Taxonomic discussion

[Zephyr]

Okay... I can't help but think... How many Thamnophis species/ subspecies there are and who could be making the decisions about them.
Two of which being T. sirtalis pallidulus vs T. sirtalis sirtalis and T. sirtalis tetrataenia vs T. sirtalis infernalis.

[Stefan-A]

The International Commission on Zoological Nomenclature (ICZN) decides what gets changed (and garters get moved around a lot), based on the suggestions that people make. Some suggestions they reject, some get approved. If you want a change made, you better have a good reason. Somebody suggested merging tetrataenia with infernalis and some populations of infernalis with concinnus in 1996, but Barry protested and the ICZN rejected the proposal.

IIRC


Here are the species that are currently recognized:

1. Thamnophis angustirostris (Longnose Garter Snake)

2. Thamnophis atratus (Pacific Coast Aquatic Garter Snake)
T. a. atratus (Santa Cruz garter snake)
T. a. hydrophilus (Oregon garter snake)
T. a. zaxanthus (Diablo Range garter snake)

3. Thamnophis bogerti (Bogert's Garter Snake)

4. Thamnophis brachystoma (Short-Headed Garter Snake)

5. Thamnophis butleri (Butler's Garter Snake)

6. Thamnophis chrysocephalus (Golden-Headed Garter Snake)

7. Thamnophis conanti (Conant's Garter Snake)

8. Thamnophis couchii (Sierra Garter Snake)

9. Thamnophis cyrtopsis (Black-Necked Garter Snake)
T. c. collaris (Tropical blackneck garter snake)
T. c. cyrtopsis (Western blackneck garter snake)
T. c. ocellatus (Eastern blackneck garter snake)

10. Thamnophis elegans (Western Terrestial Garter Snake)
T. e. elegans (Mountain garter snake)
T. e. terrestris (Coast garter snake) <---- Uncertain.
T. e. vagrans (Wandering garter snake)

11. Thamnophis eques (Mexican Garter Snake)
T. e. carmenensis
T. e. cuitzeoensis
T. e. diluvialis
T. e. eques (Mexican garter snake)
T. e. insperatus
T. e. obscurus
T. e. patzcuaroensis
T. e. scotti
T. e. megalops (Northern Mexican garter snake)
T. e. virgatenuis

12. Thamnophis errans (Mexican Wandering Garter Snake)

13. Thamnophis exsul (Exiled Garter Snake)

14. Thamnophis fulvus (Mesoamerican Highlands Garter Snake)

15. Thamnophis gigas (Giant Garter Snake)

16. Thamnophis godmani (Godman's Garter Snake)

17. Thamnophis hammondii (Two-Striped Garter Snake)

18. Thamnophis lineri (Liner's Garter Snake)

19. Thamnophis marcianus (Checkered Garter Snake)
T. m. bovallii
T. m. marcianus
T. m. praeocularis

20. Thamnophis melanogaster (Mexican Black-Bellied Garter Snake)
T. m. canescens (Gray blackbelly garter snake)
T. m. chihuahuaensis (Chihuahuan blackbelly garter snake)
T. m. linearis (Lined blackbelly garter snake)
T. m. melanogaster (Mexican blackbelly garter snake)

21. Thamnophis mendax (Tamaulipan Montane Garter Snake)

22. Thamnophis nigronuchalis (Southern Durango Spotted Garter Snake)

23. Thamnophis ordinoides (Northwestern Garter Snake)

24. Thamnophis postremus (Tepalcatepec Valley Garter Snake)

25. Thamnophis proximus (Western Ribbon Snake)
T. p. alpinus (Chiapas Highland ribbon snake)
T. p. diabolicus (Aridland ribbon snake)
T. p. orarius (Gulf coast ribbon snake)
T. p. proximus (Western ribbon snake)
T. p. rubrilineatus (Redstripe ribbon snake)
T. p. rutiloris (Mexican ribbon snake)

