Aoruroides queenslandensis n. sp. (Oxyurida: Thelastomatoidea), a new nematode from Australian Panesthiinae (Blattodea: Blaberidae)

Systematic Parasitology 59: 65–69, 2004. © 2004 Kluwer Academic Publishers. Printed in the Netherlands.

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Aoruroides queenslandensis n. sp. (Oxyurida: Thelastomatoidea), a new nematode from Australian Panesthiinae (Blattodea: Blaberidae) Aaron R. Jex1, Tom H. Cribb1 & Margaret A. Schneider2 1 Department of 2 Department of

Microbiology and Parasitology, The University of Queensland, Brisbane, Qld 4072, Australia Zoology and Entomology, The University of Queensland, Brisbane, Qld 4072, Australia

Accepted for publication 17th February, 2004

Abstract A new thelastomatid, Aoruroides queenslandensis, is described from two native Australian cockroaches, Panesthia tryoni tryoni Shaw and P. cribrata Saussure, from sub-tropical rainforest in south-eastern Queensland. Species of Aoruroides Travassos & Kloss, 1958 have previously been reported from cockroaches found in Brazil and the Philippines, but A. queenslandensis n. sp. is the first species of this genus found in Australia. The new species differs from the other members of Aoruroides principally in the position of the nerve-ring and egg morphology.

Introduction Although much has been written regarding the pinworm nematodes parasitic in terrestrial arthropods (e.g. Cobb, 1920; Basir, 1956; Kloss, 1966; Adamson & Van Waerebeke, 1992), there has been little study of Australian examples of this association. Just four species have been reported. Johnston (1914) described Johnstonia alatum (Johnston, 1914) Basir, 1956 from a scarab beetle found in northern Queensland. Cephalobellus papilliger Cobb, 1920 was described from a scarab beetle found in Moss Vale, New South Wales (Cobb, 1920). Both Blattophila spharolaima Cobb, 1920 and Leidynemella fusiformis Cobb in Chitwood & Chitwood, 1934 were described from Panesthia cribrata Saussure from Moss Vale, New South Wales (Cobb, 1920; Chitwood & Chitwood, 1934). Australia has at least 420 species of native cockroaches (Roth, 1991). The parasitic fauna of this diverse group is largely unknown and in need of study. One group of Australian cockroaches that is particularly attractive for the study of internal parasites is the Panesthiinae (Blaberidae). The diet of the Panesthiinae, which is primarily wood, and their tendency to aggregate, makes them likely to harbour thelastomatid nematodes. Also, most male panesthiines are wingless or become wingless shortly after an initial dispersal flight, leading to potentially isolated host populations that may support distinct thelast-

omatid speciation. Australia has 14 described species of panesthiines and this study begins to explore panesthiine-thelastomatoid associations by describing a new thelastomatid found in the hindguts of Panesthia cribrata and P. tryoni tryoni Shaw taken from south-eastern Queensland.

Materials and methods Cockroaches were collected from sites in southeastern Queensland, beneath and within moist decaying logs. Individuals were caught by hand and stored in plastic screw-top jars. The cockroaches were maintained in jars with perforations in the lids for air, and fed on moistened wood chips and leaf litter until dissection. The cockroaches were killed in 95% ethanol and identified using Roth’s (1977) key to species. Cockroaches were measured for length of left hind tibia, body width at the widest point on the ventral surface and body length along the ventral longitudinal axis. A transverse incision was then made along the posterior end of the abdomen, with special care taken to avoid damage to the genitalia, which are important for host identification. The hindgut was then teased out into 0.85% saline and severed at the point just anterior to the origin of the malphigian tubules. The cockroach body was then preserved in 80% ethanol, and voucher specimens for each cockroach species were

66 lodged in the University of Queensland Insect Collection. The excised hindgut was teased apart in 0.85% saline under an Olympus SZ-ST binocular dissecting microscope. All nematodes found were extracted with micro-needles and fixed in TAF (2% triethylamine, 7% formaldehyde), then preserved in 70% ethanol. Preserved nematodes were mounted on a glass slide in 20% glycerol and covered with a coverslip. The coverslip was sealed around the edges with nail polish to prevent evaporation. Nematodes were then examined under an Olympus BH-2 light microscope and drawn using a camera lucida. Nematode measurements were made using an ocular micrometer and are given as a range followed by the mean and standard deviation in parentheses. All measurements are given in micrometres unless otherwise stated. Abbreviations: QM, Queensland Museum, Brisbane, Queensland, Australia. BMNH, British Museum (Natural History), Collection at The Natural History Museum, London, UK. LNP, Lamington National Park, Queensland, Australia. NNP, Noosa National Park, Queensland, Australia.

