Pristionchus undetermined
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publication ID |
https://doi.org/ 10.1111/zoj.12041 |
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publication LSID |
lsid:zoobank.org:pub:ED727996-47DD-44B4-A15D-2A5540D7A4A8 |
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persistent identifier |
https://treatment.plazi.org/id/03E5047B-FFAD-887A-FC00-FAA4EEB12CB8 |
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treatment provided by |
Carolina |
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scientific name |
Pristionchus undetermined |
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SP. |
PRISTIONCHUS TRIFORMIS SP. NOV.
= Pristionchus sp. 6 apud Herrmann, Mayer & Sommer (2006); Mayer et al. (2007); Weller et al. (2010)
Description
Measurements: See Table 1.
Adults: Species androdioecious, with males and self-fertile hermaphrodites. Three different stomatal forms, i.e. stenostomatous, euryatomatous, and megastomatous, present, with known intermediates between the latter two forms.
Stenostomatous form: Metastegostom bearing: a crescent-shaped right subventral ridge varying between being transversely symmetrical and with ridge apex turning inwardly, ridge sometimes with one minute denticle ( Fig. 3F View Figure 3 ); in the left subventral like or pointed right subventral tooth ( Fig. 3D View Figure 3 ); a left subventral ridge of small denticles of varying shape, size, and number, i.e. between five and seven, arising from a split cuticular plate ( Fig. 3C View Figure 3 ). Dorsal tooth and right subventral tooth movable. Movement not observed in left subventral denticles.
sector, three or four blunt or weakly pointed left subventral denticles apparently projecting from a common cuticular plate that sometimes appears split in lateral view ( Fig. 3E, G View Figure 3 ).
Eurystomatous form: Cheilostom divided into six distinct per- and interradial plates ( Figs 3C, D View Figure 3 , 4D). Anterior end of each plate rounded and elongated to stick out from stomatal opening and form a small flap ( Fig. 3C, D View Figure 3 ). Gymnostom with thick cuticle, forming a short, barrel-shaped tube. Metastegostom bearing: a large claw-like dorsal tooth ( Fig. 3C, D View Figure 3 ); a large, claw- Megastomatous (12-plated eurystomatous) form: Cheilostom divided into 12 complete, distinct per- and interradial plates ( Figs 3A, B, H View Figure 3 , 4A, 5B View Figure 5 ). Anterior end of each plate rounded and elongated to stick out from stomatal opening and form a small flap ( Fig. 3H View Figure 3 ). Occasional intermediates between 12-plated and sixplated eurystomatous forms observed, e.g. where the common 12-plated form shows incomplete division of an individual plate, such that it culminates in a single flap, resulting in 11 flaps in total. Anterior margin of stegostom (pro- and mesostegostom) coarsely serrated ( Figs 3A, B, H View Figure 3 , 4B). Metastegostom bearing: a large and strongly sclerotized claw-like dorsal tooth ( Figs 3A, B, H View Figure 3 , 4C); a large, claw-like or pointed right subventral tooth ( Fig. 3B, H View Figure 3 ), with shape varying from dorsoventrally symmetrical to strongly hooked ( Fig. 3B View Figure 3 ); in the left subventral sector, a ridge of large denticles of varying shape, size, and number, i.e. between six and eight, arising from a split cuticular plate ( Figs 3A, H View Figure 3 , 4B), in addition to one or two posterior adventitious denticles ( Fig. 3A, H View Figure 3 ). Although the number of denticles is variable, it commonly exceeds the extent of complexity observed in the sixplated eurystomatous form. Telostegostom not sclerotized, deeper in ventral side than dorsal side, posterior part narrowing to procorpus. Dorsal tooth and right subventral tooth movable. Movement not observed in left subventral denticles.
Male: Spontaneous (= fatherless) males very rare (<0.5%) in culture. Squared manubrium at anterior end of spicule ( Fig. 6G View Figure 6 ). Gubernaculum conspicuous, about 40% spicule length, slightly broader anteriorly such that dorsal wall is recurved, and that dorsal and ventral walls separate at a 30° angle at posterior end ( Fig. 6G View Figure 6 ). In lateral view, anterior half of gubernaculum with two serial curves separated by anteriorly directed process, and with long terminal curvature about half of gubernaculum length and proximal curvature about one-third of gubernaculum length; posterior half forming a tube-like process enveloping spicules ( Fig. 6G View Figure 6 ). Nine pairs of genital papillae and a pair of phasmids present, and arranged as <P1, P2d, P3, C, P4, P5d, Ph, (P6, P7, P8, P9d)> [= <v1, v2d, v3, C, v4, ad, Ph (5, v6, v7, pd)> in the nomenclature of Sudhaus & Fürst von Lieven, 2003] ( Fig. 6F View Figure 6 ). Positions of P1 papillae are located about one cloacal body diameter posterior to cloacal slit, P2d equidistant between P1 and P4, P3 clearly posterior to P2d, P4 within one-third of cloacal body diameter of C, P5d closer to P4 than to P6, and equidistant between P4 and Ph, Ph clearly anterior to P6, P6–P8 linearly arranged, and P9d overlapping P7–P8 ( Figs 6F View Figure 6 , 12A View Figure 12 ).
