Description

A large-sized, robust frog, Latonia nigriventer has a snout-vent length range in females of 69.0 – 128.4 mm and in males of 66.6 – 121.4 mm (Perl et al. 2017). The head is flattened and the width is equal to the length. The snout projects beyond the mouth. There is no canthus rostralis present. The square-shaped nostrils are closer to the snout than the eyes. The internarial distance is smaller than the distance between the eye and the nostril. The interorbital distance is about the same size as the width of the eyelid. The diameter of the eye is larger than the distance between the eye and the tympanum (Mendelssohn and Steinitz 1943). The iris is heart-shaped (Perl et al. 2017). The tympanum is indistinct and shorter in height than in width. There are two glandular ridges that extend from the posterior side of the eye. The first passes over the tympanum and ends at the insertion of the forearm. The second extends backwards and diffuses at the shoulder girdle into several glandular elevations on the dorsum (Mendelssohn and Steinitz 1943). There is a distinct dermal fold that transverse the neck. The forearms are strong (Perl et al. 2017). The fingers do not have webbing and the tips vary in appearance from round to pointed. The relative finger lengths are 3 > 2 > 4 > 1. There are three palmar tubercles, with the inner tubercle being about twice as large as the smallest palmar tubercle (Mendelssohn and Steinitz 1943). The hindlimbs are relatively short (Perl et al. 2017). When the legs are placed at right angles to the body the heels overlap. When the leg is stretched along the body the tibiotarsal articulation meets the middle of the eye and the metatarsal articulation reaches slightly beyond the snout. The foot is slightly shorter than the tibia. The toes are webbed at the base and the tips are obtusely rounded with a relative length of 4 > 3 > 5 > 2 > 1 (Mendelssohn and Steinitz 1943). There is a broadening of toes III and IV; females typically have a broadening of the 3rd phalanx of toe III and both the 3rd and 4th phalanx on toe IV while the 2nd phalanx in males is broadened on toe III and the 3rd phalanx of toe IV. Males have dark nuptial pads, keratinised excrescences on the thorax, ventral surface of the limbs, and planter parts of the outer edge of the webbing during the breeding season (Perl et al. 2017).

Latonia nigriventer differs from Discoglossus pictus in having a wider interocular distance, longer forelimbs, and a snout that projects less. Additionally, the two species can be differentiated by the darker ventral coloration in L. nigriventer (Mendelssohn and Steinitz 1943).

In life, L. nigriventer has a dark belly (as its name implies) with small white spots. The dorsal pattern is ochre and rust colored patches grading into dark olive-grey to greyish-black (Mendelssohn and Steinitz 1943). There is a light-colored, incomplete mid-dorsal band on the posterior portion of the dorsum (Perl et al 2017).

Despite differences in distinctiveness and contrast, color patterns between individuals were similar. Keratinised excrescences can be found on dorsal surfaces of the feet of some male during the breeding and some females may have excrescences on the plantar surfaces, webbing edge, and sparsely on the thorax.Statistically, there is no difference between the sexes. However, females had weaker webbing than males and the sexes differ in which phalanx of toes III and IV are broadened (Perl et al. 2017).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Israel

View distribution map in BerkeleyMapper.

Latoina nigriventer can be found at the Hula Nature Reserve in the Hula Valley of Northern Israel (Biton et al. 2013) and at two sites located 1 km southeast of the reserve near the village of Yesod HaMa’ala (Perl et al. 2017). It is assumed to be at Hgamon Ha-Hula Nature Park, Ein Te’o Nature Reserve based on environmental DNA. The species appears to have strong preference to its historic marsh, swamp, and lake habitats but can also be found to less optimal sites, possibly by using a complex network of canals and streams that flow mainly from the north to the south and from the east and west to the center of the valley (Renan et al. 2017).