Aoruroides queenslandensis n. sp. Type-host: Panesthia tryoni tryoni Shaw (Blaberidae). Type-locality: LNP, Queensland, Australia, 28◦ 10 S, 153◦ 25 E. Other hosts: Panesthia cribrata Saussure. Other localities: LNP, Queensland, Australia. 28◦10 S, 153◦ 25 E (P. cribrata); NNP, Queensland, Australia, 26◦ 25 S, 153◦5 E (P. cribrata); Rainforest near Eumundi, Queensland, Australia, 26◦ 35 S, 152◦58 E (P. cribrata). All specimens were collected by Aaron Jex or Peter Cook. Type-material: Holotype (female) (QM G 219498) ex P. tryoni tryoni. Paratypes (QM G 219499) ex P. tryoni tryoni; (QM G 219500) ex P. tryoni tryoni; (QM G 219501) ex P. tryoni tryoni; (BMNH 2004.4.6.1-8) ex P. tryoni tryoni. All type-material was collected at LNP, 5 July, 2002. Local ecology: Within and beneath moist decaying logs. Prevalence: P. cribrata 90 of 97 (92.3%); P. tryoni tryoni 24 of 30 (80%).

Description Adult female (Figures 1A–C, 2A,B) Based on 14 gravid specimens. Length 3.20–4.99 (4.18, 0.52) mm; width 0.28–0.44 (0.32, 0.05) mm (Figure 1A). Cephalic extremity formed of simple first annule 10–24 (18, 4) long, followed by enlarged second annule 53–72 (61, 6) long. Second annule separated from remainder of body by deep cleft (Figures 1B, 2A). Mouth hexagonal, surrounded by 8 cephalic papillae (Figure 2B). Oesophagus 525–596 (563, 25) long; corpus, pyriform, short, 121–222 (177, 26) long, with posterior pseudobulb; isthmus, straight, 213–308 (259, 30) long; and valvular bulb 112–159 (136, 15) in diameter (Figure 1B). Nerve-ring halfway along isthmus, 232–339 (289, 30) from anterior end of body. Excretory pore posterior to base of oesophagus, 526–766 (622, 65) from anterior end of body. Intestine with anterior dilation but no distinct cardia. Vulva near mid-body, 45.5–52.2 (50.0, 2.2)% of total body length from the anterior end of body. Vagina muscular, anteriorly directed, branches into 2 uteri. Anterior uterus continues anteriorly to base of intestinal swelling, reflexes posteriorly, communicates with ovary which continues posteriorly, reflexes anteriorly and terminates near vulva. Posterior uterus short, runs posteriorly, leads into posteriorly directed ovary, soon reflexes anteriorly, terminates near base of oesophagus. Egg large, ellipsoidal, 113–163 (129, 14) × 56–91 (73, 9), with distinct striation running down each side of longitudinal axis (Figure 1C). Anus 0.74–1.47 (1.06, 0.16) mm from posterior end of body. Tail initially subconoid, then with subulate projection; subulate portion, 0.68–1.33 (0.92, 0.14) mm long. Adult male (Figures 1D–F, 2C,D) Based on 4 specimens. Length 1.92–3.01 (2.29, 0.51) mm long; width 0.13–0.21 (0.17, 0.04) mm. Cephalic extremity with simple first annule, 1.59–4.77 (3.18, 1.3) and enlarged second annule, 11.13–14.31 (12.32, 1.52) (Figure 1D). Anterior end with many cervical cuticular projections, from anterior end to mid-corpus level (Figure 1E and 2C). Mouth round; surrounded by 8 cephalic papillae, amphidial apertures present as circular openings (Figure 2D). Oesophagus 337–350 (343, 6) long; corpus, clavate, 196–209 (201, 5) long; isthmus, short, 55–64 (60, 4) long; and valvular bulb 77–83 (80, 3) in diameter (Figure 1D). Nerve-ring at mid-corpus, 100–132 (114, 13) from anterior end. Five caudal papillae, with1 pair lateral pre-anal, 1 pair lateral post-anal and single large papilla median pre-anal

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Figure 1. Aoruroides queenslandensis n. sp.: A. Adult female, entire; B. Female, oesophageal region; C. Egg; D. Adult male, entire; E. Male, anterior end; F. Male, posterior end. Abbreviation: ep, excretory pore. Scale-bars: A, 200 µm, B,D-F, 100 µm, C, 20 µm.

