Until very recently, the only evidence of sexual parasitism in this family was an anomalous case of a 20-mm male Melanocetus johnsonii attached to the upper lip of a 168-mm female Centrophryne spinulosa (LACM 30843-1). However, the attachment did not involve fusion of male-female tissue and is therefore not considered to be a parasitic association. Two similar couplings in Melanocetus, but between sexes of the same taxon, have recently been discovered. One of these, a 23.5-mm male attached to a 75-mm female Melanocetus johnsonii (BMNH 2004.6.3.2-3), was collected in the eastern North Atlantic off Ireland in 1999 by the RRS Discovery in a cruise partially funded by the British Broadcasting Corporation for the celebrated “Blue Planet” video series. The second example is part of collections made by Hiromitsu Endo, aboard the R/V Tansei-Maru, west of Okinawa, in April 2002: a 15-mm male attached to a 73-mm female Melanocetus murrayi (BSKU 57842). Both males are only loosely attached, with tissue of the female pinched by the tightly closed denticular jaws of the male, the BMNH example hanging from the middle of the belly of the female, the BSKU specimen attached to the right side of the head of the female, just beneath the sphenotic bone. In both cases, it does not appear that any fusion of male and female tissue has taken place. Either the connections of the two were so recent that the tissues did not have time to fuse, or, more likely, these are the first and only known examples of a non-parasitic coupling—male ceratioids caught in the act of temporary attachment.
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