Nygmatonchus Cobb, 1933

Venekey, Virag, Gheller, Paula F., Kandratavicius, Noelia, Cunha, Beatriz Pereira, Vilas-Boas, Ana Carolina, Fonseca, Gustavo & Maria, Tatiana F., 2019, The state of the art of Chromadoridae (Nematoda, Chromadorida): a historical review, diagnoses and comments about valid and dubious genera and a list of valid species, Zootaxa 4578 (1), pp. 1-67 : 25-26

Genus Nygmatonchus Cobb, 1933

The genus Nygmatonchus was established by Cobb (1933) when the type species N. scriptus was described. Later N. fossiferus , N. alii and N. minutus were described by Wieser (1954), Murphy (1965) and Gerlach (1967), respectively. Wieser (1954) also suggested the transfer of Spiliphera edentata Cobb, 1914 to Nygmatonchus . Inglis (1969) reviewed Nygmatonchus and transferred Neochromadora bicoronata to it and N. alii to a new genus ( Austranema ). Inglis (1969) also commented about the doubtful status of N. fossiferus , N. bicoronata and N. minutus . Boucher and De Bovée (1971) transferred N. fossiferus when described the new genus Trochamus . Riemann & Rachor (1973) established the new combination N. spinosus [originally described by Gerlach (1957)] when transferred Prochromadorella spinosa to Nygmatonchus and synonymized N. bicoronata with it. Juario (1974) described N. minimus . Boucher (1976) created the genus Endeolophos and stated that N. fossiferus , N. minutus and N. spinosus should be transferred to it and N. minimus to Trochamus . Timm (1978) redescribed N. edentata (using its original name Spilophora edentata ) based on new specimens and transferred this species to Neochromadora . Considering all changes within the genus, only the originally described type species N. scriptus remained in Nygmatonchus . The species was described nearly 100 years ago and is not well detailed but here we consider Nygmatonchus as valid due to distinctive characteristics compared to other genera in the family (cuticle pattern and only one small tooth in the buccal cavity).

Diagnosis (modified from Inglis 1969): Cuticle complex with basket-work markings anteriorly, elongate punctuations posteriorly on middle of body; distinct lateral differentiation. Six outer labial sensilla and four setiform cephalic setae arranged in a single circle. Amphideal fovea prominent with double contour. Buccal cavity with small hollow anteriorly directed dorsal tooth. Pharynx without definitive posterior bulb. Tail long and slim. Possible pre-cloacal modification on males and gubernaculum not L-shaped.

Number of valid species: 1.

Genus Nygmatonchus Cobb, 1933

VALID SPECIES

1. Nygmatonchus scriptus Cobb, 1933 (Massachusetts, USA)