Triplonchium Cobb, 1920
Systematics of the genus Tylolaimophorus de Man, 1880 (Nematoda Diphtherophoridae), with description of T. minor (Thorne, 1939) Goodey, 1963 from Iran
Ghaderi, Reza
Asghari, Ramezan
Eskandari, Ali
Zootaxa
2020
2020-03-24
4755
2
322
340
de Man, 1880
de Man
1880
[238,621,837,864]
Secernentea
Diplogasteridae
Tylolaimophorus
Animalia
Diplogasterida
1
323
Nematoda
genus
de Man
1880
[413,619,154,181]
Secernentea
Diplogasteridae
Tylolaimophorus
Animalia
Diplogasterida
3
325
Nematoda
genus
= Triplonchium Cobb, 1920
Diagnosis [After Brzeski (1994)with some modifications]. Small to medium-sized nematodes ( 0.4-2.1 mm), with exceedingly dense, granular bodies which obscure the details of the internal anatomy. Anterior sensilla in two labial circles of six sensilla in each and a cephalic circle of four sensilla. Amphidial apertures large, perpendicular to the body axis. Lip region continuous, slightly or deeply offset. Buccal cavity with thickened plates anteriorly, serving as attachments for spear protractors. Dorsal tooth needle-like, projecting from the basal part of the buccal cavity. Narrow stoma extension ending with three small thickenings. A pair of lateral pores may occur posterior to spear in some species. Pharynx usually anteriorly swollen, then narrowing, ending with short, rounded to pyriform enlargement. Three large cardiac cells between pharynx and intestine. Female reproductive organs paired, reflexed, with germinal zones directed toward vulva. Oviduct composed of four cells. Vagina short, with thick walls. Male reproductive system monorchic, spicules paired and variable in shape: straight, arcuate or strongly bent ventrally, each spicule surrounded by a muscular capsule. Ventromedian papillae may occur in precloacal and in neck region. Rectum often thick walled. Intestine extending into the tail region as a post-rectal sac in some species. Tail usually short and cylindrical with rounded terminus, rarely longer and conical with pointed terminus, similar in both sexes. A pair of caudal pores may sometimes be observed.
Taxonomic remarks:J. B. Goodey (1963)made Triplonchiuma synonym of Tylolaimophorus, but this act was not recognized as valid by Thorne (1974). Since then, various authors attributed species to either genus. Jairajpuri (1964)didn’t concur with Goodey’s synonymy of Tylolaimophorusand Triplonchiumon the grounds that Triplonchiumdoes not have the perioral circlet of minutely mammiform papillae typical of Tylolaimophorus, and the spear illustrated by de Man (1880)has little resemblance to that of Triplonchium. Jairajpuri regards Tylolaimophorusas genus inquirendaein the Tyleptine. However, Jairajpuri & Ahmad (1992)accepted synonymy. The designation of a neotypeof Tylolaimophorus typicusby Brzeski (1994)helped to clarify the taxonomic position of the species. Brzeski (1994)presented a good synopsis of the genus. He also redescribed the type species, accepting notes from published works by de Coninck (1932)and Arpin (1973). Sauer (1968)mentioned that the eight described species of Tylolaimophorusknown at that time seem to fall into two groups which show some striking differences. T. cylindricus( Cobb, 1920) Goodey, 1963, T. bulgaricus( Andrássy, 1958) Goodey, 1963and T. pileatus( Andrássy, 1961) Sauer, 1968are relatively large species, over 1 mm, with characteristically curved spicules surrounded by conspicuous musculature. T. rotundicaudaPaesler, 1955(now considered as Longibulbophora rotundicauda(Paesler, 1955) Yeates, 1967), T. digitatus Husain & Khan, 1967and T. indicus Husain & Khan, 1967are under 0.5 mmin length, with cephalated spicules. T. minor( Thorne, 1939) Goodey, 1963( 0.6 mm) and T. typicus de Man, 1880( 0.8 mm) are intermediate in size but unfortunately, no males are known for either species. He further noted that T. constrictus Sauer, 1968and T. pugio Sauer, 1968link the two groups in some respects. Thorne (1961), Husain & Khan (1967), Jairajpuri & Ahmad (1992)and Zullini (2006)all agreed that the males of this genus are monorchic, with a single outstretched testis, whereas Brzeski (1994)illustrated the male of Tylolaimophorus typicusas possessing an anteriorly and a posteriorly directed testis. Andrássy (2009)concluded that Brzeski’s observation may be incorrect. However, Eroshenko & Tepljakov (1977)also reported two testes for T. corpulentus Eroshenko & Tepljakov, 1977. T. obtusicaudatus( Schuurmans Stekhoven & Teunissen, 1938) Arpin, 1973is inadequately described, and Goodey (1963), after studying typespecimens, doubted its generic status. Therefore, the species is here