26. Thamnophis pulchrilatus (Yellow-Throated Garter Snake)

27. Thamnophis radix (Great Plains Garter Snake, Plains Garter Snake)

28. Thamnophis rossmani (Rossman's Garter Snake)

29. Thamnophis rufipunctatus (Narrow-Headed Garter Snake)

30. Thamnophis sauritus (Eastern Ribbon Snake)
T. s. nitae (Bluestripe ribbon snake)
T. s. sackenii (Peninsula ribbon snake)
T. s. sauritus (Eastern ribbon snake)
T. s. septentrionalis (Northern ribbon snake)
31. Thamnophis scalaris (Mexican Alpine Blotched Garter Snake, Longtail Alpine Garter Snake)

32. Thamnophis scaliger (Mesa Central Blotched Garter Snake, Short-tail Alpine Garter Snake)

33. Thamnophis sirtalis (Common Garter Snake)
T. s. annectens (Texas garter snake)
T. s. concinnus (Red-spotted garter snake)
T. s. dorsalis (New Mexico garter snake)
T. s. fitchi (Valley garter snake)
T. s. infernalis (California red-sided garter snake)
T. s. pallidulus (Maritime garter snake)
T. s. parietalis (Red-sided garter snake)
T. s. pickeringii (Puget Sound garter snake)
T. s. semifasciatus (Chicago garter snake)
T. s. similis (Blue-striped garter snake)
T. s. sirtalis (Eastern garter snake)
T. s. tetrataenia (San Francisco garter snake)

34. Thamnophis sumichrasti (Sumichrast's Garter Snake)

35. Thamnophis validus (Mexican Pacific Lowlands Garter Snake)
T. v. celaeno
T. v. isabelleae
T. v. thamnophisoides
T. v. validus

[Garter_Gertie]

Stefan, I think that's one o'those sticky/article things. That's important stuff to have around here to refer to. GOOD JOB!

[aSnakeLovinBabe]

I personally think that florida blue easterns should be their own subspecies... or something. They are simply way too different from all other easterns to be just typical easterns in my book. You look at any other eastern garter and you would have no clue where it came from. You look at the FL blues and you can identify them in a heartbeat, EVEN when they have no blue. They have a different head and body shape than other sirtalis, especially as babies. And I noticed on my female that she has VERY large rear teeth (fangs) the likes of which I have never seen on other easterns. Their scales are even more keeled than my other easterns and there is just so much about them tht I notice that is so different from ALL other sirtalis.

[Zephyr]

I personally think that florida blue easterns should be their own subspecies... or something. They are simply way too different from all other easterns to be just typical easterns in my book. You look at any other eastern garter and you would have no clue where it came from. You look at the FL blues and you can identify them in a heartbeat, EVEN when they have no blue. They have a different head and body shape than other sirtalis, especially as babies. And I noticed on my female that she has VERY large rear teeth (fangs) the likes of which I have never seen on other easterns. Their scales are even more keeled than my other easterns and there is just so much about them tht I notice that is so different from ALL other sirtalis.

I agree.
They have a more pronounced dorsal stripe as well.
There's definitely more of a difference between them and other easterns than there is between sirtalis sirtalis and sirtalis pallidulus.

[aSnakeLovinBabe]

yes... a LOT. haha. In fact.... I don't really see anything alike between the FL blue sirtalis and other sirtalis... everything about their patterns, body shapes... enlarged rear teeth (can someone check out their fl blues and see if they notice this too?)

[snakeman]

All garters have enlarged rear teeth.Just let one chew on you for a while.You will feel and probally see them.I agree on the florida blues also.I am wondering what the easterns look like as you get up into n. florida and georgia.

[Zephyr]

On the T. s. tetrataenia and infernalis... I think they may just be color phases of one another with tetrataenia being morph... Obviously this was rejected, but I don't know if they actually did blood work to test the hypothesis.

[Steven@HumboldtHerps]

On the T. s. tetrataenia and infernalis... I think they may just be color phases of one another with tetrataenia being morph... Obviously this was rejected, but I don't know if they actually did blood work to test the hypothesis.

