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Theristus

Theristus Bastian, 1865 (ref. ID; 3571)

Monhysterida Filipjev, 1929: Family Monhysteridae De Man, 1876: Subfamily Monhysterinae De Man, 1876 (ref. ID; 3571)

Chromadoria: Superfamily Monhysteroidea: Family Xyalidae Chitwood, 1951 (ref. ID; 7906)

Monhysterida (ref. ID; 6180)

Family Monhysteridae (ref. ID; 6182, 6740, 7629)

ref. ID; 1766

The genus characterized by asymmetrical spicules had their centre of evolution in marine sublittoral sand habitats, according to Lorenzen (1973). (ref. ID; 1766)

ref. ID; 3571

Type species

Theristus acer Bastian, 1865 (ref. ID; 3571)
  1. Theristus (Daptonema) acanthospiculum Allgen, 1959 (ref. ID; 3571)
  2. Theristus (Theristus) acer Bastian, 1865 (ref. ID; 3571) reported author and year? (ref. ID; 1729, 1735)
    Syn; Theristus steineri Filipjev, 1922 (ref. ID; 3571)
  3. Theristus acidus Vitiello, 1971
    See; Cylindrotheristus acidus (ref. ID; 3571)
  4. Theristus (Penzancia) acribus Gerlach, 1956 (ref. ID; 3571)
  5. Theristus (Theristus) acriformis (De Man, 1922) (ref. ID; 3571)
    Syn; Monhystera acriformis De Man, 1922 (ref. ID; 3571)
  6. Theristus acrilabiatus De Coninck & Stekhoven, 1933
    See; Pseudotheristus acrilabiatus (ref. ID; 3571)
  7. Theristus (Penzancia) aculeatus Schulz, 1935 (ref. ID; 3571)
  8. Theristus (Daptonema) adiectus (Schulz, 1932) Wieser, 1956 (ref. ID; 3571)
    Syn; Monhystera adiecta Schulz, 1932 (ref. ID; 3571)
  9. Theristus (Penzancia) agilis (De Man, 1880) Filipjev, 1918 (ref. ID; 3571)
    Syn; Monhystera agilis De Man, 1880 (ref. ID; 3571); Monhystera macrocephala Rahm, 1924 (ref. ID; 3571)
  10. Theristus aegypticus Gerlach, 1964
    See; Mesotheristus aegypticus (ref. ID; 3571)
  11. Theristus (Daptonema) albigensis (Riemann, 1966) Hopper, 1968 (ref. ID; 3571)
    Syn; Promonhystera albigensis Riemann, 1966 (ref. ID; 3571)
  12. Theristus alternus Wieser, 1956
    See; Cylindrotheristus alternus (ref. ID; 3571)
  13. Theristus (Penzancia) ambronensis Schulz, 1936 (ref. ID; 3571)
  14. Theristus angulatus Stekhoven, 1920
    See; Cylindrotheristus angulatus (ref. ID; 3571)
  15. Theristus anisotrichus Lorenzen, 1971 (ref. ID; 7629 original paper), Theristus (Theristus) anisotrichus Lorenzen, 1972 (ref. ID; 3571)
  16. Theristus anteferens Wieser, 1956
    See; Pseudosteineria anteferens (ref. ID; 3571)
  17. Theristus anticipans Wieser, 1956
    See; Pseudosteineria anticipans (ref. ID; 3571)
  18. Theristus arcospiculum Allgen, 1947
    See; Pseudosteineria arcospiculum (ref. ID; 3571)
  19. Theristus (Daptonema) arcticus (Steiner, 1916) Filipjev, 1922 (ref. ID; 3571)
    Syn; Monhystera filamentosa Ditlevsen, 1928 (ref. ID; 3571); Monhystera lata subsp. arctica Steiner, 1916 (ref. ID; 3571)
  20. Theristus (Theristus) asymetricus Vitiello, 1967 (ref. ID; 3571)
  21. Theristus (Penzancia) athesinus Andrassy, 1962 (ref. ID; 3571)
  22. Theristus (Daptonema) australis Allgen, 1951 (ref. ID; 3571)
  23. Theristus australis (Cobb, 1894)
    See; Theristus pacificus (ref. ID; 3571)
  24. Theristus (Theristus) bastiani (ref. ID; 3571)
    Syn; Theristus gerlachi Wieser, 1956 (ref. ID; 3571)
  25. Theristus bathylaimoides Allgen, 1959 (ref. ID; 3571)
  26. Theristus bathylaimus Allgen, 1959
    See; Cylindrotheristus bathylaimus (ref. ID; 3571)
  27. Theristus (Penzancia) biarcospiculum Timm, 1952 (ref. ID; 3571)
  28. Theristus bidontolaimus Allgen, 1959 (ref. ID; 3571)
  29. Theristus biggi Gerlach, 1965
    See; Cylindrotheristus biggi (ref. ID; 3571)
  30. Theristus (Penzancia) bipunctatus (G. Schneider, 1906) Filipjev, 1929 (ref. ID; 3571)
