Paraheligmonelloides singauwaensis, Smales, 2009

Smales, L. R., 2009, Helminths Of Melomys Rufescens And Melomys Spp. (Muridae: Hydromyinae) From Papua New Guinea With The Descriptions Of A New Genus And Five New Species In The Heligmonellidae (Nematoda: Trichostrongyloidea), Raffles Bulletin of Zoology 57 (1), pp. 5-15 : 13

Paraheligmonelloides singauwaensis , new species

( Figs. 44–53 )

Material examined. – Holotype male, allotype female: BBM-NG- 24762 from the small intestine of Melomys rufescens ( Muridae : Hydromyinae ), type host, Singauwa River, Lae, 6°07'S 146°59'E, Morobe Province, Papua New Guinea, coll. P. J. Shanahan, 7 Apr.1966.

Paratypes: 3 males, BBM-NG-24762, collecting data as above.

Prevalence. – Two of 25 M. rufescens.

Etymology. – The species name is taken from the type locality.

Description. – Small coiled worms; prominent cephalic vesicle present; buccal capsule vestigial. Mouth opening triangular with rudimentary lips; labial and cephalic papillae not observed. Oesophagus claviform. Nerve ring surrounds oesophagus in middle third; deirids and excretory pore at about same level, in posterior third of oesophagus length. Synlophe of pointed longitudinal cuticular ridges extends from the posterior margin of the cephalic vesicle to just anterior to bursa or vulva; 17 ridges in anterior, 20–22 in midbody. Axis of orientation of ridges passing from ventral right to dorsal left sides, inclined about 80° from sagittal axis; 8–11 ridges dorsal side, 9–13 ridges ventral side. Ridge 1’ more developed than ridge 1 in anterior; ridges 1’, 2’ more developed than ridges 1, 2 in midbody. Ridges 1–11 increasing in size; ridges 3’–5’ increasing in size, ridges 7’–11’ decreasing in size. Posterior region of body with 22–23 (male) 20–21 (female) ridges reducing in size, retaining axis of orientation.

Male (holotype and 4 paratypes): Length 2.35–2.75 (2.6) mm, maximum width 99–100 (99). Cephalic vesicle 37.5–42.5 (40) long, 30.5–34 (32.5) wide. Oesophagus 320––350 (345) long; nerve ring 165, excretory pore 240 from cephalic end. Bursa asymmetrical, right lobe larger, rays of left lobe more robust; with small median dorsal notch. Dorsal ray symmetrical, divided at about 2 thirds its length, each branch dividing again at distal tip; terminal divisions, rays 9, 10 symmetrical; rays 8 arising at slightly different levels proximally to division of dorsal ray. Rays 4, 5, 6 with common stem, reaching margin of bursa, rays 6 more slender than rays 4, 5. Rays 2, 3 with common stem, robust, diverging distally, curving posteriorly, reaching margin of bursa. Genital cone short, lightly sclerotized; ventral lobe with unpaired papillae 0, dorsal lip bifid, each lobe with single papilla 7. Spicules equal, filiform, proximal ends rounded, tips simple pointed, 230–290 (265) long. Gubernaculum 34–35.5 (35) long.

Female (allotype): Length 2.9 mm, maximum width 130. Cephalic vesicle 42.5 long, 34 wide. Oesophagus 390 long. Vulva opens 95 from tail tip. Posterior end reflected dorsally; body wall extended to form praepuce. Monodelphic; ovejector with sphincter, 80, longest, infundibulum, 50, vestibule, 30, smallest element. Tail conical tip with spike. Eggs thinshelled, ellipsoidal, in utero 45 by 30.

Remarks. – Paraheligmonelloides singauwaensis , new species, is characterized by having a synlophe with ridge 1´much more developed than ridge 1, and with the relative sizes and orientation of the ridges as described for the southeast Asian members of the genus ( Ow Yang et al., 1983; Hasegawa et al., 1999). Of these P. singauwaensis , new species, most closely resembles Paraheligmonelloides triangulus Ow Yang et al., 1983 in the number of ridges on the synlophe. It differs from P. triangulus in having more ridges in the midbody (20–22 ridges compared with 19–21 ridges), as well as in the length of the spicules (230–290 compared with 61–85) the form of the spicule tips and the size of the eggs (45 by 30 compared with 67 by 36) ( Ow Yang et al., 1983).

Figures

Figs. 44–53. Paraheligmonelloides singauwaensis, new species from Melomys rufescens and Melomys spp. from Papau New Guinea: 44, male anterior end, lateral view; 45, male cross section, anterior body; 46, bursa left lateral view; 47, male cross section, midbody; 48, genital cone, ventral view; 49, male cross section, posterior body; 50,genital cone, lateral view; 51, female posterior end, lateral view; 52, spicule tips; 53, dorsal ray. Scale bars: 44 = 50 μm; 45–50, 52, 53 = 25 μm; 51 = 100 μm.