Austrostrongylus smalesae, Durette-Desset & Beveridge, 2012

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 : 23-28

Austrostrongylus smalesae sp. nov.

( Figs. 13–15)

Synonyms: Austrostrongylus n. sp. of Aussavy et al. (2011)

Types: holotype ♂, SAM 45727 ; allotype ♀, SAM 45728 ; paratypes, 25 ♂♂, 5 ♀♀ SAM 45729 , 10 ♂♂, 8 ♀♀, MNHN 583 MQ, 5 ♂♂, BMNH 2009.10.8.1–5.

Type locality: Laharum , Victoria, Australia .

Date of collection: 14.vi.2008.

Type host: Macropus rufogriseus (Desmarest) .

Other hosts: M. fuliginosus (Desmarest) , M. giganteus Shaw , Wallabia bicolor (Desmarest) .

Site in host: small intestine.

Etymology: named after Dr L. R. Smales in appreciation of her work on the nematodes of marsupials.

Material examined: From Macropus rufogriseus : Queensland: 6 ♂♂, Swanfels ( SAM 45701) ; Victoria: types; 21 ♂♂, Wartook ( SAM 45721) ; 3 ♂♂, Mt Zero ( SAM 45722) ; 26 ♂♂, Brimpaen ( SAM 45724, 45725 ) ; 2 ♂♂, Jimmy's Creek , Grampian Range ( SAM 45692) ; 1 ♂, Mirranatwa ( SAM 45694) ; 4 ♂♂, Cape Conran ( SAM 10429) ; 5 ♂♂, Casterton ( SAM 45699) ; 3 ♂♂, Portland ( SAM 45723) ; South Australia: 3 ♂♂, Joanna ( SAM 45698) ; Tasmania: 15 ♂♂, Cape Barren Island ( SAM 45693) ; 8 ♂♂, Launceston ( SAM 45695) ; 21 ♂♂, Waterhouse ( SAM 45696, 45697 ) ; 3 ♂♂, Sassafrass ( SAM 45749) ; 4 ♂♂, Blessington ( SAM 45700) ;

From Macropus fuliginosus : Victoria: 4 ♂♂, 2, ♀♀, Brimpaen (34M) ( SAM 45725); 2 ♂♂, Dadswell's Bridge ( SAM 34631) .

From Macropus giganteus : Tasmania: 15 ♂♂, Maria Is. ( SAM 45746) ; 4 ♂♂, White Hills ( SAM 45750) ; Victoria: 1 ♂, Brimpaen ( SAM 45896) .

From Wallabia bicolor : New South Wales: 4 ♂♂, Nowra ( SAM 45742) ; Victoria: 1 ♂, Beaufort ( SAM 45726) ; 3 ♂♂, Stawell ( SAM 45895) .

Description: (based on specimens from Macropus rufogriseus

Anterior part of body: ( Fig. 13A–D) 6 tiny interno-labial papillae; excretory pore and deirids slightly anterior to oesophago-intestinal junction.

Male: (measurements of holotype) length 6.41 mm; maximum width 174; length of cephalic vesicle 87; length of oesophagus 413; nerve ring, deirids and excretory pore 250, 380 and 360 from anterior end respectively. Spicules 565 long, calomus 228, lamina 337; gubernaculum 38 long; (measurements of 5 specimens, paratypes) length 5.11–6.52 (6.04) mm; maximum width 130–174 (152); length of cephalic vesicle 76–92 (86); length of oesophagus 402–467 (430); nerve ring, deirid and excretory pore 228–283 (257), 348–380 (366) and 348–370 (357) from anterior end respectively. Spicules 565–652 (616) long, calomus 163–217 (191), lamina 402–435 (420); gubernaculum 38–65 (45) long. Bursa slightly dissymmetrical, with left lobe longer than left lobe; bursal pattern of type 1–3–1 tending to 1– 4 type in both lobes with rays 3 diverging proximally to rays 6 on their common trunk, then rays 4 and 5 diverging last; rays 8, arising from common trunk with rays 2–6; rays 9 arising near origin of dorsal ray; then ray branching in distal quarter with two branchlets ray; 10 elongate, external and usually with short internal phasmid ( Fig. 13L, M); dorsal ray may or may not reach margin of bursa. Genital cone prominent; papillae 7 paired on small, conical projections ( Fig. 13K). Spicules slender, simple, dark brown in colour, with characteristic sinuous distal ends in lateral views ( Fig. 13F); tips bifid enclosed in rounded terminal ala ( Fig. 13H). Gubernaculum poorly sclerotised, scarcely visible in lateral view ( Fig. 13J), quadrangular in median view ( Fig. 13I).

Female: (measurements of allotype) length 7.2 mm; maximum width 180; length of cephalic vesicle 84; length of oesophagus 484; nerve ring, deirid and excretory pore 276, 473 and 408 from anterior end respectively. Vulva 1.14 mm from posterior end; tail 95 long, attenuated extremity 21 long; 16 eggs in anterior uterus, 11 in posterior uterus; egg 89 x 47; (measurements of 5 specimens, paratypes) length 6.8 (6.0–7.4) mm; maximum width 166–189 (177); length of cephalic vesicle 87–95 (91); length of oesophagus 447–500 (466); nerve ring, deirids and excretory pore 260–310 (289), 374–395 (384) and 342–429 (387) from anterior end respectively. Vulva 0.92–1.22 (1.05) mm from posterior end ( Fig. 13P); measurements from single female: vagina vera 90 long, vestibule 145 long, anterior and posterior sphincters 54 long, anterior infundibulum 210 long, posterior infundibulum 176 long; 10–16 (12) eggs in anterior uterus, 9–13 (11) in posterior uterus; eggs 79–89 (82) long, 47–58 (53) wide; tail 79–121 (114) long with attenuated extremity 16–21 (19) long ( Fig. 13G).

