Tetrigidae: Tetrix vs Paratettix

The family Tetrigidae of pygmy grasshoppers has been relatively neglected in the party of taxonomy. This has led to several contradictions in identification and much confusion. I have noticed a lot of requests for keys, which are lacking, most of which are outdated, and contain confusing terminology that may bore those interested in this group. In addition, some checklists involve species with no accessible records of occurrence in the covered region(s) and contradictory/outdated generic and specific placements. Now fortunately this group appears to have been treated much better and more recently outside of North America. The most recent, useful source in tetrigid taxonomy for North America, specifically Canada, was a 1985 article in the Government of Canada's The Insects and Arachnids of Canada series, authored by Vickery and Kevan titled "The grasshoppers, crickets and related insects of Canada and adjacent regions : Ulonata: Dermaptera, Cheleutoptera, Notoptera, Dictuoptera, Grylloptera, and Orthoptera". Obviously, this publication does not cover the numerous additional tropical genera and species of tetrigids found further south.

In this journal post, I'm starting rather simple, with the separation of the genera Paratettix and Tetrix. Firstly, the family Tetrigidae can be characterized by the pronotum or thorax being extended backward into a point, with this point looking like the end of pairs of wings but are actually not; the wings/tegmina if present consist of a usually darker, more rigid membranous mass visible just under the end point of the pronotum. Thus the pronotum often covers the wings entirely.

Paratettix and Tetrix are similar to each other and also probably the most common along with Tettigidea, which has less protruding eyes, a pronotum that covers a little bit of the neck giving a hooded appearance, and looks more like an acridid grasshopper in build.

Differences between Tetrix and Paratettix:

In the future, the Nearctic species of Tetrix may be delineated, but Paratettix is more problematic to identify to species. I may also form a more photographic and comprehensive guide to tetrigid fauna.

Posted by aispinsects aispinsects, January 15, 2020 05:02

Comments

Great resource. I was just about to post an observation of Paratettix cucullatus.

Posted by cotinis almost 2 years ago (Flag)

Wonderful! Thank you for putting this together, Arturo.

Posted by sambiology almost 2 years ago (Flag)

Thank you for this. Hopefully this will help me figure them out.

Posted by walkingstick2 almost 2 years ago (Flag)

This post is a great help, even if you do no more! I bet a lot of mine are bad angles, but I'll look through them to see if I can improve the IDs. Thank you!!
@pfau_tarleton

Posted by kimberlietx almost 2 years ago (Flag)

Thanks! Very useful.

Posted by bachandy almost 2 years ago (Flag)

An excellent tool to keep. Thank you !

Posted by alainhogue almost 2 years ago (Flag)

Dear colleagues, both Tetrix are Paratettix are currently polyphyletic genera and are in great need revision, mostly because of the historical practice, to put everything in either Tetrix or Paratettix - this led to a lot of species remaining in those genera, but not having the true evolutionary/taxonomic affinity to other taxa/species (e.g. P. voeltzkowiana is not Paratettix for sure). This is from me for now. I will write a more detailed answer or the whole post on the problem of tetrigidae taxonomy. For example, one of the problems is the lack of colleagues studying N American species in iNaturalist. Generally, Paratettix is characterized by narrow vertex, and by median carina which is absent in the frontal part of prozona. Tetrix, on the other hand, has wider vertex (usually projected), and continuous median carina. Again, this is 'scholar difference' which is in practice sometimes inapplicable. The only way for now to ID tetrigidae species with certainty is to compare new records with types until the system will be more evolutionary and good keys would exist.

Posted by skejo almost 2 years ago (Flag)

Skejo, thanks for your comment. I didn't think it could get any worse than this. Would you mind elaborating on the "studying North American species on iNaturalist"? Do you mean identifications or simply the study of the group in general?

Posted by aispinsects almost 2 years ago (Flag)

You are welcome. And - oh yes, it is a great mess - especially those genera you mentioned. I wanted to say that generally, orthopterists' community lacks experts on N American Tetrigidae. There are some good papers from the past (Grant, Rehn, Hancock, Hebard), but they did not have a chance to deal with material from some regions of N America. Especially not with so diverse material as is present now in iNaturalist has, and I am sure that this huge amount of new material (including both photographs and material in museums that is not identified) could provide new insights into natural history - for example, borders between the subspecies, or even the status of certain species. For example, Josef Tumbrinck and I think that American subulata represent distinct species from the European one, but American brunnerii represents a synonym of fuliginosa. To check those hypotheses, it would be cool to have tetrigidae experts/students in N America. Also, probably I make mistakes when identifying tetrigidae in iNaturalist, as there are so many of them, and it would be cool to have feedback.

Posted by skejo almost 2 years ago (Flag)

If you can, invite your colleagues! It'll probably be beneficial for them too knowing the amount of tetrigids in iNaturalist.

Posted by aispinsects almost 2 years ago (Flag)

@lisa281 For your list

Posted by kimberlietx over 1 year ago (Flag)

Hi @aispinsects, I'm the project leader to create a user-friendly field guide to Orthoptera of the Pacific Northwest. As far as my records go, there are three species of pygmy grasshoppers in my project perimeters; Awl-shaped Pygmy (Tetrix subulata), Mexican Pygmy (Paratettix mexicana) and Aztec Pygmy (Paratettix aztecus). I have seen both Paratettix species and I find the identification pretty simple. However, I've never quite established the physical differences between Tetrix and Paratettix. Now, if I have it correct, identification comes mostly by head shape/fastigium. Middle femora feature won't work in my case since Paratettix aztecus has a straight bottom margin. Thanks!

Posted by birdwhisperer 7 months ago (Flag)

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