Hyloscirtus pantostictus

Coloma, Luis A., Carvajal-Endara, Sofía, Dueñas, Juan F., Paredes-Recalde, Arturo, Morales-Mite, Manuel, Almeida-Reinoso, Diego, Tapia, Elicio E., Hutter, Carl R., Toral, Eduardo & Guayasamin, Juan M., 2012, 3364, Zootaxa 3364, pp. 1-78 : 39-42

Hyloscirtus pantostictus

Description. The oral disc of an individual of series QCAZ 45440 is depicted in Figure 15C. The following description is based on another individual in Stage 25 from the same tadpole series (QCAZ 45440). The specimen was obtained in a slow moving pool along the margins of the stream margins at Creek 2 (00° 38' 37'' N, 77° 31' 56'' W; 2586 m), Santa Bárbara, Provincia de Sucumbíos, Ecuador, by Juan F. Dueñas and Ítalo G. Tapia on 29 September 2008. Tadpoles were gregarious and took shelter under the sand at bottom of pool when disturbed. All values are in millimeters. Total length 48.4; body length 13.6 (28.2% of total length). Body ovoid and depressed; width at the level of spiracle 7.0, and height at same position 5.5; head width at level of the eyes 6.5; anterior margin of snout uniformly rounded in dorsal view and sloping at level of nares in lateral view; lateral-line system evident displaying supraorbital, infraorbital, longitudinal oral, mandibular, angular, posterior infraorbital, middle body, dorsal body, and ventral body lines. The arrangement of the lateral-line system is symmetrical, except for ventral lines; mandibular line originates at anterior end of venter and runs laterally forming an arch around each side of oral apparatus; ventral lines originate anterior to vent tube, run diagonally over trunk until they make a sharp turn down and return to the venter; angular line continuous with infraorbital line and extends perpendicular to infraorbital, longitudinal oral, and mandibular lines. The longitudinal oral line originates at midlevel of angular line and runs parallel to longitudinal axis until reaching the arch of mandibular line. Supra and infra orbital lines originate at snout and run posteriorly until they merge around the eyes. The nostrils are small, bean-shaped and directed anterolaterally; opening 2.6 from tip of snout; internarial distance 3.3. Eyes positioned and directed dorsolaterally; eye length 1.5, eye width 1.1; interorbital distance 5.0. Spiracle sinistral, located at midbody level, inner wall free from body; tube length 1.4, tube transverse width 1.1; spiracular opening directed posterodorsally, diameter 0.4; distance from tip of snout to spiracular opening 9.7. Vent tube free, opening directed dextrally; tube length 2.9, tube transverse width 1.8. Tail length 34.1; caudal musculature robust, narrowing gradually until tail terminus; at tail-body junction, tail muscle width 3.2; tail muscle height 4.1; maximum height of tail 7.3.

Oral disc located anteroventrally, emarginated twice ventrally; transverse width 4.9; completely bordered by two rows of small and rounded papillae; submarginal papillae absent; upper jaw sheath forming an arch, no pigmentation present; transverse width including lateral processes 2.1 (42.9% of transverse width of oral disc); lower jaw sheath V- shaped; finely serrate edges present in both sheaths. Labial tooth row formula 4(3–4)/6(1). Only A-3 and A-4 have natural gaps, other discontinuities were caused by labial tooth losses. Tooth row A-1, 2.8 in length, having one region with missing teeth; A-2 length 3.7; A-3 length 3.6 including medial gap; A-4 length 3.1 with medial gap included. P-1 length 2.5 including medial gap; P-2 length 2.8; P-3 length 2.8; P-4 length 2.8; P-5 length 2.4; P-6 length 1.8.

Color in preservative. In dorsal view, body tan gray with dark T- shaped fleck between eyes. Tail having a cream streak, flanked by two black parallel stripes, starting slightly anterior to tail/body junction. Snout gray. In lateral view, flanks tan gray at level of spiracle, becoming progressively lighter towards the venter. Fins translucent; black stippling and gray filiform melanophores scattered irregularly over tail muscles, and dorsal and ventral fins. Tail muscles are uniformly gray. Dorsal stripes bold and continuous in the proximal two-thirds of tail, becoming progressively thinner and irregular towards posterior end of tail. Distal half of spiracle translucent, only pigmented by few widely scattered stipples and filiform melanophores. Base of spiracle gray as body flanks. Iris black. Venter translucent (gut visible through skin); oral apparatus cream covered with dark gray blotches.

