Description

Allobates sieggreenae is a nurse frog with a snout vent length of 15.2 - 16.4 mm in males and a slightly longer snout vent length of 15.4 - 17.2 mm in females. The head length is about 30% of the snout vent length. The head is slightly wider than long. Females and males have relatively similar head lengths and widths. The snout takes up approximately one fifth of the head length. The nostrils are located on the dorsolateral side of the snout. The distance between nostrils is about 40% of the head width. The distance from eye to nostril is smaller than the distance between nostrils. The eye diameter is slightly bigger than the distance from eye to nostril. The distance between the nostrils is about the same (if a little bigger) than the distance between the eyes. The tympanum diameter is about half that of the eye diameter, and is not visible unless under a microscope. The frog has a single vocal sac extending from the middle of the throat to the chest (Gagliardi-Urrutia et al. 2021).

Males and females have very similar forearm lengths with male forearm length ranging from 3.4 - 3.8 mm and females ranging from 3.4 - 4.0 mm. The forearm length is about one fifth the length of the snout-vent length. The upper arm is only slightly longer if not the same as the forearm length. The carpal pad is absent. The thenar tubercle is clearly visible. The diameter of the palmar tubercle is 0.4 - 0.8 mm in males and 0.3 - 0.7 mm in females. The diameter of thenar tubercle is 0.3 - 0.6 mm in males and 0.3 - 0.5 mm in females. The maximum diameter of the thenar tubercle is 83% of the maximum diameter of the palmar tubercle. Allobates sieggreenae has four fingers. The length of Finger II is 81% of Finger I length, and when fingers are adpressed the tip of Finger IV reaches the distal end of the distal subarticular tubercle of Finger III. The relative lengths of fingers are: IV < II < I < III. The fingers II and III are swollen in adult males but not swollen in females. The width of the third phalanx of Finger III is 0.3 - 0.5 mm in males and 0.2 - 0.4 mm in females. On the digits there are paired dorsal scutes. On finger IV the lateral subarticular tubercle (tubercle below the joint and away from center) is absent. The discs on fingers I - IV are moderately expanded. There is no webbing on fingers, and no metacarpal ridge. Males do not have excrescences on their thumbs. The gland usually on the arm is absent (Gagliardi-Urrutia et al. 2021)

The thigh length is 6.6 - 8.0 mm in males and 6.8 - 9.6 mm in females. Tibia length is 7.0 - 8.3 mm in males and 7.1 - 8.1 mm in females. The thigh is about 40 - 50% of the snout vent length. Thigh length is similar in length to tibia for males and slightly longer in females. Foot length (6.2 - 7.3 mm in males and 6.1 - 7.1 mm in females) is slightly smaller than thigh length. The frog has a tubercle-like and strongly curved tarsal keel. The relative lengths of toes is I < II < V < III < IV. The width of the disc on toe IV is 0.5 - 0.9 mm in males and 0.6 - 0.8 mm in females. The width of toe IV distal phalanx is 0.3 - 0.4 mm in males and 0.3 - 0.6 mm in females. The disc on Toe I is slightly expanded, and the discs on the rest of the toes are more expanded. Webbing is present between toes III and IV but absent between the rest of the toes. There is no metatarsal fold (Gagliardi-Urrutia et al. 2021).

The skin texture of the dorsum is granular, and there are flat granules scattered throughout the body. The texture is more granulated towards the posterior region. There is no dermal flap above the cloaca (Gagliardi-Urrutia et al. 2021).

DIAGNOSIS

This species is found in the Amazon with several other Allobates species, but can be differentiated from other Amazonian Allobates by size, coloration, patterning, and/or call. The most closely related species is Allobates trillineates. However, A. trilineatus have a dark brown dorsum, blackish brown lateral stripe, and they’re usually paler from mid-body to groin than A. sieggreenae. Allobates sieggreenae also have a shorter head, as A. trilineatus' head length is about 5.8 - 6.2 mm (compared to 4.3 - 5.5 mm of A. sieggreenae). The adult males of A. trilineatus have abundant and dense dark melanophores (melanin cells) on the throat, belly, and chest. This makes a solidly dark background with only a few small scattered cream/white patches on areas with no melanophores. In comparison, A. sieggreenae has a light gray or brown throat and chest with no dark spots. On the dorsal side of the thighs, there is usually a dark transverse bar that is not present in A. sieggreenae (Gagliardi-Urrutia et al. 2021).

