Stefania riae Duellman and Hoogmoed 1984

Barrio-Amorós, César L. & Brewer-Carías, Charles, 2010, Venezuelan Guayana, with the description of five new species, Zootaxa 1942, pp. 1-68 : 23-26

Stefania riae Duellman and Hoogmoed 1984

Sarisarinama carrying frog, Rana Stefania del Sarisariñama, Müdü Wënäwësiye

Camps II (EBRG 4533–35; 4537–42) and IV (EBRG 4536).

The description of Stefania riae was based on three specimens collected by P. Bermúdez during the 1974 Sarisariñama expedition. We collected a sample of 12 individuals, and comment on morphological variation ( Table 2), coloration in life, and pattern variability.

Color patterns. Pattern types.— Duellman and Hoogmoed (1984) described two different color patterns for Stefania riae , one for the holotype (KU 174688) and USNM 212331, consisting of an irregular pattern of indistinct dark brown spots ( Duellman and Hoogmoed 1984:Fig. 21), whereas KU 174689 has two pale dorsolateral stripes that fade on the posterior part of the back. These authors also recognized three color patterns among S. scalae (their S. evansi ; Duellman and Hoogmoed 1984:Fig. 9): (A) unpatterned; (B) with pale dorsolateral stripes; and (C) with chevrons or spots on the dorsum. We observed these three patterns plus an additional pattern (here called Pattern D) in S. riae ; there is no consistent sexual dimorphism in color patterns.

Pattern A (Fig. 9A).— This pattern occurs in the holotype ( KU 174688), USNM 212331 , and EBRG 4537 , 4541–42 , 4662 . The dorsum of the body is mostly pale brown with or without a few indistinct darker spots; the limbs have dark brown transverse bars (nearly indistinct in EBRG 4662 ). All have a dirty white to pale brown interorbital bar and a dark brown supratympanic stripe. The ventral coloration varies from pale brown with darker brown spots in EBRG 4662 and EBRG 4537 to white with pale brown spots in EBRG 4541 and was brown, darker than the surrounding area, with a pale yellow annulus. Irregular dark brown spots were present on the upper lips. The flanks were pink. Upper surfaces of hands, feet and concealed surfaces of hind limbs also pink .

Pattern B.—This pattern is seen in KU 174689 and in EBRG 4533–36, 4663. This is a variable pattern, in which the only consistent feature is the presence of paler than dorsal background dorsolateral stripes. The dorsum can be dark brown to yellowish brown, separated from the flanks by paler dorsolateral stripes that are distinct (EBRG 4533–34, 4663), nearly indistinct (EBRG 4536), or present only on the anterior part of the body and fading posteriorly (EBRG 4535, KU 174689). In EBRG 4533–34, the dorsolateral stripes extend nearly to the cloacal opening. All individuals have a distinctive pale interorbital bar of the same color as the dorsolateral stripes, and all, except EBRG 4536, have transverse bars on the limbs. The venter is pale brown in EBRG 4533, and 4536, 4663; it is white with irregular brown spots and reticulations in EBRG 4535 and uniform 4534 white in EBRG 4535. In life, EBRG 4535 had a brown dorsum, darkest on the back, with small dark brown and yellow spots and rather indistinct orange dorsolateral stripes, blending into the dorsal ground color in the scapular region. The anterior part of the head and the upper lips were yellow with distinct dark brown labial bars; the flanks were violet. Dorsolateral stripes are common among Stefania ; the only specimen of S. breweri and some individuals of S. evansi , S. goini , S. marahuaquensis , S. roraimae , and S. scalae have dorsolateral stripes ( Barrio-Amorós and Fuentes 2003).

Pattern C (Fig. 9B).— This pattern only occurs in EBRG 4539–40 . These two specimens have a dorsal pattern similar to that of Morph C of S. scalae ( Duellman and Hoogmoed 1984:Fig. 9). A complete interorbital bar is present only in EBRG 4539 , but it is incomplete in EBRG 4540 . The dorsum is pale brown ( EBRG 4539 ) or yellowish brown ( EBRG 4540 ), with dark brown markings of different sizes on the head and body; in EBRG 4539 the markings consist in complete or incomplete chevrons, whereas in EBRG 4540 the head and anterior part of the body have reticulations and chevrons across the posterior part of the body. Both individuals have distinct dark brown transverse bars on the limbs, a white venter with pale brown mottling, and pale brown ventral surfaces of the legs. In life, the dorsum of EBRG 4540 was bright golden yellow with black markings (Fig. 9B). The groin is purple grayish. Dorsal surfaces of discs dirty yellow and purple gray, all looking much paler .