    Syn; Monhystera bipunctata G. Schneider, 1906 (ref. ID; 3571)
  31. Theristus (Penzancia) blandicor Rachor, 1971 (ref. ID; 3571)
  32. Theristus (Penzancia) borosi Andrassy, 1958 (ref. ID; 3571)
  33. Theristus brachysetosus Allgen, 1959 (ref. ID; 3571)
  34. Theristus brevicollis (Cobb, 1894) Filipjev, 1922 (ref. ID; 3571)
    Syn; Monhystera brevicollis Cobb, 1894 (ref. ID; 3571)
  35. Theristus brevisetosus Alekseev, 1992 (ref. ID; 7916 original paper)
  36. Theristus buelkiensis (Schulz, 1932)
    See; Mesotheristus buelkiensis (ref. ID; 3571)
  37. Theristus (Daptonema) buetschlii Bresslau & Stekhoven in Stekhoven, 1935 (ref. ID; 3571)
    Syn; Theristus oistospiculoides Allgen, 1959 (ref. ID; 3571)
  38. Theristus (Daptonema) buetschlioides Chitwood, 1951 (ref. ID; 3571)
  39. Theristus calcaneus Stekhoven, 1950
    See; Pseudotheristus calcaneus (ref. ID; 3571)
  40. Theristus calceolatus De Coninck & Stekhoven, 1933
    See; Cylindrotheristus calceolatus (ref. ID; 3571)
  41. Theristus (Penzancia) calx Wieser & Hopper, 1967 (ref. ID; 3571)
  42. Theristus chitinolaimus (Allgen, 1932) (ref. ID; 3571)
    Syn; Monhystera chitinolaima Allgen, 1932 (ref. ID; 3571)
  43. Theristus circulus Vitiello, 1971
    See; Pseudotheristus circulus (ref. ID; 3571)
  44. Theristus circumscriptus Wieser 1959
    See; Mesotheristus circumscriptus (ref. ID; 3571)
  45. Theristus clavicaudatus Gerlach, 1953
    See; Spirotheristus clavicaudatus (ref. ID; 3571)
  46. Theristus (Theristus) conicaudatus Allgen, 1959 (ref. ID; 3571)
  47. Theristus coronatus (Stekhoven, 1950)
    See; Metadesmolaimus coronatus (ref. ID; 3571)
  48. Theristus coronatus Gerlach, 1955
    See; Pseudosteineria coronata (ref. ID; 3571)
  49. Theristus (Daptonema) curvatus Gerlach, 1956 (ref. ID; 3571)
  50. Theristus curvispiculum Gerlach, 1953
    See; Cylindrotheristus curvispiculum (ref. ID; 3571)
  51. Theristus cuspidospiculum (Allgen, 1932)
    See; Pseudotheristus cuspidospiculum (ref. ID; 3571)
  52. Theristus dentatus Wieser, 1956
    See; Cylindrotheristus dentatus (ref. ID; 3571)
  53. Theristus (Theristus) denticulatus Warwick, 1970 (ref. ID; 3571)
  54. Theristus (Theristus) diversispiculum Gerlach, 1953 (ref. ID; 3571)
  55. Theristus donsi Allgen, 1948
    See; Cylindrotheristus donsi (ref. ID; 3571)
  56. Theristus donsi Allgen, 1949
    See; Cylindrotheristus paradonsi (ref. ID; 3571)
  57. Theristus dubius (Butschli, 1873)
    See; Mesotheristus dubius (ref. ID; 3571)
  58. Theristus ecphygmaticus Wieser, 1959
    See; Cylindrotheristus ecphygmaticus (ref. ID; 3571)
  59. Theristus elaboratus Chitwood, 1951
    See; Cylindrotheristus elaboratus (ref. ID; 3571)
  60. Theristus elegans Kreis, 1929
    See; Pseudotheristus elegans (ref. ID; 3571)
  61. Theristus (Theristus) ensifer Gerlach, 1951 (ref. ID; 3571)
  62. Theristus erectus Wieser & Hopper, 1967
    See; Mesotheristus erectus (ref. ID; 3571)
  63. Theristus (Daptonema) euxinus (Filipjev, 1918) Wieser, 1956 (ref. ID; 3571)
    Syn; Penzancia euxina Filipjev, 1918 (ref. ID; 3571)
  64. Theristus exutus Wieser, 1956
    See; Pseudotheristus exutus (ref. ID; 3571)
  65. Theristus falklandiae Allgen, 1959 (ref. ID; 3571)
  66. Theristus (Cylindrotheristus) fallax Lorenzen, 1971 (ref. ID; 7629 original paper), Theristus fallax Lorenzen, 1972 (ref. ID; 3571)
    See; Cylindrotheristus fallax (ref. ID; 3571)
  67. Theristus filicaudatus Allgen, 1929
    See; Pseudotheristus filicaudatus (ref. ID; 3571)
  68. Theristus (Daptonema) filispiculum (Allgen, 1932) Wieser, 1956 (ref. ID; 3571)
