Gongylonema aguilarense, Spratt, 2023

Spratt, David M., 2023, Redescription of species of Gongylonema Molin, 1857 (Nematoda: Spiruroidea Gongylonematidae) parasitic in some Australian vertebrate hosts and description of three new species, Zootaxa 5239 (2), pp. 204-220 : 211-213

Gongylonema aguilarense sp. nov.

Type specimens. Holotype ♂ AHC 49229, allotype ♀ AHC 49230, 2 ♂♂ paratypes AHC 49231,) 3 ♀♀ paratypes AHC 49232, 2 ♀♀ paratypes and 2 anterior ends (AHC 49233), 1 ♀ anterior end (AHC 49234).

Type locality. Brown’s Road , Mt. Glorious , D’Aguilar Range, Qld .

Type host. Rattus fuscipes (Waterhouse) ( Rodentia : Muridae ) (Australian bush rat).

Site of infection. Stomach mucosa

Material examined. Qld: from Rattus fuscipes types; Jolly’s Lookout , Mt. Nebo, D’Aguilar Range, 4 ♀♀ (AHC 32088), 1 ♂, 3 ♀♀ (AHC 32092), 3 ♀♀ (AHC 12454) .

Etymology. The specific name refers to the region of rainforest northwest of Brisbane which includes both Mt. Glorious and Mt. Nebo within the D’Aguilar National Park, localities where the hosts of the specimens were collected. The specific epithet is a neuter adjective, as the generic name, Gongylonema , is neuter.

Description ( Fig. 3 A–J .)

General: Nematodes with marked sexual dimorphism, cuticular bosses present on anterior end, pronounced transverse cuticular striae present. Cephalic end with raised cephalic cuticular plate, buccal capsule present. Oral opening not elongated dorso-ventrally, 2 pairs of internal papilliform projections on rim of cephalic plate, 2 pairs of cephalic papillae and 2 large lateral amphids. Deirids situated anteriorly near origin of lateral alae. Oesophagus long, divided into anterior muscular and posterior glandular regions.

Male (holotype in italics, 2 paratypes in parentheses): Total length 8.6 (13.4, 13.2) mm. Maximum width 155 (166, 166). Cuticular bosses not sparse, occurring predominantly on dorsal and ventral surfaces, extending 579 (499, 520) from anterior end. Prominent transverse cuticular striae present. Buccal capsule 58 (52, 52) long, 10 (8,13) wide. Deirids immediately anterior to origin of lateral alae, 115 (108,129) from anterior end. Lateral alae present entire body length, widening posteriorly to form asymmetric caudal alae, right wider than left, extending to tail tip. Nerve ring 156 (146,156), excretory pore 318 (293, 348) from anterior end. Muscular oesophagus 323 (291, 353), glandular oesophagus 2093 (2412, 2750) long. Spicules unequal, different in length, right spicule 114 (110, 114), left spicule 842 (811, 847), finely striated; gubernaculum 73 (73, 73) long, 17 (23, 16) wide, hook-shaped with shorter section, 40 long, accommodating right spicule. Caudal end with 4 pairs pedunculated pre-cloacal papillae, 4 pairs pedunculated post-cloacal papillae, single median sessile papilla immediately anterior to the fourth pair and terminal papilla flanked by two minute papillae ( Fig. 3D ). Tail 125 (125, 128) long. Phasmids not observed.

Female (allotype in italics; 5 paratypes + 2 anterior fragments in parentheses). Total length 53 46 (25–63) mm. Maximum width 308 249 (212–292) at tail end. Cuticular bosses not sparse, occurring predominantly on dorsal and ventral surfaces, extending 980 1121 (848–1352) from anterior end. Prominent transverse cuticular striae present. Buccal capsule 52 52 (42–58) long, 10 10 (10–11) wide. Deirid 114 129 (122–139) from anterior end. Nerve ring 270 264 (177–343) from anterior end, excretory pore not observed. Muscular oesophagus 715 871 (562–1200) long, glandular oesophagus 5062 4458 (3551–5326) long. Vulva 7076 6128 (5432–6636) from posterior extremity. Tail conical, 250 222 (186–280) long. Larvated eggs 58 55 (53–58) long, 37 32 (30–35) wide with thick smooth shells.

Remarks. The type and additional specimens from R. fuscipes from Mt. Glorious and Mt. Nebo Qld. were identified by the collectors as G. beveridgei . However, G. aguilarense sp. nov. is readily distinguished from G. beveridgei by the presence of bosses on the dorsal and ventral surfaces of the male rather than restricted solely to the left side and the presence of two lateral alae rather than a single right lateral ala in the male. The tail tip in male G. aguilarense is unlike any other species described herein with a terminal papilla flanked by two minute lateral papillae. In other features, G. aguilarense is similar to G. beveridgei although with slightly longer right spicules and shorter tails in males and a shorter glandular oesophagus in females. Given the morphological distinctions noted above in males and the state of the types and only material of G. beveridgei , I have established a new species, G. aguilarense sp. nov. Further comparison of the two species awaits collection of fresh specimens from R. f. murrayi and a more thorough re-description of G. beveridgei .

Gongylonema aguilarense sp. nov. is distinguished from G. alecturae by the shorter lengths of muscular and glandular oesophagus of males and glandular oesophagus in females, the shorter right spicule, the smaller number of pre- and post-cloacal papillae, the latter arranged asymmetrically, the shorter tail in males and the much shorter distance of vulva from the posterior extremity.

Of the approximately 50 species of Gongylonema described from birds and mammals on every continent except Antarctica, 13 have been described from rodents (Cordeiro et al., 2018). In particular, Gongylonema neoplasticum Fibiger and Ditlevsen, 1914 emend. Ransom and Hall, 1915 has a cosmopolitan distribution in rodents but has not, until now, been recorded from rodents in Australia.

Gongylonema aguilarense sp. nov. is distinguished from G. neoplasticum , as described in this manuscript and by Cordeiro et al. (2018), by the greater length of males and especially females, the longer left spicule, the larger gubernaculum, fewer pedunculate post-cloacal papillae in the males, and by the greater extent of bosses, greater length of the muscular and glandular oesophagus and the greater distance of the vulva from the tip of the tail in females.

Figures

FIGURE 3A–J. Gongylonema aguilarense sp. nov. A, Cephalic end female, en face view.B, Anterior end holotype male, lateral view. C, Vulva and vagina, female, lateral view. D, Posterior end holotype male, ventral view. E, Spicules and gubernaculum male, dorsal view. F, Tail tip holotype male, ventral view. G, Embryonated egg, lateral view. H, Proximal end right spicule, lateral view. I, Distal end left spicule, lateral view. J, Posterior end female, lateral view. Scale bars: Figs. 3A, 3E, 3F, 3H, 3I = 20µm. Figs. 3B–3D, 3G, 3J = 50µm.