I probably won't be mistaken if I name the lake frog ( Pelophylax ridibundus ), as one of our most famous amphibians. It is this frog that arranges concerts on the reservoirs on warm summer evenings. And in general, this is the most massive and widespread species of frogs, which inhabits almost any water body.
All frogs were captured in a small reservoir (near the village of Alekseevka, Chamzinsky district, Mordovia) during the 2019 field season. They were also measured there for morphology, after which they were photographed and released to swim further. During these manipulations, not a single animal was injured. Fishing was mainly carried out along the coast, which is opposite to the settlement. Since on the nearest, in good weather (and in bad weather, why go?), Young people frolic and frighten frogs. I caught it most often in the evening, after work, but did not catch the total catch, but caught it along the way with photographing various insects. I caught only adults, sexually mature individuals, did not pay attention to small ones. Some individuals were photographed in the water or on the shore without capture. The caught individuals were identified by the calcaneal tuberosity.
The main types of coloration of green frogs are described in the methodological manual "Methodology for field studies of the ecology of amphibians and reptiles" (Shlyakhtin G.V., Golikova V.L., 1986). Unfortunately, this edition has become a bibliographic rarity for a long time, so it is very difficult to find it in electronic form, but in hard copy. At one time, when I was still a student, I copied several pages from there, just in color. Actually, a schematic representation of these phenotypes has long been on the page of my site dedicated to the marsh frog (Pelophylax ridibundus). At the same time, in the majority of herpetological literature (if we do not take into account scientific articles on phenotypes), the color of the marsh frog is described as follows: ". The color of the upper side of the body is very diverse, most often it is all kinds of shades of green, but there are also gray and brown frogs. Large, uneven dark spots are scattered throughout the body. Often a light stripe runs along the back. The ventral side is light, usually with dark specks or spots "(Orlova, Semenov, 1998). According to the literature, the following types of phenetics are distinguished in the marsh frog:
- morph maculata - spotted, on the back there are a number of large spots, the number and location of which varies,
- morph hemimaculata - semi-spotted, the number of spots is much less,
- bursni morph - clean, characteristically complete, or almost complete, the absence of spots on the back,
- morph punctata - speckled, on the back with large spots, or without them, there are a lot of “dots” of specks,
- morph hemipunctata - semi-speckled, mottling is weak, the number of dots is small,
- morph striata - striped, this morph is characterized by a light dorsomedial stripe. Sometimes the band does not pass through the entire body, but only through the body and the degree of its severity may be different. The genetic nature of the distinct stripe is quite definite, but it is not known for the weakly expressed stripe. For example, Vershinin (2004) proved that individuals with a morph striata high resistance to anthropogenic loads and they are better adapted to geochemical anomalies of the environment.
- morph astriata - stripless, dorsomedial stripe is not expressed
At the same time, one individual, quite calmly and without straining, can combine several morphs. In addition, their color may change under the influence of some factors. For example, when exposed to low temperatures, the general background becomes paler, to the point that the spots on the belly disappear completely. This fact has been repeatedly noticed when frogs are overexposed in the refrigerator.
Another interesting point. When I was writing my dissertation and processing data on morphology, I noticed such garbage - in some individuals P. ridibundus the lower leg is shorter than the thigh. According to the literature, this is characteristic of the pond frog (Pelophylax lessonae), and in normal lakes the tibia usually exceeds the length of the thigh. At that time, this was typical for 22% of the total sample in Mordovia and has now been observed in 3 individuals.
♂ L. 57 mm, punctata (large spots of irregular shape with the presence of small spots) + astriata (no bar). Despite the yellowness on the inner side of the thighs and lower abdomen, along the heel tubercle is a typical lake ,. It is not clear why this color turned out.
♂ L. 48 mm, maculata (large spots, small ones are almost absent) + astriata (no bar). Now one more thing. For some reason, I have not found data on the phenotype of the stripes on the sides anywhere. There is even on the belly and on the throat, but these stripes are not mentioned. Although this is also one of the signs.
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♀ L. 63 mm typical maculata (large spots are almost even, small ones are absent) + striata (there is a dorsomedial stripe, from the cloaca to the edge of the muzzle) And again - almost complete absence of stripes on the sides.
♂ L. 46 mm, probably hemipunctata (mottling is weak, the number of dots is small) + hemistriata (dorsomedial stripe is short, dotted)
♂ L. 52 mm, maculata (although the spots are hard to see, they almost merge with the general background) + hemistriata (dorsomedial stripe is also dotted)
♂ L. 54 mm punctata (large spots of irregular shape with the presence of small spots) + astriata (no bar)
♀ L. 73 mm. maculata (large spots are almost even, small ones are absent) + astriata (no band). Until that moment, I thought that lateral stripes are only present in males (something like one of the signs of sexual demorphism), but it turned out that they are also found in females. I also did not find, in the literature, a mention of the light edging of the spots.
♂ L. 63 mm, maculata (large spots of uneven shape, small ones are absent) + astriata (no band). Also a question - how are these leopard-type spots called scientifically? And in general, are they taken into account when describing phenetics?
♂ L. 54 mm, Another similar specimen - maculata (large spots of uneven shape, small ones are absent) + astriata (no bar)
♀ L. 73 mm, Who is this? maculata ? But, the spots merged into one spot along the strip. This is the first time I see this, or I simply did not pay attention before. But in any case, the coloring is interesting. Well + striata (dorsomedial stripe, from cloaca to muzzle edge)
♀ L. 68 mm, maculata (large spots of uneven shape, small ones are absent) + striata (there is a dorsomedial stripe, from the cloaca to the edge of the muzzle)
♀ L. 84 mm, it is immediately clear that it is not easy maculata , and maculat'his! There is no other way to name this plump female. Stains are not like jagged edges. they defy any form at all. Well astriata, naturally, since the band is absent.
And at the end, a few photos of frogs photographed in their natural environment, without catch. Therefore, I do not know gender and dimensions.
maculata (large spots are almost even, small ones are absent) + astriata (no bar)
The nature of the spots is difficult to understand. so let it be maculata + striata ... But, interestingly, the color of the body matches the color of the substrate. If greens sit in duckweed or coastal vegetation (photo above), then gray and brown on the shore. I wonder how quickly it will change color if it swims into the duckweed?
Same - maculata + striata
And here just two frogs are sunbathing. Both maculata + striata, although small it is possible that hemipunctata
Thus, despite the fact that this species of frogs has been studied along, across and diagonally, not everything is clear with it and there is something to think about. For example, why on a relatively small area there are individuals with completely different phenotypes? Are they sailing from the other side? Maybe. But why? Or why are the coloring elements not fully described? I'm talking about the side stripes and the shape of the spots (light edging, and "holes" in the center). Or is it all overlooked and ignored? In general, there are more questions than answers.