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Figure 38. — Collections of larvae and pelagic juveniles of Pontinus 

 Type B from various sources. Open circles, Scripps Tuna 

 Oceanography cruises, closed circles, EASTROPAC Expedition; 

 open squares, Scripps Institution of Oceanography iish collection. 



Ectreposebastes Garman 



Literature. — In their review of the scorpaenid sub- 

 family Setarchinae, Eschmeyer and Collette (1966) gave 

 a brief description of two larval specimens (15 and 16 mm 

 SL) of E. imus. Illustrations of the larvae have not ap- 

 peared in the literature. 



Distinguishing features. — Larvae of Ectreposebastes 

 can be distinguished from those of other eastern Pacific 

 scorpaenid genera by a combination of characters. They 

 have enormous pectoral fins. The depth of the fin base is 

 19 to 22% of the body length while in the larvae of other 

 tropical scorpaenid genera, except Scorpaenodes, it 

 ranges from 12 to 18% of the body length. In Scor- 

 paenodes, the depth of the pectoral fin base ranges from 

 16 to 21% of the body length over most of the larval 

 period. Larvae of Scorpaenodes have a bifurcate parietal 

 ridge whereas Ectreposebastes larvae have a spikelike 

 spine at the terminus of each parietal ridge. Also, the 

 pectoral fins of Ectreposebastes are longer than in other 

 scorpaenid genera. In larvae which have completed 

 notochord flexion, the pectorals reach or extend beyond 

 the base of the caudal fin. Also, larvae of Ectreposebastes 

 are deeper-bodied than other scorpaenid genera in the 

 eastern Pacific. The rays of the dorsal and anal fins are 

 highly elongate and the pterygiophores and overlying 

 muscles appear to protrude from the body profile. Esch- 

 meyer and Collette (1966) considered Ectreposebastes to 

 be a monotypic genus of the tropical Atlantic and Pacific 

 but, in a recent paper, Eschmeyer and Randall (1975) 

 suggested that E. niger (Fourmanoir) may be a distinct 

 species. Only a single larval form was recognizable and is 

 herein referred to as E. imus. 



Ectreposebastes imus Garman, Figure 39 



Literature. — As above. 



Distinguishing features. — Size at hatching is un- 

 known; the smallest larva in our collection is 2.8 mm. 

 The larvae attain a larger size than any other known 

 species in the family. A 28.2-mm specimen is just begin- 

 ning to develop juvenile pigmentation on the head. 



Larvae of E. imus are the deepest- and narrowest- 

 bodied of all known eastern Pacific scorpaenid larvae. 

 Body depth averages 31% of body length in the preflex- 

 ion larvae and increases gradually thereafter to 55% in 

 the 28.2-mm transforming specimen (Table 38). The gut 

 has a compact anterior mass with a long intestinal sec- 

 tion extending posteriad to the anus. Snout-anus dis- 

 tance is large; it averages 53% of the body length in 

 preflexion larvae and increases thereafter to a maximum 

 of 76% in the 23.0-mm specimen. 



The head is large and develops a pair of spikelike 

 parietal spines, each with a short posteriorly directed 

 nuchal spine behind it. Head length averages 34% of the 

 body length before and during notochord flexion, and 

 averages 38% at completion of flexion. The eyes are small 

 and undergo a relative diminution during the larval 

 period. Eye diameter averages 32%i of head length before 

 and during notochord flexion and is gradually reduced to 

 a minimum of 22% in the 23.0-mm larva. Snout length 

 averages 33% of head length over the entire larval period. 



Larvae of E. imus have distinctive fins. The pectoral 

 fins are the longest of any known scorpaenid. Pectoral fin 

 length averages 33% of the body length in preflexion lar- 

 vae, 38%i during flexion, and increases to a maximum of 

 57% of the body length in the transforming specimen. 

 They extend to or beyond the hypural elements in larvae 

 6.7 mm and longer. Also, the fin base is unusually deep; 

 it ranges from 19 to 22% of the body length during the 

 larval period. Although there were too few larvae in the 

 series to permit staining, the development of fin rays can 

 be observed on unstained specimens. The full com- 

 plement of 18 to 20 pectoral rays is present in the 

 smallest larva (3.8 mm) in our collection. The pelvic fin 

 is moderate in size and is first apparent in the 5.5-mm 

 larva where its length is 9%. of the body length. Fin length 

 increases gradually during the remaining larval period to 



Table 38. Measurements (rm) of larvae of Ectreposebastes imus . [Specirrens between dashed 

 lines are undergoing notochord flexion.) 



•Transforming specimen. 



67 



