Morphology Data of Potamothrissa acutirostris
Identification keys
Abnormalities
Main Ref. Whitehead, P.J.P., 1985
Appearance refers to
Bones in OsteoBase

Sex attributes

Specialized organs no special organs
Different appearance males alike females
Different colors males alike females
Remarks

Descriptive characteristics of juvenile and adult

Striking features none
Body shape lateral fusiform / normal
Cross section compressed
Dorsal head profile more or less straight
Type of eyes more or less normal
Type of mouth/snout more or less normal
Position of mouth terminal
Type of scales cycloid scales
Diagnosis

Diagnosis: Body slender, its depth 19-27% of standard length; pre-pelvic scutes fairly strongly keeled, beginning under or just before pectoral fin base, 11-13 pre-pelvic and 10-12 post-pelvic scutes; snout pointed; lower jaw not projecting, included in upper when mouth closed, deepest at mid-point of jaw, with small saw-like teeth on either side; pre-maxillae with rather peg-like teeth, those near mid-line pointing forward; maxilla very slender, its blade over 3 times as long as deep, upper edge ridged, lower edge without denticulations; posterior supra-maxilla very small, spatulate, its shaft about as long as its blade; lower gillrakers 16-18 (Ref. 188). It differs from Potamothrissa obtusirostris and P. whiteheadi in its pointed snout, more gillrakers, 16-18 vs. 14-16 and 14-17 respectively, and first pre-pelvic scute beginning under or just before pectoral fin base (Ref. 188, 28136). Other pellonulines lack saw-like teeth at the sides of the lower jaw (Ref. 188).

Description: Body slender, its depth 19-27% of standard length (Ref. 188). Caudal peduncle a little longer than deep (Ref. 1877, 1878, 93833). The upper profile of the head is a little less oblique than the lower profile; snout, acutely pointed and and projecting slightly beyond lower jaw, is as long as eye diameter, which is one third of head length and slightly exceeds interorbital width; maxillary extending a little beyond anterior border of eye; a well-developed adipose eye lid; teeth unequal in size, none very strongly enlarged (Ref. 1877, 1878). Gill-rakers slender, much shorter than branchial filaments, about 16-18 on lower part of anterior arch (Ref. 188, 1878, 93833). Dorsal fin with 13-14 rays, its origin above first ray of pelvic fin, much nearer end of snout than base of caudal fin; anal fin with 16-20 rays, its origin well behind last rays of dorsal fin, nearly twice as distant from base of pelvic fin as from caudal fin; pectoral fin not reaching pelvic fin; caudal fin forked, with pointed lobes (Ref. 1877, 1878, 93833). Scales: 36-42 scales in longitudinal series; 10 transversal scales (Ref. 1877, 1878, 93833). With 11-13 keeled pre-pelvic scutes and 10-12 post-pelvic scutes; pre-pelvic scutes fairly strongly keeled, beginning under or just before pectoral fin base (Ref. 188, 1877, 1878, 28136).

Colouration: Olive coloured dorsally, whitish ventrally, with a silvery lateral band; sometimes a large dark spot on gill-cover and scapular region, and another at base of caudal fin; iris silvery, with a yellow circle around the pupil, which is elongated vertically (Ref. 1877, 1878).

Ease of Identification

Meristic characteristics of Potamothrissa acutirostris

Lateral Lines Interrupted: No
Scales on lateral line
Pored lateral line scales
Scales in lateral series 36 - 42
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 16 - 18
on upper limb
total
Vertebrae
preanal
total

Fins

Dorsal fin(s)

Attributes no striking attributes
Fins number 1
Finlets No. Dorsal   
Ventral  
Spines total 0 - 0
Soft-rays total 13 - 14
Adipose fin absent

Caudal fin

Attributes forked; more or less normal

Anal fin(s)

Fins number 1
Spines total 0 - 0
Soft-rays total 16 - 20

Paired fins

Pectoral Attributes  more or less normal
Spines     
Soft-rays   
Pelvics Attributes  more or less normal
Position    abdominal  beneath origin of D1
Spines     
Soft-rays   
Main Ref. (e.g. 9948)
Glossary ( e.g. cephalopods )
Entered by Binohlan, Crispina B.
Modified by Boden, Gert
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