Research Article
Print
Research Article
A new genus and species of native exotic millipede in Australia (Diplopoda, Polydesmida, Paradoxosomatidae)
expand article infoRobert Mesibov, Catherine A. Car§
‡ Queen Victoria Museum and Art Gallery, Launceston, Tasmania, Australia
§ Western Australian Museum, Welshpool, Australia
Open Access

Abstract

Taxidiotisoma portabile gen. n., sp. n. is described from scattered populations in New South Wales, Victoria and Tasmania, Australia. Populations of T. portabile in Victoria, Tasmania and parts of New South Wales occur in urban, suburban and agricultural areas, with no collections of the species in natural habitats in the same district. Taxidiotisoma portabile is likely to be a native exotic species whose home range is in eastern New South Wales.

Keywords

Diplopoda, Polydesmida, Paradoxosomatidae, New South Wales, Victoria, Tasmania, Australia

Introduction

We use the term “native exotic” for a species introduced and established well outside its native range, but still within its broader native region (Mesibov 2008, Car 2009). Three Australian paradoxosomatid millipedes clearly fit this description: Akamptogonus novarae (Humbert & de Saussure, 1869), Heterocladosoma bifalcatum (Silvestri, 1898) and Solaenodolichopus pruvoti (Brolemann, 1931).

Although its original range is still uncertain, A. novarae is believed to be native to eastern Australia (Hoffman 1979). It occurs in urban and suburban areas in New South Wales, Tasmania, Victoria and Western Australia (locality records in Mesibov 2006–2015), and has been introduced to New Zealand (Rowe and Sierwald 2006), the Hawaiian Islands (Shelley and Lehtinen 1998) and San Francisco, California, in the United States (Hoffman 1979).

Heterocladosoma bifalcatum is likely to be native to the Brisbane area in southeast Queensland (Mesibov 2008), but it is now found in the Sydney metropolitan area (Rowe and Sierwald 2006) and elsewhere in New South Wales (Mesibov 2006–2015).

Solaenodolichopus pruvoti is also likely to be native to the Brisbane area (Mesibov 2014). It was first described from a town in New Caledonia and is now well established in the Perth metropolitan area in Western Australia, 3600 km from Brisbane (Mesibov 2014).

Here a new genus and species of Australian paradoxosomatid is described which we suspect is native to eastern New South Wales, but which has also been collected in urban, suburban and agricultural areas in New South Wales, Tasmania and Victoria.

Materials and methods

“Male” and “female” in the text refer to adult individuals. In this paper, the labeling of the different structures on the gonopod mainly follows that of Car and Harvey (2013) for convenience, and is not intended to suggest homologies with podomeres nor, necessarily, with similarly labeled structures in other papers (Car and Harvey 2013, Car et al. 2013).

All specimens are stored in 75–80% ethanol in their respective repositories. Gonopod images were generated with a Leica MZ16A automontage imaging system using Leica Application Suite Version 3.7.0. Other photomicrographs are manually stacked composites, taken with a Canon EOS 1000D digital SLR camera mounted on a Nikon SMZ800 binocular dissecting microscope equipped with a beam splitter and processed with Zerene Stacker 1.04 software. Images were prepared for publication using GIMP 2.8. The locality map (Fig. 5) was prepared using ArcView 3.2 GIS.

Suppl. material 1 tabulates data for known specimen lots of the new species as of 30 March 2015 (data also available online in Mesibov 2006–2015). Locality details are given with latitude and longitude based on the WGS84 datum. Our estimate of the uncertainty for a locality is the radius of a circle around the given position, in metres or kilometres.

Abbreviations in text and Suppl. material 1 (all in Australia): AM = Australian Museum, Sydney; NMV = Museum Victoria, Melbourne; NSW = New South Wales; QVMAG = Queen Victoria Museum and Art Gallery, Launceston; Tas = Tasmania; Vic = Victoria.

Results

Order Polydesmida Pocock, 1887
Suborder Strongylosomatidea Brölemann, 1916
Family Paradoxosomatidae Daday, 1889
Subfamily Australiosomatinae Brölemann, 1916
Tribe Antichiropodini Brölemann, 1916

Taxidiotisoma Mesibov & Car, gen. n.

