Overview

Comprehensive Description

General Description

Body moderately deep, 20.5-23.7% SL, greatest depth near origin of dorsal fin. Head long, 23.5-24.9% SL, its depth 73-78% HL. Head may be slightly elongated in adult males. Dorsal profile continuously convex from the origin of the dorsal fin to the snout. Ventral profile moderately concave on the underside of the head, then straight to the origin of the anal fin. Snout rounded and protruding, snout length 8.1-9.4% SL, 18.1-26.4% HL. Snout may be sexually dimorphic, being higher and less rounded in the largest males (greater than 250 mm SL). Mouth subterminal, below the nostrils, and large, its posterior margin slightly anterior to anterior margin of eye, its width 25% HL. Chin with a moderate submental swelling. Teeth slightly notched in juveniles, worn flat or conical in larger individuals, five in upper jaw, six in lower. Median lower teeth much larger than others, protruding from lower jaw like the incisors of a beaver, Castor canadiensis, for which this species receives its name. Nostrils close to one another, level with the lower margin of the eye. Posterior nostril, 5.4-5.8% HL away from eye. Eye large, 14.1-20.2% HL. Dorsal fin base length 24.5-27.5% SL with 31-32 rays, height 14.6-15.7% SL. Predorsal distance, 58.6-61.1% SL. Anal fin base length 26.4-27.6% SL with 31-34 rays, height 13.9-14.3% SL. Pectoral fin: length 15.1-18.2% SL with 12 rays. Prepectoral length, 24.2-24.4% SL. Pelvic fin length 9.1-10.5% SL, prepelvic distance, 35.8-36.6% SL. Caudal peduncle depth 22.9-29.5% of its length with 16 circumpeduncular scales; scales along the lateral line, 80-81; 21-22 rows of scales above the lateral line, 19-21 between lateral line and pelvic fin. The caudal fin is deeply forked. Maximum size: 305 mm.

Coloration: deep chocolate-brown with a dark band running from the most anterior rays of the dorsal fin to the most anterior rays of the anal fin, flanked on both sides by lighter coloured bands. Dark bands run to the ends of the longest dorsal and anal rays. Younger specimens (up to 120 mm SL) have pronounced light bands in the form of parentheses ‘()’ extending from the origin of the dorsal to the origin of the anal, flanking the darker band that remains prominent. Width of dark band eight to nine scales at the lateral line.

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Distribution

Range Description

This species is a Lower Guinea endemic restricted to the Sanaga, Wouri, Lokoundje, and This species is known from upper Cross Rivers of Cameroon.
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Africa: Sanaga and Lokoundje Rivers in Cameroon. Also known from the Cross River, Nigeria. Similar to Hippopotamyrus pictus and Hippopotamyrus paugyi.
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Restricted to the Sanaga, Wouri, Lokoundje and upper Cross Rivers of Cameroon.

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West-central Africa: Cameroon.
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Physical Description

Size

Maximum size: 260 mm SL
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Max. size

26.0 cm SL (male/unsexed; (Ref. 2915))
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to 305 mm SL

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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
This mormyrid grows to 26 cm SL. It is a demersal species, and uses a weak electrical discharge to locate prey.

Systems
  • Freshwater
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Environment

demersal; freshwater
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Life History and Behavior

Behavior

Electric Organ Discharge

The EOD has three phases and the total duration is approximately 0.21 msec (not including the small initial peak, P0, which is less than the 2% of the threshold that is used to measure EOD durations). The main peaks of the EOD are P1 and P2, which are about equal in amplitude. The height of P0 is less than 0.2% of the peak to peak height. The power spectrum peaks at about 5,000 Hz.

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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2010

Assessor/s
Moelants, T.

Reviewer/s
Brummett, R., Mbe Tawe, A.N., Dening Touokong, C., Reid, G.M., Snoeks, J. Staissny, M., Moelants, T., Mamonekene, V., Ndodet, B., Ifuta, S.N.B., Chilala, A., Monsembula, R., Ibala Zamba, A., Opoye Itoua, O., Pouomogne, V., Darwall, W. & Smith, K.

Contributor/s

Justification
Although restricted to Cameroon, this species' range falls within the Cross River National Park and it is not known to be facing any major threats. It is therefore assessed as Least Concern.
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Population

Population
No information available.

Population Trend
Unknown
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Threats

Major Threats
There is no information available on threats to this species.
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Least Concern (LC)
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Management

Conservation Actions

Conservation Actions
Its distribution falls within the Cross River National Park.
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