﻿TERRESTRIAL 
  ISOPODS 
  COLLECTED 
  IN 
  COSTA 
  RICA 
  BY 
  

   MR. 
  PICADO, 
  WITH 
  THE 
  DESCRIPTION 
  OF 
  A 
  NEW 
  

   GENUS 
  AND 
  SPECIES. 
  

  

  By 
  Harriet 
  Richardson, 
  

  

  Collaborator, 
  Division 
  of 
  Marine 
  Invertebrates, 
  United 
  States 
  National 
  Museum. 
  

  

  Some 
  terrestrial 
  isopods 
  collected 
  in 
  Costa 
  Rica 
  by 
  Mr. 
  C. 
  Picado 
  

   were 
  sent 
  by 
  Mr, 
  J. 
  F. 
  Tristan 
  to 
  the 
  United 
  States 
  National 
  Museum 
  

   for 
  determination. 
  They 
  were 
  found 
  on 
  epiphytic 
  plants 
  of 
  the 
  

   family 
  Bromeliaceae 
  ("wild 
  pines") 
  and 
  were 
  mostly 
  collected 
  at 
  an 
  

   altitude 
  of 
  2,000-2,500 
  meters. 
  Among 
  them 
  are 
  some 
  specimens 
  

   representing 
  a 
  new 
  genus 
  of 
  Oniscidae. 
  

  

  Other 
  terrestrial 
  isopods 
  collected 
  in 
  Costa 
  Rica 
  by 
  Mr. 
  J. 
  F. 
  

   Tristan 
  were 
  also 
  sent 
  to 
  the 
  United 
  States 
  National 
  Museum 
  about 
  

   the 
  same 
  time. 
  These 
  were 
  collected 
  in 
  theBromelias 
  in 
  the 
  old 
  crater 
  

   of 
  '' 
  Reventado 
  " 
  near 
  the 
  Volcano 
  Irazu. 
  Mr. 
  Tristan 
  writes 
  that 
  the 
  

   old 
  crater 
  is 
  covered 
  with 
  forest. 
  

  

  Family 
  ONISCID^. 
  

  

  PENTONISCUS, 
  new 
  genus. 
  

  

  Body 
  with 
  the 
  abdomen 
  abruptly 
  narrower 
  than 
  the 
  thorax. 
  

  

  Head 
  with 
  median 
  and 
  antero-lateral 
  lobes 
  small. 
  

  

  Second 
  antennae 
  with 
  a 
  flagellum 
  composed 
  of 
  five 
  articles, 
  the 
  

   third 
  and 
  fourth 
  rather 
  indistinctly 
  separated. 
  

  

  Mouth 
  parts 
  as 
  in 
  the 
  other 
  genera 
  referred 
  to 
  this 
  family. 
  Inner 
  

   lamella 
  of 
  the 
  second 
  maxilla 
  furnished 
  with 
  two 
  plumose 
  setae. 
  

   Mandibles 
  with 
  molar 
  expansion 
  obsolete, 
  and 
  replaced 
  by 
  a 
  recurved 
  

   seta; 
  cutting 
  edge 
  formed 
  of 
  three 
  blunt 
  teeth. 
  MaxUlipeds 
  with 
  

   palp 
  composed 
  of 
  three 
  articles, 
  the 
  last 
  very 
  narrow 
  and 
  elongate; 
  

   masticatory 
  lobe 
  short 
  and 
  truncate 
  at 
  tip. 
  

  

  Terminal 
  segment 
  of 
  abdomen 
  triangular, 
  with 
  apex 
  obtuse. 
  

  

  Uropods 
  of 
  a 
  structure 
  similar 
  to 
  those 
  in 
  the 
  other 
  genera 
  in 
  the 
  

   family. 
  

  

  The 
  type 
  of 
  the 
  genus 
  is 
  Pentoniscus 
  pruinosus, 
  new 
  species. 
  

  

  This 
  genus 
  differs 
  from 
  all 
  the 
  known 
  genera 
  of 
  Oniscidae 
  in 
  having 
  

   the 
  flagellum 
  of 
  the 
  second 
  antennae 
  composed 
  of 
  five 
  articles. 
  

  

  Proceedings 
  U. 
  S. 
  National 
  Museum, 
  Vol. 
  44— 
  No. 
  1954. 
  

   69077°— 
  Proc.N.M. 
  vol.44— 
  13 
  22 
  337 
  

  

  