Austrostrongylus wallabiae Johnston & Mawson, 1939

Durette-Desset, M. C. & Beveridge, I., 2012, Redescriptions and descriptions of new species of Austrostrongylus Chandler, 1924 (Nematoda: Trichostrongylina), from Australian marsupials with a comparative study of features of the synlophe, Zootaxa 3512, pp. 1-41 : 32-37

Austrostrongylus wallabiae Johnston & Mawson, 1939

( Figs. 19–21)

Type material: allotype ♀, Yetholme , New South Wales, Dec. 1910, coll. Randell, SAM 41370 .

Type host: Macropus rufogriseus (Desmarest) .

Site in host: small intestine.

Material examined: From Macropus rufogriseus: NSW : allotype; 5 ♀♀, same data as type ( SAM 3090 ) ; Victoria: 8 ♂♂, 7 ♀♀, Laharum ( MNHN 583 MQ) ; 1 ♂, Wartook ( SAM 45715) (33 T) ; 10 ♂♂, Jimmy's Creek , Grampian Range ( SAM 45702) ; 1 ♂, Portland ( SAM 45607) ; South Australia: 2 ♂♂, Joanna ( SAM 45707) ; Tasmania: 1 ♂, Cape Barren Island ( SAM 45703) ; 8 ♂♂, Rushy Lagoon ( SAM 45704) ; 8 ♂♂, Waterhouse ( SAM 45705, 45706 ) ; 2 ♂♂, Blessington ( SAM 45708) .

Redescription. Anterior part of body: ( Fig. 19A–D) 6 tiny labial papillae present; excretory pore and deirids slightly anterior to oesophago-intestinal junction.

Male: (measurements of 5 specimens) length 8.3–10.3 (9.3) mm; maximum width 150–190 (160); length of cephalic vesicle 80–105 (89); length of oesophagus 420–480 (450); nerve ring, deirids and excretory pore 250–330 (290), 400–460 (440) and 360–420 (390) from anterior end respectively. Spicules 590–640 (610) long, calomus 109–152 (130) long, lamina 470–531 (480); gubernaculum 30–55 (44) long. Bursa sub-symmetrical; bursal pattern of type 1–3–1 tending to 1– 4 type in both lobes with rays 6 diverging proximally to rays 3 on their common trunk; rays 8 arising from base of dorsal ray, rays 9 ventrally-directed arising asymetrically at about mid-length, right ray 9 arising first; then dorsal ray divided in distal quarter into 2 branches, each subdividing distally or immediately, in 2 branchlets, each branchlet, internal phasmid shorter or longer than external ray 10. ( Fig. 19I, J). Genital cone prominent; papillae 7 paired on elongate, recurved projections ( Fig. 19K). Spicules needle-like ( Fig. 19E), yellow in colour; straight, tips single, sharply pointed ( Fig. 19F). Gubernaculum spindle-shaped in median view ( Fig. 19H).

Female: (measurements of 5 specimens) length 10.1–11.9 (10.7) mm; maximum width 180–220 (200); length of cephalic vesicle 90–100 (98); length of oesophagus 500–650 (570); nerve ring, deirids and excretory pore 310–370 (330), 410–510 (460) and 370–420 (410) from anterior end respectively. Vulva 1.25–1.40 (1.31) mm from posterior end ( Fig. 19L); measurements from single female: vagina vera 140 long, vestibule 220 long, anterior sphincter 53 long, posterior sphincter 58 long, anterior infundibulum 180 long, posterior infundibulum 110 long; uterus with 8–22 (14) eggs, 85–90 (88) long, 50–55 (52) wide; tail 100–160 (120) long, attenuated extremity 20–40 (27) long ( Fig. 19G).

Synlophe: Studied in 1 male 9.9 mm long, 1 female 11.1 mm long. In both sexes, cuticular ridges arising between posterior margin of cephalic vesicle and anterior to excretory pore. Ridges disappearing in distal quarter of body in male except ridge 1’ which disappears at mid-body; ridges disappear within median third of body in female, except ridge 3’ which disappears just anterior to vulva.

Right float with small peduncle at mid-body ( Figs. 20F, 21D); at mid-body, right float smaller than left float. In male, size of right float increasing to mid-body then decreasing regularly in posterior two-thirds of body where it disappears ( Fig. 20H); size of left float increasing slightly to about 1.2 mm anterior to bursa ( Fig. 20I), then decreasing to level of bursa where it disappears ( Fig. 20K). In female, size of right float increasing to beginning of median third of body ( Fig. 21E) then decreasing slightly to level of vulva and becoming a large dilatation encircling body to anus ( Fig. 21K).