    Syn; Monhystera filispiculum Allgen, 1932 (ref. ID; 3571)
  69. Theristus fimbriatoides Chitwood & Murphy, 1964
    See; Wieserius fimbriatoides (ref. ID; 3571)
  70. Theristus (Daptonema) fimbriatus (Cobb, 1920)
    See; Mesotheristus fimbriatus (ref. ID; 3571)
    Syn; Daptonema fimbriatum (ref. ID; 3571)
  71. Theristus (Daptonema) fissidens (Cobb, 1920) Wieser, 1956 (ref. ID; 3571)
    Syn; Daptonema fissidens Cobb, 1920 (ref. ID; 3571)
  72. Theristus (Cylindrotheristus) fistulatus Wieser & Hopper, 1967 (ref. ID; 7629), Theristus fistulatus Wieser & Hopper, 1967 (ref. ID; 3571)
    See; Cylindrotheristus fistulatus (ref. ID; 3571)
  73. Theristus flevensis Schuurmans-Stekhoven, 1935 (ref. ID; 881, 3571) or Stekhoven, 1935 (ref. ID; 7906)
    Syn; Penzancia flevensis (ref. ID; 881)
  74. Theristus floridanus Wieser & Hopper, 1967
    See; Trichotheristus floridanus (ref. ID; 3571)
  75. Theristus fluviatilis (subsp.) Paramonov, 1925 (ref. ID; 3570)
    See; Mesotheristus setosus subsp. fluviatilis (Paramonov, 1925) (ref. ID; 3571)
  76. Theristus franzbergeri Schiemer, 1984 (ref. ID; 1766 original paper)
  77. Theristus galeatus Wieser & Hopper, 1967
    See; Trichotheristus galeatus (ref. ID; 3571)
  78. Theristus gerlachi (subsp.) Meyl, 1955
    See; Mesotheristus setosus (ref. ID; 3571)
  79. Theristus gerlachi Wieser, 1956
    See; Theristus bastiani (ref. ID; 3571)
  80. Theristus (Penzancia) gobiensis Tsalolichin, 1985 (ref. ID; 7916)
  81. Theristus (Theristus) gracilis (De Man, 1876) Filipjev, 1918 (ref. ID; 3571)
    Syn; Monhystera gracilis De Man, 1876 (ref. ID; 3571)
  82. Theristus gracillimecaudatus Allgen, 1946
    See; Cylindrotheristus gracillimecaudatus (ref. ID; 3571)
  83. Theristus grahami Allgen, 1959
    See; Cylindrotherisuts grahami (ref. ID; 3571)
  84. Theristus groenlandicus (Ditlevsen, 1928)
    See; Cylindrotheristus gyrophorus (ref. ID; 3571)
  85. Theristus gyrophorus Wieser, 1956
    See; Cylindrotheristus gyrophorus (ref. ID; 3571)
  86. Theristus hamatus Gerlach, 1956
    See; Metadesmolaimus hamatus (ref. ID; 3571)
  87. Theristus heteroscanicus Wieser in Brink et al. 1956 (ref. ID; 3571) reported author and year? (ref. ID; 881)
    See; Theristus (Penzancia) scanicus (ref. ID; 3571)
  88. Theristus (Theristus) heterospiculoides Gerlach, 1953 (ref. ID; 3571)
  89. Theristus (Theristus) heterospiculum (Allgen, 1932) Gerlach, 1953 (ref. ID; 3571)
    Syn; Monhystera heterospiculum Allgen, 1932 (ref. ID; 3571)
  90. Theristus heterus Gerlach, 1957
    See; Trichotheristus heterus (ref. ID; 3571)
  91. Theristus hirsutus Vitiello, 1967
    See; Mesotheristus hirsutus (ref. ID; 3571)
  92. Theristus hirtus Gerlach, 1951
    See; Mesotheristus setosus (ref. ID; 3571)
  93. Theristus inaequispiculatus Platonova, 1971
    See; Pseudosteineria inaequispiculata (ref. ID; 3571)
  94. Theristus (Penzancia) inermis Gerlach, 1953 (ref. ID; 3571)
  95. Theristus (Theristus) interstitialis Warwick, 1970 (ref. ID; 3571)
  96. Theristus izhoricus (subsp.) Filipjev, 1929
    See; Mesotheristus setosus (ref. ID; 3571)
  97. Theristus kornoeensis (Allgen, 1929)
    See; Cylindrotheristus kornoeensis (ref. ID; 3571)
  98. Theristus latissimus Filipjev, 1922 (ref. ID; 3571)
  99. Theristus laxus Wieser, 1956
    See; Mesotheristus laxus (ref. ID; 3571)
  100. Theristus (Theristus) leptosoma Allgen, 1950 (ref. ID; 3571)
  101. Theristus (Daptonema) leviculus Lorenzen (ref. ID; 3571)
  102. Theristus levis Lorenzen, 1971 (ref. ID; 7629 original paper) or 1972 (ref. ID; 3571)
    See; Theristus (Daptonema) leviculus (ref. ID; 3571)
