Morphology Data of Protocheirodon pi
Identification keys
Main Ref. Vari, R.P., B.F. Melo and C. Oliveira, 2016
Appearance refers to
Bones in OsteoBase

Sex attributes

Specialized organs
Different appearance
Different colors

Descriptive characteristics of juvenile and adult

Striking features
Body shape lateral fusiform / normal
Cross section
Dorsal head profile
Type of eyes
Type of mouth/snout
Position of mouth
Type of scales cycloid scales

Protocheirodon pi can be distinguished by possessing four synapomorphies proposed for the Cheirodontinae by Malabarba (1998): presence of a pseudotympanum, a hiatus in the body wall musculature lateral to at least a portion of the anterior chamber of the swimbladder; absence of dark humeral spot; possession of pedunculate dentition; and presence of only a single row of regularly arranged premaxillary teeth. It differs from all species of the Cheirodontinae and indeed members of the Characiformes by the unique form of the swimbladder which has a smaller rotund anterior chamber and the posteriorly chamber elaborated into two vertically elongate, side by side, slightly inclined chambers. These modifications resulted to a unique overall pi (?)-shaped structure (Ref. 109753).

Ease of Identification

Meristic characteristics of Protocheirodon pi

Lateral Lines Interrupted: No
Scales on lateral line 32 - 39
Pored lateral line scales
Scales in lateral series
Scale rows above lateral line 7 - 8
Scale rows below lateral line
Scales around caudal peduncle
Gill clefts (sharks/rays only)
Gill rakers
on lower limb
on upper limb


Dorsal fin(s)

Attributes no striking attributes
Fins number
Finlets No. Dorsal   
Spines total
Soft-rays total 9 - 10
Adipose fin present

Caudal fin

Attributes forked

Anal fin(s)

Fins number
Spines total
Soft-rays total 47 - 51

Paired fins

Pectoral Attributes  
Soft-rays   12 - 13
Pelvics Attributes  
Position    abdominal
Soft-rays   5 - 6
Main Ref. (e.g. 9948)
Glossary ( e.g. cephalopods )
Entered by Torres, Armi G.
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cfm script by eagbayani, 17.10.00, php script by rolavides, 13/03/08 ,  last modified by sortiz, 06.27.17