Hughjonestrongylus spratti, 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 : 561-562

Hughjonestrongylus spratti n. sp.

( Figs 7A –J )

Type host. Paramelomys mollis (Thomas)

Site in host. Small intestine.

Type specimens. Holotype male, allotype female, paratypes 8 males, 14 females BBM NG 102174, from Paramelomys mollis from southeast slopes Mount Giluwe , 2700 m, Southern Highlands, Papua New Guinea (9° 53´S 149° 23´E); coll. A. B. Mirza, 25. ii. 1973.

Other material examined. From P. mollis From Papua New Guinea, Morobe Province, 10 males, 4 females, Mount Missim, BBM NG 52061; From Southern Highlands Province, 5 males, 4 females, South east slopes Mount Giluwe , BBM 102171 B; From Central Province 1 male, 1 female, Kosipe , SAMA AHC 11722 .

Etymology. This species is named in recognition of the contribution of Dr David Spratt to the study of the helminths of the rodents of Australia and New Guinea.

Description. General: Small, slightly coiled, nematodes. Cephalic vesicle prominent with about 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 in anterior half of oesophageal region, excretory pore and deirids not seen.

Synlophe: (based on sections from 8 worms) Longitudinal pointed ridges extend from posterior margin of cephalic vesicle to anterior to bursa or vulva; 21–28 ridges; 21 in males in anterior body; 22–25 in males in mid body; 22 in females in anterior body, 28 in females in mid body; 23 in females in posterior body. Ridges markedly different in size. Axis of orientation of ridges oblique from right ventral to left dorsal; 10–12 ridges dorsal side, 10–17 ventral side. Left ridge distinct from ridge 1´; lateral left and lateral right ridges largest, ridge 2´smaller than ridge 1´ventral ridges 3´–17´about same size, more robust than dorsal ridges; dorsal ridges 1–7 decreasing in size, ridges 8–12 /13 increasing in size. Ridges losing size gradient, reducing in size posteriorly.

Male: (measurements of 10 specimens). Length 2.8–3.4 (3.7) mm, maximum width 64–99 (86). Cephalic vesicle 33–43 (37) long. Oesophagus 320–440 (387) long; nerve ring 139, 170 (2 measurements) from anterior end, deirids and excretory pore not seen. Bursa relatively large, tightly infolded in many specimens, slightly dissymmetrical, left lobe larger; pattern of rays 2–3. Dorsal lobe shorter than laterals; dorsal trunk symmetrical divided at about 2/3 its length, terminal divisions rays 9, 10 symmetrical, rays 8 dissymmetrical, right ray arising anteriorly to, left ray arising at about same level as, bifurcation of dorsal trunk reaching margins of bursa; lateral rays 6 smaller than rays 4, 5, reaching margin of bursa, rays 3, 2 arise together from common trunk, reaching margin of bursa. Genital cone prominent, ventral lip elongated. Spicules sub equal, filiform, tips straight, 300–360 (336) long; spicule to body length ratio 9.1 %. Gubernaculum 26–40 (31) long.

Female. (measurements of 10 specimens) Length 2.4–3.2 (2.8) mm, maximum width 70–94 (82). Cephalic vesicle 24–40 (30) long. Oesophagus 380–550 (402) long; nerve ring, deirids and excretory pore not seen. Vulva opens 120 (2 measurements) from tail tip; tail reflected ventrally, mature females usually with large cement plug in the flexion. Ovejector monodelphic, infundibulum 80, 120 long, sphincter shortest element 25, 30 long, vestibule 60, 80 long, vagina 30, 50 long. Tail conical with blunt tip, 30, 40 long. Eggs thin shelled, ellipsoidal, up to 14, in utero, 56.1–57.8 (56.7) long, 32.3–34.0 (33.4) 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 the key to the species of Hughjonestrongylus of Smales (2019) Hughjonestrongylus spratti n. sp. with a synlophe of 22–28 ridges at the mid body is placed between species with more and species with fewer than 25 ridges at the mid body and is closest to H. wanumaensis Smales, 2019 with 22–23 ridges at the mid body, H. mirzai with 21–24 ridges, and H. woolleyae Smales, 2017 , with 25–27 ridges at the mid body. Hughjonestrongylus spratti can be further distinguished from each of these species as follows: H. spratti has males with spicules 300–360 long, 9.1% of body length compared with H. mirzai , spicules 250–320 long, 9.8 % of body length, H. woolleyae has spicules 290–390 long, 8.3% of body length and H. wanumaensis has spicules 145–230 long, 13.6 % of body length ( Smales 2009, 2017, 2019). Females of H. spratti can be distinguished from all congeners, including H. alisoni , H. arfakiensis and H. digianiae by the combination of the characters, shape of the female posterior end (not swollen, flexed ventrally, usually holding a cement plug in the flexion), a short blunt tail, the proportions of the ovejector, infundibulum the longest element, and about 14 eggs in utero.

Figures

FIGURES 7. Hughjonestrongylus spratti 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. Male, gubernaculum and spicules lateral view; B. Male, mid body transverse section; C. Male, cervical end lateral view; D. Male, anterior end lateral view; E. Female, posterior end transverse section; F. Male, genital cone lateral view; G. Male, dorsal ray; H. Female, posterior end lateral view showing ovejector with ball of cement; I. Male, bursa left lobe; J. Male, bursa right lobe. Scale bars in µm: A, 12.5; B, E, F, G I, J, 25; C, 55; D, H, 50.