  103. Theristus (Daptonema) levis Rieger & Ott, 1971 (ref. ID; 3571)
  104. Theristus (Penzancia) lineatus Gerlach, 1965 (ref. ID; 3571)
  105. Theristus (Penzancia) lingi (Hoeppli & Chu, 1932) Andrassy, 1960 (ref. ID; 3571)
    Syn; Microlaimoides lingi Hoeppli & Chu, 1932 (ref. ID; 3571)
  106. Theristus (Theristus) littoralis Filipjev, 1922 (ref. ID; 3571)
  107. Theristus longicaudatus Filipjev, 1922
    See; Cylindrotheristus longicaudatus (ref. ID; 3571)
  108. Theristus longicaudatusviviparus Allgen, 1952 (ref. ID; 3571)
  109. Theristus longisetosus Stekhoven & De Coninck, 1933
    See; Mesotheristus longisetosus (ref. ID; 3571)
  110. Theristus (Penzancia) longispicula (Platonova, 1971) (ref. ID; 3571)
    Syn; Penzancia longispicula Platonova, 1971 (ref. ID; 3571)
  111. Theristus (Daptonema) macrocirculus Allgen, 1959 (ref. ID; 3571)
  112. Theristus (Penzancia) macroflevensis Gerlach, 1954 (ref. ID; 3571)
  113. Theristus macropapillatus Allgen, 1959 (ref. ID; 3571)
  114. Theristus maeoticus Filipjev, 1922
    See; Cylindrotheristus maeoticus (ref. ID; 3571)
  115. Theristus (Penzancia) maior Gerlach, 1956 (ref. ID; 3571)
  116. Theristus (Theristus) manicatus Wieser, 1956 (ref. ID; 3571)
  117. Theristus marinae Tchesunov, 1981 (ref. ID; 7916)
  118. Theristus marylandicus Timm, 1952
    See; Cylindrotheristus marylandicus (ref. ID; 3571)
  119. Theristus maspapillatus (Cobb, 1891) Filipjev, 1918 (ref. ID; 3571)
    Syn; Monhystera maspapillata Cobb, 1891 (ref. ID; 3571)
  120. Theristus (Penzancia) megalaimus (Stewart, 1914) Wieser, 1956 (ref. ID; 3571)
    Syn; Monhystera megalaima Stewart, 1914 (ref. ID; 3571)
  121. Theristus (Penzancia) megalaimoides Wieser, 1956 (ref. ID; 3571)
  122. Theristus meridianus (Cobb, 1914) Filipjev, 1922 (ref. ID; 3571)
    Syn; Monhystera meridiana Cobb, 1914 (ref. ID; 3571)
  123. Theristus metacoronatus Wieser, 1959
    See; Pseudosteineria coronata (ref. ID; 3571)
  124. Theristus (Penzancia) metaflevensis Gerlach, 1955 (ref. ID; 3571)
  125. Theristus metanorvegicus Wieser, 1956
    See; Mesotheristus norvegicus (ref. ID; 3571)
  126. Theristus (Penzancia) meyli Riemann, 1966 (ref. ID; 3571)
  127. Theristus miamiensis (Hopper, 1969)
    See; Cylindrotheristus miamiensis (ref. ID; 3571)
  128. Theristus microspiculum Gerlach, 1953
    See; Pseudotheristus microspiculum (ref. ID; 3571)
  129. Theristus mirabilis Stekhoven & De Coninck, 1933
    See; Trichotheristus mirabilis (ref. ID; 3571)
  130. Theristus (Theristus) modicus Wieser, 1956 (ref. ID; 3571)
  131. Theristus monstrosus Gerlach, 1954 (ref. ID; 5411 original paper), Theristus (Penzancia) monstrosus Gerlach, 1954 (ref. ID; 3571)
  132. Theristus (Cylindrotheristus) nanus Lorenzen, 1971 (ref. ID; 7629 original paper), Theristus nanus Lorenzen, 1971 (ref. ID; 3571)
    See; Cylindrotheristus nanus (ref. ID; 3571)
  133. Theristus (Penzancia) neglectus (Cobb, 1930) Wieser, 1956 (ref. ID; 3571)
    Syn; Monhystera neglecta Cobb, 1930 (ref. ID; 3571)
  134. Theristus nidrosiensis (Allgen, 1933) Wieser, 1956 (ref. ID; 3571)
    Syn; Monhystera nidrosiensis Allgen, 1933 (ref. ID; 3571)
  135. Theristus nidrosiensis (subsp.) Allgen, 1933
    See; Cylindrotheristus normandicus subsp. metanidrosiensis (ref. ID; 3571)
  136. Theristus normandicus (De Man, 1890)
    See; Cylindrotheristus normandicus (ref. ID; 3571)
  137. Theristus (Penzancia) norwegicus (Allgen, 1933) Wieser, 1956 (ref. ID; 3571)
    Syn; Monhystera norwegica Allgen, 1933 (ref. ID; 3571)
  138. Theristus norwegicus Allgen, 1946
    See; Mesotheristus norwegicus (ref. ID; 3571)
