Morphology Summary - Acanthurus nigros
Morphology Data of Acanthurus nigros
Identification keys
Abnormalities
Main Ref. Hanahara, N., K. Miyamoto and S-I. Oka, 2021
Appearance refers to
Bones in OsteoBase

Sex attributes

Specialized organs
Different appearance
Different colors
Remarks

Descriptive characteristics of juvenile and adult

Striking features none
Body shape lateral  (shape guide) short and / or deep
Cross section compressed
Dorsal head profile clearly concave
Type of eyes more or less normal
Type of mouth/snout more or less normal
Position of mouth terminal
Type of scales ctenoid scales
Diagnosis

This species is characterized by the following: D IX,25; pectoral rays 16; gill rakers 25; teeth incisiform, denticulate, and close-set, with the distal end of upper teeth rounded with 12

upper and 14 lower teeth; body depth 1.9 in SL. Colouration: body light to dark brown with irregular, longitudinal, dotted stripes narrower than brown interspaces; suborbital and opercular region with stripes paralleling snout outline; rear base of dorsal and anal fins with a pupil-sized black blotch; dorsal and anal fins with bands paralleling outer edge (Ref. 138601).

Description: This species differs from A. nigrofasciatus by the following: presence of

the lines parallel to the snout on the suborbital and opercular regions (vs. spots on those regions in A. nigrofuscus); size of the black blotch at the rear base of the dorsal fin is larger in A. nigros; absence of a dark margin around the caudal-peduncle spine (vs. present ); posterior tips of the dorsal and anal fins less pointed when these fins are elevated (vs. more pointed); bands on the dorsal and anal fins more visible in preserved specimens (vs. less distinct) (Ref. 1920, 138601).

Ease of Identification

Meristic characteristics of Acanthurus nigros

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 0
Gill clefts (sharks/rays only)
Gill rakers
on lower limb
on upper limb
total 25 - 25
Vertebrae
preanal 9 - 9
total 22 - 22

Fins

Dorsal fin(s)

Attributes extending over most of the back length
Fins number 1
Finlets No. Dorsal   0 - 0
Ventral  0 - 0
Spines total 9 - 9
Soft-rays total 25 - 25
Adipose fin absent

Caudal fin  (shape guide)

Attributes more or less truncate; more or less normal

Anal fin(s)

Fins number 1
Spines total 3 - 3
Soft-rays total 25 - 25

Paired fins

Pectoral Attributes  more or less normal
Spines     0
Soft-rays   16 - 16
Pelvics Attributes  more or less normal
Position    thoracic
Spines     1
Soft-rays   5 - 5
(e.g. 9948)
(e.g. oophagy)
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