P6REZ FARFANTE: ROCK SHRIMP GENUS SICYONIA 



Mexico, which Burkenroad described as having 

 the dorsum brown and the sides white, and also 

 differs from shrimp occurring in North Carolina, 

 in which the ground color is off-white. 



Maximum size. — According to Holthuis (1980), 

 153 mm tl. Largest individuals examined by me: 

 males 32 mm cl, about 125 mm tl; females 37 mm 

 cl, about 130 mm tl. The only specimen from the 

 Pacific, a male from off Puerto Madero, Chiapas, 

 Mexico, measures 18.1 mm cl, 70 mm tl (latter from 

 Burkenroad 1934a). 



Geographic and bathymetric ranges. — In the east- 

 ern Pacific, off southern Mexico, from Colima 

 (Chapa Saldaha 1964) to Chiapas (Fig. 25). In the 

 western Atlantic, from Norfolk, Va., along the 

 coast of the United States and the Bahamas to the 

 southern coast of Cuba, and around the Gulf of 

 Mexico from the Florida Keys to off Isla Contoy, 

 Yucatan; perhaps also off Guyana (McConnell 

 1960). In the western Atlantic it occurs from shal- 

 low water to 329 m (Williams 1965), usually be- 

 tween 10 and 110 m, and rarely at depths >190 m. 

 Exploitable populations are found between 34 and 

 55 m (Huff and Cobb 1979). 



This species prefers sand and shell-sand sub- 

 strates, but occasionally it is found on mud bot- 

 toms (Hildebrand 1954, 1955; Menzel 1956; Wil- 



liams 1965; Cobb et al. 1973; Kennedy et al. 1977; 

 Huff and Cobb 1979). The depths and substrates 

 with which it was associated in the eastern Pacific 

 were not recorded. 



Discussion. — Sicyonia brevirostris is rather 

 closely related to the western Atlantic S. typica 

 and the eastern Pacific S. disedwardsi . It differs 

 from both in possessing three, instead of two, large 

 teeth on the postrostral carina posterior to the 

 level of the hepatic spine and a caudodorsal de- 

 pression on the fourth abdominal somite. It differs 

 further from S. disedwardsi in 1) exhibiting 

 well-marked posterior pleural sulci on the first 

 three abdominal somites, which are lacking in the 

 latter shrimp or, if present, weak, often distinct on 

 only one or two somites; 2) having the distal pro- 

 jection of the dorsolateral lobule of the petasma 

 turned dorsomesially, compressed distally, and 

 produced apically in a short, subacute, dorsally 

 directed salient — in contrast, in S. disedwardsi 

 the projection is turned mesially and then dor- 

 solaterally, its apical extremity produced in a rela- 

 tively elongate, acutely pointed, laterally directed 

 salient which often bears a crest; and 3) lacking 

 an ocellus on the posterior part of the branchioste- 

 gite rather than bearing a large, brightly colored 

 one such as that in S. disedwardsi. 

 Sicyonia brevirostris occupies water of high sa- 





20 



10 



100 



Figure 25. — Geographic distribution of Sicyonia brevirostris. 



29 



