Morphology Data of Xenurolebias myersi
Identification keys
Main Ref. Costa, W.J.E.M. and P.F. Amorim, 2014
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

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

Xenurolebias myersi differs from all other congeners by having the caudal fin sub-lanceolate, never forming a distinctive tip posteriorly in larger individuals (vs. lanceolate, with a pronounced posterior tip) and distinctive light yellow spots on the distal portion of the anal fin in males (vs. light yellow narrow bars). It is also distinguished from X. cricarensis and X. izecksohni in having fewer dark brown bars on the caudal fin in males (4-6, vs. 7-10 in X. cricarensis and 9-12 in X. izecksohni); from X. izecksohni by having fewer dark grey bars on the flank in females (9-11 vs. 12-13), the dorsal fin, in males, with short light bars on the basal portion and small round light spots on the distal portion (vs. branching bars), absence of oblique short bars on the ventral portion of the caudal fin in males (vs. presence), deeper body (29.0-31.4% SL in males and 30.1-33.9% in females, vs. 27.1-28.5% and 28.5-30.6%, respectively), and longer lower jaw (22.4-24.5% of head length in males and 19.6-21.4% iin females, vs. 18.6-20.9% and 17.7-19.7%, respectively); and from X. pataxo in having wider head (71.5-74.6% SL in males and 74.5-81.1% in females, vs. 65.7-71.1% and 65.8-70.3%, respectively), shorter filaments on the dorsall fin in males (reaching between base and middle of the caudal fin, vs. reaching posterior portion of the caudal fin), and the presence of black spots on the posterior part of the caudal peduncle in females (vs. absence) (Ref. 96072).

Description: Dorsal fin with 16-18 rays in males, 12-15 rays in females; anal fin with 20-23 rays in males, 19-22 rays in females; extremity of dorsal fin pointed and long in males, rounded to slightly pointed in females; tip of anal fin pointed in males, rounded in females; and caudal fin sub-lanceolate (Ref. 96072).

Ease of Identification

Meristic characteristics of Xenurolebias myersi

Lateral Lines Interrupted: No
Scales on lateral line
Pored lateral line scales
Scales in lateral series 27 - 28
Scale rows above lateral line
Scale rows below lateral line
Scales around caudal peduncle 12 - 12
Gill clefts (sharks/rays only)
Gill rakers
on lower limb
on upper limb
total 28 - 29


Dorsal fin(s)

Attributes other
Fins number 1
Finlets No. Dorsal   
Spines total
Soft-rays total 12 - 18
Adipose fin absent

Caudal fin

Attributes other (see remark)

Anal fin(s)

Fins number
Spines total
Soft-rays total 19 - 23

Paired fins

Pectoral Attributes  
Soft-rays   14 - 15
Pelvics Attributes  
Position    abdominal  before origin of D1
Soft-rays   6 - 6
Main Ref. (e.g. 9948)
Glossary ( e.g. cephalopods )
Entered by Torres, Armi G.
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