Number of ridges: in both sexes: 8 (2 dorsal, 6 ventral) at oesophago-intestinal junction ( Figs. 20E, 21C) and 7 (2 dorsal, 5 ventral) at mid-body ( Figs. 20F, 21D). At mid-body, single axis of orientation inclined at 90° to sagittal axis.

Sequence of origin of ridges: from posterior margin of cephalic vesicle to 250 µm anterior to excretory pore in male: ridges 3’, 4’, 2 ( Fig. 20A), then 2’, 5’ ( Fig. 20B), then 1 ( Fig. 20C), then 1’, 6’ ( Fig. 20D). In female from posterior margin of cephalic vesicle to 160 µm anterior to excretory pore, ridges 2’, 3’, 4’, 5’, 2 ( Fig. 21A), then 1’, 6 ‘, 1 ( Fig. 21B).

Sequence of disappearance of ridges: in male at mid-body, ridge 1’ ( Fig. 20F), in female at beginning of median third of body. In male, ridge 1’, then from 2.2 mm anterior to bursa (2.35 anterior to caudal extremity) to level of bursa, ridges 5’, 6’ ( Fig. 20G), then 2 ( Fig. 20H), then 1 ( Fig. 20I), then 4’ ( Fig.20J), then 2’, 3’ ( Fig. 20K). In female, from 3.9 mm anterior to vulva (5. 7 mm anterior to caudal extremity) to 3.4 mm anterior to vulva, ridges 1 ( Fig. 21E), then 5’ ( Fig. 21F), then 6’, 2 ( Fig. 21G), then 4’ ( Fig. 21H), then 2’ ( Fig. 21), then 3’, 50 µm anterior to vulva ( Fig. 21J).

Position of left ridge 1’: arising in dorsal position ( Figs. 20D, 21B); in same position until its disappearance at mid-body. Ridges 1’ and 2’ are equidistant from left lateral field ( Figs. 20E, 21C).

Remarks. This species was redescribed by Mawson (1973) based on specimens from Logan Village, Queensland (SAM 5465). Her specimens were re-examined but are extremely dark and broken and their identity could not be confirmed. Therefore, they have not been included among the material examined. As there is no holotype male, the current specimens were identified as A. wallabiae based on the redescription of the species by Mawson (1973), particularly the characteristics of the spicules.

The label associated with the type specimen gives the locality as "Bathurst district, New South Wales ", as cited in the original publication ( Johnston & Mawson, 1939). However , additional material ( SAM 3090 ) from the same area provides additional information, indicating the collection locality as Yetholme, a locality near Bathurst, as a well as the surname of a collector and a date. The additional material consists only of females most of which are broken, but some of which are clearly A. wallabiae . The collection contains additional small females which cannot be identified .

This is the only previously described species from M. rufogriseus in which the females could be confidently identified on the basis of their large size and for which, consequently, an adequate series of measurements can be provided. The species is readily distinguished from congeners by its needle-like spicules terminating in straight, sharp, unadorned tips. In all material examined, the cuticle of the posterior end of females, from the vulva to the tail, was inflated. This may have been an artefact but was not present in the females of most other species processed and fixed in the same way and may therefore be a characteristic of the species. A similar inflation is present in A. chandleri . However, because of uncertainties surrounding these features, they are not included in the above description.

The number of ridges in the synlophe reaches its maximum of 8 (2 dorsal, 6 ventral) anterior to the excretory pore in both sexes ( Figs. 20D, 21B); at the oesophago-intestinal junction, there are 8 ridges (2 dorsal, 6 ventral) in both sexes ( Figs. 20E, 21C); at mid-body there are 7 ridges (1 dorsal, 6 ventral) in both sexes ( Figs. 20F, 21D).

In the male, ridges terminate just anterior to the bursa, at which level, the right float is absent and the left float is small ( Fig. 20K). In the female, ridges are absent anterior to the vulva at which level, the right float is absent and the left float is replaced by a large dilatation encircling the body ( Fig. 21K).

This species is found commonly in M. rufogriseus , frequently in mixed infections with A. chandleri , A. macropodis and A. smalesae . It was found in 46% of 14 animals examined in western Victoria (Grampian Range) ( Aussavy et al., 2011), but was also present in material examined from Queensland, New South Wales, other regions of Victoria, Tasmania and South Australia.