Pattern D (Fig. 9C).—This pattern is seen only in EBRG 4538. This specimen has a brown dorsum lacking dorsolateral stripes and chevrons but possessing several dark brown spots and golden spots scattered irregularly on the head, body, and limbs. These give the appearance of the frog being dusted with gold. The venter is pale brown. In life, the dorsum of the head, body, and limbs were brown with many irregular black spots, and many yellow golden spots of different sizes. The head was marked with black canthal and supratympanic stripes and yellow labial bars; the fingers and toes were gray, and the iris was bronze.

Morphology. Stefania riae , along with S. tamacuarina , is the only species exhibiting one or more knobs on the canthus rostralis, a character that separates them from other Stefania species. Stefania riae can be differentiated from S. tamacuarina by its slightly larger discs on fingers and toes, almost indistinct supernumerary tubercles on hands (small, round, and distinct in S. tamacuarina ), and shagreeneded dorsal skin (weakly granular in S. tamacuarina ). The easiest distinction is via the dorsal color pattern, consisting in S. tamacuarina of a dark rectangular blotch on the anterior dorsum, with the anterior corner of the blotch reaching onto the upper eyelid, and with one or two dorsal blotches posterior to first ( Myers and Donnelly 1997), although this probably will vary when a wider sample of individuals will be available.

Natural history. All individuals except for one were found on successive nights in and around the most humid places inside Sima Mayor, where they were especially abundant on mossy walls soaked by water, on bushes and plants 0.3–1.5 m above the ground, and on sandstone walls inside caves or crevices. No Stefania were seen at Camp I, at the edge of Sima Mayor. One individual was seen at Camp IV on a mossy wall near a small, slow creek, but 100 m distant from a large cascade with a spray zone.

One female (EBRG 4542) contained fat bodies but no oviducal eggs. No reproductive activity, nor females carrying eggs or juveniles, were observed at Sarisariñama, as was noted for members of this genus at other localities by Gorzula et al. (1983), Jungfer and Böhme (1991), Mägdefrau (1991), MacCulloch and Lathrop (2002), Kok and Benjamin (2007), and Kok et al. (2006). Observations of reproductive activity in the dry season at Ayanganna, Guyana, led MacCulloch and Lathrop (2002) to suggest that reproduction in Stefania is not seasonally constrained. These authors also commented on the few individuals of Stefania usually encountered at any one locality, with the exception of S. ayangannae , which is the most abundant amphibian at 1400 m altitude on Ayanganna. Stefania riae was also fairly abundant inside Sima Mayor, where we collected ten individuals on the first and second nights; although several more were observed on the succeeding six nights, only two more were collected.

A male (EBRG 4535) contained a large insect (Homoptera) in its stomach. No advertisement calls of Stefania riae , as were reported for S. riveroi by Mägdefrau (1991), were heard, although a release call was emitted by some frogs upon being captured.

Remarks. The head of Stefania riae is slightly wider than long ( Table 2). In the original description, Duellman and Hoogmoed (1984) stated that the head is as long as wide or slightly longer than wide. In our sample, the head is slightly wider than long in nine individuals and as wide as long in three individuals, but this parameter can vary depending on the methodology used to measure it. Relative head width has been used to distinguish between the S. evansi group (head longer than wide or as long as wide) and the S. goini group (head distinctly wider than long). According to Rivero (1970), the former group inhabits lowlands to uplands (up to 1500 m), and the latter inhabits highlands above 1500 m. There are few cases of species of different groups living sympatrically, for example S. percristata ( S. evansi group) occurs sympatrically with S. oculosa ( S. goini group) on Jaua-tepui at 1600 m, and S. goini ( S. goini group) occurs syntopically on Duida with S. marahuaquensis ( S. evansi group). Myers and Donnelly (1997) mentioned that S. tamacuarina has a slightly wider than long head in the diagnosis as well as in the description of the species, but later, in their Remarks section they stated that “the head of Stefania tamacuarina is barely longer than wide.” They stated further that “head length/head width values (0.985 in holotype, 0.994 in paratopotype), are intermediate between values reported for members of the two species groups by Duellman et Hoogmoed (1984: Table 1), but closer to the evansi group.” Barrio-Amorós and Fuentes (2003) assigned S. breweri to the S. evansi group. The three species, S. riae , S. tamacuarina , and S. breweri occur on uplands in different mountains in the Venezuelan Guiana Shield, and their head proportions are clearly closer to species in the S. evansi group than those of the S. goini group, which have much wider heads and moderate to well-developed frontoparietal crests. However, the use of head width to distinguish between the two groups of Stefania needs to be re-evaluated; these species groups are phenetic and therefore probably mean very little in evolutionary terms.

Although is unlikely that Stefania riae occurs outside of the Sarisariñama massif, some Ye’kwanas who had never been to the summit of the massif (due to mythological taboos), recognize this species and call it müdü wënäwësiye.