Pristionchus auriculatae Kanzaki & Herrmann & Weiler & Röseler & Theska & Berger & Rödelsperger & Sommer 2021, n. sp.

Pristionchus auriculatae n. sp.

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Etymology. The species name is derived from the substrate from which the species was recovered. The type strain was isolated from a rotting fig of Ficus auriculata from soil substrate.

Measurements. See Table 5

Adult. General characters are as described above for the triformis -group.

Stenostomatous form. Cheilostom, gymnostom, pro-mesostegostom and telostegostom as described above. 12- plated form not found. Arrangement of tooth and denticles in metastegostom as described above; dorsal movable tooth triangular, anterior end slightly curved, tooth sometimes directed anteriorly; left subventral ridge with three minute, blunt or pointed adventitious denticles on a plate; right subventral ridge with one or two distal rounded or blunt adventitious denticles. Whole stoma including the tooth and denticles is narrow and more pointed in males.

Eurystomatous form. Cheilostom as described above, anterior half of each cheilostomal plate often split into two tips to form 12-flapped form. Six-flapped form (without split cheilostomal plate) rare. Gymnostom in both types 1 and 2 short and thick, forming cuticular ring. Pro-mesostegostom well-developed, internally overlapping with posterior end of gymnostom; type 1 form short, somewhat flattened and bearing weak serrates at anterior end; type 2 with few small spines on inner surface. Arrangement of tooth and denticles in metastegostom as described above; dorsal movable tooth claw-like as typical of the genus; left subventral ridge with three large plates, each often has split tips and extra denticles on middle forming spiny plate; right subventral movable tooth claw-like and sometimes bears an extra peak on the ventral side. Telostegostom as described above.

Male. Paired papillae and the phasmid are arranged as <v1, v2d, v3, co, v4, ad, (ph, v5, v6, v7, pd)>, where v1 located about 1 CBD anterior to co; v2d just less than 1/5 CBD anterior to co; v3 adcloacal; v4 at 1/3 CBD posterior to co, i.e., v2d, v3, co and v4 are close to each other; ad about 1 CBD posterior to co; ph 2/3 distance from ad and root of tail spike; v5–v7 forming triplet, just posterior to ph; and pd at level of triplet, i.e., ph, triplet papillae and pd are close to each other. v1, v3, v4 and ph subventral, v2d and ad lateral, v5–7 ventral and pd subdorsal in male tail. General shape of spicule and gubernaculum as described above.

Female. Gonadal characters of female as described above. Tail elongate conoid with slightly filiform terminus, i.e., posterior half of tail is more elongated compared to anterior part. Phasmid ventro-laterally located at about 1.5 ABD posterior to anal opening.

Diagnosis and relationships. Pristionchus auriculatae n. sp. is characterized by the slightly anteriorly curved triangular dorsal tooth and the right and left subventral ridges with three denticles of stenostomatous form, right subventral stegostomal tooth may have a blunt peak on the ventral side in eurystomatous form, sparsely serrated pro-mesostegostomal wall in type 2 eurystomatous form, the arrangement of male genital papillae, <v1, v2d, v3, co, v4, ad, (ph, v5, v6, v7, pd)> where v2d, v3, co and v4 and ph, v5, v6, v7, pd are close to each other, respectively, and a long spike occupying more than 2/3 of tail length of male tail. In addition, the arrangement of v1, v2d and ad genital papillae, where the distance between v1 and v2d is almost same as that between v2d and ad is characteristic to this species.

Pristionchus auriculatae n. sp. is typologically close to P. hoplostomus. The new species and P. hoplostomus share triangular and pointed dorsal tooth in stenostomatous form, right subventral tooth in eurystomatous form, sometimes have an extra peak on its ventral side, and the arrangement of genital papillae, closely located v2d, v3, co and v4 and pd overlapping with v5–7 triplet. The new species is distinguished from P. hoplostomus by the absence vs. presence of 12-plated stenostomatous form, right subventral ridge in stenostomatous form, with blunt vs. pointed denticles, and the arrangement of posterior four pairs of genital papillae, i.e., pd is overlapping with triplet vs. posterior to v7.

Further, the new species is distinguished from all other species by mating experiments and also characterized by a ca. 1,600-bp fragment of the SSU rRNA gene (GenBank accession number MW017216), the sequence of which is distinct from that of all other Pristionchus species.

Type host and locality. Isolated from rotting Ficus auriculata fruits from soil substrates collected at the Botanical garden, Shanghai - conservatory 1, Shanghai, PRC.

Type material and type strain. Type strain RS5989 frozen at the nematode collection of the MPI Tübingen and available as living culture upon request. Voucher specimens sent to the following museums: Holotype male, Paratype male and female: Museum für Naturkunde Karlsruhe, Germany; Paratype male and female: Swedish Natural History Museum, Stockholm, Sweden; Paratype male and female: University of California in Riverside Nematode Collection (UCRNC), Riverside, CA, USA.