considered species inquirendae. Although not designating it as a new combination, Arpin (1973)was the first to use the binomen T. obtusicaudatus. List of species Typespecies Tylolaimophorus typicus de Man, 1880= T. pannonicus Andrássy, 1988 Other species T. bulgaricus( Andrássy, 1958) Goodey, 1963 = Triplonchium bulgaricum Andrássy, 1958 T. cavicaudatus Eroshenko & Tepljakov, 1977 T. constrictus Sauer, 1968 T. corpulentus Eroshenko & Tepljakov, 1977 T. cylindricus( Cobb, 1920) Goodey, 1963 = Triplonchium cylindricum Cobb, 1920 T. digitatus Husain & Khan, 1967 = Triplonchium digitatum( Husain & Khan, 1967) Ivanova, 1977 T. indicus Husain & Khan, 1967 = Triplonchium indicum( Husain & Khan, 1967) Ivanova, 1977 T. kasbegi( Eliashvili, 1986) Brzeski, 1994 = Triplonchium kasbegi Eliashvili, 1986 T. minor( Thorne, 1939) Goodey, 1963 = Triplonchium minor Thorne, 1939 = Triplonchium parvum Thorne, 1974 T. pileatus( Andrássy, 1961) Sauer, 1968 = Triplonchium pileatum Andrássy, 1961 T. pugio Sauer, 1968 T. tegmentum( Ivanova, 1980) Jairajpuri & Ahmad, 1992 = Triplonchium tegmentum Ivanova, 1980 Species inquirendae T. obtusicaudatus( Schuurmans Stekhoven & Teunissen, 1938) Arpin, 1973 = Triplonchium obtusicaudatum Schuurmans Stekhoven & Teunissen, 1938 Nomina nudum T. curvicaudatus Eroshenko & Tepljakov, 1977: appears in Jairajpuri & Ahmad (1992), and Andrássy (2009).
1. Rectal walls distinctly thickened; tail broadly rounded; anterior part of pharynx with median swelling.................. 2 - Rectal walls thin; tail conical; anterior part of pharynx cylindrical............................................. 12 2. Lip region offset by a deep groove....................................................................... 3 - Lip region continuous, narrower or offset by a depression..................................................... 4 3. Spicules strongly bent; spear protractor attachments sclerotized......................................... T. pileatus - Spicules arcuate; spear protractor attachments non-sclerotized....................................... T. constrictus 4. Female body length less than 0.7 mm..................................................................... 5 - Female body length more than 0.8 mm.................................................................... 6 5. Spear 10-12 µm; males do not occur................................................................ T. minor - Spear 15-17 µm; spicules almost straight, cephalated; males common................................. T. tegmentum 6. Spicules wide, almost straight........................................................................... 7 - Spicules narrow, arcuate to strongly bent.................................................................. 9 7. Pair of subventral papillae on male tail.................................................................... 8 - No subventral papilla on male tail.................................................................. T. pugio 8. a= 15.................................................................................... T. corpulentus - a= 20-25................................................................................ T. cavicaudatus 9- Body length less than 1 mm........................................................................... 10 - Body length more than 1 mm.......................................................................... 11 10- Spicules arcuate, with ventrally directed processus................................................... T. typicus - Spicules strongly bent, no processus............................................................... T. kasbegi 11. Five distinct ventromedian precloacal supplements................................................ T. bulgaricus - At most a single ventromedian precloacal supplement.............................................. T. cylindricus 12. Spear 16-17 µm; a= 16-18..................................................................... T. digitatus - Spear 18-23 µm; a= 19-21...................................................................... T. indicus
Diagnostic compendium of species Species of Tylolaimophoruscan be distinguished by 12 morphological and morphometric characters ( Table 1). Data are obtained from the original descriptions and other reported populations worldwide.
Description and differential diagnosis of species For each species, measurements, description of females and males, diagnosis and relationships with closely related species and distribution are provided here. Data in parentheses are calculated from the drawings in the relevant papers.