The species utilizes both terrestrial and aquatic habitats. Within the Hula marshes, individuals were found in decomposing leaf litter on peaty, damp, and loose soil, in dense blackberry thickets, in reeds, and among fig trees. At the Yesod HaMa’ala sites individuals were found in and around ditches with permanent water, mud bottoms, and vegetation. The soil around ditches was composed of sandy, compressed mineral soil. Individuals found in terrestrial sites were found under drying grass tufts or in crab or small mammal holes at the water’s edge (Perl et al. 2017).

Life History, Abundance, Activity, and Special Behaviors

Individuals are nocturnal and solitary and can be found almost year round (Perl et al. 2017). Analysis based on environmental DNA techniques and modeling with presence-absence data, show that L. nigriventer has a strong preference for its historical marsh, swamp, and lake habitats but has adapted to man-made sites such as ditches. The occurrences of organic and colluvial-alluvial soil types, indicating the current or past presence of a wetland, are correlated with positive environmental DNA results (Renan et al. 2017).

From November to March, juveniles were found on land under humid leaf litter. From February to September, which is assumed to be their breeding season, adults could be found in water with only their rostrum exposed. Individuals are sensitive to artificial light (Perl et al. 2017).

When captured, the terrestrial caught frogs initially did not move, but upon recovery, tried to walk or slowly jump away. When walking, individuals retracted their eyes. When the soil allowed, individuals would produce more mucus and try to move underground head first away from researchers, with their eyes retracted, by pushing back with all their limbs (Perl et al. 2017).

When individuals in the water were disturbed they would retreat into the water and try to push head first into dense vegetation (Perl et al. 2017).

Based on mark and recapture data, disturbed frogs are known to move distance of more than 20 m. However, three radio tracked individuals only move 2 m over 5 – 18 days (Perl et al. 2017).

Dissection of a road-killed female showed several hundred greyish-black oocytes measuring 1.5 – 2.0 mm in diameter. The species is assumed to have opportunistic breeding consisting of short and intense inguinal amplexus, at which time several clutches of eggs are attached stones, aquatic plants, or the bottom of water bodies. The reproductive period is also assumed to be long, possibly from February to September, based on secondary sexual characterizes in males, tadpole presence, and weight loss in recaptured females (Perl et al. 2017).

Both sexes produce release calls, which sound similar to advertisement calls. Advertisement calls are of low intensity and frequency that consist of what is presumed to be an expiratory and inspiratory note. Calls were recorded under sub-optimal conditions in a lab setting at air temperatures of 13.5 – 18 degrees C and water temperatures between 14 – 15 degrees C. Calls were produced in series and had inter-call intervals ranging between 246 – 1606 ms. Calls consisted of two continuous notes that are attributed to expiration and inspiration of air into the lungs. Structurally, the notes are spectral, pulsatile, and are only differentiated by the lower frequency and higher intensity of the second note. The dominate frequency ranged from 0 – 1500 Hz. The call duration lasted between 725 – 1212 ms and consisted of a longer first, expiratory note (Perl et al. 2017). The calls are difficult for humans to detect in their natural environment (Renan et al. 2017).

The small snout-vent length of metamorphs coupled with large adult sizes also indicates the species is long-lived. Small tadpole and juvenile numbers further indicate low reproduction and recruitment and suggest that populations are sustained by long-lived individuals (Perl et al. 2017).

The species may be cannibalistic as the species authority reported that the holotype swallowed a smaller adult specimen when they were kept alive in a terrarium together (Mendelssohn and Steinitz 1943).

Predators of adult L. nigriventer include White-throated kingfishers (Halcyon smyrnensis). Juveniles and tadpoles are assumed to be preyed upon by other animals that commonly eat amphibians (Perl et al. 2017).