In general, A. sieggreenae is smaller (max 16.4 mm) than many species such as the Allobates femoralis complex (including A. femoralis, A. hodli, A. myersi, and A. zaparo, min 22.2 mm), A. masniger (17.9 mm), A. nidicola (18.5 mm), A. nunciatus (20.8 mm) and A. paleovarzensis (19.7 mm). The minimum snout vent length of adult A. kingsburyi, A. mcdiarmidi, A. melanolaemus, and A. vanzolinius is 19.6 mm. Male A. undulatus (min 19.6 mm) are also bigger than the A. sieggreenae (Gagliardi-Urrutia et al. 2021).

Allobates sieggreenae has a slightly lighter brown dorsum, with its sides flanked by a pale straight dorsolateral stripe. In comparison, A. brunneus, A. carajas, A. crombiei, A. flaviventris, A. gasconi, A. goianus, A. humilis, A. juanii, A. magnussoni, A. ornatus, A. pacaas, and A. undulatus all either have a rhombus-shaped, hourglass-shaped or wave-edged dark brown mark on the dorsum. Allobates olfersioides have X-shaped dark brown marks on the dorsum and a solid iridescent white ventrolateral stripe that goes straight from the groin to the upper lip. Allobates algorei has a wide dark brown band down the center of the dorsal surface, flanked by two dark brown rows. Lastly, there is no defined pale dorsolateral stripe in A. amissibilis, A. caeruleodactylus, A. crombiei, and A. subfolionidificans and A. granti, A. masniger, and A. nidicola have no pale dorsolateral stripe at all (Gagliardi-Urrutia et al. 2021).

Male A. sieggreenae have throats and vocal sacs that are white or cream to translucent, with light gray or light brown melanophores scattered on the chin, throat and chest leading to a light cream to translucent abdomen with yellowish coloration towards the groin and thigh. In comparison, A. gasconi have a gray throat and chest with dark spots and A. bacurau and A. grillisimilis have mostly translucent to white undersides with no yellow. Male A. pacaas have a densely pigmented throat and male A. ornatus have darkly pigmented throats. Allobates melanolaemus males have solid black throats, A. vanzolinius throats are dark gray, A. kingsburyi throats have black spots. Male specimens of A. fuscellus, A. granti, A. insperatus, A. marchesianus, A. masniger, A. nidicola, A. nunciatus, A. paleovarzensis and A. pittieri have a darkly pigmented throat with dark black or brown melanophores that form a uniform dark background or distinct pattern. Male A. tapajos and A. tinae have a bright yellow vocal sac. And the underside of male A. conspicuus, A. subfolionidificans, A. sumtuosus and A. tapajos is uniform and has no melanophores (Gagliardi-Urrutia et al. 2021).

Female A. sieggreenae have translucent, yellow throats with uniformly yellow ventrums. In contrast, female A. tinae have a white underside and female A. bacurau have scattered melanophores on the throat (Gagliardi-Urrutia et al. 2021).

Allobates pacaas have a distal subarticular tubercle present on Finger IV that A. sieggreenae does not have. Male A. undulatus have a swollen supra carpal pad on the wrist while A. sieggreenae has no wrist supra carpal pad. Allobates caeruleodactylus have sky-blue fingers while A. sieggreenae have brown fingers. Allobates sieggreenae only has webbing between toes III - IV while A. mcdiarmidi has webbing in all toes (Gagliardi-Urrutia et al. 2021).

Allobates sieggreenae has brown thighs with no dark bars while A. sumtuosus have blue to gray thighs and A. bromelicola have olive-colored dorsal surfaces. Members of the A. femoralis complex have bright red, orange, or yellow flash marks on the dorsal surface of the thighs and black and white marbling on the abdomen that differentiated from A. sieggreenae, which has none of these features. Allobates amissibilis, A. carajas, A. conspicuus, A. gasconi, A. insperatus, A. marchesianus, and A. pacaas have at least one dark transverse bar on the dorsal surface of the thighs (Gagliardi-Urrutia et al. 2021).