  139. Theristus (Daptonema) notoistospiculoides Allgen, 1959 (ref. ID; 3571)
  140. Theristus notosetosus Allgen, 1959
    See; Mesotheristus notosetosus (ref. ID; 3571)
  141. Theristus obtusicephalus Stekhoven, 1950 (ref. ID; 3571)
  142. Theristus oistospiculoides Allgen, 1959
    See; Theristus (Daptonema) buetschlii (ref. ID; 3571)
  143. Theristus (Penzancia) oistospiculum (Allgen, 1932) (ref. ID; 3571)
    Syn; Monhystera (Penzancia) oistospiculum Allgen, 1932 (ref. ID; 3571)
  144. Theristus oistospiculum Allgen, 1946
    See; Theristus (Daptonema) buetschlii (ref. ID; 3571), Theristus oistospiculoides (ref. ID; 3571)
  145. Theristus (Daptonema) ostentator Wieser & Hopper, 1967 (ref. ID; 3571)
  146. Theristus (Theristus) otoplanobius Gerlach, 1951 (ref. ID; 3571)
  147. Theristus oxycercus (De Man, 1888)
    See; Cylindrotheristus oxycercus (ref. ID; 3571)
  148. Theristus oxyuroides (Stekhoven, 1931)
    See; Cylindrotheristus oxyuroides (ref. ID; 3571)
  149. Theristus pacificus (Johnston, 1938) Filipjev, 1918 (ref. ID; 3571)
    Syn; Monhystera pacifica Johnston, 1938 (ref. ID; 3571)
  150. Theristus (Daptonema) papillatus Murphy, 1965 (ref. ID; 3571)
  151. Theristus (Daptonema) parabutschlii Timm, 1961 (ref. ID; 3571)
  152. Theristus paraelaboratus Timm, 1952
    See; Cylindrotheristus paraelaboratus (ref. ID; 3571)
  153. Theristus (Penzancia) parambronensis Timm, 1952 (ref. ID; 3571)
  154. Theristus paranormandicus (Micoletzky, 1922)
    See; Paramonohystera (Leptogastrella) paranormandica (ref. ID; 3571)
  155. Theristus paranormandicus Timm, 1952
    See; Cylindrotheristus normandicus (ref. ID; 3571)
  156. Theristus parasetosus (Allgen, 1928) (ref. ID; 3571)
    Syn; Monhystera (Theristus) parasetosa Allgen, 1928 (ref. ID; 3571)
  157. Theristus paratenuispiculum (Allgen, 1942)
    See; Pseudotheristus paratenuispiculum (ref. ID; 3571)
  158. Theristus paratortus Vitiello, 1971
    See; Cylindrotheristus paratortus (ref. ID; 3571)
  159. Theristus (Penzancia) paravelox (Allgen, 1934) (ref. ID; 3571)
    Syn; Penzancia paravelox Allgen, 1934 (ref. ID; 3571)
  160. Theristus (Daptonema) paroistospiculoides Allgen, 1959 (ref. ID; 3571)
  161. Theristus (Penzancia) parvulus Timm, 1952 (ref. ID; 3571)
  162. Theristus (Penzancia) pellucidus Allgen, 1939 (ref. ID; 3571)
  163. Theristus pertenuis Bresslau & Stekhoven in Stekhoven, 1935 (ref. ID; 3571) reported author and year? (ref. ID; 1729)
  164. Theristus (Theristus) pictus Gerlach, 1951 (ref. ID; 3571)
  165. Theristus planieris Vitiello, 1971
    See; Cylindrotheristus planieris (ref. ID; 3571)
  166. Theristus (Penzancia) polychaetophilus Hopper, 1966 (ref. ID; 3571)
  167. Theristus (Penzancia) pratti Murphy & Canaris, 1964 (ref. ID; 3571)
  168. Theristus (Theristus) problematicus (Allgen, 1928) Wieser, 1956 (ref. ID; 3571)
    Syn; Monhystera problematica Allgen, 1928 (ref. ID; 3571)
  169. Theristus (Daptonema) procerus Gerlach, 1951 (ref. ID; 3571)
  170. Theristus prominens (Vitiello, 1971)
    See; Mesotheristus prominens (ref. ID; 3571)
  171. Theristus proprius Lorenzen, 1971 (ref. ID; 7629 original paper), Theristus (Daptonema) proprius Lorenzen, 1972 (ref. ID; 3571)
  172. Theristus psammoides Warwick, 1970
    See; Trichotheristus psammoides (ref. ID; 3571)
  173. Theristus pseudosetosus Filipjev, 1918
    See; Mesotheristus setosus (ref. ID; 3571)
  174. Theristus pseudotortus Vitiello, 1971
    See; Cylindrotheristus pseudotortus (ref. ID; 3571)
  175. Theristus (Penzancia) pyronasi Gerlach, 1965 (ref. ID; 3571)
  176. Theristus resimus Wieser, 1959
    See; Cylindrotheristus resimus (ref. ID; 3571)
