oblique line with VO5. Luminous scales at PLO large, the tissue in short wavy lines or 

 convoluted D. anderseni 



3b. Dn small but prominent; Vn minute*. So larger than Dn or Vn, very much enlarged in 

 males, wedge-shaped, the apex anteriorly, filling space between upper jaw and orbital 

 margin and extending to about under hind margin of orbit; So of females much shorter 

 than in males, elliptical. SAO, on level of last 2 VO. Luminous scale at PLO small and 

 thin, the tissue appearing as vertical striations D. diadematus* 



4a. First AOa not or but very slightly elevated. Posterodorsal margin of operculum moder- 

 ately angulate 5 



5a. So behind vertical from posterior margin of pupil. No luminous scale at PLO 6 



5b. So before vertical of posterior margin of pupil. Pupil more or less elongated horizontally. 

 Luminous scale at PLO 7 



6a. Pupil vertically elongate; a notable space usually present ventrally between lens and 

 iris. Orbit large, 58-60% of upper jaw. So surrounded by and separated from Vn by dark 

 pigment. A large, profusely ramified melanophore immediately posteroventral to So. 

 Body deep, robust, its depth about 34% of SL. Photophores of upper series very low on 

 body. Caudal peduncle short, deep. Vn long, underlying most of orbit, narrow in females, 

 much widened in males; So a small knob at end of Vn D. brachycephalus 



6b. Pupil round, no appreciable space ventrally between lens and iris. Orbit about 50% of 

 upper jaw. So not surrounded by or separated from Vn by dark pigment. No large 

 melanophore posteroventral to So. Very similar to D. brachycephalus (Ga) but body less 

 deep and robust, its depth about 22-24% of SL D. richardsoni 



7a. Caudal-peduncle length about 22-24% of SL, its depth 48% (44-51% ) of its length. Lumi- 

 nous scale at PLO about half the pupil in size, the tissue in short, wavy lines radiating 

 away from PLO D. theta 



7b. Caudal peduncle very short and deep, its length 12-13% of SL, its depth 68% (65-71%') of 

 its length. Luminous scale at PLO half or less the size of pupil, the tissue in short, wavy, 

 laterally directed lines D. longleyi 



8a. Posterodorsal margin of opercle notably angulate and recurved. Gill rakers 5-6 +1-1- 

 12-13; AO 5-6 + 3-4 (rarely 5). Luminous scale at PLO small, the tissue appearing 

 convoluted or granular D. mollis 



8b. Posterodorsal margin of operculum only moderately angulate and very little if at all 

 recurved. Gill rakers highly variable in number, totals ranging from 13 to 27. Luminous 

 scale at PLO large and prominent; absent in one form ...D. fulgens-rafinesquii (a complex) 



9a. Ant absent (a tiny photophore-like and pigment-ringed luminous dot, present in some 

 species above and often in contact with Dn, is not to be interpreted as an Ant). Pupil 

 essentially round 10 



9b. Ant present. Dn and Vncontiguous 25 



10a. Dn and Vn widely separated 11 



10b. Dn and Vn contiguous or confluent 16 



11a. Vn elongated. Dn and Vn widely separated (Fig. 84B) 12 



lib. Vn small, not elongated. Dn and Vn widely separated (Fig. 84B) 13 



12a. Vn smooth on dorsal surface. Vn very much enlarged in males, wedge-shaped, the apex 

 anteriorly, filling space between upper jaw and orbital margin and extending to about 



under hind margin of orbit D. diadematus 



12b. Dorsal surface of Vn bearing 4 or 5 luminous dots embedded in a heavy streak of dark 

 pigment and protruding into orbital rim. Vn long and slender in females, much more 

 massive in males, extending under much of orbital rim. SAO, on level of last 2 VO. 



*D. diadematus may be more properly placed in that group having the Dn and Vn widely separated (couplet 111 and 

 connected by a strand of dark tissue bearing one or more dots of luminous tissue. However, one of these dots is often 

 enlarged and may be interpreted as a small Vn, and the larger posterior organ as an So. 



99 



