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 49. Pentastoma (tongue worms)

  1. about 130 described species
  2. most species reside in the respiratory tract, especially in reptiles. One genus uses mammals as definitive hosts, and two genera use birds
  3. elongate, with annulation, and a distinct forebody and hindbody. The forebody possesses 2 pair of sclerotized hooks that can be withdrawn into pockets
  4. thin exoskeleton composed of chitin
  5. external papillae on the anterior end
  6. complete gut; feed on blood and secretions while attached to endothelium
  7. dioecious, with males a bit smaller than females
  8. male reproductive structures
    1. most species with single testes (one genus with two)
    2. genital pore midventral
    3. males may mate with multiple females
  9. female reproductive structures
    1. single ovary, which often splits to form 2 oviducts
    2. oviducts coiled, join to form a coiled uterus
    3. females mate once
  10. typical life-cycle
    1. eggs passed up trachea and are usually swallowed; passed in feces
    2. larvae with 4 short legs, each with 1-2 claws, already within egg
    3. eaten by intermediate host (i.e. lizards, fish, insects, rodents); often definitive hosts can also act as intermediate hosts
    4. larvae hatch
    5. penetrate gut with claws; migrate into viscera/mestenteries
    6. become dormant
    7. metamorphose into nymph (grub-like stage); molt (generally, 4-6 molts in entire life-cycle)
    8. eaten along with intermediate host by definitive host; some use paratenic hosts
    9. penetrate host gut
    10. migrate anteriorly; bore across diaphragm; enter lungs directly
    11. mature into adults (one or more molts depending upon species)
  11. pathology includes damage of internal organs by migrating larval stages in intermediate hosts (relatively uncommon). Occasionally, larval stages may enter eye.
  12. traditionally, the pentastomes have been placed within their own phylum. However, recent morphologic studies have shown that they best fit as a subclass (subclass Pentastomida Diesing, 1836) within the crustacea (see Martin and Davis, 2001, An updated classification of the recent crustacea. Natural History Museum of Los Angeles County science series no. 39, 132 pp.). Two orders are recognized, although different authors have placed various genera in different families which has confused the taxonomy (at least for me):
    1. order: Cephalobaenida Heymons, 1935
      1. mouth ventral and anterior to the hooks
      2. hooks simple, arranged as isosceles trapezoid on ventral surface of head, on parapodial-like projections or surrounded by three parapodial lobes
      3. uterus saccate, with opening anterior on ventral surface of abdomen near junction of trunk with the head
      4. some species appear to have direct life-cycles
      5. thus far, over 40 described species
        1. Cephalobaenidae Fain, 1961
          1. two genera
          2. Cephalobaena with one species (Cephalobaena tetrapoda) in South American tree snakes
          3. Raillietiella, with perhaps 40 known species that occur in lizards, snakes, a bufonid, and a single species in a vulture (Raillietiella trachea in the white-backed vulture)
            1. the genus Gretillatia has been synonymized with Raillietiella
            2. the genus Mahafaliella has been synonymized with Raillietiella
            3. the genus Travassostulida has been synonymized with Raillietiella
        2. Reighardiidae Heymons, 1935
          1. only two genera and, thus far, all members of this family infect birds
          2. Reighardia, with two species in aquatic/semi-aquatic birds (Reighardia sternae in gulls and R. lomviae in guillemots)
          3. Hispania, with a single species (Hispania vulturis in the black vulture)
    2. order: Porocephalida Heymons, 1935
      1. head flat ventrally
      2. hooks in horizontal line on mouth level
      3. female genital pore on or near posterior annulus
      4. about 6 families
        1. Armilliferidae Fain, 1961
          1. three genera, Armillifer, Cubirea, and Gigliolella
          2. the genus Ligamifer has been synonymized with Armillifer
          3. some authors place these genera within the Porocephalidae
        2. Linguatulidae Heymons, 1935
          1. lance-shaped, with one genus (Lingulata) and multiple species in nasopharyngeal passages of mammals
          2. i.e. Linguatula serrata in mammalian carnivores and rarely humans/numerous mammals
        3. Porocephalidae Fain, 1961
          1. head thicker than abdomen; abdomen largest anteriorly; annulations usually distinct
          2. definitive hosts snakes; intermediate hosts include amphibia, reptiles, and mammals
          3. two genera, Kiricephalus and Porocephalus
          4. i.e. Kiricephalus coarctatus in colubrid snakes/small mammals
          5. i.e. Porocephalus crotali in crotalids/small mammals
        4. Sambonidae Fain, 1961
          1. vagina and anus separated by several complete annuli
          2. four genera, Elenia, Parasambonia, Sambonia, and Waddycephalus
          3. the genus Megadrepanoides has been synonymized with Sambonia
        5. Sebekiidae Fain, 1961
          1. chitinous shield over hook base spinose and well developed; nymphal hooks double
          2. seven genera, Agema, Alofia, Diesingia, Leiperia, Pelonia, Sebekia, and Selfia
          3. the genus Diesingia had previously been synonymized with Sebekia, but recent workers have re-established the genus
          4. i.e. Sebekia mississippiensis in alligators/nymphs in fish, turtles, snakes, and mammals
        6. Subtriquetridae Fain, 1961
          1. single genus, Subtriquetra
          2. four species, adults in crocodilians (South America or Africa) and nymphs in fish
  13. In addition to extant pentastomes, a couple of papers have published descriptions of fossil pentastomes from late Cambrian limestone. The hosts are unknown (1994, Trans R Soc Edinburgh, Earth Sci 85: 1-37; 1994, Can J Earth Sci 31: 1664-1671)
    1. Boeckelericambria (1 sp.)
    2. Haffnericambria (1 sp.)
    3. Heymonsicambria (ca 6 spp.)

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