How to tell Caridina apart from Neocaridina

[fishmosy]

This article was written by Werner Klotz, the scientist who authored the recent description of CRS and tigers from Southern China. I have written permission from the author to translate and reproduce the article here. I thank the author for permission to post this information here. I apologise in advance if my translation differs substantially from the original.

 

The original article can be found (in german) here: http://www.wirbellose.de/klotz/neocaridina.html
 
Caridina or Neocaridina?

© Werner Klotz

 

 

Many of our dwarf shrimp do not have a scientific name and are instead referred to as Caridina sp. or Neocaridina sp.. In aquarists literature - (I believe the author is referring to online forums, magazines, ect., but not scientific literature), one occasionally finds the idea that species with large eggs and direct-developing larvae (larvae that essentially hatch as mini adults) belong to the genus Neocaridina, whilst species that have planktonic larvae and small larvae belong to the genus Caridina. This is incorrect. The type of larval development has nothing to do with which shrimp belong in which genus.

 

In 1938, the genus Neocaridina was divided from the genus Caridina by Japanese scientists (1). The separation of the two genera was based on the inner branch (Endopod, En) of the first swimming leg pair of male animals.

 

In species of the genus Neocaridina, this has a pear-shaped, distally broadened shape. The internal appendix (ai), a small appendage on the inside of the endopod, is found (if present) always in the basal region (bottom) of the endopods (Figure 1).   
 
Figure 1

 

 

In the species of the genus Caridina, the endopod has an elongated, sheet-like, distal, narrow shape. An internal appendix is found (if present) near the distal end (the end furthest away) of the endopods (Figure 2).

Figure 2

 
 
 
Another thing which differentiates Neocaridina and Caridina can be found in females as well. On the first maxilliped (the legs around the mouth that assist in feeding), many (but not all) species of the genus Caridina have an exopodite (a finger like spur). This is absent for species in the genus Neocaridina (Figure 3 & 4 - arrow). 

 
 

It should be noted that the separation of the genus Neocaridina has been opposed by some taxonomists. In their opinion, the term Neocaridina is just a synonym for Caridina (2).

 

The genus Neocaridina was recently reviewed by Cai (3) who confirmed the genus as being separate to Caridina.

 

Literature cited:

 

1) I.Kubo, J. Imp. Fish. Inst. Tokyo 33:67-100,1938 On the Japanese atyid shrimps
2) MS Hung, J. of Crustacean Biology, 13(3): 481-503, 1993 Aytyd shrimps (Decapoda: Caridea) of Taiwan, with descripitons of three new species
3) Cai, Y, Acta Zootaxon. Sinica 21: 129-60, 1996 A revision of the genus Neocaridina (Crustacea: Decapoda:Atyidae) 
 
 

Text and photos © Werner Klotz 2003
 

 

Edited December 5, 2014 by fishmosy

[buck]

thats a good little read, thanks for going to the effort to share it!   

[Jenbenwren]

Another great informative read. Thanks fishmossy

[Squiggle]

Fantastic thread Ben, very interesting!

[Shrimpin]

Thanks for sharing