Panagrolaimus leperisini Massey, 1974

Girgan, Chantelle, Swart, Antoinette, Marais, Mariette & Fourie, Hendrika, 2018, Aphelenchoides spp. (Nematoda: Aphelenchida) and Panagrolaimus leperisini (Nematoda: Rhabditida) found associated with grass seeds in the Telperion Nature Reserve, South Africa, Zootaxa 4370 (2), pp. 137-155 : 149-152

Panagrolaimus leperisini Massey, 1974

( Fig. 7 )

Panagrolaimus . Leperisini was first described in the U.S.A. as an associate of the bark beetle Leperisinus aculeatus (Say) in green ash ( Fraxinus pennsylvanica Marshall ) ( Massey 1974). This is the only known report of this species.

Measurements. See table 5.

Description. Female (n = 2): Habitus slightly curved ventrally. Cuticle moderately annulated, annule width 2 µm at midbody. Fine longitudinal striations. Lateral field with three incisures, about one-seventh of corresponding body width. Lips rounded, each bearing one small seta ( Fig. 7A–B ). Six labial and four cephalic setae. Stoma 11– 12 µm in length. Cheilostom distinct, 3 µm in length, gymnostom 4–5 µm and stegostom 3 µm long. Meso-, meta- and telorhabdions fused ( Fig. 7A–B ). Metarhabdions bearing prominent dorsal tooth ( Fig. 7A–B ). Corpus twice the isthmus length ( Fig. 7A–B ). Corpus-isthmus junction distinct, isthmus narrower than corpus ( Fig. 7A–B ). Nerve ring situated at mid-isthmus, 124–130 µm from anterior end. Basal bulb ovoid with well-developed valves ( Fig. 7A–B ). Excretory pore slightly posterior to nerve ring, passing through hemizonid ( Fig. 7A–B ). Cardia distinct, 6 µm in length. Vulva at 56%, vulval lips protruding ( Fig. 7C ). Vagina one-third of corresponding body width, directed anteriorly. Reproductive system monodelphic-prodelphic ( Fig. 7C ). Ovary reflexed. Post-vulval uterine sac short, less than half the corresponding body width ( Fig. 7C ). Anus and rectum distinct with prominent anal glands ( Fig. 7D–E ). Phasmid situated at 65–73 % of the tail length ( Fig. 7D–E ). Tail conoid to acute terminus, 47– 55 µm long.

Male: (n = 1) Pharyngeal morphology as in female. Body more ventrally curved at posterior end. Testis single, reflexed dorsally anteriorly. Spicules 29 µm in length, manubrium spheroid and lamina curved ventrally ( Fig. 7F ). Gubernaculum less than half the length of spicules, curved ventrally. Five pairs of caudal papillae: two preanal ventrosubmedian, 1 subdorsal and 2 postanal ventrosubmedian. Tail conoid to acute terminus ( Fig. 7F ).

Discussion. Panagrolaimus specimens recovered from B. burchellii , C. longus and P. patens samples collected in the Telperion Nature Reserve were identified as P. leperisini based on the characteristic shape of the lips and presence of a dorsal tooth on each metarhabdion ( Fig. 7A–B ). Identification was aided by the key provided by Abolafia & Peña-Santiago (2006) and measurements and morphological features were compared with those in Massey (1974). This species is reported for the first time in South Africa. Only two species have been previously reported from South Africa: P. magnivulvatus and P. subelongatus . Specimens were deposited in the NCN with accession numbers 50542, 50544, and 50545.

Relationships. Closely related species, based on morphology, are P. goodeyi Rühm, 1956 and P. subelongatus ( Cobb, 1914) Thorne, 1937 . Panagrolaimus subelongatus differs in the absence of a dorsal tooth on the metarabdions, head with three lips and six pairs of caudal papillae in males. P. goodeyi differs in having seven pairs of caudal papillae in males; longer tails (c = 16.2–18.4, in both males and females vs. c> 19 in P. leperisini ) and a more anterior phasmid (54 % of tail length vs. 65–73 % in P. leperisini ).

Figures

FIGURE 7. Panagrolaimus leperisini, female (A–E). A–B: Anterior region; C: Reproductive system; D-E: Tail region. Male, F: Tail regionshowing spicules and gubernaculum.