I would agree that there are many similarities b/n tetrataenia and infernalis, but then a subspecies is just a subspecies, meaning that they should technically be able to intergrade in the wild - they are the SAME species. As for the similar colors and variable patterns, or whether or not recessive genes are responsible - I don't know. We know striping is a recessive gene in corn snakes, but recessive genes vary from species to species, genus to genus, and so forth... The blues that show up in both subspecies may actually have nothing to due with recessive genes. The effects could be ontogenetic, as when a local population changes its diet or migrates to new terrain. You are what you eat, and appropriate camouflage and behaviors addressing a new locale are a big part of where evolutionary change begins. For instance, we know a lot of animals display bright red colors when they are toxic, or even when they perhaps dine on normally toxic prey. Could red flecking in some of our western species be a by-product of salamander toxins? Questions, questions....

Thamnophis genetics is still so elusive in its understanding, more genetic sampling needs to be done! The sirtalis clade is so widespread over the continent, I am curious if Eastern and Western species can intergrade so smoothly. I personally don't endorse far-flung intergrades, nor any captive intergrades due to preferring to maintain the integrity of the "local" characteristics. still, what would the verdict be? Does anyone know if it's been done (whether or not it produces a muddled mutt or takes on a dominant trait from one of the parents)?

The infernalis / concinnus connection seems to be way off in my mind. These two subspecies are separated by fitchi populations. I guess, though after a long passage of time, genetic traits could "pass the bucket" all the way up the coast!?

While the eastern / western ssp. intergrade question remains, I am still more interested in the possibility of inter-special hybrids occurring right here in Humboldt County, CA.

I've gone on about this topic before, but I'd like to post a few example photos here to show my frustration with the gestalt of some of these snakes. First, Stefan-A, I understand T. e. terrestris has been absorbed by T. e. elegans (Great! Now the elegans clade has a whole plethora of morphs to add to its list!), but could you find me a link about this, as I would love to read it. So... "Mountain Garters" here on the coast and in our coastal ranges come in all kinds of patterns and colors, but most all the coastals have olive-green, olive-brown, light olive-tan, or near black heads.
Contrarily CA Red-sided Garters usually have red heads perhaps with some black. Also, I am not going to focus too much on labial scale counts, as they are highly variable b/n the 2 species. Designated scale rows b/n the species are also sometimes variable (19 or 21). Red dorso-lateral or ventral flecking is characteristic of coastal elegans. Faded or absent lateral stripes are characteristic of infernalis.

So what do you think of these?


Ignore the title of the picture, as I believe ordinoides might not be the culprit here. This snake basically looks like an infernalis (perhaps with some light fitchi influence - the further north you travel up Humboldt, the more fitchi they appear...)

A closer look reveals red-flecking.

...and ventral flecks at the caudal end...


This 2nd specimen at the same location looks like an infernalis with subdued features, but what's with the olive head?

Olive or red? Both!? Hmmm....

Looks like sirtalis from the side....

I've got one more pic of what looks like a bonafide coastal elegans. But i've posted 6 pics already... To be continued.

[Steven@HumboldtHerps]

A muddled "Coast" with all the red flecking...


While these specimens might just be crazy variations, the possibility of hybridization in the wild fascinates me. I don't believe that there's any complete hybridization possible, since that might muddle all the local traits (unless we are really dealing with a variety of recessive or co-dominant, etc traits). I suspect partial hybridization where perhaps fertile females are possible. As with inter-generic crosses like that of creating jungle corns, males are often sterile. Keeping this in mind, it is possible that subspecies traits could be reaffirmed by crossing female hybrids back to one or the other subspecies, thus preventing over-all muddling within a specific locality.

The truth (HA!) of the matter is, we just don't know it all yet. Recessives, co-dominants, intergrade and hybrid effects, diet, environment, inter-breeding in isolated populations.... The sky is the limit.

Thamnophis - truly a conundrum at times!

Steve