Hyloscirtus larinopygion

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 : 32-34

Hyloscirtus larinopygion

Description. The oral disc of an individual of series QCAZ 38418 is depicted in Figure 15A. The following description is based on another individual in Stage 25 from the same tadpole series (QCAZ 38418) obtained from a margined pool (with algae) in a stream at Cerro Centella, Cascada Centella (on Tulcán–Maldonado road), 2709 m, Provincia de Carchi, Ecuador, by Juan F. Dueñas and Ítalo G. Tapia on 17 September 2008. All values are in millimeters. Total length 46.7; body length 17.8 (38.0% of total length). Body ovoid and depressed; width at the level of spiracle 8.8, and height at same position 7.5; head width at level of eyes 8.5; 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. The nostrils are small, rounded and directed anterolaterally; aperture situated 3.6 from tip of snout; internarial distance 4. Eyes positioned and directed dorsolaterally; eye length 1.9, eye width 1.2; interorbital distance 6.8. Spiracle sinistral, located at mid-body level, inner wall free from body; tube length 1.7, tube transverse width 1.4; spiracular opening directed posterodorsally, diameter 0.7. Vent tube free, opening directed dextrally; tube length 3.0, tube transverse width 4.6. Tail length 28.8; caudal musculature robust, narrowing gradually until tail terminus; at tail/body junction, tail muscle width 4.7; tail muscle height 5.4; maximun height of tail 10.3.

Oral disc located anteroventrally, emarginated twice ventrally; transverse width 6.3; completely bordered by two rows of small rounded papillae; submarginal papillae present; upper jaw sheath forming an arch, no pigmentation present; transverse width including lateral processes 2.1 (33.3% of transverse width of oral disc); lower jaw sheath V- shaped; finely serrate edges present in both sheaths.

Labial tooth row formula 5(4–5)/7(1). Only A-3 and A-4 have natural gaps, other gaps were caused by labial tooth losses. Tooth row A-1, 4.01 in length; A-2 length is 5.0; A-3 length 4.9; A-4 length is 4.5 with medial gap included; A-5 3.8 with medial gap included; P-1 length 3.1 including medial gap; P-2 length 3.5; P-3 length 3.8; P- 4 length 3.8; P-5 length 4.1; P-6 length 2.8; P-7 length 2.8.

Color in preservative. In dorsal view, body brown. Tail muscles cream, flanked by two brownish tan parallel stripes. Snout brown to translucent. In lateral view, flanks brown at spiracle level, becoming progressively gray towards the venter. Fins translucent. Tail muscles uniformly cream. Dorsal stripes are bold and continuous in the proximal two-thirds of the tail, becoming progressively thinner and irregular up to the tip of the tail muscles. Spiracle translucent. Base of spiracle gray. In ventral view, venter translucent (gut visible through skin); oral apparatus cream.

Color in life. In dorsal view, body olive brown. Tail having a golden mid-dorsal stripe flanked by a pair of tan brown stripes. Snout brown, gradually becoming pale brown anteriorly. In lateral view, flanks olive brown covered by mottled cream suffusion. Fins translucent; predominantly cream blotches scatter irregularly over dorsal fins and ventral fins. Caudal muscles reddish brown at tail/body junction to beige near the terminus. Spiracle unpigmented. Venter translucent, pigmented by widely scattered cream melanophores. Oral apparatus cream. Iris bluish gray.

Variation. Meristic variation of tadpoles in Stages 25–35 ( QCAZ 38418 , 45462 , and 4172) from Provincia de Carchi, Ecuador, is shown in Table 8. QCAZ 45462 was collected in an artificial reservoir of a stream in Quebrada Centella, 2806 m, by Juan F. Dueñas on 26 September 2008, and QCAZ 4172 was collected in an artificial reservoir of a stream at 22 km E of Maldonado, 2560 m, (on Tulcán-Maldonado road), by Felipe Campos-Yánez and Luis A. Coloma on 17 July 1993. Nine tadpoles in Stages 25–35 greatly varied in total length, ranging from 46.7–82.8 mm; body length 14.8–27.4 mm; tail length ranged from 28.8–58.0 mm .

LTRF varied from 5(4–5)/7(1) to 5(4–5)/6(1) in two specimens that were in Stage 25 ( Fig. 15D); 77.8% of tadpoles showed incomplete oral apparatus, 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. Lateral-line system was evident in all individuals examined; however, a slight difference in the placement and start of lines is observed among individuals .

During ontogenetic development considerable changes in coloration occurred ( Fig. 16). Between Stages 40–42, posterior limbs developed and acquired cream coloration, the dorsum and flanks of the body also acquired black mottling and the anterior area of the tail developed numerous aggregated cream blotches ( Fig. 16). By Stage 42, the dorsum and flanks have became grayish brown with black mottling (except near the ventral lateral areas of the flanks, which became cream), and the limbs developed a contrasting black mottling pattern over a cream and gray combined background. At Stage 44, the dorsum and head became uniformly brown, the flanks and limbs became mottled, and the fingers and toes became cream and started to show a black coloration on the dorsal surfaces of the discs. Finally as a metamorphosed juvenile ( Fig. 16), the dorsum, head, and limbs became yellow brown with the some black spots on the dorsum and head, and black vertical bars on limbs. The ventral lateral surface became white with black vertical bars.