Type species

Taxidiotisoma portabile Mesibov & Car, sp. n., by present designation.

Other assigned species

None.

Diagnosis

In gonopod structure, Taxidiotisoma gen. n. is closest to Antichiropus Attems, 1911, Australodesmus Chamberlin, 1920, Pogonosternum Jeekel, 1965 and Pseudostrongylosoma Verhoeff, 1924 in the Australian paradoxosomatid fauna (see Remarks). Differs from Antichiropus in lacking a process on the lateral surface of the femorite, from Pogonosternum in having the distal portion of the acropodite divided into two rather than three branches, from Pseudostrongylosoma in having a divided solenomere, and from Australodesmus in having a Y-shaped solenomere rather than a flagellum-and-sheath solenomere.

Name

Greek taxidiotis, “traveller” + soma, Greek “body’, often used as an ending for generic names in Paradoxosomatidae; neuter gender.

Remarks

The gonopod of Taxidiotisoma portabile sp. n. appears most similar to that of species in Antichiropus Attems, 1911, Australodesmus Chamberlin, 1920, Pogonosternum Jeekel, 1965 and Pseudostrongylosoma Verhoeff, 1924, all four of which have been assigned to Antichiropodini by Jeekel (1968, 1979). In all five genera a long, well-demarcated femorite abruptly ends in several prominent processes, one of which is the solenomere. In Antichiropus there may be more than one non-solenomere process, but there is always one that arises on the lateral surface of the femorite; this lateral process is lacking in T. portabile sp. n. In addition, Antichiropus species have a long, free solenomere that tends to spiral, whereas that of T. portabile sp. n. is short and Y-shaped. In Pogonosternum species there are three acropodite branches, while in Australodesmus, Pseudostrongylosoma and Taxidiotisoma gen. n., there are only two, of more or less equal size. Pseudostrongylosoma sjoestedti Verhoeff, 1924 has an undivided solenomere. In T. portabile sp. n. the solenomere is Y-shaped, i.e. divided into two sub-branches spaced well apart and not greatly different in size, while in Australodesmus divergens Chamberlin, 1920 the solenomere is divided into a thin, flagellum-like branch carrying the terminus of the prostatic groove and a much larger, flattened, cowl-like branch sheathing the thinner branch.

Taxidiotisoma portabile sp. n. is also characterized by a peculiar flattening of the head in lateral view, the result of depression of the clypeus.

Taxidiotisoma portabile Mesibov & Car, sp. n.

Figs 1, 2, 3, 4

Holotype

Male, Munmorah State Reserve, NSW, 0.5 km along beach track opposite National Parks and Wildlife Service Station turnoff, site MUNI01/09, -33.2094 151.5894 ±25 m, pitfall 13–23 May 1998, L. Wilkie, AM KS.94041.

Paratypes

2 males, 1 female, details as for holotype but 21 April - 1 May 1997, site MUNI01/10, AM KS.93366.

Other material

100 males, 22 females and 5 juveniles (see Suppl. material 1 for details).

Description

Male/female approximate measurements: length ca 20/20 mm, maximum midbody width 1.5/1.8 mm. Body shiny (Fig. 1), colour in alcohol medium brown, dark brown either side of waist and dorsal portion of sides, dorsally with large, light brown patch spanning rear of metazonite and front of prozonite; antennae medium brown, darker distally; legs tan to pale brown, darker distally.

Figure 1.

Taxidiotisoma portabile sp. n., male ex NMV K-12071. A Habitus B dorsal views of midbody rings C lateral views of midbody rings; anterior to right D Lateral views of head E oblique views of head. Scale bars: 2.5 mm (A); 1 mm (B, C); 0.5 mm (D, E).

