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PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES 
Series 4, Volume 65, 28 Sept. 2018, No. 4 
Results 
Family Argulidae Rafinesque, 1815 
Argulus Muller, 1785 
Argulus floridensis Meehean, 1940 
Florida fishlouse Figures 1-6. 
Material examined.— Holotype (unique), adult male, 5.46 mm total length [Meehean 1940: 
5.85 mm], USNM 77810 [see note], Key West, Florida, 1884, collector: A.E. Verrill [= Addison 
Emery Verrill]. Note: Meehean (1940, p. 467) listed the catalog number as “77810 (old number 
60589);” mentioned here in case of relevant information in historical records under the old num¬ 
ber. 
Diagnosis. — Two respiratory areas with smaller oblong “area” anterior to slightly larger 
oblong posterior “area;” single postantennal spines very broad; male with 77 support rods in suc¬ 
tion cup; 14-19 sclerites per rod in male; mouth tube with at least 19 scales on basal half; basal 
plate of second maxilla with 3 stout spines, scales covering nearly entire raised pad, one stout, 
naked seta on posterior margin of pad; accessory spines on thorax large, very broad base on raised 
pad with many scales, tapering to rounded tips; first 2 pairs of legs lacking flagella; posteroventral 
surface of coxae of second legs of male expanded into a broadly-rounded lobe that is covered with 
many small and closely-arranged scales; third legs of male with two pegs issuing from cleft on 
dorsal side of legs and two fingerlike papillae; small fleshy lobe at posterior of thorax; male 
abdomen bilobate with testes extending to the level of the anal sinus base; caudal rami long, slen¬ 
der, basal in anal sinus. 
Description. — Total length 5.46 mm [Meehean 1940: 5.85 
mm]. Carapace shape is “ovate, sinuses shallow, cephalic areas 
broad...; alae reaching abdomen [Meehean 1940].” Carapace length 
[Meehean 1940: 4.88 mm]. Maximum carapace width [Meehean 
1940: 4.28 mm]. Pair of compound eyes anteriorly with diameters 
250 (left) and 220 (right) pm. Transverse distance between eyes 
0.83 mm (830 pm). Nauplius eye with one anterior and two poste¬ 
rior ocelli. Sclerotized dorsal ridges not forked anterior of eyes. 
Ventrally, carapace with small, posteriorly-projecting spines along 
outer margin [due to the deteriorated condition of the carapace alae, 
additional details cannot be included here]. Respiratory areas con¬ 
sist of two oblong-shaped areas, anterior one slightly smaller than 
posterior [from Meehean 1940] (Fig. 1). No pigmentation present 
(but probably lost in preservative and/or due to clearing). 
Thorax compressed dorsoventrally, 4-segmented, with 2 pairs 
of posteriorly-projecting spines ventrally. Spines digitate with 
broad base, anterior pair (accessory spines) larger than posterior 
pair (postmaxillary spines), both pairs angled mesially. Accessory 
spines between basal segments of second maxillae; very broad base 
on a raised pad covered with many scales; spines tapering to round¬ 
ed tips (Fig. 2). Male with ovoid fleshy lobe at posterior of fourth 
thoracic segment between natatory lobes (Figs. 3A, 4). Thorax with Figure l. Argulus floridensis: 
, , . shape of anterior and posterior 
scales scattered on ventral surface; thoracic segment at base of third reS piratory areas (redrawn from 
leg produced laterally into expanded anterolateral lobe with scales Meehean 1940). 
