FISHERY BULLETIN: VOL. 83, NO. 1 



Figure 60. — Sicyonia ingentis, -. 23 mm cl, southeast of Punta 

 Tasco, Isla Santa Margarita, Baja California Sur, Mexico. 

 Thelycum. Scale = 1 mm. 



margin of sternite XI, spines broad basally and 

 sharp or sometimes needlelike apically. 



The smallest impregnated females encountered 

 had a carapace of 14 mm, about 57 mm tl. 



Maximum size. — Males 157 mm tl; females 180 

 mm tl, measured from "telson to base of antenna" 

 (Herkelrath 1977). In my sample: males 31 mm cl, 

 about 112 mm tl; females 40.2 mm cl, about 133 

 mm tl. 



Geographic and bathymetric ranges. — Monterey 

 Bay, 36^50 'N, 121°50'W (Perez Farfante and 

 Boothe 1981), California, southward to Isla Maria 

 Madre, 22°00'N, 106°16'W, Nayarit, Mexico; in the 

 Gulf of California (Fig. 52) along the central part 

 of the eastern coast; and in the southern part along 

 both coasts. This species has been found between 5 

 and 293-307 m and is most abundant from 55 to 82 

 m, at which depth it is commercially fished off 

 Ventura, Calif. (Frey 1971); also most of the many 



specimens examined by me were taken within this 

 range. According to Carlisle (1969) it is common at 

 depths between 61 and 183 m. Sicyonia ingentis 

 occurs on substrates of sand, shell, and green mud, 

 but seems to prefer sandy bottoms on which com- 

 mercial concentrations are located. 



This species is the only member of Sicyonia that 

 has been recorded along the west coast of the 

 United States and north of Punta Canoas, Baja 

 California Sur — about 1,000 km south of Mon- 

 terey Bay, the northern limit of its range. The 

 record from Isla Maria Madre, Nayarit, is the first 

 from waters south of the Gulf of California. 



Discussion. — Sicyonia ingentis, the largest east- 

 ern Pacific species in the genus, has its closest 

 affinities with the much smaller, sympatric S. 

 disdorsalis . It differs from the latter in possess- 

 ing 1) a carapace bearing, not lacking, patches of 

 long setae, 2) a robust postrostral carina rather 

 than a slender one, 3) a strong branchiocardiac 

 carina instead of an almost indistinct one, 4) a 

 carina on the fifth abdominal somite which slopes 

 gently to near the posterior cleft rather than being 

 truncate or produced in a spine, 5) an anterome- 

 dian pleural sulcus on the first abdominal somite 

 which continues as a shallow depression almost to 

 the ventral margin of the pleuron instead of end- 

 ing abruptly and well above it, 6) an unarmed 

 antero ventral extremity on the pleuron of the first 

 abdominal somite rather than one armed with a 

 strong spine, 7) curved, instead of angular, pos- 

 teroventral pleural margins on the first two ab- 

 dominal somites, 8) well-developed telsonic spines 

 instead of minute or indistinct ones, and 9) long 

 uropodal rami that considerably surpass the apex 

 of the telson instead of falling short of or barely 

 overreaching it. 



Sicyonia ingentis also differs from S. disdorsalis 

 in characters of the genitalia. The distal projection 

 of the dorsolateral lobule of the petasma is di- 

 rected distolaterally instead of curving distome- 

 sially and is produced in a short apical filament 

 which is lacking in S. disdorsalis. The distal pro- 

 jection of the ventrolateral lobule reaches, instead 

 of falls short of, the terminal margin of the dor- 

 solateral lobule; furthermore, it is neither bifur- 

 cate laterally nor does it bear a transverse rib. In 

 the thelycum, the median depression on the pos- 

 terior part of the median plate of sternite XIII is 

 narrower than the usually rounded protuberances 

 flanking it, whereas in S. disdorsalis the depres- 

 sion is much broader than the flat or concave areas 

 which occupy the position of the two protuber- 



72 