  177. Theristus (Theristus) rhynchonemoides Hopper, 1961 (ref. ID; 3571)
  178. Theristus (Theristus) roscoffiensis Vitiello, 1967 (ref. ID; 3571) reported author and year? (ref. ID; 1752)
  179. Theristus (Penzancia) ruffoi Andrassy, 1959 (ref. ID; 3571)
  180. Theristus rusticus Kreis, 1929
    See; Pseudotheristus resticus (ref. ID; 3571)
  181. Theristus sabulicola (Filipjev, 1918) Wieser, 1956 (ref. ID; 3571)
    Syn; Cobbia sabulicola Filipjev, 1918 (ref. ID; 3571)
  182. Theristus sanctimarteni Timm, 1957
    See; Mesotheristus sanctimarteni (ref. ID; 3571)
  183. Theristus (Penzancia) scanicus Allgen, 1949 (ref. ID; 3282, 3571)
    Syn; Theristus heteroscanicus Wieser in Brink et al. 1956 (ref. ID; 3571)
  184. Theristus (Daptonema) septentrionalis (Cobb, 1914) Wieser, 1956 (ref. ID; 3571)
    Syn; Monhystera septentrionalis Cobb, 1914 (ref. ID; 3571)
  185. Theristus setifer Gerlach, 1952
    See; Mesotheristus setifer (ref. ID; 3571)
  186. Theristus setosus (Butschli, 1874) (ref. ID; 3571), (Butschli, 1874) Filipjev, 1922 (ref. ID; 881)
    See; Mesotheristus setosus (ref. ID; 3571)
    Syn; Mesotheristus setosus (ref. ID; 881)
  187. Theristus simplex Allgen, 1959
    See; Cylindrotheristus simplex (ref. ID; 3571)
  188. Theristus (Daptonema) sinuosus Wieser, 1959 (ref. ID; 3571)
  189. Theristus sphaerolaimoides (Schulz, 1932)
    See; Mesotheristus sphaerolaimoides (ref. ID; 3571)
  190. Theristus spirus Gerlach, 1959
    See; Pseudotheristus spirus (ref. ID; 3571)
  191. Theristus steineri Filipjev, 1922
    See; Theristus acer (ref. ID; 3571)
  192. Theristus stichotricha Stekhoven, 1950 (ref. ID; 3571)
  193. Theristus strandi Allgen, 1934 (ref. ID; 3571)
  194. Theristus (Penzancia) stranus Gerlach, 1957 (ref. ID; 3571)
  195. Theristus subsetosus W. Schneider, 1943
    See; Mesotheristus setosus (ref. ID; 3571)
  196. Theristus svalbardensis Gerlach, 1965
    See; Cylindrotheristus svalbardensis (ref. ID; 3571)
  197. Theristus tenuicaudatus Allgen, 1951 (ref. ID; 3571)
  198. Theristus tenuicaudatus (subsp.) Allgen, 1959
    See; Cylindrotheristus normandicus subsp. metatenuicaudatus (ref. ID; 3571)
  199. Theristus tenuiseta (subsp.) Allgen, 1959
    See; Theristus (Penzancia) pellucidus subsp. tenuiseta (ref. ID; 3571)
  200. Theristus tenuispiculum (Ditlevsen, 1918)
    See; Cylindrotheristus tenuispiculum (ref. ID; 3571)
  201. Theristus tersus Gerlach, 1956
    See; Metadesmolaimus tersus (ref. ID; 3571)
  202. Theristus tortuosus Timm, 1961
    See; Spirotheristus tortuosus (ref. ID; 3571)
  203. Theristus tortus Wieser & Hopper, 1967
    See; Cylindrotheristus tortus (ref. ID; 3571)
  204. Theristus trabeculosus (G. Schneider, 1906)
    See; Cylindrotheristus trabeculosus (ref. ID; 3571)
  205. Theristus trecuspidatus Wieser, 1959
    See; Cylindrotheristus trecuspidatus (ref. ID; 3571)
  206. Theristus (Daptonema) trichinus Gerlach, 1956 (ref. ID; 3571)
  207. Theristus (Daptonema) trichospiculum (Allgen, 1933) Wieser, 1956 (ref. ID; 3571)
    Syn; Monhystera trichospiculum Allgen, 1933 (ref. ID; 3571)
  208. Theristus (Daptonema) uncinatus Wieser, 1959 (ref. ID; 3571)
  209. Theristus (Penzancia) velox (Bastian, 1865) (ref. ID; 3571)
  210. Theristus (Penzancia) vesentiniae Andrassy, 1962 (ref. ID; 3571)
  211. Theristus vicinus Riemann, 1966
    See; Cylindrotheristus vicinus (ref. ID; 3571)
  212. Theristus (Penzancia) wegelinae Andrassy, 1962 (ref. ID; 3571)
  213. Theristus (Theristus) wimmeri Wieser, 1959 (ref. ID; 3571)
  214. Theristus xyaliformis Wieser & Hopper, 1967
    See; Cylindrotheristus xyaliformis (ref. ID; 3571)

