HAWAIIAN ACANTHURID CALIGOIDS — LEWIS 179 



Material. — Eleven adult females from gill cavity of Acanthurus 

 olivaceous Bloch and Schneider (USNM 105091), ten adult females 

 and one adult male from external surface and gill cavities of Acanthurus 

 triostegus sandvicensis Streets (USNM 105092), one adult male from 

 external surface of Acanthurus olivaceous Bloch and Schneider (USNM 

 105093), and one immature male from external surface of Zehrasoma 

 Havescens (Bennett) (USNM 105090). These 24 specimens were 

 selected from a collection of over 300 specimens taken from Oahu, 

 Hawaii, by the author and represent the Hawaiian population of 

 this species in the following description. 



Measurements. — Thirteen adult females: Average length from 

 anterior margin to posterior end of caudal rami, excluding setae, 

 2.30 mm.; range 1.93-3.04 mm. Average of greatest length of 

 cephalo thorax, including frontal region, 1.47 mm.; range 1.01-1.93 

 mm. Average of greatest width of cephalo thorax, excluding marginal 

 flange, 1.47 mm.; range 1.29-1.84 mm. Average of greatest length 

 of genital segment 0.62 mm. ; range 0.49-0.78 mm. Average of greatest 

 width of genital segment 0.70 mm.; range 0.57-0.98 mm. Average 

 of greatest length of abdomen, excluding caudal rami, 0.12 mm.; 

 range 0.08-0.21 mm. 



One adult male: Length from anterior end of body to tips of caudal 

 rami, excluding setae, 2.20 mm. Greatest length of cephalo thorax, 

 including frontal region, 1.58 mm.; greatest width, excluding marginal 

 flanges, 1.42 mm. Greatest length of genital segment 0.40 mm.; 

 greatest width 0.33 mm. Greatest length of abdomen, excluding 

 caudal rami, 0.12 mm. 



Description. — Body of female and male light yellow or yellowish 

 brown in alcohol with scattered blue and few red pigment spots, 

 some stellate, over entire body but concentrated on posterior portion 

 of cephalothorax and genital segment. Eyes red. 



Cephalothorax of female and male ovoid, frontal region distinct, 

 separated from cephalothorax by distinct groove. Lateral margin of 

 cephalothorax with distinct membranous flange. Posterior sinuses 

 distinct, of shallow V-shape. Median thoracic region extending 

 posteriorly slightly past posterior extension of lateral regions. Middle 

 of third thoracic leg-bearing segment protruding slightly, forming 

 junction of third and fourth leg-bearing segments. Major cephalo- 

 thoracic grooves in form of irregular H with lateral distance between 

 ends of H greater than length of anteriorly curving cross groove. 

 Heavily chitinized, barlike strengthening process extending from 

 region of junction of cross groove with two longitudinal grooves 

 laterally and posteriorly, terminating in region of lateral margin. 

 Other indistinct grooves present in region of eyes and frontal plates. 

 Eyes distinct, situated in anterior region of cephalothorax. Two 