Advertisement calls of A. trilineatus consists of trills of note-pairs where trills are 0.96 – 1.61 s long. In comparison, A. sieggreenae trills are single notes and last much longer than advertisement calls of A. trilineatus. Advertisement calls of A. femoralis, A. myersi, and A. nunciatus are emitted as trills of three, four, six or eight notes (which is different from the single note trills of A. sieggreenae). Other species with advertisement calls formed by trills of pairs of notes are A. flaviventris, A. granti, A. hodli, A. kingsburyi and A. tapajos. Advertisement calls of A. goianus, A. magnussoni, A. nidicola and A. masniger are a continuous single note, spaced with regular silent intervals, and not arranged in note trills. Advertisement calls of A. algorei, A. caeruleodactylus and A. subfolionidificans are never arranged in note trills. Calls of A. amissibilis, A. bacurau, A. crombiei, A. grillisimilis, A. humilis, A. insperatus, A. juami, A. melanolaemus, A. paleovarzensis and A. tinae have regularly spaced notes. In comparison, A. sieggreenae have irregular silent intervals and their calls are arranged in note trills. The advertisement calls of A. bacurau, A. crombiei, A. insperatus, and A. juami have a larger number of closely spaced notes with a pooled number of 25 – 81 notes, while A. sieggreenae calls have a pooled number of 5 – 16 notes. In A. grillisimilis, note peak frequency is higher than A. sieggreenae and the silent interval between notes is shorter (Gagliardi-Urrutia et al. 2021).

COLORATION:

In life, the dorsum is dark brown in the center and light brown around the snout and urostyle region. The frog has a broad, pale brown to cream colored stripe located on dorsolaterally. The lateral sides of the frog have a dark thick brown strip (color darker than dorsum) that is continuous from snout to groin. There may be a short, faint, stripe of cream colored dots on the lateral brown band, described above, towards the rear of the frog near the groin region. There is a ventrolateral wave-edged, irregular, iridescent stripe under the lateral dark brown stripe from under the eye to the groin. The ventrolateral stripe merges with the light cream color of the frog’s underside laterally. The upper lip is the same pale color as the ventrolateral stripe and iridescent; the lip gets darker only ventrally on the occlusion surface. In female A. sieggreenae the throat is translucent and yellow. In males, the throat and vocal sac are white or cream to translucent, with light gray or light brown melanophores scattered on the chin, throat and chest. The remaining underside of females is uniformly yellow, getting paler medially on the abdomen around the peritoneum. In males, the abdomen is light cream to translucent, becoming yellowish towards the groin and on the underside of the thigh. The dorsal surface of the arm has irregular brown spots scattered on a dark yellow to dark orange background. The ventral surface of the upper arm and the inner lateral surface of the forearm are translucent yellow. The outer lateral surface of the forearm and the ventral view of the carpal and metacarpal regions are dark brown. The fingers are brown from a ventral and dorsal view, and darker in the ventral view. The dorsal scutes on the finger discs are mostly iridescent white, but sometimes they are black or dark gray. The surfaces immediately adjacent to the vent are light brown. The paracloacal mark is short, comma-shaped, and colored iridescent cream. The dorsal surface of the thigh is brown, with sparse and irregular dark brown blotches at the tips of larger skin granules. The dorsal surface of the shank (knee to ankle) and tarsal region is generally darker than the thigh, with densely scattered dark brown spots and blotches. The ventral surface of the thigh is translucent yellow, with dark brown spots and blotches appearing towards the lateral inner and outer surfaces. The underside surfaces of the shank and tarsal region are a translucent yellow with large dark brown blotches. The plantar region is dark brown in ventral view. The toes have gray and dark brown patterning. The paired dorsal scutes on the toe discs are mostly iridescent white, but sometimes black or dark gray. The eye iris is dark gold with a dark brown pattern (Gagliardi-Urrutia et al. 2021).

