Morphology Data of Rheocles derhami
Identification keys
Abnormalities
Main Ref. Stiassny, M.L.J. and D.M. Rodriguez, 2001
Appearance refers to
Bones in OsteoBase

Sex attributes

Specialized organs
Different appearance always different morphology between mature adults
Different colors always different colors between mature adults
Remarks In mature males second dorsal and anal fins have long filamentous extensions and falcate borders, and the pectoral fins are enlarged (Ref. 39832).

Descriptive characteristics of juvenile and adult

Striking features
Body shape lateral fusiform / normal
Cross section
Dorsal head profile
Type of eyes more or less normal
Type of mouth/snout
Position of mouth superior
Type of scales
Diagnosis

Rheocles derhami is readily distinguished from R. sikorae and R. wrightae by length of upper jaw (32-41%HL versus 46-58) and absence of black pigmentation of genital papilla, from R. pellegrini by number of gill rakers on lower limb of first arch (9-10 versus 6-7), from R. lateralis by caudal peduncle length (67.3-78.6%SL versus 84.6-96.7), and from R. alaotrensis by absence of chest and belly scales and paired predorsal scale rows (Ref. 39832). In life males normally light grey, the second dorsal, anal and caudal fins are bright silvery blue, the throat region is orange-red, light grey females are not brightly colored; preserved specimens are creamy yellow, scale rows in dorsal midline heavily pigmented and darkened (Ref. 39832).

Ease of Identification

Meristic characteristics of Rheocles derhami

Lateral Lines Interrupted: No
Scales on lateral line
Pored lateral line scales
Scales in lateral series
Scale rows above lateral line
Scale rows below lateral line
Scales around caudal peduncle
Barbels
Gill clefts (sharks/rays only)
Gill rakers
on lower limb 9 - 10
on upper limb
total
Vertebrae
preanal
total 35 - 38

Fins

Dorsal fin(s)

Attributes
Fins number 2
Finlets No. Dorsal   0 - 0
Ventral  0 - 0
Spines total 2 - 2
Soft-rays total 14 - 19
Adipose fin absent

Caudal fin

Attributes forked; more or less normal

Anal fin(s)

Fins number 1
Spines total 1 - 1
Soft-rays total 15 - 21

Paired fins

Pectoral Attributes  more or less normal
Spines     
Soft-rays   
Pelvics Attributes  more or less normal
Position    thoracic  before origin of D1
Spines     
Soft-rays   
Main Ref. (e.g. 9948)
Glossary ( e.g. cephalopods )
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