Hypsiboas riojanus (Koslowsky)

Kolenc, Francisco, Borteiro, Claudio, Alcalde, Leandro, Baldo, Diego, Cardozo, Dario & Faivovich, Julián, 2008, Advertisement call and female sexual cycle in Uruguayan populations of Physalaemus henselii (Anura, Leiuperidae), Zootaxa 1927 (2), pp. 1-66 : 25-29

Hypsiboas riojanus (Koslowsky)

Figs. 2F and 3H

External morphology.— Lot MLP DB 2440, Figs. 7C and 7D. Body depressed (BMH/BMW = 0.86 ± 0.02); body length little longer than one third of total length (BL/TL = 0.35 ± 0.02); body shape ovoid in dorsal view with a constriction behind eyes; widest at posterior third of body, behind spiracle. In lateral view, ventral contour of body flat in gular and branchial regions, convex in abdominal region. Dorsal contour of body almost flat from eyes to origin of dorsal fin. Snout semicircular in dorsal view and rounded in lateral view. Nostrils oval, with thin marginal rim, with a small rounded or subtriangular fleshy projection in medial margin; nostrils dorsolaterally located (EN/BWN = 0.54 ± 0.06), placed in a depression, closer to eyes than to the tip of snout (FN/END = 1.32 ± 0.15), more visible in dorsal than in lateral view. Eyes large (E/BWE = 0.21 ± 0.01), dorsally positioned (EO/BWE = 0.75 ± 0.03), dorsolaterally directed, not visible in ventral view. Spiracle single, lateral and sinistral; its inner wall fused to body except for its distal end; its opening oval, slightly elevated, with a diameter smaller than tube diameter, located between second and posterior thirds of body (RSD/ BL = 0.65 ± 0.03), posterodorsally directed, visible in lateral and dorsal views. Lateral line system visible. Intestinal assa located at centre of abdominal region. Vent tube starting at midline, at posterior end of body, reaching margin of lower fin, opening dextral. Tail large (TaL/TL = 0.65 ± 0.02), with both fins slightly lower than body height (MTH/BMH = 0.98 ± 0.04). Dorsal fin originates at tail-body junction. Ventral fin origin concealed by vent tube. Edges of both fins sub-parallel for first and second thirds, convergent in last one. Tail axis straight, tail tip rounded; tail musculature not reaching tail tip. Oral disc ( Figs. 8H and 9F) anteroventral, small (OD/BMW = 0.33 ± 0.02, disc measured folded), with a well marked infraangular constriction on each side of oral disc (also a less marked supraangular constriction in one example). Marginal papillae simple, longer than wide, with rounded or pointed tip. Dorsal gap present, medium-sized (DG/OD = 0.39 ± 0.09). Row of marginal papillae single or double; some infraangular submarginal papillae present. Upper jaw sheath widely arch-shaped. Lower jaw sheath with U-shaped free margin. Jaw sheaths well developed, but appear smooth and sparsely pigmented distally. Labial tooth row formula 2(2)/3(1). P3 almost as long as P2. Tooth of all rows spatulated and concave bearing 8–10 well-marked distal cusps ( Fig. 10F).

Coloration in preservative.— Body dark brown in dorsal view, even darker next to the inner margins of nostrils, with small dark spots on the head and body. Almost black laterally. Venter translucent. Caudal musculature in dorsal view dark brown, except at the insertion of the dorsal fin; in lateral view yellowish, with a dark brown marbled pattern. Fins translucent, delicately marbled in dark brown.

Variation.— MLP DB 2440. Three specimens (stages 28 and 31) exhibited some labial teeth anterior to A1, at one or both sides of the dorsal gap. In many specimens, labial teeth are partially lost from some rows.

One specimen (stage 35) with some labial teeth arranged as a short P4, and another one (stage 28) with one lateral submarginal flap with labial teeth. Two additional specimens at later developmental stages (37 and 40) with LTRF 2 (2)/3(1), without extra labial teeth. Lot MLP DB 3303 . LTRF 2 (2)/3(1) in four specimens (stages 26–37), 2(2)/4(1) in another three (stages 35–39). When present, P4 appears irregularly fragmented. A1 is bent at the middle, with an angle directed to the front. Some lateral submarginal flaps with labial teeth are present in five specimens (stages 26–37), absent in another two (stages 27 and 39) .

Oral cavity morphology.— ( Figs. 12D and 14D).

Buccal roof: There are about 11 blunt pustules on the central region of the prenarial arena. Three of them are transversely arranged, tending to but not forming a crest. Choanae transversely oriented, with anteromedial and rounded vacuities, posterior margins forming the narial valves, and both margins undulated by the presence of small prenarial pustules, in particular the anterior one. There are about 12 pustules, 2 short and 6 long conical papillae on the postnarial arena. The six longest postnarial papillae are placed anteriorly and between the two lateral ridge papillae, forming a discontinuous arch. None of these papillae seems to be bifid. Each square-shaped lateral ridge papilla possesses 6 digitiform projections on the free margin. The high, rounded and narrow median ridge presents 6 undulations distributed in all the free margin and one short papillae per side. There are approximately 200 pustules and 25 conical papillae on the BFA. The pustules are occupying all the area of the arena. The papillae are mostly arranged in a V-shaped pattern on the posterior margin of the arena, but some of them are scattered among the central pustules. The lateral regions of the arena possess few pustules. Posterior area of the roof with secretory pits and dorsal velum bearing lobated margin.

Buccal floor: Infralabial papillae on infrarostral cartilages absent. There are 2 long and digitiform infralabial papillae placed at the level of cartilago meckeli (not figured). The lingual anlage bears 2 long and conical lingual papillae very near to each other, and some pustules surrounding them. Buccal pockets mostly transversal to the axial axis. Prepocket area with 14 conical papillae of moderate size and 48 pustules. There are 40 long and conical papillae, 24 short and conical papillae and about 100 pustules on the BFA. The papillae are not arranged in two V-shaped patterns. The ventral velum has a well-marked median notch, three weaklymarked serrations on each side on the posterior margin and many secretory pits.