Color in life. In dorsal view, body brown and covered with thin sandy-gold suffusion that extends over the proximal third of tail muscles. Black transverse bar between eyes. Tail with white streak flanked by two segmented black stripes. Snout brown, gradually clearing as approaching tip. In lateral view, flanks reddish brown to translucent, covered by mottled golden suffusion; dorsal fins with predominantly cream and few scattered black blotches. Ventral fins exhibit only white blotches. Caudal muscles reddish brown at tail-body junction to beige near terminus. Spiracle unpigmented, however a silver gold iridescence can be depicted in certain light conditions. Venter translucent, pigmented by widely scattered golden melanophores. Oral apparatus cream. Iris black, with a single irregular green concentric reticulation.

Variation. There is variation in ventral pigmentation patterns ( Fig. 20). Meristic variation of tadpoles in Stages 25–41 (QCAZ 45440) are shown in Table 8. Eleven tadpoles in Stages 25–39 greatly varied in total length, ranging from 37.7–80.5; body length ranged from 12–25.8; tail length ranged from 25.7–53.8. Five lab-reared tadpoles in Stages 40–41 also varied in total length measuring 67.5–83.8; body length was 22.4–25.4, and tail length ranged from 46.5–59.1.

LTRF greatly varied from 4(4)/5(1) to 6(4–6)/7(1) ( Fig. 15B); 53.6% of tadpoles showed incomplete oral apparatus (Stages 25–27, 36–39), partially or entirely depleted of denticles, showing variable number of labial papillae and abraded tooth rows. Absence of keratinized teeth may be due to chytrid infection. The lateral-line system was evident in all individuals examined; however, a slight difference in the placement and origin of lines is observed among individuals. Arrangement of ventral bodyline may be symmetrical or asymmetrical on the left flank of body where spiracle is located.

Overall color patterns as well as arrangement and coloration of blotches in fins greatly varied among individuals and through ontogenetic development ( Fig. 19). Individuals of about the same size and Gosner stage show variation in dorsal and lateral color patterns from opaque brown ( Fig. 19A) to light brown ( Fig. 19C) passing through an intermediate state where both tones produce a contrasting pattern in overall body coloration (19B). The same applies for the blotches on dorsal and ventral fins, where the pattern ranges from small randomly scattered cream blotches to small, more numerous blotches. An alternative state is shown in one individual ( Fig. 19B), in which dark blotches are also present.

Considerable change in coloration occurred during ontogenetic development of lab-reared Hyloscirtus pantostictus ( Fig. 21). Between Stages 39–41, the posterior limbs developed yellow coloration and the dorsum became opaque and gray but the flanks of the body still exhibited a golden brown suffusion. By Stage 42, the entire dorsum and flanks had become dark gray with black mottling all over, the snout was reduced, and the limbs developed a pattern of black mottling pattern over a bright yellow background. At Stage 45, the dorsum and head were uniformly tan-gray with lighter flanks. Black mottling was still present, especially on anterior and posterior limbs and over the posterior portion of the dorsum.

Juveniles showed great variation in coloration. Some exhibited a pale gray dorsal pattern ( QCAZ 42350 from Santa Bárbara, 2709 m, Provincia de Sucumbíos, Ecuador, collected as tadpole by Juan F. Dueñas, Ítalo G. Tapia, Diego Páez-Moscoso, and Jennifer M. García on 18 September 2008; SVL 32.4 mm) whereas most exhibited a predominantly tan brown dorsum with black blotches. Cephalic flanks as well as anterior and posterior limbs showed a slightly lighter brown color with yellow dots and bars. The venter and digits were white. Finally, a subadult exhibited a pattern resembling that of adults but with slightly different colors; the dorsal surfaces of the head and dorsum were brown with yellow spots. The hidden surfaces of the hind limbs were black with yellow vertical bars and the exposed surfaces of all limbs had yellow spots both in anterior and posterior limbs .