Hi, are you sure that it is an aquatic taxon? For me it Looks like a terrestrial beetle larvae (e.h. no gill structures visible, no haiers/bristles for Swimming etc.).  

I'm curious about further answers... cheers Olli

Dear Olli,

For it is from a benthic sample I have to say that I can think of nothing else. Though your remarks made me curious as well... If you are right, than it can only be due to some kind of "accident"...

On the other hand if you take a look at the apex of abdomen, the sclerites there are "open" (there's a gap between them) where filaments can be observed which for me are looking like tufted gills (eg. by Hydropsychidae). However, I can be wrong...

B.r.: Peter

Many aquatic Midges in larval form have no gills....for example Chironomidae and Ceratopogonidae. So gill is not a factor..here is more important, presence of prolegs, which is un common in Diptera and Hymenoptera....some homoptera and Colioptera have the same structure. I would like to see more photograph for further comment.   

Dear Viktor,

This makes sense, because adults of Macronychus quadrituberculatus (Müller 1806) were found in other samples and there are references on the presence of other Elmidae (e.g. Limnius volckmari) from this part of the sampled river.

I'll check the larval descriptions of these taxa.

Thank you for the answer.

Best wishes,

Peter

Coleoptera Elmidae

This is clearly an Elmidae: Coleoptera - riffle beetles. Where was it collected?

@Clifford B Keil: It was collected in West Hungary during a sampling done at river Zala.

Updated: I have checked the references I found on Elmidae larvae and it seems that it belongs to genus Macronychus.

Try sending this to John Morse, Clemson University.  He is a Trichoptera expert

@David: Thank you for the suggestion, I'll keep it in mind for further works, but this question is sold, it is not a caddisfly larva.

I agree on Coleoptera Elmidae. I read the hypotheses expressed in other answers: in my opinion larvae of caddisflies (Trichoptera) must be excluded definitely and, as regards larvae of Diptera, these have neither thoracic legs nor prolegs (it must be outlined that prolegs are abdominal false legs, not the thoracic legs present e.g. in this larva). This is clearly a beetle larva. Additional comment: I think it's always useful to indicate the size (length) of a specimen, when a photo is posted, in order to make easier its identification. Regards,

Rinaldo Nicoli

It is definitely an elmid.  Not sure of genus, but it appears closet to Stenelmis.

There is the possibility of DNA-Barcoding using the "Life-Scanner" App for iOS. See http://lifescanner.net/ for descriptions.

It was introduced to me at a symposium in Trondheim and sounds quite promising

I back the Colepotera Elmidae proposal : 4 articles visible on the first leg, 9 abdominal segments, the head is visible, abdominal gills are present. The animal looks mostly cylindrical and it seems you have the two final abdominal claws separated by the rounded end of the abdomen which points to Stenelmis as proposed by david.

http://www.perla.developpement-durable.gouv.fr/index.php/arbre/page/685/

I am in agreement with the Coleoptera, Elmidae identification.The head, legs and sclerotization of the abdomen all tell me Elmidae, I am not as confident on the genus but I think Stenelmis is a very likely possibility.

I recently came across same here in Africa and initially thought it was a caddisfly (probably Ecnomidae) but upon further scrutiny, I found out that one could not distinguish any pro, meso or metanotum from the abdominal segments, thus striking out Trichoptera. Then the thought of it being a Coleopteran larva came to mind. I later found out that it was under the family Elmidae. Identified it as Limnius.

It appears to be a beetle larvae. Elmidae.

It is an elmid larva.

it is coleoptera larva

Take some dorsal pictures of the head.

Es un elmido pero no es Stenelmi

Definitivamente es una larva de Stenelmis

A specimen in the larval stage of Elmidae, with certainty. Stenelmis? Most likely Stenelmis, we should see the details