Melomystrongylus somoroensis Smales &amp; Heinrich 2010, sp. nov.
Creators: name: Smales, L. R.
name: Heinrich, B.
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Nematoda
Secernentea
Strongylida
Heligmonellidae
Melomystrongylus
Melomystrongylus somoroensis

description: <i>Melomystrongylus somoroensis</i> sp. nov. (Figs 38–50) <b>Type host.</b> <i>Paramelomys rubex</i> (Thomas) <b>Site in host.</b> Small intestine. <b>Material examined.</b> Holotype male, allotype female from <i>Paramelomys rubex</i> Somoro Summit, Torricelli Mts, (3° 24´S; 142° 8´E), West Sepik District, Sanduan Province, Papua New Guinea, coll. T. Flannery 16. vi. 1988, AM W.36787, W.36788; paratypes 1 male, 3 females, same data AM W.36789. <b>Other material examined.</b> From <i>Paramelomys rubex</i> <b>Papua New Guinea, Sanduan Province</b>; 2 males, 1 anterior end Somoro Summit, Torricelli Mts., (3° 24´S; 142° 8´E): <b>Indonesia, Papua</b>; 1 male Mokwan area, Arfak Mts (1° 6´S; 133° 56´E), AM W.36785, W.36786. <b>Etymology.</b> The specific name is derived from the type location of the species. <b>Description. General:</b> Small worms, prominent cephalic vesicle present with about 3 annulations; buccal capsule vestigial. Mouth opening triangular with rudimentary lips; labial and cephalic papillae not observed. Oesophagus claviform. Nerve ring, deirids and excretory pore at about same level in mid oesophageal region. Synlophe (based on sections from 5 worms) of continuous pointed longitudinal cuticular ridges in both sexes, extends from posterior margin of cephalic vesicle to immediately anterior to bursa or vulva; 13–15 ridges in anterior, 15–17 in midbody, 17–18 in posterior. Axis of orientation of ridges passing from ventral right to dorsal left sides, inclined about 60° from sagittal axis in anterior and mid body; 5–7 ridges dorsal side, 7–8 ridges ventral side. In anterior body ridges 1– 5 increasing, ridge 6, 7 decreasing in size; ridges 1´–4´(male) 1´–5´(female) increasing in size, ridge 5´(male) 6´(female) largest, ridges 6´–8´increasing in size (male) 7´– 8´about same size (female) 7–8 decreasing in size. In mid and posterior body ridges becoming smaller losing size gradients; and orientation. <b>Male:</b> (Measurements of 4 specimens) Length 1930–2400 (2090), maximum width 56–68 (61). Cephalic vesicle 25–32 (29) long. Oesophagus 235–290 (265) long; nerve ring 120, deirids, excretory pore 125, 196 from anterior end. Bursa (based on 4 worms) slightly asymmetrical, right lobe larger; pattern of rays 3–2 for both lobes; rays 2, 3 4, diverge distally, recurved ventrally; rays 5, 6 recurved dorsally. Dorsal lobe with median notch, shorter than laterals; dorsal trunk bifurcates at about 2/3 its length, each branch dividing again at distal tip; terminal divisions, rays 9, 10, symmetrical, rays 8 arising at same level from dorsal trunk proximally to division of dorsal ray, right ray slightly larger than left. Genital cone elongated, heavily sclerotised; ventral lip with unpaired papilla 0, dorsal lip with paired papillae 7. Spicules filiform tips hooked 310–330 (318) long. Gubernaculum 37–44 (40) long. <b>Female:</b> Length 2300–2500 (2400), maximum width 63–73 (67). Cephalic vesicle 30–36 (33.5) long. Oesophagus 265–310 (292) long; nerve ring, deirids, excretory pore 126, 133 from anterior end. Monodelphic ovejector, vulva near posterior end, 78, 80 from tail tip; vagina 45, sphincter, 20, shortest, infundibulum 50, vestibule, 70, longest element. Tail reflected ventrally, 47.5–59.5 (52.7) long; tail tip relatively long, conical. Eggs thin shelled, ellipsoidal, about 6 in utero 52.8–59.5 (56.8) by 28.9–33 (30.4). <b>Remarks.</b> Having an hypertrophied ventral ridge in the anterior region of the synlophe, an asymmetrical bursa and the dorsal ray divided distal to the level of the branching of rays 8 places the new species within the genus <i>Melomystrongylus</i>. <i>Melomystrongylus somoroensis</i> <b>n. sp.</b> differs from its congener <i>M. sepikensis</i> in the number of ridges, 13–18 compared with 8–16, the length of the spicules, 310–330 compared with 450–610, and a longer female tail, 47.5–59.5 compared with 16.5 –24.0 (Smales 2009). The generic diagnosis of <i>Melomystrongylus</i> includes: “bursa asymmetrical, left lobe larger”, the determination having been made after examining bursae that had not been completely rolled flat. In <i>M. somoroensis</i> the right lobe is the larger one and since this could also be the case for <i>M. sepikensis</i> the diagnosis needs to be reconsidered.
description: Published as part of <i>Smales, L. R. &amp; Heinrich, B., 2010, Gastrointestinal nematodes of Paramelomys rubex (Rodentia: Muridae) from Papua Indonesia and Papua New Guinea with the descriptions of three new genera and four new species of Helligmonellidae and Herpetostrongylidae (Nematoda: Trichostrongylida), pp. 1-28 in Zootaxa 2672 (1)</i> on pages 10-12, DOI: 10.11646/zootaxa.2672.1.1, http://zenodo.org/record/5301321
description: {"references": ["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 Helligmonellidae (Nematoda: Trichostrongyloidea). The Raffles Bulletin of Zoology, 57, 5 - 15."]}