Hughjonestrongylus digianiae, Smales, 2020

Smales, Lesley, 2020, Gastrointestinal nematodes of Paramelomys levipes and P. mollis (Rodentia Muridae) from Papua, Indonesia and Papua New Guinea with the descriptions of three new genera and nine new species (Nematoda), Zootaxa 4861 (4), pp. 544-572 : 559-561

Hughjonestrongylus digianiae n. sp.

( Figs 6 A–O)

Type host. Paramelomys mollis (Thomas)

Site in host. Small intestine.

Type specimens. Holotype male AHC 49062, allotype female AHC 49063, paratypes 40 males, 40 females AHC 49064 from Paramelomys mollis , from Kosipe. 2044 m, Central Province, Papua New Guinea (8° 27´S 147° 13´E); coll T. Flannery , 1982.

Other material examined. From P. mollis From Papua New Guinea, Milne Bay Province, 20 males, 14 females, Goyou Ravine, BBM NG 109420 , 109422, 109423; 7 males, 6 females, Garatin Ridge, BBM NG 109414 .

Etymology. This species is named for Dr Maria Digiani in recognition of her work on the Trichostrongylina .

Description. General: Small worms, slightly or tightly coiled, body tapering from anterior to mid oesophageal region. Males and females about same size. Cephalic vesicle prominent with 8–10 transverse annulations. Buccal capsule vestigial, mouth opening triangular with rudimentary lips; cephalic and labial papillae not seen, 2 lateral amphids. Oesophagus claviform, nerve ring, excretory pore and deirids not seen.

Synlophe: (based on sections from 11 worms) Longitudinal pointed ridges extend from posterior margin of cephalic vesicle to anterior to bursa or vulva; 14–22 ridges; 14 in males in anterior body; 20–22 in males, 21–23 in females in mid body; 17–20 in males, 18 in females in posterior body. Ridges markedly different in size. Axis of orientation of ridges oblique from right ventral to left dorsal; 9–11 ridges dorsal side, 11–12 ventral side. Left ridge distinct from ridge 1´; lateral left and lateral right ridges largest, ridge 1´hypertrophied, larger than ridge 2´, ventral ridges 3´–11´about same size, more robust than dorsal ridges. dorsal ridges 1–5 decreasing in size, ridges 6–9 increasing in size. Ridges losing size gradient, becoming smaller posteriorly.

Male: (measurements of 10 specimens) Body length 2.1–2.6 (2.4) mm, width 66–101 (80). Cephalic vesicle 32–40 (35) long. Oesophagus 290–350 (328) long; nerve ring, deirids and excretory pore not seen. Bursa relatively large, usually tightly coiled, dissymmetrical, left lateral lobe larger; pattern of rays 2–3. Dorsal lobe shorter than laterals; dorsal trunk symmetrical divided at about ½ its length, terminal divisions rays 9, 10 symmetrical, rays 8 arising from dorsal trunk at slightly different levels, dissymmetrical, left ray larger, reaching margin of bursa, lateral ray 4 larger than rays 5, 6 reaching margin of bursa, rays 3, 2 arise together from common trunk, reaching margin of bursa. Genital cone prominent, elongated. Spicules slightly unequal, filiform, tips curved, 250–400 (324) long; spicule to body length ratio 13.4 %. Gubernaculum 20–26 (23) long.

Female: (measurements of 10 specimens) Length 1.8–3.8 (3.3) mm, maximum width 66–106 (85). Cephalic vesicle 33–40 (35) long. Oesophagus 300–400 (378) long; nerve ring, deirids, excretory pore not seen. Vulva opens 70–120 (88) from tail tip; region of ovejector enlarged, bent laterally, tail more or less straight, posterior end forming an ‘L’ shape. Ovejector monodelphic, infundibulum, 60, 90 and vestibule 70, 80 longest elements, sphincter 25, 30 long, shortest element vagina 40, 60 long. Tail conical with pointed tip, 17–34 (32) long. Eggs thin shelled, ellipsoidal, 4 in utero, 74.8–82.5 (77.0) long, 36.3–39.6 (37.1) wide.

Remarks. This new species belongs to the genus Hughjonestrongylus because it has a synlophe showing the same arrangement of pointed ridges as described in the diagnosis of Durette-Desset & Digiani (2015) and a dissymmetrical bursa with a type 2–3 pattern of bursal rays ( Digiani & Durette-Desset 2014). In having a synlophe with 19–22 ridges in the mid body Hughjonestrongylus digianiae n. sp. comes closest to H. singawauensis with 19–23 synlophe ridges, in the key to the species of Hughjonestrongylus of Smales (2019). Hughjonestrongylus digianiae can be differentiated from H. singawauensis , although having spicules of similar length (250–400 compared with 230–385) in having a spicule to body length ratio of 13.4% compared to 11.5 %. The females of H, singawauensis have the tail reflected dorsally, may have a praepuce and have up to 13 eggs in utero, eggs 64.5–73.0 long compared with, a bent and enlarged ‘L’ shaped posterior end with 4 eggs in utero, eggs 74.8–82.5 long, for H. digianiae .

Figures

FIGURE 6. Hughjonestrongylus digianiae sp. n. In all illustrations of the synlophe in transverse section the dorsal aspect of the body is oriented towards the top of the page and the left side of the nematode to the left of the page. The dorsal and ventral (numbers with superscripts) ridges are numbered, as are the lateral rays of the bursa (right rays with superscripts). A. female, anterior end lateral view, showing the tapered body; B. Male anterior transverse section; C. Male, spicules anterior end; D. Male, mid body transverse section; E. Male, spicule tips; F. Female, mid body transverse section; G. Male, posterior body transverse section; H. Male, genital cone lateral view; I. Female, posterior body transverse section; J. Male, bursa dorsal lobe; K. Male, gubernaculum lateral view; L. Male, bursa left lobe; M. Female posterior end lateral view showing ovejector; N. Male, bursa shape when lobes curled in; O. Female, posterior end shape in lateral view.Scale bars in µm: A, B, D, F, G, H, I, J, L, 25; C, E, K, 12.5; M, N, O, 50.