Theristus (Theristus) acer Bastian, 1865 (ref. ID; 3571) reported author and year? (ref. ID; 1729, 1735)

Synonym

Theristus steineri Filipjev, 1922 (ref. ID; 3571)

Descriptions

Marine nematode. (ref. ID; 1729)

Theristus brevisetosus Alekseev, 1992 (ref. ID; 7916 original paper)

Diagnosis

Within the genus Theristus (including the subgenus Penzancia de Man, 1889) Chesunov (1981) identified a group of brackish and euryhaline species similar in the structure of the copulatory apparatus, in particular, the distal end of the gubernaculum was clawlike. Of this group of species our form is closest to two species: T. marinae Tchesunov, 1981 and T. (Penzancia) gobiensis Tsalolichin, 1985 in which the males have spicules which are not twisted like a screw. The feature of the new species includes short cephalic setae (3-4 vs. 10-13 µm) and thin contours of the amphids. In addition, our form differs from T. marinae in having a wide stoma, strongly sclerotized rhabdions and longer spicules (42-46 vs. 37 µm). Our form differs from T. gobiensis, additionally, in having a thicker body (a=17-22 vs. 31-42), the presence of two large, versus three smaller, caudal glands, and different number and location of the caudal setae. (ref. ID; 7916)

Descriptions

Average size nematodes. Cuticle finely annulated. Cephalic setae except for the lateral ones are paired, their length 2-3. Somatic setae present only in males and only in the precloacal and caudal parts of the body. The most ordered of them are the caudal setae, 8-9 pairs of subventral and 1-2 pairs of subdorsal. In the precloacal region, there are several small setae and 3-4 ventral pores. The length of the caudal setae is 2-5 µm. Amphids are rounded, their outline is difficult to discern because of the very delicate contours. Diameter of the amphids 6-7 µm; they are situated at the level of the basal part of the stoma. At the cephalic end, the cuticle has a slit, and there are an endcapsule and stomatal ring. The latter marks the boundary between the two anterior sections of the stoma: the vestibule and stoma proper. The structure of such a stoma is close to the theristoidal type (Fadeyeva and Belogurov 1987). We also note that, in our nematodes posterior to the stomatal ring, there is one other esophageal ring described by Chesunov (1980) in species of Mesotheristus and Cylindrotheristus. Both these rings are close together, and therefore one may speak about the absence of the so-called buccal region of the stoma. Overall depth of the stoma in males is 13-16 µm, in females 15-18 µm, maximum diameter is 8-11 µm and 9-10 µm, respectively. Stomatorhabdions are sclerotized and longitudinally differentiated. The esophagus is cylindrical, without a cardiac thickening. Length of the esophagus 294-340 µm. Cardia is short, conical. Diameter of intestine is one-third to one-half diameter of body. In the intestine, there are valves of diatom algae. The hidgut (20-35 µm) is more than half of the diameter of the body at the anus. No renette cell was found. The spinneret consists of two large incadual glands. Testes are paired, the anterior one is situated to the left of the intestine, the posterior one is difficult to see, apparently is located to the right. The ejaculatory duct opens to the middle part of the cloaca. The spicules are of uniform length (42-46 µm) and shape, comparatively slender and slightly arched, the spicular heads are not pronounced. The gubernaculum bears a clawlike formation distally and an apophysis. Length of the gubernaculum 15-16 µm. Females are monodelphic. Ovary, oviduct and uterus situated to the left of the intestine (4 specimens) and in one nematode to the right. Length of the reproductive tubule 545-570 µm. The tip of the ovary is arched ventrally. Eggs are 50-55x35-39 µm. There are two sac-like seminal receptacles 86-110 µm in length. Sperm are primarily oval (10-11x6-7 µm). The tail is conical with a rounded tip. Length of the tail in males 143-158 µm (3-4.8 times and diameter); in females, 177-188 µm (4.6-5.9). (ref. ID; 7916)

Examined materials

Seven males, 8 females, 7 juveniles. Holotype male NP-2819 (3): body length 1102 µm, a=20, b=3.9, c=7.4. Paratypes males (6 specimens): body length 1070-1248 µm, a=17.1-20.7, b=2.2-4.3, c=7.2-7.4. Paratypes female (5 specimens): body length 1080-1424 µm, a=18-22.6, b=3-4.1, c=7-7.5, V=54-68 percent. Lake Khanka, mouth of the Mel'gunovka River, depth 0.5-1.5 m, sand with mud, August 1987. (ref. ID; 7916)

Type specimens

The specimens are deposited in the Department of Zoology of the Far East University. (ref. ID; 7916)

Theristus flevensis Schuurmans-Stekhoven, 1935 (ref. ID; 881, 3571) or Stekhoven, 1935 (ref. ID; 7906)

Synonym

Penzancia flevensis (ref. ID; 881)

Descriptions

This species found brackish water. (ref. ID; 881)

