Biology 625
Fall semester lecture note outline

Updated: 14 March 2005

The text below simply represents a crude lecture outline of one of the topics covered in class. It is not meant to substitute for attending lectures or ignoring the textbook. Additional material, including line drawings, kodachromes, and more extensive information on life-cycles and basic biology, will be supplied in the lectures.

Topic #22. The Order: Oxyurida (pinworms)

  1. monoxenous
  2. over 850 known species
  3. very distinct, monophyletic group (but not necessarily all families) thought to have originally become established in arthropods
  4. only major nematode group with adult representatives in both vertebrate and invertebrate hosts
  5. often eggs are slightly flattened along one side
  6. sometimes termed "threadworm" in the literature
  7. thought to have arisen from free-living, oral contaminative ancestor
  8. pinworms exhibit haplodiploidy, where males are haploid and arise by parthenogenesis via unfertilized eggs and females are diploid and develop from fertilized eggs. This results in a high degree of inbreeding
  9. life-cycles are very simple and direct
    1. adults in gut; often gravid female dies
    2. eggs in feces
    3. L1-L2-L3 in egg
    4. ingested by new host
    5. L4-adult in gut
  10. Thumbing through an old book many years ago, I ran across an ancient Fiji remedy for pinworms. I recommend not trying it for a couple of reasons, not the least of which is that only gravid females would be present near the anus. It claims that pinworms can be cured by covering ones finger with chili and then inserting the finger into the anus.
  11. two superfamilies (the Rhigonematida are sometimes included in the Oxyuroidea, but this is an erroneous placement)
    1. Oxyuroidea in vertebrates (3-8 families, depending upon the author), especially in lizards, terrestrial chelonia, rodents, lagomorphs, marsupials, and primates. Rare in fish. NOTE: dogs and cats DO NOT get pinworms. The elongate and highly motile proglottids of Dipylidium caninum are often mistaken for pinworms in dogs and cats.
      1. Pharyngodonidae (predominately in posterior gut of herbivorous lower vertebrates, with a few species in archaic mammals)
        1. amphids pedunculate, closely adherent to cephalic surface or jutting forward
        2. genital cone often supported by V-shaped sclerotized structure
        3. Gyrinicola batrachiensis in tadpoles (but not adult frogs and toads) in Canada
        4. some other genera include Ichthyouris, Linstowiella, Pharyngodon, Skrjabinodon, Thelandros, and Travnema
      2. Heteroxynematidae (in many host taxa, including mammals, as above)
        1. amphids non-pedunculate
        2. genital cone without sclerotized supporting structure
        3. tail of male regular in shape
        4. genital papillae concentrated primarily in perianal region
        5. Aspiculuris tetraptera in intestine of old world mice and rats
        6. some other genera include Dentostomella, Fastigiuris, Heteroxynema, Labiostomum, Rauschoxyuris, and Syphaciella
      3. Oxyuridae (in many host taxa, including mammals, as above)
        1. amphids non-pedunculate
        2. genital cone without sclerotized supporting structure
        3. tail of male irregular in shape
        4. genital papillae often large and digitiform, extending into caudal alae
        5. Enterobius vermicularis (Family: Oxyuridae) in humans, chimpanzees, and baboons
          1. sometimes asymptomatic, but when symptoms do occur they include anal itching, restlessness and irritability especially in children, insomnia, puritis ani
          2. although worms are often found in the appendix, only rarely do they cause appendicitis
          3. occasionally ectopic migration of gravid females from the anal region, especially in the human female. This can include infections in the uterus and fallopian tubes, uterine granulomas, invasion of the ovary and, rarely, worms in the peritoneum
          4. antihelminthic therapies include mebendazole, albendazole, and pyrantel pamoate. At the proper doeses, all are highly effective
        6. Oxyuris equi in caecum and colon of equids
        7. Passalurus ambiguus in large intestine of lagomorphs
        8. Skrjabinema ovis in colon of sheep and goats
        9. Syphacia obvelata in large intestine of rodents
        10. some other genera include Acanthoxyurus, Citellina, Lemuricola, and Protozoophaga
    2. Thelastomatoidea in invertebrates, especially in herbivorous arthropods with a fermentation chamber such as diplopods, cockroaches, crickets, and passalid, scarab, and hydrophilid beetles. The taxon has been extensively revised and many genera synonymized (1992, Syst Parasitol 21: 21-63; 169-188). Five families are currently recognized although new ones are frequently popping up and sometimes being synonymized:
      1. Hystrignathidae
        1. genera include Hystrignathus with numerous species, Mentecle, and Paraxyo
        2. review of Hystrignathus (1982, Revue Nematol 5: 285-294)
      2. Protrelloididae
        1. in Blattodea
        2. genera include Napolitana, Protellatus, Protrelleta, Protrelloides, and Protrellus
      3. Pseudonymidae
        1. predominately parasites of water scavenger beetles
        2. genera include Itaguaiana, Jarryella, Pseudonymus, Stegonema, and Zonothrix
      4. Thelastomatidae
        1. perhaps a paraphyletic group
        2. Blatticola blattae in Blatella germanica (German cockroach)
        3. Hammerschmidtiella diesingi in Periplaneta americana (American cockroach) and Blatta orientalis (Oriental cockroach)
        4. Leidynema appendiculata in Periplaneta americana (American cockroach), Periplaneta australasiae (Australian cockroach), and Blatta orientalis (Oriental cockroach)
        5. Thelastoma spp. in many invertebrates, including T. bulhoesi and T. periplaneticola in Periplaneta americana (American cockroach)
        6. genera also include Blattophila, Cephalobellus, Coronostoma, Johnstonia, and Severianoia
      5. Travassosinematidae
        1. mainly parasites of mole crickets, some species in diplopods
        2. genera include Binema, Chitwoodiella, Indiana, Isobinema, Mohibiella, Pteronemella, Pulchrocephala, Singhiella, and Travassosinema

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