"Hi," Thanks, and P. Paludosis or Macrobrachium?

[GunmetalBlue]

Hi everyone, I've been "lurking" here awhile, trawling through old threads and doing catch-up reading from this informative site. I've only recently been bitten by the shrimp bug, so won't be able to add much; maybe an occasional question or personal observation.

I have two "*Ghost?" and two Bamboo shrimp. I'm slowly working towards Red Cherries after I get another tank... Is that how it goes? You start with one kind of shrimp and the next thing you know you want to collect them all for observation? Anyway, thanks Mustafa for this site and to all those providing questions and the much needed answers.

As most new people do, I'm searching for that "one answer" that brought me here in the first place. The answer I'm searching for, I almost found from this thread: viewtopic.php?t=81 That shrimp looks exactly like mine. Unfortunately, at the time, there was not an answer as to what kind of shrimp that is. Is there one now?

Basically, I have two shrimps that were sold to me as "grass shrimp" and told they were "friendly" to fish. And furthermore, it's the fish (depending on what kind I have) to watch out for. I originally presumed they were Ghost shrimp but my guys are predatory. They amazingly caught and ate three of my smaller fish - one White Cloud and two Zebra Danios <<<something I never dreamed could be possible! before I realized they are not "peaceful." So I've provided a separate tank for them.

They are about 1.5 inches long.


Sorry for the use of flash but I don't have enough light due to black gravel and only 10 watt lights. They're mostly translucent with a light brown/tan tint. They also have dark line markings and dark eyes.


They are a very lively, fun shrimp to watch. I enjoy giving them personal attention via food handouts using the blunt end of wooden BBQ skewers as chopsticks to hold their food (they'll come and get it) during feeding time.


Any input as to what they are is much appreciated as I don't want to continue calling them Ghost shrimp if in fact they are not. I'm presuming now they are some type of Macrobrachium?

Thanks! Blue

[Veneer]

They are most definitely Macrobrachium spp. of some sort, though whether they are adults (in that case, possibly M. lanchesteri) or juveniles has undoubtedly yet to be determined.

[Mustafa]

Although it might be a Macrobrachium, this shrimp might also be a Palaemon species, which in the US, are mostly in brackish water, although some venture into freshwater, too. This would make sense since most freshwater "ghost shrimp" in the trade in the US come from Florida and it would not surprise me that sometimes some Palaemon species are mixed in.

Palaemon, Palaemonetes and Macrobrachium are actually pretty closely related, so it's hard to tell sometimes what species is at hand without looking at the rostrum and comparing other body parts to a key in a journal article.

It's definitely not P. paludosus as Veneer said.

Mustafa

[Veneer]

Palaemon, Palaemonetes and Macrobrachium are actually pretty closely related, so it's hard to tell sometimes what species is at hand without looking at the rostrum and comparing other body parts to a key in a journal article.

Incidentally, is Macrobrachium, as some sources state, "immediately distinguished" from Palaemon in its possession of a hepatic spine?

GunmetalBlue - if this is the case, you may wish to view the comparative diagram shown on the ninth page of this PDF.

[With Macrobrachium rosenbergii, according to http://www.fao.org/documents/show_cdr.a ... 100e03.htm, "the carapace is hard and smooth, except for two spines on either side; one (the antennal spine) is just below the orbit and the other (the hepatic spine) is lower down and behind the antennal spine." I must note that vertical orientation of the hepatic spine (with respect to the antennal spine) varies from species to species.]

[Mustafa]

Yes, the hepatic spine is mentioned as one differentiating charecteristic. The absence of a branchial spine in Macrobrachium is another. However, who knows what taxonomists will come up with in the future to distinguish different species. A lot, if not all, Macrobrachium species used to be called Palaemon as in Palaemon (=Macrobrachium) lanchester1 or Palaemon (=Macrobrachium) hendersoni.

I think future DNA research will lead the way in creating new species groups instead of just looking at body parts under the microscope. For now, however, that's largely what we have to go by.

Mustafa

[GunmetalBlue]

Thank you Veneer and Mustafa for your replies. So my shrimp are definitely not P. Paludosus then.

Mustafa, so I gather even if I were to say I'm 99.9% sure the Macrobrachium lanchesteri shown here http://www.wirbellose.de/arten.cgi?acti ... &artNo=003 are the spitting image of my shrimp, without actually observing key body parts and comparing to a journal, I can never be sure due to many similarities between the Palaemon, Palaemonetes and Macrobrachium species. Is it wrong to refer to them as Macrobrachium lanchesteri in the meantime? Or should I refer to them simply as long arm shrimp? I want to be able to call them something other than just "shrimp."

Veneer, I really appreciated your links and will study it, unfortunately at this time I'm too much of a newbie to be able to make the technical comparisons. I do believe they are adults; I've had them for 4 months with 4 molts, along with its ensuing eggs except for the last month. Both are females (no males), so the eggs drop within a week. They haven't grown all that much more since I've gotten them and your mention of M. lanchesteri is the closest thing (without technical observation) I come to knowing which species they *might be.

Blue