COMPLETE HAIG : EASTERN PACIFIC PORCELLANIDAE 211 



Walking legs long and slender, lightly rugose, with scattered plu- 

 mose and non-plumose hairs; no spines on anterior margins. 

 Telson of abdomen composed of seven plates. 



Variations : The spinules on the frontal and lateral margins and on 

 the anterior margins of the manus and carpus are usually stronger in 

 females than in males. The crests on the dorsal surface and posterior 

 margin of the carpus, and dorsal surface and outer margin of the manus, 

 are sometimes spinulate and sometimes not; these spinules are more 

 often present in females. 



The dactylus of the minor cheliped is more markedly contorted in 

 males than in females. 



Material examined: See Table 62. 



Measurements: Males, 2.1 to 4.9 mm; non-ovigerous females, 1.8 

 to 3.7 mm; ovigerous females, 2.4 to 4.7 mm. The ovigerous female 

 holotype measures 4.5 mm in length, 4.6 mm in width. 



Color: In alcohol, carapace cream; chelipeds orange-red; ambulatory 

 legs cream, banded with red or orange. (Glassell, 1938a) The color in 

 life has not been recorded. 



Ecology: Pisidia magdalenensis has occasionally been taken under 

 stones in the intertidal zone, probably at low tide. It occurs more com- 

 monly in deeper water, and has been dredged in depths to 25 fathoms. 

 The types were taken "evidently among sponges and corallines" (Glas- 

 sell) ; the Zaca dredged it from a bottom covered with mangrove leaves, 

 and the Askoy from mud and sand and from coral. Analysis of sub- 

 strates from which Hancock Foundation specimens were recovered 

 showed the following: sand (7 stations) ; sand and shell (5) ; and rock; 

 shell ; rock, shell, and gorgonids ; mud and shell ; rock, coral, and nulli- 

 pores; rock and sand; sand and mud; shells and vegetation, 1 station 

 each. It was taken from sponge dredged by the Velero IV in 1-4 fathoms 

 at Acapulco. Except for its occasional association with corals and 

 sponges, it is apparently not a commensal species. 



Ovigerous females have been collected in every month from Decem- 

 ber through May, and in July. 



Relationships : This species is the sole New World representative of 

 its genus. It seems to be most closely allied to the east Atlantic Pisidia 

 longicornis (Linnaeus), 1766, and the Indo-Pacific P. serratifrons 

 (Stimpson), 1858. 