Male with vertex and frons almost bare, clypeus sparsely setose; clypeus strongly depressed, head truncate in profile (Figs 1D, 1E); vertigial sulcus distinct, ending above level of antennal sockets; post-antennal groove moderately deep; antennal sockets separated by 1.3× socket diameter. Antenna slightly clavate, reaching dorsally only to rear of collum; antennomeres with relative lengths (2=3)>(4=5=6); 6 thickest but 5 and 6 subequal in apical width. Collum with subparallel anterior and posterior margins in dorsal view, strongly convex, lateral corner rounded. Head very slightly narrower than collum; collum to ring 18 nearly uniform in width, rings 2 and 3 slightly narrower. Ring 2 paranotum a thin, longitudinal ridge set low on ring, a little below collum corner; no paranota on other rings. No trace of pleural keels. Prozonites and metazonites (Fig. 1B, C) smooth, bare; transverse furrow at ca 2/3 metazonite length from waist, indistinct, not extending laterally as far as ozopores; waist very short, shallow, indistinctly sculptured with longitudinal ridges; limbus a narrow, thin, continuous sheet. Pore formula normal; ozopore very small, round, opening just above 1/2 ring height and just posterior to 1/2 metazonite length; slight bulging of ring around ozopore. Spiracles on diplosegments above and just anterior to leg bases; anterior spiracle ovoid, long axis subvertical, rim produced anterodorsally as rounded tab; posterior spiracle subtriangular, rim low; spiracular filters slightly emergent. Midbody sternites very sparsely setose, longer than wide, cross impressions subequal in width and depth; no cones or projections on any sternites. Midbody legs with relative podomere lengths (prefemur=femur)>tarsus>(postfemur= tibia); femur ca 1.2× as long as tarsus; anterior leg prefemora only very slightly swollen dorsally. Pre-anal ring sparsely setose; epiproct extending past anal valves, in dorsal view tapering and truncate, tip ca 1/4 width of pre-anal ring; hypoproct broadly paraboloid; spinnerets in rectangular array, wider than long. Leg 1 (Fig. 2A) with large, pointed process on medial femur surface, directed mediodistally and slightly anteriorly.

Figure 2.

Taxidiotisoma portabile sp. n., male ex NMV K-12071. A Leg 1 B Sternal lamella on ring 5, posterior view. Scale bars: 0.2 mm.

Gonopore small, round, opening on slight distomedial bulge of leg 2 coxa. Sternal lamella (Fig. 2B) wide, >90% of width between leg 4 bases on ring 5, strongly leaning anteriorly; lateral margins straight, vertical; corners rounded; ventral margin slightly raised medially. Dense brush setae on tibiae and tarsi of all legpairs except legpair 1 and last 2 legpairs; brush setae long, fine, curving distally.

Gonopod aperture just wide enough to accommodate gonocoxae, ca 1/2 ring 7 prozonite width. Gonopod telopodites (Figs 3, 4) straight, parallel, reaching leg 6 bases when retracted; sternite between legpairs 6 and 7 excavate. Gonocoxa (C) robust, much thicker than femorite but shorter, ca 1/2 femorite length; prefemur (PF) ovoid, ca 1/3 femorite length, leading directly into femorite with no noticeable process at femorite base; femorite (F) ca 2/3 acropodite length, upright, cylindrical; non-seminiferous branch (NSB) slightly shorter than solenomere (S), curved, thickest mid-length with asymmetrical pointed tip and distinct “elbow” at base; S broad, proximal end as thick as femorite, curved, divided at mid-length into shorter, pointed process (s1) carrying prostatic groove, finger-like in anterior view, and longer, broader, cowl-shaped process (s2) carrying noticeable tooth (t) at about mid-length. Prostatic groove running straight along anteromedial surface of telopodite, looping slightly into base of NSB before touching base of S, then running on medial surface of S to tip of s1 (Fig. 4).

Figure 3.

Taxidiotisoma portabile sp. n., holotype male (AM KS. 94041), left gonopod. A posterior B anterior C medial and D lateral views. Abbreviations: C coxa, F femorite, NSB non-seminiferous branch, PF prefemur, S solenomere, s1 process with prostatic groove, s2 cowl-shaped process. Scale bars: 0.5 mm.

Figure 4.

Taxidiotisoma portabile sp. n., holotype male (AM KS. 94041), detail of left gonopod tip, anterior view. Abbreviations: F femorite, NSB non-seminiferous branch, S solenomere, s1 process with prostatic groove, s2 cowl-shaped process, pg prostatic groove, t tooth. Dotted line denotes path of prostatic groove. Scale bar: 0.2 mm.

Female with depressed clypeus, without leg modifications; epigynum not raised, nearly straight, ca 1/4 ring 2 width; cyphopods not examined.

