Gongylonema macropodum, 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 : 216-218

Gongylonema macropodum sp. nov.

Type specimens. Holotype ♂, AHC 49235 , allotype ♀, AHC 49236, 4 ♂♂ paratypes, AHC 49237, 3 ♂♂ paratypes, AHC 49238, 3 ♀♀ paratypes, AHC 49239, 2 ♀♀ paratypes, AHC 49240.

Type locality. Townsville, Qld.

Type host. Notamacropus agilis (Gould) (Marsupialia: Macropodidae ) (agile wallaby).

Site of infection. Oesophageal and stomach mucosa.

Additional host. Macropus giganteus Shaw (Marsupialia: Macropodidae ) (eastern grey kangaroo).

Material examined. Qld: from Notamacropus agilis , types; Hervey’s Range , Townsville 2 ♂♂ (AHC 7770), 2 ♂♂ (AHC 7792); Ingham , 1 ♂ (AHC 19896); Tully , 1 ♂, anterior end (AHC 7787); Cromarty (south of Townsville ) 1 ♀ in 4 fragments (QM GL11304). From Macropus giganteus stomach Rockhampton, 3 ♀♀ (AHC 11060) .

Etymology. The specific name is derived from the family name, Macropodidae , of the wallaby and kangaroo hosts of the nematode parasite.

Description ( Fig. 5 A–I )

General: Nematodes with marked sexual dimorphism, cuticular bosses present on anterior end, prominent transverse cuticular striae present. Cephalic end with peri-buccal ring, buccal capsule present. Oral opening dorsoventrally elongated, 2 cuticular formations at outer margins of dorso-ventral axis and extending over opening, 6 small internal papilliform, labial projections, 3 on each side on inside rim of buccal capsule, 2 pairs of internal papillae, 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, 7 paratypes mean and range in parentheses: Total length 32, 33 (31–36) mm. Maximum width 239, 231 (212–265). Cuticular bosses initially on all surfaces, constrained to lateral surfaces from about junction of muscular and glandular oesophagus, extending 868, 480 (385–768) from cephalic extremity. Buccal capsule 42, 40 (35–42) long, 21, 23 (15–27) wide. Deirids immediately anterior to lateral alae, 156, 155 (129–177) from anterior end. Lateral alae present, continue entire body length, widening to form asymmetric caudal alae, right wider than left and extending to tail tip. Nerve ring 282, 280 (260–302), excretory pore 480, 498 (416–600). Muscular oesophagus 663, 641 (520–824) long, glandular oesophagus 5697, 6134 (4823–7685) long. Spicules unequal, markedly different in length, right spicule 187, 172 (146–187) long, 27, 38 (31–42) maximum width; left spicule 13780 13391 (12798–13177) long, finely striated; portion of gubernaculum accommodating left spicule 125, 127 (125–130) long, portion accommodating right spicule 83, 86 (83–94) long. Tail twisted, approximately 260, 240 (221–260) long, with 6 pairs of pedunculated pre-cloacal and 3 pairs of pedunculated post-cloacal papillae with 1 or 2 pairs of smaller sessile post-cloacal papillae, variably distributed near caudal extremity. Tail in AHC 7792 not twisted and two pairs minute papillae visible on tail tip, not detectable in male tails which are normally twisted.

Female (allotype in italics, 5 paratypes mean and range in parentheses: Total length 78, 55 (45–80) mm. Maximum width 342, 296 (239–371) at posterior end. Dense cuticular bosses on all surfaces initially, confined to lateral surfaces from about junction of muscular and glandular oesophagus, extending 1299, 1252 (1066–1510) from cephalic extremity. Buccal capsule 52 47 (46–50) long, 21, 23 (21–24) wide. Deirids anterior to origin of lateral alae, 208, 176 (156–214) from anterior end. Nerve ring 370, 355 (274–437), excretory pore 645, 585 (532– 634) from anterior end. Muscular oesophagus 1092, 768 (718–832), glandular oesophagus 8848 7587 (6599–8957) long. Vulva 9164, 6900 (5062–8848) from posterior extremity. Tail 335 325 (292–370) long. Larvated eggs 52, 49 (42–52) long, 33, 30 (22–33) wide, with thick smooth shells.

Female: (GL 11304) Length> 64 mm (tail end missing). Maximum width 344. Cuticular bosses over entire body anteriorly, confined to right lateral subsequently, extending 901. Buccal capsule 42 long, 18 wide. Deirids anterior to broad lateral alae, 177 from cephalic end. Nerve ring 395, excretory pore 594 from cephalic end. Muscular oesophagus 795, glandular oesophagus 8800 long. Vulva not observed. Eggs 52x37, shell thick 8, unfertilised.

Remarks. Specimens of G. macropodum sp. nov. from kangaroos and wallabies were all collected from the mucosa/submucosa of oesophagus and/or stomach. They are distinguished from G. alecturae by the different morphology of the right spicule including its greater length and width, shorter length of left spicule, the greater distance bosses extend beyond the cephalic extremity particularly in females, the greater length of muscular and glandular oesophagus and of the tail in both sexes, and the much shorter distance of the vulva from the tip of the tail in females from N. agilis but not M. giganteus . A single male specimen from N. agilis , not twisted in the caudal region, bore 2 pairs of minute terminal papillae, a feature able to be observed rarely on account of the normally twisted tails of males.

Apparently, Mawson (1971) was not aware of four fragments of a female specimen held in the Queensland Museum (GL11304) and collected by J.W. Fielding 25 July 1913 from the oesophagus of Notamacropus agilis (as Macropus agilis ) from Cromarty (south of Townsville), Qld. The label reads Gongylonema cf. pulchrum Molin, 1857 . Measurements are similar to G. alecturae and G. macropodum sp. nov. which were unknown at the time. In the absence of a male I have determined the specimen as Gongylonema cf. macropodum . If correct, it would indicate that the species has been known from macropodids for more than a century.

Figures

FIGURE 5 A–I. Gongylonema macropodum sp. nov. A, Cephalic end female, en face view. B, Anterior end holotype male, dorsal view. C, Vulva and uterus, lateral view. D, Right spicule, ventral view. E, Tip of left spicule, lateral-ventral view. F, Two pairs minute papillae on tail tip of male. G, Posterior end of male, latero-ventral view. H, Spicules and gubernaculum, ventral view. I, Female posterior end, lateral view. Scale bars: Figs. 5A, 5E, 5F, 5H = 20 µm. Figs. 5B, 5C, 5D, 5G, 5I = 50µm.