PROCEEDINGS OF THE HELMINTHOLOGICAL SOCIETY can species of Gyrodactylus, Am. Midi. Nat. Price, E. W. 1938. The monogenetic trema- 79: 205-215. todes of Latin America. In Livro Jubilar Mizelle, J. D., and D. C. Kritsky. 1967a. Prof. Travassos, Rio de Janeiro, Brazil. 3: Studies on monogenetic trematodes. XXX. 407-413. Five new species of Gyrodactylus from the Rogers, W. A. 1968. Eight new species of Pacific tomcod, Microgadus proximus (Gi- Gyrodactylus (Monogenea) from the South- rard). J. Parasit. 53: 263-269. eastern U.S. with redescriptions of G. fair- , and . 1967b. Studies on mono- porti Van Cleave, 1921, and G. cyprini genetic trematodes. XXXIII. New species of Diarova, 1964. J. Parasit. 54: 490-495, Gyrodactylus and a key to the North Ameri- , and T. L. Wellborn. 1965. Studies can species. Tr. Am. Micr. Soc. 86: 390-401. on Gyrodactylus (Trematoda: Monogenea) Price, C. E., and W. A. Bussing. 1967. Mono- with descriptions of five new species from genean parasites of Costa Rican fishes. Part Southeastern U.S. J. Parasit. 51: 977-982. 1. Descriptions of two new species of Cleido- Turnbull, E. R. 1956. Gyrodactylus bullata- discus Mueller, 1934. Riv. Parassit. 28: 81- nidis n. sp. from Leblstes reticulatus Peters 86. with a study of its life cycle. Can. ]. Zool. , and . 1968. Monogenean para- 34: 583-594. sites of Costa Rican fishes. II. Proposal of Yamaguti, S. 1963. Systema helminthum. IV. Palombitrema heteroanci&trium n. gen., n. sp. Monogenea and Aspidocotylea. Interscience Proc. Helm. Soc. Wash. 35: 54-57. Publishers, Inc., New York. On the Plant-parasitic Nematode Genera Merlinius gen. n. and Tylenchorhynchus Cobb and the Classification of the Families Dolichodoridae and Belonolaimidae n. rank MOHAMMAD RAFIQ SIDDIQI Commonwealth Bureau of Helminthology, St. Albans, Hertfordshire, England ABSTRACT: Merlinius gen. n. is proposed for 32 species of Tylenchorhynchus, sensu lato, which have six incisures in the lateral fields, rather cylindroicl spicules with prominently notched distal end, a non- protruding gubernaculum and a moderately developed bursa. Tylenchorhynchus Cobb is redefined and T. iiliginosus sp. n. and T. papyrus sp. n. are described from swampy areas in Uganda. The diagnoses, composition and relationships of Dolichodoridae and Belonolaimidae n. rank are detailed. Tetylenchus Filipjev is placed in a new subfamily Tetylenchinae under Tylenchiclae. In his review of the genus Tylenchorhynchus Allen) and T. dubhis (Biitschli) from Holland, Cobb, 1913, Allen (1955) pointed out the Belgium and England which was regarded as existing diversity in the morphological char- type by Filipjev (1934) for his new subgenus acters exhibited by various species and prophe- Bitylenchus, later (1936) synonymized by him sied the creation of new genera within this with Tylenchorhynchus. group; two related genera, Nagelus and Geo- This study shows that whereas T. dubins cenamus, have since been proposed by Thorne and T. cylindricus are congeneric, a number of and Malek (1968). Tarjan (1964) and de other species show considerable differences in Ouiran (1967) gave differential keys for 68 their morphology which are considered of ge- and 71 valid species of Tylenchorhynchus re- neric status. Consequently, Merlinius gen. n. is spectively and 25 more new species have since here proposed for those species of Tylenchor- been described. I had the opportunity of hynchus, sensu lato, which have six incisures studying the specimens of over fifty valid in the lateral fields, deirids frequently present, species in this genus including the type species, a small trough-shaped nonprotrusible guber- T. cylindrical Cobb (made available by Dr. naculum and characteristic spicules which Copyright © 2011, The Helminthological Society of Washington OF WASHINGTON, VOLUME 37, NUMBER 1, JANUARY 1970 69 markedly differ from those of Tylenchorhyn- M. dubius (Steiner, 1914) comb. n. chus. Both the genera are described below. syn. Aphelenchus dubius Steiner, 1914 Anguillulina macrura Goodey, 1932 Merlinius} gen. n. Tylenchorhynchus macrurus (Goodey, DIAGNOSIS: Tylenchorhynchinae: Dolicho- 1932) Filipjev, 1936 doridae. Lateral fields with six incisures. ? T. graminicola Kirjanova, 1951 Deirids frequently present. Lip region sym- M. galeatus (Litvinova, 1946) comb. n. metrical, with four or more annules but without syn. T. galeatus Litvinova, 1946 a perioral disc. Amphids prominent pores or M. grandis (Allen, 1955) comb. n. oblique slits close to oral opening. Labial syn. T. grandis Allen, 1955 framework lightly to heavily sclerotized. A M. hexagrammus (Sturhan, 1966) comb. n. single papilla on outer margins of each sub- syn. T. hexagrammus Sturhan, 1966 median lip. Protrudor muscles of spear at- M. hexincisus (Jairajpuri and Baqri, 1968) tached to