Cephalic cuticular structures: The somatic cuticle has a more complex structure than in Monhystera sp. and Gammarinema. Cuticle rings are very conspicuous, outlined by deep transverse grooves. Epicuticle lines have continuous rings and grooves. It has three layers (external and internal layers electronically dense, medial layer is paler); on the bottom of the grooves, the epicuticle is electron paler. In the exocuticle, two zones are distinguished; the external zone is finely grained (approximately one-third of the exocuticle thickness) and the internal zone has regular radial striations. Internal grooves penetrate until the lowest surface of the cortex, but do not interrupt it. The cortex is clearly separated from the thin, to dense, layer of the mesocuticle, which is formed of loose granulated fibrous material. The endocuticle is formed of thicker, dense fibers. The wavy endocuticule is as thick as the mesocuticle. Convex and concave sites of the endocuticle are in agreement with rings and grooves of the cortex. Before the beginning of the head, looking from behind, transverse rings of the cuticle disappear. The cuticle thickness is reduced by half due to the disapperance of the mesocuticle layer and a thinner endocuticle. The endocuticle is immediately attached to the cortex. Closer to the head, the cuticle again expands as a result of separation of layers of the exo- and endocuticule. Between these two adjacent layers, the granulated, fibrous mesocuticle appears again. It rapidly increases its thickness toward the lips. In the thickest site, near the stome walls, the cephalic cuticle is 2.08-2.25 times thicker than the somatic cuticle. The lips are thin, with folds on the inner surface. The mesocuticle of the cephalic part appears as nonhyaline trabecules. The peripheral layer of the cuticle in the direction of the cheilostome is more dense, like the cortex. In this site, sometime striation perpendicular to the surface can be seen. The epicuticle separates and is easily discernible; it leads from the somatic cuticle to the lips area, then goes to the inner surface of the lips, descends on the wall of the cheilostome, and continues above the internal cuticular lining of the esophagus. The cuticle of the esophastome is homogeneous, close to the somatic cuticle, but separated from it by a sharp border. In the anterior wide part of the esophastome, cuticle thickness is 180-250 nm; posteriorly, it thins to 84-100 nm. (ref. ID; 7906)

Examined materials

This species were collected and fixed in the summers of 1985-1987 at the White Sea Biological Station of Moscow State University (Kandalaksha Gulf of the White Sea, the Karelian shore, Kindo Peninsula). (ref. ID; 7906)

Theristus franzbergeri Schiemer, 1984 (ref. ID; 1766 original paper)

Diagnosis

The male of T. franzbergeri can be readily distinguished from all known species of the genus by the peculiar form of the asymmetrical spicular apparatus. The form of the elongated and spirally coiled left spicule is so aberrant that no confusion with any other species is possible. Males of T. franzbergeri showed no setation in the preanal area and no preanal papillae as have been found to be characteristic for some of the Theristus species with asymmetrical spicules. (ref. ID; 1766)

Descriptions

Body slender, cylindrical, tapering only slightly towards the head end. Cuticle in the mid-body region approximately 1 µm thick, annulated. Annules 1-1.5 µm wide. Somatic setation very weak, with few thin and short setae, which have been observed only with interference and phase contrast microscopy. Tail conical to the tip, not swollen at the end. No terminal setae present. Head with prominent lips, 5-6 µm high, set off by a faint constriction. The lips bear very small papillae. 10 cephalic setae, all 12-13 µm long (60% of head width). Amphids circular, situated 20 µm (1.5-1.6 head diameters) behind the head end. Amphid diameter 6-7 µm (35-45% of the corresponding body diameter). Stoma only weakly cuticularized; oesophagus cylindrical, with large glandular cells at the hind end. Nerve ring situated at about 40% of the oesophagus length. Cardia longer than wide, 14 µm long, protruding into the intestine. (ref. ID; 1766)
  • Male: Testes diorchic; the proximal testis is situated left, the distal one right of the intestine. Both testes end in enlarged vesciculae seminales, from which a single vas deferens leads to the cloaca. The spicular apparatus is of a very complex, asymmetrical form. The right spicule is elongated, ribbonlike and spirally coiled in five turns. The left spicule is distinctly shorter with a knee-shaped bend. The distal end is trifurcate. It appears to be a guiding organ for the elongated left spicule; Gubernaculum with a strong dorsal apophysis. (ref. ID; 1766)
  • Female: The ovary is followed by a saclike uterus which functions as a storage organ for the spematozoids. The uterus leads into an elongate and strongly muscular vaginal tube with a narrow passage. The form of this organ indicates that it functions as a guide for the enlarged and spirally coiled left spicule during copulation. (ref. ID; 1766)

    Type locality

    This species found in the groundwater of the Danube near Vienna. (ref. ID; 1766)

    Theristus heteroscanicus Wieser in Brink et al. 1956 (ref. ID; 3571) reported author and year? (ref. ID; 881)

    See

    Theristus (Penzancia) scanicus (ref. ID; 3571)

    Descriptions

    This species found fresh water. (ref. ID; 881)

    Theristus pertenuis Bresslau & Stekhoven in Stekhoven, 1935 (ref. ID; 3571) reported author and year? (ref. ID; 1729)

    Descriptions

    Marine nematode. (ref. ID; 1729)

    Theristus (Theristus) roscoffiensis Vitiello, 1967 (ref. ID; 3571) reported author and year? (ref. ID; 1752)

    Descriptions

    Marine species. (ref. ID; 1752)