Differential diagnosis: Pristionchus triformis sp. nov. is diagnosed from all other species of Pristionchus and Diplogastridae by the presence versus absence of two distinct eurystomatous forms: (1) a form with six cheilostomatal plates, putatively homologous with the eurystomatous form of other Pristionchus species ; and (2) a ‘megastomatous’ form with 12 cheilostomatal plates or flaps, accompanied by a more complex left subventral ridge. It is further distinguished from all other species of Pristionchus , except P. hoplostomus sp. nov. and P. fukushimae sp. nov., by an lateral view. G, gubernaculum and spicule, right lateral view. anteriorly serrated versus smooth stegostomatal ring in the eurystomatous form, and by a finely serrated versus smooth anterior gymnostomatal ring of the eurystomatous form; P. elegans has a coarsely serrated anterior gymnostom in the stenostomatous form, although no eurystomatous form is known for this species. Pristionchus triformis is distinguished from all other Pristionchus species by having a mouth form with 12 separate cheilostomatal plates, and is thus distinguished from P. hoplostomus sp. nov. and P. fukushimae sp. nov. by the cheilostomatal plates of the megastomatous form being completely separated into 12 plates versus fused for the posterior one-third of their length. Although 12 plates are found in the genus Parapristionchus , P. triformis sp. nov. is distinguished from Parapristionchus by having 12 plates in only one morph of the eurystomatous form versus constituently having 12 plates in both the eurystomatous and stenostomatous forms; it is further distinguished from Parapristionchus by all other diagnostic generic characters, most notably by a flint-shaped versus claw-like dorsal tooth in the stenostomatous form. Pristionchus triformis sp. nov. is further distinguished from P. hoplostomus sp. nov. by the absence ·
tinguished from both P. hoplostomus sp. nov. and P. fukushimae sp. nov. by P5d being equidistant between Ph and Ph versus closer to Ph than to P4. Pristionchus triformis sp. nov. is distinguished from all other species by its unique SSU rRNA sequence, an 830-bp fragment of which differs from the phylogenetically close species P. hoplostomus sp. nov. and P. fukushimae sp. nov. by 5 and 10 nucleotides, respectively. Finally, P. triformis sp. nov. is distinguished from P. hoplostomus sp. nov. and P. fukushimae sp. nov. by a hermaphroditic versus gonochoristic mode of reproduction.
Type host (carrier) and locality: The culture from which the type specimens were obtained was originally isolated from the body of an adult dung beetle, Anoplotrupes stercorosus (Hartmann in Scriba, 1791) ( Coleoptera : Scarabaeidae ), collected by M. Herrmann in the Schönbuch Forest near Tübingen, Germany, in July 2004.
versus presence of a distinct, additional left subventral plate with multiple denticles. The species is distinguished from P. fukushimae sp. nov. by a gubernaculum that broadens anteriorly at a 30° versus 15° angle, and by P4 being less than one-third versus more than one-half of a cloacal body diameter from the cloacal opening (C). Pristionchus triformis sp. nov. is tentatively distinguished from P. hoplostomus sp. nov. by: P2d clearly anterior to, versus slightly anterior to or overlapping, P3; P4 being equidistant between P3 and P5d; P9d overlapping versus being clearly posterior to P7–P8. It is also tentatively dis- Distribution: Besides its collection from the type locality and type host on several occasions ( Herrmann et al., 2006; Weller et al., 2010), including strain RS5232, the species was isolated by M. Herrmann from soil containing parts of dead Marronus borbonicus Coquerel, 1866 ( Coleoptera : Dynastidae ) on La Réunion Island in January 2012 and by James H. Thomas from soil in Vancouver, BC, Canada. This species has been additionally identified by its SSU rRNA sequence from several localities in Great Britain (Robbie Rae, pers. comm.).
Type material and strain: Holotype megastomatous hermaphrodite and three paratype megastomatous hermaphrodites are deposited in the University of California Riverside Nematode Collection ( UCRNC), CA, USA. Two paratype megastomatous hermaphrodites and one paratype stenostomatous hermaphrodite are deposited in the Swedish Natural History Museum , Stockholm, Sweden. Two paratype megastomatous hermaphrodites and one paratype stenostomatous hermaphrodite are deposited in the Natural History Museum , Karlsruhe, Germany. The type strain is available under culture code RS5233.
Etymology: The species epithet is a Latin adjective meaning ‘having three forms’, and refers to the sten-
ostomatous, six-plated eurystomatous, and ‘megastomatous’ morphs of this species.
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Chicago Academy of Sciences |
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