PEREZ FARFANTE: REVISION OF GENUS PSEUDARISTEUS 



stn 5463. 1 9, USNM, Lagonoy Gulf, E of southern 

 Luzon; 13°39'42"N, 123°40'39"E; 914 m; gray mud; 

 17 June 1909; Albatross stn 5465. 1 9, USNM, 

 Verde Island Passage, N of Mindoro; 13°36'11"N, 

 120°45'26"E; 622 m; fine sand; 20 January 1908; 

 Albatross stn 5114. 4 9, USNM, Lagonoy Gulf, E 

 of southern Luzon; 13°35'27"N, 123°37'18"E; 878 

 m; gray mud; 18 June 1909; Albatross stn 5467. 2 

 o* 5 9, USNM, Lagonoy Gulf, E of southern Luzon; 

 13°36'48"N, 123°38'24"E; 914 m; green mud; 18 

 June 1909; Albatross stn 5469. 



Diagnosis.— Optic calathus relatively short, mesial 

 margin 1.0-1.3 times distal width. Anterolateral 

 carina lacking. Ventral extremity of cervical carina 

 forming sharp-edged arc. Posterior extremity of 

 hepatic sulcus turned ventrally. Third article of 

 antennular peduncle expanded laterally, forming 

 large subtriangular projection in males, but weak 

 to rounded prominence in females; males with ven- 

 tral antennular flagellum never sinuous, and ulti- 

 mate article of third maxilliped strongly curved, 

 spatulate and bearing patch of strong, rigid setae. 

 Pereopods not covered with minute setae. Petasma 

 with ventral costa only slightly inclined distomesial- 

 ly, and ventral surface of dorsolateral lobule lack- 

 ing setae. Thelycum with plate of sternite XIV 

 rather long and produced at either side in short 

 anterolateral hood; median plate of sternite XIII 

 moderately long (not nearly reaching spine on ster- 

 nite XII), rather broad (maximum width 0.65-0.75 

 length) but not expanded posterolaterally in con- 

 spicuous prominences. 



Description.— Body slender (Fig. 2), densely studded 

 with minute setae. Rostrum in males usually short, 

 its length 0.25-0.45 CL (but in one male, 24 mm CL, 

 1.4 CL), and roughly lanceolate; in females long (Fig. 

 3), 1-1.15 CL (but in one female 23 mm CL, 0.70 CL), 

 relatively deep and convex basally, styliform and 

 slightly unturned anteriorly. Rostral plus epigastric 

 teeth 3; rostral teeth situated variably in males, 

 basally in females. Adrostral carina strong, in males 

 almost reaching apex, in females (and in male with 

 long rostrum) extending just anterior to second 

 tooth. Antennal spine sharp; branchiostegal spine 

 as long as or longer than antennal and acutely 

 pointed. Cervical sulcus crossing postrostral carina 

 (rarely only reaching it) at about 0.45 CL from or- 

 bital margin, with ventral part turning anteriorly; 

 accompanying carina blunt except for sharp strongly 

 arched ventral extremity; weak postcervical sulcus 

 reaching, but not crossing, postrostral carina at 

 about 0.70 CL from orbital margin. Postrostral 



carina, extending 0.75-0.80 CL from orbital margin, 

 well marked and sharp to cervical sulcus, low and 

 blunt posteriorly, and followed by small tubercle 

 situated near posterior margin of carapace. Antero- 

 lateral carina lacking; gastro-orbital carina well 

 defined; antennal carina rather short; branchios- 

 tegal-hepatic carina long, raised and sharp. Orbito- 

 antennal sulcus shallow; hepatic sulcus fusing with 

 branchiocardiac sulcus, then turning obliquely 

 almost ventrad, forming small branch nearly reach- 

 ing margin of branchiostegite; branchiocardiac 

 sulcus, accompanied by carina, long, extending pos- 

 teriorly to near margin of carapace; blunt, dorsally 

 concave ridge (disposed dorsal to posterior part of 

 hepatic sulcus and anterior part of branchiocardiac 

 sulcus) delimited dorsally by weak groove, latter 

 approaching cervical sulcus anteriorly and ending 

 about level of postcervical sulcus posteriorly. 



Eye (Fig. AC) with optic calathus relatively short, 

 length of mesial margin 1.0-1.3 times distal width; 

 mesial tubercle strong and situated between distal 

 0.25 and 0.30 length of margin. 



Gnathal appendages, except third maxilliped, 

 illustrated in Figure 1. 



Antennular peduncle with stylocerite produced in 

 sharp spine falling conspicuously short of mesial 

 base of distolateral spine; latter small and sharp; 

 third article in adult males uniquely produced in 

 large subtriangular or ax-head shaped projection 

 (Fig. 2) directed ventrolaterally, in females (Fig. 5B) 

 expanded laterally in broadly rounded prominence. 

 Dorsal flagellum reaching between distal 0.20 and 

 0.15 of scaphocerite; ventral flagellum straight and 

 long, although incomplete in all specimens ex- 

 amined, in one male with 19 mm CL its length at 

 least 2.75 times CL. 



Scaphocerite extremely long, surpassing anten- 

 nular peduncle by as much as 0.4 its own length; 

 strong lateral rib ending in sharp spine falling con- 

 siderably short of distal end of lamella. Antennal 

 flagellum at least 1.25 times TL of shrimp. 



Third maxilliped sexually dimorphic. In males 

 (Fig. 5A ) with penultimate article often slightly to 

 strongly inflated proximally, compressed and pro- 

 duced in strong, subelliptical or acuminate process 

 (overhanging proximal part of ultimate article) 

 distally; article also bearing brush of long thickly set 

 setae on both mesial and lateral surfaces, and dense 

 row of setae along distal margin of process. Ulti- 

 mate article subspatulate, strongly arched, not ex- 

 panded basally, bearing distally dense patch of 

 strong, rigid setae on lateral surface, proximalmost 

 setae short and more distal ones considerably 

 longer; terminal margin with tuft of very long flex- 



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