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Figure 2. Scanning electron micrographs of Aoruroides queenslandensis n. sp.: A. Female anterior end, showing enlarged second annule and marked separation from the remainder of the body posterior to second annule; B. Female mouth, showing eight cephalic papillae and hexagonal mouth; C. Male anterior end, showing numerous cervical projections; D. Male mouth, showing eight cephalic papillae and lateral amphidial apertures. Dorsal surface of nematode is uppermost in all micrographs.

(Figure 1F). Single testis directed posteriorly, reflexing anteriorly near anus, terminating near mid-body. Spicules absent. Anus 0.39–0.85 (0.61, 0.21) mm from posterior end of body. Tail initially subulate, then with subulate projection. Subulate portion, 0.32–0.68 (0.51, 0.15) long.

Discussion The female specimens reported here agree with Aoruroides Travassos & Kloss, 1958 in that they have a cephalic extremity comprised of a small first circumoral annule followed by an enormously enlarged second annule, a pyriform corpus, the isthmus twice the length of the corpus, the vulva near mid-body,

a relatively short vagina and ellipsoidal eggs. Although none of these characteristics is restricted to Aoruroides, the combination is diagnostic for this genus. Aoruroides has two described species, the type-species, A. philippinensis (Chitwood & Chitwood, 1934) Travassos & Kloss, 1958 described from Panesthia javanicum in the Philippines, and A. legionarius Kloss, 1966 described from Eublaberus sp. (Blaberidae) in Brazil. A. queenslandensis n. sp. closely resembles A. philippinensis in the shape of the oesophageal region, the presence of two uteri and their orientation within the body. However, three significant differences distinguish the two species. In A. philippinensis the nerve-ring is at the anterior end of the isthmus, just posterior to the base of the corpus, whereas in A. queenslandensis it is near the isthmus

69 mid-point. Secondly, A. philippinensis has the excretory pore 0.84 mm from the anterior end of the worm, whereas the excretory pore in A. queenslandensis is closer (0.53–0.77 mm) to the anterior end. Finally, the egg of A. philippinensis, as described by Chitwood & Chitwood (1934), apparently lacks the two marginal striations running parallel to the longitudinal axis seen in A. queenslandensis. Male thelastomatoids are often difficult to identify due to their lack of striking morphological characters and lack of morphological similarity to the female of the species. However, mating pairs have been found in copula confirming the association between the two sexes. Although no male has been described for A. philippinensis, the male A. queenslandensis is similar to that described for A. legionarius. Both worms have a clavate corpus leading into a short isthmus, and neither male has a spicule. In both A. queenslandensis and A. legionarius the testis originates near the cloaca and runs anteriorly. One significant taxonomic feature of the A. queenslandensis male is the presence of cuticular projections in the cervical region of the worm. These projections are quite distinctive and apparently are not seen in A. legionarius males. However, as A. philippinensis males have not been described, it is uncertain whether this morphological character can be used as a diagnostic character for A. queenslandenis males. A. queenslandensis and A. philippinensis have been found in adjacent geographical regions and the hosts for both are panesthiine cockroaches. The distribution of A. legionarius in a non-panesthiine blaberid, Eublaberus sp., from Brazil might cast doubt on the placement of A. legionarius within Aoruroides, but the morphological characteristics of A. legionarius do not suggest its removal from the genus.

Acknowledgements Aaron Jex was supported by several scholarships and grants: Queen Elizabeth II Centennial Scholarship (Government of British Columbia, Canada), University of Queensland International Postgraduate Research Scholarship, the International Postgraduate Research Scholarship (Government of Australia) and the Australian Biological Research Study. The authors would like to Rick Webb of the Centre for Microscopy and Microanalysis for his technical expertise involved in SEM work, Dr Geoff Monteith for his expertise in host identification and Peter Cook for his help in sample collection.

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