the base of labial framework. Basal comb. n. bulb large, with well developed carclia. Vulva syn. T. hexincisus Jairajpuri and Baqri, usually with double epiptygma and lateral 1968 membranes; cloaca with two pedunculate pa- M. icarus (Wallace and Greet, 1984) comb. n. pilla-like protuberances ventro-laterally, here syn. T. icarus Wallace and Greet, 1984 named as hypoptygma. Ovaries symmetrical. M. laminatus (Wu, 1969) comb. n. Female tail cylindroid to subcylindroid; male syn. T. laminatus Wu, 1969 tail enveloped by a moderately developed M. lenorus (Brown, 1956) comb. n. bursa. Spicules stout, rather cylindroid; distal syn. T. lenorus Brown, 1956 end broadly rounded, notched and devoid of M. leptus (Allen, 1955) comb. n. large ventral flanges. Gubernaculum small, syn. T. leptus Allen, 1955 trough-shaped in lateral view, not protrusible. M. lineatus (Allen, 1955) comb. n. syn. T. lineatus Allen, 1955 Type species M. macrodens (Allen, 1955) comb. n. Merlinius brevidens (Allen, 1955) comb. n. syn. T. macrodens Allen, 1955 syn. Tylenchorhynchus brevidens Allen, 1955 M. microdorus (Geraert, 1966) comb. n. syn. T. microdorus Geraert, 1966 Other species M. nothus (Allen, 1955) comb. n. syn. T. nothus Allen, 1955 Merlinius affinis (Allen, 1955) comb. n. M. obscurisulcatus (Andrassy, 1959) comb. n. syn. Tylenchorhynchus affinis Allen, 1955 syn. T. obscurisulcatus Andrassy, 1959 M. alpinus (Allen, 1955) comb. n. M. obscurus (Allen, 1955) comb. n. syn. T. alpinus Allen, 1955 syn. T. obscurus Allen, 1955 M. bavaricus (Sturhan, 1966) comb. n. M. quadrifer (Andrassy, 1954) comb. n. syn. T. bavaricus Sturhan, 1966 syn. T. quadrifer Andrassy, 1954 M. berberides (Sethi and Swarup, 1968) comb. T. ornatus Allen, 1955 n. M. rugosus (Siddiqi, 1962) comb. n. syn. T. berberides Sethi and Swarup, 1968 syn. T. rugosus Siddiqi, 1962 M. bogdanovikatjkovi (Kirjanova, 1941) comb. M. socialis (Andrassy, 1962) comb. n. n. syn. T. socialis Andrassy, 1962 syn. T. bogdanovikatjkovi (Kirjanova, 1941) M. stegus (Thorne and Malek, 1968) comb. n. Loof, 1959 syn. T. stegus Thorne and Malek, 1968 Anguillulina bogdanovikatjkovi Kirjanova, M. supsrbus (Allen, 1955) comb. n. 1941 syn. T. superbus Allen, 1955 M. conicus (Allen, 1955) comb. n. M. tartuensis (Krall, 1959) comb. n. syn. T. conicus Allen, 1955 syn. T. tartuensis Krall, 1959 M. cylindricaudatus (Ivanova, 1968) comb. n. M. tessellatus (Goodey, 1952) comb. n. syn. T. cylindricaudatus Ivanova, 1968 syn. T. tessellatus Goodey, 1952 M. undyferrus (Haque, 1987) comb. n. 1 Named in honor of Dr. Merlin W. Allen, University of California, U. S. A. syn. T. undyferrus Haque, 1967 Copyright © 2011, The Helminthological Society of Washington 70 PROCEEDINGS OF THE HELMINTHOLOGICAL SOCIETY Figure 1. A—I. Tylenchorhynchus, J—V. Merlinius. A and B. T. cylindricus. C and D. T. capitatus. E-G. T. dubius. H and I. T. nudus from blue grass, Wisconsin, U.S.A. J-P. M. icarus from grasses, St. Albans, England. O. M. alpinus, paratype. R. M. nanus from Belgium. S. M. microdorus from onion soil, Rampur City, India. T. M. grandis, paratype. U and V. M. quadrijer from Belgium. C, E and J. En face of female. K. Transverse section through basal plate. A and P. Head end of female. S. Head end of male. L, M and V. Vulval region showing epiptygma. B, D, F, I, N, O, R, T and U. Spicular regions. J. Part of female esophagus showing deirid in lateral field. Copyright © 2011, The Helminthological Society of Washington OF WASHINGTON, VOLUME 37, NUMBER 1, JANUARY 1970 71 M. varians (Thome and Malek, 1968) comb. n. portion pointed and prominently flanged ven- syn. T. varians Thorne and Malek, 1968 trally. Gubernaculum large, rod-like in lateral Tylenchorhynchus brachycephalus Litvinova, view, sometimes with proximal portion dor- 1946 is a problematical species. The female sally bent, capable of protruding through anus. measuring 0.70-0.77 mm long has head-end Bursa terminal, well developed. and tail-end like those of Helicotylenchus TYPE SPECIES: Tylenchorhynchus cylindricus whereas the male measuring 0.93-1.20 mm is Cobb, 1913. apparently a Merlinius. However the female Two new species of this genus, T. uliginosus is reported to have six incisures in the lateral and T. papyrus, collected from swampy areas field which is contrary to the definition of in Uganda are described below. These come Helicotylenchus. close to T. rhopalocercus Seinhorst, 1963, RELATIONSHIP: Merlinius differs from Tylen- which was transferred by Seinhorst (1968) to chorhynchus in having six incisures in the the genus Trichotylenchus Whitehead, 1959. I lateral field, usual presence of deirids, the males have collected specimens of T. rhopalocercus having characteristic spicules lacking large from sugarcane soil samples originating in ventral flanges and small,