorsum boldly-marked with black blotches that unite to form irregular longitudinal lines. Groin and posterior side of thighs red with black reticulations. Males with. - Argenteohyla simiersi
10b Not as above - 11

11a Lateral skin tuberculate. Eyes extremely large, protruding and widely-spaced on head. Head notably flattened. Dorsal base colour usually green (sometimes brown). Orange colour on ventral surface of thighs. Atlantic Forest interior only. - Itapotihyla langsdorfii
11b Excessively warty laterally. Eyes normal and not particularly widely-spaced on head. Head not notably flattened. Dorsal base colour usually grey or brown. Ventral side of thighs creamy, concolorous with rest of ventral surface. Releases toxic milky secretions when handled. Widespread in all habitats. - Trachycephalus venulosus

12a SVL 30-37mm. Snout very short and rounded. Dorsal colouration complex and warty, resembling bark of a tree. Warty skin around the margin of the lower lip and crenulations on the outer edge of the limbs. Thighs purplish-brown with odd pale blotches - Dendropsophus melanargyreus
12b Not as above. - 13

13a Slender, with elongated body, slightly pointed snout and long legs. Dorsally and laterally apple-green, without darker lateral bands. Dorsal surface variably marked with red spots and stains at night. By day iris is completely white and body may be completely apple-green with only scattered round, red spots. Ventral translucent so that internal organs are visible. - Hypsiboas rubrolineatus
13b Not as above - 14

14a Of moderate size (SVL>25mm). Snout vaguely triangular in dorsal view. Dorsal colouration complex, with greyish, brownish or olivaceous ground colour and cryptic pattern of darker spots often forming vague pattern of "reverse parentheses" in the scapular region. Bright flash colours and obvious terminal disks on digits. Fingers entirely free. Pollex rudiment absent. Eye with trace of vertical crossbar. Frequently associated with bathrooms or areas human habitation. - 15
14b Not as above - 17

15a Dorsal surface excessively granular and warty. - Scinax acuminatus
15b Dorsal surface smooth or slightly granular. - 16

16a Body stout with dorsal skin slightly granular. SVL up to 50mm (often less). Posterior surface of thighs strongly yellow with bold black markings. Usually no trace of longitudinal dorsolateral line. When hindleg is adpressed the heel reaches the nostril. - Scinax fuscovarius
16b Body slender with dorsal skin smooth. SVL up to 35mm. Posterior surface of thighs lemon yellow with scattered black markings. Trace of longitudinal dorsolateral line. When hindleg is adpressed the heel reaches the eye. - Scinax nasicus

17a Tiny to small (SVL <25mm). Body elongate and slender, with vaguely "reptilian" appearance. Dorsal colouration cryptic and complex, but with suggestion of dorsolateral line. Snout not overly long and only slightly protruding over lower jaw. Concealed surface of thighs dark with scattered red or orange spots. Digital disks spatulate, narrowing toward the base. Vocalisations scratchy. - Scinax berthae
17b Not as above - 18

18a Tiny (SVL 16-26mm), elongated and slender. Snout long and strongly protruding, with upper jaw greatly protruding over lower. Ventral skin translucent. Dorsal pattern with conspicuous dorsolateral longitudinal lines. - 19
18b Not as above. - 20

19a Head very long and eyes small, barely protruding. Broad pale lateral lateral stripe, bordered by and contrasting strongly with two broad and dark lateral stripes. Upper lip concolorous with ventro-lateral colouration and without contrasting pale stripe from below the eye. When hindleg is adpressed the heel reaches between the eye and the nostril. - Scinax squalirostris
19b Head long and eyes comparatively large, clearly protruding. Broad dark lateral stripe only slightly paler than, or concolorous with the darker stripes that border it. Contrasting white line along upper lip from below eye to axilla. When hindleg is adpressed the heel reaches the eye. - Scinax fuscomarginatus

20a Snout rounded or pointed in dorsal view, with upper jaw not notably protruding over lower in lateral view. Medium-sized (SVL 30-57mm) and slender, with long head and long, thin hindlegs. Pollex rudiment present and fingers with basal webbing. Dorsal skin smooth. Eye with no trace of vertical cross bar. - 21
20b Very tiny SVL <28mm, but robust, typically with short head and strong legs. Posterior side of thighs uniform, not brightly-coloured or patterned. - 23

21a Dark dorsal markings typically restricted to the lower back, or in the form of blotchy, broken, longitudinal lines. Posterior region of thighs dark usually with paler spotting - Hypsiboas curupi
21b Dark dorsal markings absent or in the form of longitudinal lines. Posterior region of thighs pale with darker spotting. - 22

22a Dorsal surface uniform or with irregular darker markings over a green or pale brown base colour. Dark lateral stripe usually much thinner in supratympanic area and in front of the eye. - Hypsiboas pulchellus
22b Dorsal surface with three irregular longitudinal lines, base colour brownish or yellowish. Dark lateral stripe bold in front of the eye. Dark lateral stripe broad in supratympanic area and in front of the eye. - Hypsiboas caingua

23a Green dorsum. Advertising males flesh-pink at night. Tympanum usually distinct. - 24
23b Dorsum brown, yellow or orange. Advertising males may be bright orange at night. Tympanum inconspicuous. - 25

24a Dorsal surface immaculate green, colouration extending laterally to below the level of the typanum. Tibia with thin brown longitudinal line not bordered white. Advertising males typically uniformly flesh-pink at night. - Dendropsophus elianeae
24b Dorsal surface green with three partial, thin brown longitudinal lines. Green colouration extends laterally to below the level of the typanum. Tibia with thin brown longitudinal line bordered white. Advertising males typically uniformly flesh-pink at night. - Dendropsophus jimi

25a Dorsal pattern showing wide longitudinal bands or chevrons, or a prominent hour glass shape (sometimes broken into two opposing triangles) on the head and upper back. Heel reaches the nostril when adpressed. - Dendropsophus minutus
25b Dorsal pattern showing irregular thin lines, marbling or spots, often intricate or indistinct. Heel does not reach the nostril when adpressed. - 26

26a Heel reaches the eye when adpressed. No orange flash colours on thighs. Nostrils located superlaterally on slightly raised skin with either side separated by a groove. In dorsal view the snout is comparatively short and blunt. - Dendropsophus sanborni
26b Heel reaches the tympanum when adpressed. Orange flash colours on thighs. Nostrils located laterally and not protruding. In dorsal view the snout is more elongated and somewhat triangular. - Dendropsophus nanus