Larva
At Gosner stage 24, tadpoles of L. nigriventer were approximately 14 mm and at stage 34 they were 24 mm (Perl et al. 2017). Tadpoles have a maximum length of 26 mm (Renan et al. 2017). Their bodies are longer than wide or deep. The distance from the nostril to the snout is three-quarters the distance from the eye to the nostril. The distance between the eyes is two-thirds the length of the mouth. The lips are bordered by a single row of papillae with a break in the middle of the upper lip. There are two labial tooth series on the top and three on the bottom. The third tooth series on the lower jaw has an interruption in the middle. The first series on both the top and bottom each have one row of teeth. The other series each have two rows of teeth (Mendelssohn and Steinitz 1943). The spiracle is located ventrally and medially (Perl et al. 2017). The width of the spiraculum is a quarter the width of the mouth. The tail has an obtusely rounded tip. The tail muscles end proximally. The tail has a dorsal crest that extends onto the dorsum slightly (Mendelssohn and Steinitz 1943).

Tadpoles of L. nigriventer can be differentiated from D. pictus by the former having a shorter nostril-snout compared to eye to nostril distance, a mouth that is wider than the interocular distance, and a spiracle that is narrower than the length of the mouth (Mendelssohn and Steinitz 1943). The tadpoles can be further differentiated from other species with overlapping or nearby ranges, Bufotes variabilis, Hyla savignyi, Pelophylax bedriagae and Pelobates syriacus, by the focal species possessing a medial ventral spiracle, distinct epidermal reticulations, and double keratodont row, which are only found in L. nigriventer, Hoplobatrachus and extinct basal anurans from Discoglossus and Ascaphus (Perl et al. 2017).

Newly metamorphosed frogs ranged in snout-vent length from 6 - 9 mm (Perl et al. 2017).

Tadpoles of L. nigriventer are uniformly brown on the dorsum and unpigmented on the ventrum and on the ventral surface of the spiracle (Perl et al. 2017).

Because tadpoles are difficult to find and metamorphs are very small compared to adults, it is assumed that the tadpole stage of L. nigriventer is short (Renan et al. 2017).

The small snout-vent length of metamorphs coupled with large adult sizes also indicates the species is long-lived. Small tadpole and juvenile numbers further indicate low reproduction and recruitment and suggest that populations are sustained by long-lived individuals (Perl et al. 2017).

Trends and Threats
This species was thought to be extinct due to the draining of its wetland habitat in the 1950s until its rediscovery in 2011 (Biton et al. 2013). The Hula marshes were drained to eradicate malaria and to make the land suitable for agriculture use. Only 320 ha of the original 6,000 ha remain unmodified. The remaining 300 ha was set aside as the Hula Nature Reserve. Predation pressure is higher due to the decreased size of the marsh. While most of the area around the marsh is cultivated (IUCN 2012), the majority of the reserve itself is closed to the public (Perl et al. 2017).

Latonia nigriventer is now listed as “Critically Endangered” on the IUCN Red List (IUCN 2012), but more populations have been found. Between 2015 and 2017, 175 individuals were observed at four sites (Perl et al. 2017). Environmental DNA techniques have identified an additional 18 sites where individuals have not physically been captured but where their DNA is present. These new sites are mainly clustered around The Hula Nature Reserve, Hgamon Ha-Hula Nature Park, and the Ein Te’o Nature Reserve indicating the importance of habitat reserves to this species (Renan et al. 2017).

Habitat destruction and degradation remains the primary threatened to L. nigriventer. However, the species appears to tolerate highly modified and polluted habitats at the Yesod HaMa’ala sites (Perl et al. 2017). Additionally, the species is assumed to be resilient to habitat modification because it has persisted in low density in both artificial habitat and small refugias (Renan et al. 2017).

The chytrid fungal pathogen, Batrachochytrium dendrobatidis (Bd) was found in 32% of tested L. nigriventer from three of seven examined sites. Infection loads ranged between 1 - 311 genomic equivalents of zoospores per swab. However, the species appears to tolerate Bd and combat it with anti-microbial peptides in its skin secretions (Perl et al. 2017).