In alcohol, the dorsal surface of the body is tan brown, becoming lighter on the tip of the snout, canthus rostralis, and tip of the urostyle region, and darker above the eyes. There are scattered dark brown dots on the dorsum at the tip of skin granules. A well-defined pale cream dorsolateral stripe can be seen extending posteriorly from the posterior region of the eyelid to the urostyle region. The pale dorsolateral stripe is about 0.6 mm in width around the middle of the dorsum. A few dark brown dots appear irregularly on the pale stripe at the tip of larger granules. The lateral surface of the body has a solid dark brown band, extending from the tip of the snout to the groin, surrounding the body. There is a short, faded, narrow, pale, and oblique lateral stripe preset within the solid dark brown lateral band at the groin level. The pale ventrolateral stripe is not clearly visible. The upper lip is pale cream from the side, and has dark brown spots ventrally towards the occlusion surface. The background color of the ventrolateral region of the body is white, and the area is peppered with irregular light brown blotches. The ventrum is light cream, with brown dots scattered from chin to belly. The dots are densely distributed along the margin of the chin and throat regions and medially on the chest. The abdomen is uniformly light cream. From the dorsal view, arms are cream colored with scattered light brown blotches. From the ventral view, the upper arm is lighter colored, light cream to translucent. The tips of the fingers are brown. The paired scutes on finger IV is black, and the paired scutes on the other fingers are black. From the ventral view, the metacarpal, carpal, and outer surface of the forearm is solid brown. The area immediately around the vent is light brown, and there are pale, comma-shaped, para cloacal marks that get broader at its end. The dorsal surface of the thigh is mostly pale brown, but it gets slightly darker on the outer and inner lateral surfaces. There are small dark brown dots on the dorsal surface of the thigh, located at the tip of larger skin granules. The shank and tarsal region are darker than the thigh from the dorsal view, and they have dark brown dots/blotches densely compacted on a cream background. The ventral surface of the thighs and shank are translucent to cream, and there are brown blotches randomly scattered along the edges. The ventral view of the tarsal and metatarsal are dark brown. The toes are dark brown, and the paired scutes on the toes are black on Toe V but white for the rest of the toes (Gagliardi-Urrutia et al. 2021).

The color pattern of juvenile A. sieggreenae is similar to the coloring of adults, but juveniles have a solid dark brown dorsal color, making the pale dorsolateral stripe more emphasized. The ventral surfaces of juveniles are uniformly light gray to translucent, with no yellow shades or pigmentation (Gagliardi-Urrutia et al. 2021).

VARIATION:

Female A. sieggreenae are generally larger than males, however there is overlap in the ranges. In females, the fingers II and III are not swollen, while some males have fingers II and III swollen. The shade of the dorsum (ie. how light or dark the brown is) varies between individuals. About 37% of females in the sample size have scattered light gray or brown dots on their throats and chin, the rest have a solidly cream colored throat when preserved. There is general variation of how the throats of male A. sieggreenae are pigmented, with some having more even distribution and others denser coloration on the chin. The pale dorsolateral stripe ranges in width from 0.5 - 0.9 mm. On the dorsal surface of three A. sieggreenae there is a brown transverse stripe. A pale para-cloacal mark was present in 13 out of 34 specimens.

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Peru

View distribution map in BerkeleyMapper.

Allobates sieggreenae have been found in the Amazonian forest in Loreto, Peru, close to the borders with Ecuador, Columbia, and Brazil. They have also been found in the white sand forest of the Ucayali-Tapiche-Yavarí interfluve, or east of the Ucayali river. It is also possible that A. sieggreenae live to the south in the Peruvian headwaters of the Tapiche River, or to the east on the Brazilian headwaters of the Yavarí. This area has sandy soil and low canopy trees which seems to be their preferred habitat, although A. sieggreenae can occupy a variety of habitats including dense rainforests with clay soil. Annual rainfall in this area is around 3,185 mm and average air humidity reaches 88.5%. There is seasonal flooding. Average temperature is 26.6 degrees C, ranging from 22.5 - 32 degrees C throughout the year (Gagliardi-Urrutia et al. 2021).

Life History, Abundance, Activity, and Special Behaviors

Allobates sieggreenae calls are arranged in irregular trills of tonal notes. The silent intervals between notes and trills are unpredictable and can vary greatly. Trills have around 5 - 16 notes, but can also be more variable. Trills last about 2 - 8 seconds long, and consecutive trills are split by a silence of 1 - 20 seconds (Gagliardi-Urrutia et al. 2021).

Trends and Threats

The species is locally abundant, and not considered a threatened species. The sites where A. sieggreenae were found are far from any human cities (Gagliardi-Urrutia et al. 2021).

Comments
Maximum Likelihood analysis was conducted using the 16S rRNA mitochondrial DNA and indicated that their sister species is A. trilineatus (Gagliardi-Urrutia et al. 2021).

ETYMOLOGY

References

Gagliardi-Urrutia, G., Castroviejo-Fisher, S., Rojas-Runjaic, F. J. M., Jaramillo, A. F., Solís, S., Simões, P. I. (2021). "A new species of nurse-frog (Aromobatidae, Allobates) from the Amazonian forest of Loreto, Peru." ZooTaxa, 5026(3), 375-404. [link]

Species Account Citation: AmphibiaWeb 2021 Allobates sieggreenae <https://amphibiaweb.org/species/9436> University of California, Berkeley, CA, USA. Accessed Apr 16, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 16 Apr 2024.

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