Larval Hemidactylium scutatum

[Lamb]

Hello all,

Found this larval Hemidactylium scutatum during field work yesterday while dipnetting in a swampy creek. My first of this species!

 

[Lamb]

This must be my lucky month. I found 4 more larval Hemidactylium scutatum at a different stream earlier today. One of these was incredibly small, and I'm assuming a recent hatchling (the one labeled TC5). The black lines in the lateral shots represent centimeters.

 

[Lamb]

I'm kind of doubting the accuracy of my ID for the second individual (larger, with a dappling of pigment on the upper lip). Anyone have any input?

 

[Lamb]

After lots of photo exchanges with others that have had more experience with tiny, larval E. quadridigitata and H. scutatum, I regret to say that all of the larvae in these photos are likely the former (dwarf salamanders), and not the latter (four toed salamanders).

 

[Kaysie]

What a bummer!

 

[Neotenic_Jaymes]

Small larvae are always hard to ID.

 

[pierson_hill]

My vote is for Hemidactylium. Here's one I hatched from an egg:


Four-toed Salamander (Hemidactylium scutatum) by Pierson Hill, on Flickr


Here is a Eurycea quadridigitata larvae. Note the striations, elongate build, and lack of dorsal light spots.

Eurycea quadridigitata by Pierson Hill, on Flickr

 

[Lamb]

I've got two in the lab that I'll raise through metamorphosis, photographing them along the way. I'll let you know what they turn out to be.

@Pierson - From what I have seen in S MS, dwarf salamander larvae can be really variable. I have found larger larval dwarf salamanders that have similar striations to the one in your photo, but I have also found them in this part of the region without striations. As for the dorsolateral spots in the larvae in my photos, they appear to be different from the spots on larval four-toed salamanders. It seems like the spots on four-toeds are a bit larger, much more dorsal with little space between the rows, and they often have some sort of color (yellow or chestnut). Larval Eurycea cirrigera and sometimes Eurycea guttolienata have similarly spaced, small light spots, which, from what I understand, are aggregations of iridophores around the lateral line organs. So I don't think that it's unlikely that small, larval dwarf salamanders might also have dorsolateral spots. It's also worth pointing out that what we call Eurycea quadridigitata is likely a species complex, so that might explain some of the regional differences in larvae.

Another key feature that appears to hold for H. scutatum is that the dorsal fin origin is anterior to or at least at the midbody point, whereas for E. quadridigitata, it is not.

 

[taherman]

Pierson...where did your Hemidactylium larva originate? We are trying to get a handle on geographic variation in the larvae, and all my examples to compare to are from more northern populations. Yours still has all the traits of my northern Hemidactylium larvae that we have used to discern the two.


Also, the E. quad larva you posted is much later in development than Lamb's. It's these really early larvae that are giving us trouble with ID.


Thanks for the photos!

 

[pierson_hill]

Pierson...where did your Hemidactylium larva originate? We are trying to get a handle on geographic variation in the larvae, and all my examples to compare to are from more northern populations. Yours still has all the traits of my northern Hemidactylium larvae that we have used to discern the two.

Northern Florida. I can try and get you some larvae locally but we had a massive flooding rain event about a month ago that may have washed away most of the eggs (I lost the nest in my back yard).

Also, the E. quad larva you posted is much later in development than Lamb's. It's these really early larvae that are giving us trouble with ID.

True. I've seen quad larvae at much smaller sizes and they were all distinctly striated, but the vast majority were from mesic flatwoods ponds in the eastern FL panhandle.

 

[Lamb]

Northern Florida. I can try and get you some larvae locally but we had a massive flooding rain event about a month ago that may have washed away most of the eggs (I lost the nest in my back yard).

I'm jealous that you found a nest in your backyard! Have you found E. quad and H. scutatum in the same sites?

Also, were your shots taken indoors, or in a tank you carry around in the field for just that purpose? The shot of the E. quad is really nice.

 

[Todd Pierson]

FWIW, attached is a photograph of a (dead--had a rough time in the dipent) Eurycea quadridigitata larva from this past weekend. It was about 17mm SVL, had the horizontal striations, and lacked any light dorsal spots.

Also, Hemidactylium are still on eggs in the Piedmont of Georgia right now, but the nest I saw should be hatching any day. Hopefully I'll have some larval photographs of those to contribute soon.

 

[Todd Pierson]

And here's a hatchling Hemidactylium from central Georgia, just a few hours out of the egg.

 

[Lamb]

Thanks for the photos! What is your photography set up/editing process? I'm wondering how you get the background that black.

 

[Todd Pierson]

I shoot top-down into a shallow aquarium suspended several feet above a black background, but I still black out most of the background in post-processing

 

[DavidHarr]

Please get in touch with me when you have a chance regarding a question about Hemidactylum larvae. You can e-mail me direct at: david7945harr@yahoo.com

Thanks,
David Harrington