FISHERY BULLETIN: VOL. 78, NO. 1 



Table l. — Reallocation of nominal forms ofMelanocetus. Valid names on right. Synonymy for 

 species based on males after Bertelsen 1951. 



Females: 



Melanocetus johnsoni Gunther 1864 



Melanocetus krechi Brauer 1 902 



Melanocetus rotundatus Gilchrist 1903 



Melanocetus ferox Regan 1926 



Melanocetus cirrifer Regan and Trewavas 1932 



Melanocetus megalodontis Beebe and Crane 1 947 



Melanocetus polyactis Regan 1925 



Melanocetus niger Regan 1925 (in part) 



Melanocetus niger Regan 1925 (in part) 



Melanocetus murrayi Gunther 1887 



Melanocetus vorax Brauer 1 902 



Melanocetus tumidus Parr 1 927 

 Males: 



Centrocetus spinulosus Regan and Trewavas 1 932 



Xenoceratias micracanthus Regan and Trewavas 1 932 



Xenoceratias heterorhynchus Regan and Trewavas 1932 



Xenoceratias laevis Regan and Trewavas 1932 



Xenoceratias brevirostris Regan and Trewavas 1 932 



Xenoceratias braueri Koefoed 1 944 



Rhynchoceratias rostratus Regan 1926 (in part) 



Rhynchoceratias leucorhinus Regan 1926 (in part) 



Rhynchoceratias acanthlrostris Parr 1927 



Rhynchoceratias latirhinus Parr 1927 



Rhynchoceratias longipinnis Parr 1 930 



Xenoceratias regani Koefoed 1 944 



Melanocetus johnsoni Gunther 1 864 



Melanocetus polyactis Regan 1 925 

 Melanocetus niger 1 925 



Melanocetus murrayi Gunther 1 887 



Melanocetus johnsoni Gunther 1 864 



Melanocetus polyactis Regan 1 925 

 Melanocetus murrayi Gunther 1887 



yr, we are able to recognize five species based on 

 females. Four of these are previously described 

 forms: M. johnsoni, represented by 346 specimens 

 collected from all three major oceans of the world; 

 M. polyactis and M. niger, known from 15 and 6 

 specimens both restricted to the eastern tropical 

 Pacific; and M. murrayi, 140 specimens of 

 worldwide distribution. The fifth is a new species 

 recently collected by the Velero IV of the Univer- 

 sity of Southern California in the eastern Pacific 

 off Mazatlan, Sinaloa, Mexico. It differs strikingly 

 from its allies in having a considerably larger 

 escal bulb and shorter jaw teeth. 



Although the number of known male specimens 

 has increased nearly fourfold since Bertelsen's 

 (1951) work, no new diagnostic data are available. 

 We have examined 73 individuals (11.5-24 mm 

 standard length), none of which can be satisfactor- 

 ily identified to species based on females. As pre- 

 dicted by Bertelsen (1951), the variation in the 

 number of denticular teeth is greater than previ- 

 ously thought and values given in his key overlap 

 to a much greater extent than is indicated. An 

 attempt to utilize differences in larval pigmenta- 

 tion, thought to be more or less retained, at least in 

 the younger metamorphosed males, failed to sepa- 

 rate the material into groups that could be as- 

 sociated with species based on females. Although 

 Bertelsen's ( 1951 ) synonymies for nominal species 

 based on males are retained here, additional male 

 specimens are listed as Melanocetus sp. 



METHODS AND MATERIALS 



Standard lengths (SL) are used throughout un- 

 less otherwise stated. Measurements were taken 

 from the left side whenever possible and rounded 

 to the nearest 0.5 mm. To ensure accurate fin ray 

 counts, skin was removed from the pectoral fins 

 and incisions were made to reveal the rays of the 

 dorsal and anal fins. Sockets, indicating missing 

 teeth in the jaws and on the vomer, were included 

 in total tooth counts. Jaw tooth counts are the sum 

 of both right and left sides. Head depth is the 

 distance from the tip of the sphenotic spine to the 

 base of the quadrate spine. Head width is the dis- 

 tance between the anterolateralmost margins of 

 the sphenotic bones. Lower jaw length is the dis- 

 tance from the symphysial spine to the posterior- 

 most margin of the articular. Illicium length is the 

 distance from the articulation of the pterygio- 

 phore of the illicium and the illicial bone to the 

 distal surface of the esca, excluding escal append- 

 ages. The width of the pectoral fin lobe is the 

 distance between the point of articulation of the 

 uppermost fin ray to the articulation of the lower- 

 most fin ray. Terminology used in describing the 

 various parts of the angling apparatus follows 

 Bradbury (1967). Definitions of terms used for the 

 different stages of development follow Bertelsen 

 (1951). Complete locality data are given for pri- 

 mary type material only. 



The comparative osteological investigation was 



60 