Synlophe: Studied in 1 male 6.1 mm long and 1 female 7.4 mm long (paratypes). Ridges arising between posterior margin of cephalic vesicle and level of excretory pore in both sexes. In male, ridges 1’, 5’, 1 disappearing at the end of median third of body, other ridges in distal third. In female, ridges disappearing between beginning of distal third of body and 450 µm anterior to vulva.

Right float with well developed peduncle at mid-body ( Figs. 14E, 15F). Floats of similar size at level of oesophago-intestinal junction; posteriorly right float less well developed than left float. In male, size of right float increasing to mid-body ( Fig. 14E) then decreasing to disappear near bursa ( Fig. 14J). In female, size of right float increasing to mid-body ( Fig. 15F) then decreasing to 500 µm anterior to vulva ( Fig. 15M). In male, size of left float increasing regularly to about 1650 µm anterior to bursa ( Fig. 14J), then decreasing and disappearing just anterior to bursa ( Fig. 14L). In female, size of left float increasing in distal third then decreasing in size to 450 µm anterior to vulva ( Fig. 15N), then increasing in size posteriorly ( Fig.15O), surrounding body just anterior to anus ( Fig. 15P).

Number of ridges: 8 (2 dorsal, 6 ventral) at oesophago-intestinal junction ( Figs. 14D, 15E) and at mid-body ( Figs. 14E, 15F). At mid-body single axis of orientation inclined at 80° to sagittal axis in both sexes.

Sequence of origin of ridges: ridges arise from posterior margin of cephalic vesicle to level of excretory pore in both sexes. In male, ridges 2’, 3’, 4’ ( Fig. 14A), then 1’, 5’, 2 ( Fig. 14B), then 6’, 1 ( Fig. 14C); in female: ridges 3’, 4’, 5 ‘ ( Fig. 15A), then 2’, 2, ( Fig. 15B), then 1’, 6’ ( Fig.15C), then 1 ( Fig. 15D).

Disappearance of ridges: in male, at end of median third of body, ridges 1’, 5’ ( Fig. 14F), then 1 ( Fig. 14G), then between 1.75 mm anterior to bursa (1.9 mm anterior to caudal extremity) and 1.4 mm anterior to bursa, ridges 4’, 6’ ( Fig. 14H), then 2 ( Fig. 14I), then 2’ ( Fig. 14J), then 3’ ( Fig. 14K). In female, at 1.2 mm anterior to vulva (2. 4 mm from caudal extremity) and 450 µm anterior to vulva, ridge 5’ ( Fig. 15G), then 1 ( Fig. 15 H), then 2 ( Fig. 15I), then 1’ ( Fig. 15J), then 4’ ( Fig. 15K), then 6’ ( Fig. 15L), then 2’ ( Fig. 15M), then 3’ ( Fig. 15N).

Position of left ridge 1’: arising in dorsal position ( Figs. 14B, 15C) then migrating to ventral position at midbody ( Figs. 14F, 15E); in same position until disappearance ( Fig. 14F, 15J).

Remarks. This species is readily recognisable by its robust but simple, dark brown spicules with a characteristic sinuosity in lateral views. The shape of the spicules distinguishes this species from all congeners with the exception of A. incurvispiculum from Macropus fuliginosus in Western Australia. The species described here is readily distinguished from A. incurvispiculum by the fact that the spicules are yellow in the latter species but are dark brown in the new species and by the fact that A. incurvispiculum is monodelphic whereas the species described here is didelphic.

The number of ridges in the synlophe reaches its maximum of 8 (2 dorsal, 6 ventral), at the level of the excretory pore in both sexes; at the oesophago-intestinal junction, there are 8 ridges (2 dorsal, 6 ventral) in both sexes ( Figs. 14D, 15E); at mid-body there are 8 ridges (2 dorsal, 6 ventral) in both sexes ( Figs. 14E, 15F). The right float forms a well developed peduncle.

Ridges disappear in the median third of the body in the male and in the distal third in the female. In the male, ridges terminate anterior to the bursa, at which level, the both floats have disappeared ( Fig. 14L). In the female, ridges are absent anterior to the vulva at which level, the left float is replaced by a large dilatation encircling the body ( Fig. 15O, P).

Based on available collection data, A. smalesae is primarily parasitic in M. rufogriseus , but can also infect M. giganteus , M. fuliginosus and W. bicolor where these host species are sympatric with M. rufogriseus ( Aussavy et al., 2011) . In the Grampian Ranges in Victoria, it was the most common species in M. rufogriseus (62%) (as Austrostrongylus sp. n.), but was found in sympatric M. fuliginosus and M. giganteus at a much lower prevalence (6–10%) and abundance ( Aussavy et al., 2011). Collection records indicate its occasional occurrence also in W. bicolor although it was not found in this host species by Aussavy et al. (2011).

Austrostrongylus incurvispiculum was originally described from M. fuliginosus from Western Australia ( Beveridge & Durette-Desset, 1986). However, it has subsequently been recovered from Macropus irma from the same area (SAM 45486). Based on collections of the genus Austrostrongylus from eastern Australia, it is likely that M. irma is the usual host and that M. fuliginosus is an accidental host. However, additional collecting in the region is required to confirm this hypothesis.