Pristionchus magnoliae, Kanzaki & Herrmann & Weiler & Röseler & Theska & Berger & Rödelsperger & Sommer, 2021

Kanzaki, Natsumi, Herrmann, Matthias, Weiler, Christian, Röseler, Waltraud, Theska, Tobias, Berger, Jürgen, Rödelsperger, Christian & Sommer, Ralf J., 2021, Nine new Pristionchus (Nematoda: Diplogastridae) species from China, Zootaxa 4943 (1), pp. 1-66 : 29-32

Pristionchus magnoliae n. sp.

urn:lsid:zoobank.org:act:ADA242D3-23FE-4ED0-AE51-6A537385AF79

Etymology. The species name is derived from the associated substrate from which the species was recovered. The strain was isolated from rotting Magnolia grandiflora fruits with some soil material.

Measurements. See Table 4

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 somewhat narrow, i.e., the angle of anteriorly detected tip is steeper, triangular and slightly anteriorly directed in male, flint-shaped with somewhat blunt tip in female, both have strongly sclerotized surface giving an appearance of an inverted V-shape in lateral view; left subventral ridge with three minute, blunt adventitious denticles on plate; right subventral ridge with three distal rounded adventitious denticles, plate slightly narrower in male than female, thus males seems to have two pointed denticles.

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 the posterior end of gymnostom; type 1 form short, somewhat flattened and bearing weak serrates at anterior end; type 2 with 2–3 rows of 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 often bears an extra peak on the ventral side. Telostegostom as described above.

Male. Paired papillae and phasmid are arranged as <v1, v2d, v3, co, v4, ad, ph, (v5, v6, v7), pd>, where v1 located about a little more than 1 CBD anterior to co; v2d less than 1/4 CBD anterior to co; v3 adcloacal; v4 at 1/4–1/5 CBD posterior to co, i.e., v2d, v3, co and v4 are close to each other; ad about 1 CBD posterior to co; ph at midway between ad and root of tail spike; v5–v7 forming triplet, between ph and the root of tail spike; and pd around level of v7. v1, v3, v4 and ph subventral, v2d and ad lateral, v5–7 ventral, 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., the posterior half of tail more elongated compared with anterior part. Phasmid ventro-laterally located at about 1.0–1.5 ABD posterior to anal opening.

Diagnosis and relationships. Pristionchus magnoliae n. sp. is characterized by the somewhat blunt and flintshaped dorsal tooth and the right and left subventral ridges with three blunt denticles of stenostomatous form, right subventral stegostomal tooth which often has blunt peak on ventral side in eurystomatous form, well-serrated promesostegostomal wall in type 2 eurystomatous form, arrangement of male genital papillae, <v1, v2d, v3, co, v4, ad, ph, (v5, v6, v7), pd> where v2d, v3, co and v4 are close to each other, and a long spike occupying more than 2/3 of tail length. Pristionchus magnoliae n. sp. is typologically close to P. yamagatae and P. hoplostomus . The new species and the other two species share the arrangement of genital papillae, <v1, v2d, v3, co, v4, ad, ph, (v5, v6, v7), pd> where v2d, v3, co and v4 are close to each other, and right subventral tooth in eurystomatous form, often having an extra peak on its ventral side. In addition, somewhat blunt and flint-shaped dorsal tooth in the stenostomatous form is common in the new species and P. yamagatae . However, the new species is distinguished from P. hoplostomus by the absence vs. presence of 12-plated stenostomatous form and dorsal tooth of stenostomatous form, blunt vs. pointed. The typological characters of P. magnoliae n. sp. are almost identical with those of P. yamagatae , distinguished only by the relative position of ph and v5, close but clearly separated vs. very close and sometimes overlapping. 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 MW017219 ), the sequence of which is distinct from that of all other Pristionchus species.

Type host and locality. Rotting Magnolia grandiflora fruits in Changfeng Park, Shanghai, PRC .

Type material and type strain. Type strain RS5999, other strain RS 6000 from the same location, 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 .