00914nas a2200121 4500008004100000245010500041210006900146260001600215520048500231100001800716700001500734856004300749 2016 eng d00aAnal-fin ray morphology indicates sexual maturity in Brevimyrus niger (Teleostei, Mormyridae)0 aAnalfin ray morphology indicates sexual maturity in iBrevimyrus  cJan-10-20163 a

This osteological survey of 249 specimens of Brevimyrus niger ranging in size from 44 to 137 mm standard length (LS) demonstrated that developmental changes in anal-fin morphology can serve as a predictor of sexual maturity in this species. Anal-fin ray bases begin to expand when fish reach c. 90 mm LS at which size and above there were roughly equal numbers of individuals observed with expanded and unmodified anal-fin bases, reflecting a 1:1 sex ratio.

1 aStell, S., K.1 aMoller, P. uhttp://doi.wiley.com/10.1111/jfb.1316301242nas a2200157 4500008004100000022001400041245009700055210006900152260001600221300001400237490000700251520074400258100001701002700001501019856005001034 2005 eng d a0022-111200aThe anal fin complex in a weakly discharging electric fish, Gnathonemus petersii(Mormyridae)0 aanal fin complex in a weakly discharging electric fish Gnathonem cJan-01-2005 a266 - 2750 v663 a

An examination of the permanent bony structures of the anal fin complex in the mormyrid fish, Gnathonemus petersii, revealed two new structural sexual dimorphisms: longer proximal pterygiophores and wider anal fin rays in males than in females. Both structures are thought to facilitate the male’s courtship-associated anal fin reflex. Adult male mormyrid fishes are characterized by a dorsally directed indentation of the posterior body wall (anal fin indentation). The expression of this indentation in males, presumably driven by anal fin musculature, was correlated with the fish’s gonadal state: large indentations were associated with high gonado-somatic indices and small indentations with low indices.

1 aGreisman, L.1 aMoller, P. uhttp://www.blackwell-synergy.com/toc/jfb/66/101371nas a2200157 4500008004100000022001400041245011500055210006900170260001600239300001400255490000700269520085400276100001801130700001501148856005001163 1998 eng d a0022-111200aA sexually dimorphic basal anal-fin ray expansion in the weakly discharging electric fish Gnathonemus petersii0 asexually dimorphic basal analfin ray expansion in the weakly dis cJan-09-1998 a638 - 6440 v533 a

Male Gnathonemus petersii (Mormyridae) exhibit two structural, sexually dimorphic characters: anal-fin ray bone expansion and an indentation of the posterior ventral body wall (formerly described as anal-fin indentation). Females lack this bone expansion, but may show a slight indentation. Morphometric data on both characters were obtained from radiographs of 414 fish (males and females) ranging in size from 60 to 276 mm Ls. Both body wall indentation and bone expansion began to develop in males of about 120 mm Ls. At 160–180 mm, the sex ratio of fish with expansion to fish without expansion was 50 : 50. Androgens seem to affect the expression of both these sexual dimorphisms. Bone expansion may provide increased bone surface for muscle attachment and thus facilitate the anal-fin reflex during courtship behaviour.

1 aPezzanite, B.1 aMoller, P. uhttp://www.blackwell-synergy.com/toc/jfb/53/301623nas a2200145 4500008004100000245015200041210006900193260001200262300001600274490000900290520109800299100001501397700001401412856005101426 1990 eng d00aMeristic characters and electric organ discharge of Mormyrops curviceps Roman (Teleostei: Mormyridae) from the Moa River, Sierra Leone, West Africa0 aMeristic characters and electric organ discharge of Mormyrops cu c12/1990 a1031–10400 v19903 a

Mormyrids of the genus Mormyrops were collected from the Moa River around Tiwai Id., Sierra Leone, West Africa. Meristic analysis and comparison with paratypes identify these fish as Mormyrops curviceps Roman. They differ from M. deliciosus (Roman) in seven meristic characters: the number of lateral-line scales, caudal-peduncle scales, total vertebrae, caudal vertebrae, anal-fin rays, and teeth on the upper and lower jaws. From M. curviceps we recorded two electric organ discharge (EOD) pulse types, which were not related to developmental stage or sex. Individual EOD lasted on average either 0.471 msec (with a major head-positive phase followed by an equally large head-negativephase), or about three timeslonger (1.611msec) with reversed polarity (i.e.,a major head-negative phase), followed by a major head-positive phase. We contrast two views concerning mormyrid EOD: 1) the EOD of M. curviceps simply exists in two pulse-form morphs; and 2) characteristics of the EOD pulse-form function as a reproductive isolating mechanism, suggesting the existence of sibling species.

1 aMoller, P.1 aBrown, B. uhttps://mormyrids.efishgenomics.com/en/node/6900528nas a2200133 4500008004100000245015700041210006900198300001400267490000700281100001500288700001800303700002200321856005100343 2004 eng d00aPermanent and seasonal expressions of sexual dimorphisms in a weakly electric fish, Mormyrus rume proboscirostris Boulenger 1898 (Mormyridae, Teleostei)0 aPermanent and seasonal expressions of sexual dimorphisms in a we a175–1840 v701 aMoller, P.1 aSchugardt, C.1 aKirschbaum, Frank uhttps://mormyrids.efishgenomics.com/en/node/52