Flannerystrongylus chisholmae, 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 : 551-553

Flannerystrongylus chisholmae n. sp.

( Figs 2 A–N)

Type host. Paramelomys levipes (Thomas)

Site in host. Small intestine.

Type specimens. Holotype male AM W. 53154, allotype female AM W. 54155, paratypes 2 males, 2 females AM W. 53144 from Paramelomys levipes from Munimum Village , Milne Bay Province, Papua New Guinea (9° 53´S 149° 23´E); coll. A. Engellis Jnr, 12. iii. 1985.

Other material examined. From Paramelomys mollis: From Indonesia, Papua; 3 females from Bichate, Arfak Mountains AM W. 53145. From Papua New Guinea, Milne Bay Province; 1 male, 1 female, Garatin Ridge, BBM NG 109414. From P. levipes: From Papua New Guinea, Milne Bay Province; 2 males 1 female, Takutuk AM W. 53147.

Etymology. This species is named in recognition of the work of Dr Leslie Chisholm, Collection Manager of the Australian Helminthological Collection, South Australian Museum.

Description. General: Small worms, usually coiled. Cephalic vesicle prominent with about 6–8 transverse annulations. Buccal capsule vestigial, mouth opening triangular with rounded corners; mouth surrounded by 4 cephalic and 6 labial papillae and 2 lateral amphids. Oesophagus claviform, nerve ring not seen, excretory pore and deirids in region of posterior third of oesophagus.

Synlophe: (sections of 2 males, 5 females) Longitudinal pointed ridges extend from posterior margin of cephalic vesicle to anterior to bursa or vulva;14–15 ridges; 15 ridges in males, 14 –15 in females; 15 ridges in females in anterior body; 15 ridges in males, 14–15 in females in mid body; 15 ridges in females in posterior body. Ridges small without size gradient. Axis of orientation of ridges sub frontal; 7–8 ridges dorsal side, 6–8 ventral side males and females.

Male: (measurements of 8 worms) Length 3.4–5.5 (4.0) mm, maximum width 63–106 (83). Cephalic vesicle 26–49 (35) long. Oesophagus 310–410 (350) long; nerve ring not seen, deirids and excretory pore 187, 190 (2 measurements) from anterior end. Bursa dissymmetrical, left lobe larger; pattern of rays 2–3. Dorsal lobe shorter than laterals; dorsal trunk symmetrical divided at about 1/3 its length, terminal divisions rays 9, 10 symmetrical, rays 8 more or less symmetrical, arising from dorsal trunk at about same level as bifurcation of dorsal trunk, reaching margin of bursa; lateral rays 6, 5, 4 about same size, reaching margin of bursa; ventral rays 3, 2 arise together from common trunk, ray 2 not reaching margin of bursa. Genital cone elongated, sclerotized. Spicules equal, filiform, tips curved, 460–610 (531) long; spicule to body length ratio 13.2 %. Gubernaculum 22, 31 (2 measurements) long.

Female: (measurements of 8 specimens) Length 3.3–4.6 (4.1) mm, maximum width 76–106 (85). Cephalic vesicle 26–33 (32) long. Oesophagus 297–420 (359) long; nerve ring not seen, deirids, excretory pore 210 from anterior end (one measurement). Vulva opens 115–148 (130) from tail tip, posterior end reflexed ventrally in some specimens. Ovejector monodelphic, infundibulum longest element, 160 long, sphincter 30, 35, vestibule 45, 50, 60, vagina 20, 20 long. Tail conical with blunt tip, 34–51 (40) long. Eggs thin shelled, ellipsoidal, 6 in utero, 51.0–68.0 (58.4) long, 29.7–39.1 (35.1) wide.

Remarks. The characters of the synlophe, 15 small sized ridges without a size gradient and with a sub frontal orientation, allow these specimens to be placed in the genus Flannerystrongylus . Flannerystrongylus chisholmae n. sp. is a smaller worm than its congener F. abulus Smales, 2019 (males 3.4–3.6 mm compared with 5.4–8.5 mm long) with a spicule to body length ratio of 13.2% compared with 7.2% for F. abulus . Females of F. chisholmae have the vulva opening closer to the tail tip (115–148 compared with 139–165), 6 eggs in utero, not more than 14 and a shorter tail (34–51 compared with 41–80) than F. abulus . The ventral coiling of the posterior end reported for females of F. abulus was not observed in females of F. chisholmae (see Smales, 2019). Flannerystrongylus abulus is found in Paramelomys platyops and F. chisholmae in P. levipes and P. mollis .

Figures

FIGURE 2. Flannerystrongylus chisholmae 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; B. Male, cervical end lateral view; C. Male, mid body transverse section; D. Male, en face view; E. Female, mid body transverse section; F. Spicules, anterior end; G. male, bursa left lobe; H. Male, genital cone lateral view; I. Gubernaculum, lateral view; J. Male, bursa shape; K. Male, spicule tip; L. Male, bursa dorsal lobe; M. Female, posterior end showing ovejector ventral view; N. Male, bursa right lobe. Scale bars in µm: A, J, M, 50; C, D, E, F, G, H, I, K, L, N, 25.