Distribution

Taxidiotisoma portabile sp. n. has been collected over a north-south range of ca 1000 km in eastern Australia (Fig. 5). A set of localities in eastern New South Wales (filled circles in Fig. 5) are in natural habitats in national parks or partly disturbed rangeland. Eight localities outside that set (unfilled circles in Fig. 5) are in cities, towns or long-cleared agricultural areas. These eight localities are numbered in Fig. 5 as follows:

  1. A small area of riparian vegetation on the Macquarie River, surrounded by farmland;

  2. The town of Cowra (collecting site not more exactly known), surrounded by farmland;

  3. The campus of Charles Sturt University in the city of Wagga Wagga;

  4. A small area of remnant native vegetation in the city of Wagga Wagga;

  5. Disturbed native vegetation on a roadside adjoining a large artificial lake;

  6. A recreation reserve in the suburbs of the city of Melbourne;

  7. A park in the centre of the city of Melbourne;

  8. Riparian parkland under a highway bridge in the town of Perth, surrounded by farmland.

Figure 5.

Known localities for Taxidiotisoma portabile sp. n. as of 30 March 2015 (filled and open circles). The eight numbered localities are discussed in the text. Geographic projection; inset shows location of main map.

Sampling in the areas surrounding and between these eight locations, both by the authors and by other collectors, has not yet yielded any specimens of T. portabile sp. n. We therefore suspect that the species was introduced to these locations from its native range in eastern New South Wales.

Name

Latin portabilis, “portable”, adjective. This species is almost certainly being transported to new areas in Australia by cars or trucks.

Remarks

We do not know whether the eight “outlying” New South Wales, Tasmanian and Victorian samples (Fig. 5) represent long-established populations or ephemeral colonies, but the broad scattering of records suggests that this species will be found elsewhere in Australia in coming years.

Acknowledgements

We thank Graham Milledge (Australian Museum) and Peter Lillywhite and Catriona McPhee (Museum Victoria) for the loan of specimens, Wade Clarkson (Riverside, Tasmania) for alerting RM to the Tasmanian specimen of T. portabile sp. n., and Henrik Enghoff and Sergei Golovatch for valuable comments on a draft of the manuscript. This study was funded by the authors.

References

  • Car CA (2009) Keeled millipedes (Diplopoda: Polydesmida: Paradoxosomatidae) in New South Wales. General and Applied Entomology 38: 1–7.
  • Car CA, Harvey MS (2013) A review of the Western Australian genus Boreohesperus (Diplopoda, Polydesmida, Paradoxosomatidae). ZooKeys 290: 1–19. doi: 10.3897/zookeys.290.5114
  • Hoffman RL (1979) An Australian polydesmoid milliped in San Francisco (Paradoxosomatidae). Wasmann Journal of Biology 37(1–2): 55–58.
  • Jeekel CAW (1968) On the Classification and Geographical Distribution of the Family Paradoxosomatidae (Diplopoda, Polydesmida). C.A.W. Jeekel, Rotterdam, 162 pp.
  • Jeekel CAW (1979) Notes on the classification of some little-known Australian paradoxosomatid genera (Diplopoda, Polydesmida). Journal of Natural History 13: 649–658. doi: 10.1080/00222937900770481
  • Mesibov R (2008) Diversity of Queensland paradoxosomatid millipedes (Diplopoda:Polydesmida: Paradoxosomatidae). Australian Entomologist 35: 37–46.
  • Mesibov R (2014) The millipede genus Solaenodolichopus Verhoeff, 1924 (Diplopoda, Polydesmida, Paradoxosomatidae). 1. New genus diagnosis and redescriptions of named species. European Journal of Taxonomy 83: 1–36. doi: 10.5852/ejt.2014.83
  • Rowe M, Sierwald P (2006) Morphological and systematic study of the tribe Australiosomatini (Diplopoda: Polydesmida: Paradoxosomatidea: Paradoxosomatidae) and a revision of the genus Australiosoma Brölemann. Invertebrate Systematics 20: 527–556. doi: 10.1071/IS05034
  • Shelley RM, Lehtinen PT (1998) Introduced millipeds of the family Paradoxosomatidae on Pacific Islands (Diplopoda: Polydesmida). Arthropoda Selecta 7(2): 81–94.