Based on successful tadpole rearing pilots, a captive breeding program has been recommended for the species (Perl et al. 2017).

Using environmental DNA analysis along with vegetation and soil presence-absence data, researcher have constructed predictive maps of suitable habitats. Researchers are also surveying 18 sites identified by environmental DNA as having L. nigriventer for live frogs (Renan et al. 2017).

Possible reasons for amphibian decline

General habitat alteration and loss
Drainage of habitat

Comments
Prior to the rediscovery of this species, only two specimens exist: one type specimen, collected by Mendelssohn in 1940 (Mendelssohn and Steinitz 1943), and one collected by Steinitz in 1955 (Werner 1988). The two tadpole paratypes have been lost (Biton et al. 2013) and one additional specimen collected by Mendelssohn in 1940 was eaten by the other while both were kept alive in a terrarium (Mendelssohn and Steinitz 1943).

Since the single adult specimen collected in 1955, Latonia nigriventer was not seen until 15 November 2011, four decades later, by a Park Ranger, who was unsure of the identity of the adult frog (Boaz Shacham, pers.com.). Its identification has since been confirmed and will certainly renew interest in its conservation (Biton et a. 2013.

As of 2017, total of 175 L. nigriventer have been observed. Of the observed frogs, 64 were adult females, 42, adult males, 29 juveniles, and 40 tadpoles (Perl et al. 2017).

Through the sequencing of 2,503 bp DNA from three mitochondrial genes and three nuclear genes it was found that the L. nigriventer belongs in the genus Latonia. Latonia nigriventer is the only extant species in the Latonia genus. This places it in the Alytidae family. Its closest relative are the frogs of the Discoglossus genus, followed by frogs of the Alytes genus (Biton et al. 2013).

References

Biton, R., Geffen, E., Vences, M., Cohen, O., Bailon, S., Rabinovich, R., Malka, Y., Oron, T., Boistel, R., Brumfeld, V., Gafny, S. (2013). ''The rediscovered Hula painted frog is a living fossil.'' Nature Communications, 4(1959), 1-6.

IUCN SSC Amphibian Specialist Group,. 2012. Latonia nigriventer. The IUCN Red List of Threatened Species 2012: e.T6715A13339841. http://dx.doi.org/10.2305/IUCN.UK.2012-1.RLTS.T6715A13339841.en. Downloaded on 30 November 2017

Mendelssohn, H. and Steinitz, H. (1943). ''A new frog from Palestine.'' Copeia, 4, 231-233.

Papenfuss T., Disi A., Anderson S., Kuzmin S., Gasith A., Sadek R.A., Werner Y. 2004. Discoglossus nigriventer. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. . Downloaded on 25 November 2011.

Perl, R., Gafny, S., Malka, Y., Renan, S., Woodhams, D., Rollins-Smith, L., Pask, J., Bletz, M., Geffen, E., Vences, M. (2017). ''Natural history and conservation of the rediscovered Hula painted frog, Latonia nigriventer.'' Contributions to Zoology Bijdragen tot de dierkunde, 86, 11-37.

Renan, S., Gafny, S., Perl, R. G. B., Roll, U., Malka, Y., Vences, M. Geffen, E. (2017). ''Living quarters of a living fossil - Uncovering the current distribution pattern of the rediscovered Hula painted frog (Latonia nigriventer) using environmental DNA.'' Molecular Ecology, 00, 1–12.

Werner, Y. L. (1988). ''Herpetofaunal survey of Israel (1950-85), with comments on Sinai and Jordan and on zoogeographic heterogeneity.'' The Zoogeography of Israel. Y. Yom-Tov and E. Chernov, eds., Junk, Dordrecht, 355-388.

Species Account Citation: AmphibiaWeb 2022 Latonia nigriventer: Hula Painted Frog <https://amphibiaweb.org/species/1526> University of California, Berkeley, CA, USA. Accessed Nov 21, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Nov 2024.

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