I'KKKZ FARFANTE: AMERICAN SOI.ENOCERII) SMRIMi'S 



juveniles of an average total length of 21.3 mm. 

 They stated that spawning generally took place 

 the night following the capture of mature females, 

 and eggs hatched between 12 and 24 h (according 

 to the temperature) after being released. The 

 young passed through 6 nauplii, 3 protozoeae, 

 3 mysis, and an undetermined number of post- 

 larvae before becoming juveniles. The larval 

 development was completed in 19-23 days at 

 19.0°-23.5°C and juveniles reached 21.3 mm 

 (average) in 81 days after hatching. In more 

 recent experiments, Boschi and Scelzo (1976) 

 found that, at 24°C, P. muelleri attained an 

 average of 61 mm tl and 2.7 g in 180 days after 

 hatching. The studies mentioned above are the 

 only ones that have been made on the develop- 

 ment of any of the 12 species treated here. 



Remarks-Much of our knowledge of the morphol- 

 ogy of this species is due to the study of Angelescu 

 and Boschi (1960) and their subsequent contribu- 

 tion (Boschi and Angelescu 1962). These authors 

 presented detailed accounts of the external and 

 internal anatomy, and included outlines and a 

 brief description of the "green" spermatophores 

 on the female. In addition, they calculated the 

 rate of growth of the species in Argentinian wa- 

 ters, studied the development of the testis and 

 ovaries, and determined that the spawning season 

 there extends from December to February (i.e., 

 through the summer months). Furthermore, they 

 found that it feeds on organic detritus as well as 

 on small animals, such as sergestids and poly- 

 chaetes, and plants. 



Ecological notes. -Pleoticus muelleri is the only 

 species of the genus which frequents shallow 

 littoral waters; it even invades seawater channels 

 and rias like those in the vicinity of Bahia Blanca, 

 Buenos Aires, where, according to Boschi (1963), 

 the "langostino" is trapped in weirs by the fisher- 

 men. Furthermore, this shrimp not only inhabits 

 such shallow waters, but occurs in sufficient abun- 

 dance to support commercial exploitation in 

 many areas. 



This species completes its entire life cycle in the 

 sea but, as stated above, may frequent inshore 

 waters of high salinity. It occupies tropical and 

 subtropical waters off Brazil, where surface tem- 

 peratures are as high as 25°-27°C during the 

 warm months of the year, and 16°-17°C during 

 the cold ones; farther south, off Argentina, it oc- 

 curs in temperate waters where surface tempera- 



tures range between 10° and 23°C during the 

 summer, and 5° and 10°C during the winter 

 (Boschi 1964). 



This shrimp lives on mud and sand bottoms. 



Economic importance. -Pleoticus muelleri is taken 

 commercially from Ilha Santana, Rio de Janeiro, 

 to Punta Clara, Chubut. Significant catches, how- 

 ever, are made only from Santa Catarina to Punta 

 Clara, and the largest fisheries are in Argentinian 

 waters (Boschi 1964), between Punta Rasa (prov- 

 ince of Buenos Aires) and Punta Clara, i.e., 

 between 41° and 44°S. This species constitutes 

 the largest percentage of the shrimp landings 

 (which also include Artemesia longinaris Bate 

 1888) in Argentina. 



Hadropenaeus New Genus 



Hymenopenaeus. Smith 1885:179 [part]. Burken- 

 road 1936:102 [part]. Kubo 1949:212 [part]. 



Philonicus Bate 1888:273 [part]. 



Pleoticus Bate 1888:xii [part]. 



Haliporus. Bouvier 1906b:l [part]; 1908:78 [part]. 

 A. Milne Edwards and Bouvier 1909:206 [part], 

 de Man 1911:31 [part]. 



Diagnosis-Body stout, carapace proportionately 

 short, integument moderately thick, firm. Ros- 

 trum short, not overreaching distal margin of 

 first antennular article, deep, ventral margin 

 pronouncedly convex; armed only with dorsal 

 teeth; epigastric tooth and first rostral separated 

 by interval equal to, or only slightly greater than, 

 that between first and second rostral teeth. Or- 

 bital and pterygostomian spines absent; post- 

 orbital, antennal, hepatic, and branchiostegal 

 spines present. Cervical sulcus long, almost 

 reaching middorsum of carapace; hepatic sulcus 

 deep; branchiocardiac sulcus and carina absent, 

 posthepatic and submarginal carinae absent. 

 Abdomen carinate dorsally from third through 

 sixth somites. Telson with pair of conspicuous, 

 fixed, lateral spines. Prosartema long, flexible. 

 Antennular flagella longer than carapace, usually 

 subcylindrical, ventral flagellum occasionally 

 depressed. Mandibular palp two jointed, articles 

 moderately broad, distal one as long as or slightly 

 shorter than basal, and tapering to blunt apex. 

 First maxilla with unsegmented palp (endite of 

 basis) gently narrowing to rounded apex. Fifth 

 pereopod subflagelliform and considerably longer 

 than fourth. First pereopod with spine on basis, 



315 



