CHROMADORIDA CHITWOOD, 1933

Leduc, Daniel, Verdon, Valentin & Zhao, Zeng Qi, 2018, Phylogenetic position of the Paramicrolaimidae, description of a new Paramicrolaimus species and erection of a new order to accommodate the Microlaimoidea (Nematoda: Chromadorea), Zoological Journal of the Linnean Society 183 (1), pp. 52-69 : 56-57

ORDER CHROMADORIDA CHITWOOD, 1933 FAMILY PARAMICROLAIMIDAE LORENZEN, 1981

Synonyms: None.

Diagnosis: Cuticle striated from anterior edge of amphids; no longitudinal bars. Short somatic setae present. Lip pairs usually fused into three, or in some cases two, lobes. Six inner labial papillae present; six outer labial setae located in a separate circle and slightly anterior to the four cephalic setae; cephalic setae located anterior to the amphid. Four subcephalic setae sometimes present at level of amphids.Amphidial fovea spiral with less than 2 turns. Buccal cavity narrow, tubular, asymmetrical; dorsal tooth present, set within pharyngeal tissue and only protruding slightly into buccal cavity, sometimes with lateral pointed projections, always connected to a dorsal gland; smaller ventrosublateral teeth also present. Pharynx muscular, cylindrical, with posterior bulb; muscular cardia present. Secretory-excretory system present; renette cell elongated, located at level of or posterior to cardia; excretory ampulla and duct located slightly posterior to level of nerve ring. Female reproductive system didelphic-amphidelphic with equally developed branches, ovaries reflexed antidromously. Male reproductive system diorchic with two outstretched testes. Spicules symmetrical, arcuate; gubernaculum present. Row of midventral precloacal supplements consisting of cup-shaped structures with spout-like structures pointing posteriorly. Three caudal glands and spinneret present.

Remarks: The present diagnosis has been adapted from Holovachov (2014) to better correspond with our own observations, other Paramicrolaimidae species descriptions and with the current terminology of the structures described. Our observations show that the cuticle of Paramicrolaimus hohonucola sp. nov. is striated (not annulated), and that the lip region comprises two lobes, unlike other species of the genus which were described as possessing three equal lobes. In P. hohonucola sp. nov. the dorsal lobe of the lip region is enlarged and is almost equal in size and shape to the two ventrosublateral lobes, which are at least partially or completely fused together. As a result, the mouth is a straight or slightly bent transverse opening, with four inner labial papilla along its ventral side and two inner labial papilla dorsally.

The subcephalic setae were described as absent in previous diagnoses, but four subcephalic setae are present in P. hohonucola sp. nov. at the level of the amphids. Males have also been described as monorchic or diorchic because only one testis was observed in the original descriptions of P. spirulifer by Jensen (1978). However, Lorenzen (1981) observed that this species is in fact diorchic like the rest of the Paramicrolaimidae .