Morphology Data of Trigonostigma heteromorpha
Identification keys
Main Ref. Tan, H.H., 2020
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
Cross section compressed
Dorsal head profile
Type of eyes
Type of mouth/snout
Position of mouth
Type of scales

This species is shares with T. truncata, presence of a large black axine starting from approximately mid-body with dorsal apex near dorsal-fin origin, ventral apex near pelvic-fin origin, and caudal apex near caudal-fin base. It differs from all its congeners in the following set of characters: a

steep sloping lateral head to pre-dorsal region (shared with T. espei, vs. a gentle sloping lateral profile from posterior of head to predorsal region for T. truncata, T. hengeli, T. somphongsi); terminal mouth (shared with all except truncata with a sub-superior mouth); caudal apex of axine

reaching caudal-fin base (shared with all except truncata with caudal apex not reaching); dorsal and ventral apices of axine originate near to both dorsal-fin and pelvic-fin origins (shared with truncata vs. dorsal apex starting up to 3 scale-width posterior to dorsal-fin origin and ventral apex starting two scale-width after pelvic-fin origin in espei, hengeli, while axine is reduced to thick black stripe in somphongsi); dorsal fin with distinct orange/red pigments shared with truncata, espei (vs. hengeli, somphongsi with almost hyaline dorsal fin) (Ref. 122370).

Ease of Identification

Meristic characteristics of Trigonostigma heteromorpha

Lateral Lines Interrupted: No
Scales on lateral line 25 - 28
Pored lateral line scales 5 - 9
Scales in lateral series
Scale rows above lateral line
Scale rows below lateral line
Scales around caudal peduncle 10 - 10
Gill clefts (sharks/rays only)
Gill rakers
on lower limb
on upper limb


Dorsal fin(s)

Fins number 1
Finlets No. Dorsal   
Spines total 1 - 1
Soft-rays total 7 - 7
Adipose fin

Caudal fin


Anal fin(s)

Fins number 1
Spines total 1 - 1
Soft-rays total 6 - 6

Paired fins

Pectoral Attributes  
Spines     0
Soft-rays   12 - 12
Pelvics Attributes  
Spines     1
Soft-rays   5 - 5
Main Ref. (e.g. 9948)
Glossary ( e.g. cephalopods )
Entered by Capuli, Estelita Emily
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