Tasmaniosoma hickmanorum, Mesibov, 2010

Mesibov, Robert, 2010, The millipede genus Tasmaniosoma Verhoeff, 1936 (Diplopoda, Polydesmida, Dalodesmidae) from Tasmania, Australia, with descriptions of 18 new species, ZooKeys 41 (4), pp. 31-80 : 66-68

Tasmaniosoma hickmanorum sp. n.

urn:lsid:zoobank.org:act:271BC147-2CDE-4392-91E0-F9A5930643F0

Figs 1E, 1I, 5D, 19; map Fig. 23

Holotype. Male, Australia, Tasmania, Mossy Marsh Creek , 42°18'34"S 146°22'44"E ( DP 487155 ) ± 100 m, 630 m, 18 February 1994, R. Mesibov, QVM 23 :51669.

Paratypes. 6 males, details as for holotype, QVM 23 :46089 ; 3 males, Tarraleah, Tas, 42°18'19"S 146°25'52"E ( DP 530160 ) ± 10 km, May 1952, V. V. Hickman, from dead fern leaves, QVM 23 :46042 ; 1 male, same details but under logs, QVM 23 :46043 ; 8 males, 6 females, same details but 26 December 1952 to 2 January 1953, QVM 23 :46044 ; 5 males, Tarraleah, Tas, 42°18'44"S 146°21'48"E ( DP 474161 ) ± 100 m, 690 m, 16 April 1992, R. Mesibov, plot 1, QVM 23 :46057 ; 2 males, same details but 42°18'11"S 146°21'48"E ( DP 474162 ) ± 100 m, 700 m, plot 3, QVM 23 :46058 ; 1 male, 1 female, same details but 42°17'58"S 146°21'48"E ( DP 474166 ) ± 100 m, 710 m, 18 April 1992, plot 11, QVM 23 :46060 ; 1 male, 1 female, same details but 42°16'27"S 146°21'35"E ( DP 471194 ) ± 100 m, 750 m, 2 May 1992, plot 47, QVM 23 :46065 ; 1 male, same details but 42°16'21"S 146°21'36"E ( DP 471196 ) ± 100 m, 760 m, plot 45, QVM 23 :46066 ; 2 males, same details but 3 May 1992, plot 52, QVM 23 :51668 ; 1 male, same details but 42°16'08"S 146°21'40"E ( DP 472200 ) ± 100 m, 790 m, plot 50, QVM 23 :46068 ; 2 males, same details but 4 May 1992, plot 55, QVM 23 :46069 ; 1 male, same details but 42°16'24"S 146°21'57"E ( DP 476195 ) ± 100 m, 720 m, 8 May 1992, plot 73, QVM 23 :46071 .

Other material examined. 154 males, 67 females, 3 stadium VI males and 1 stadium VI female from 120 other sites (see Appendix).

Diagnosis. Metatergites with three transverse rows of large, low, contiguous tubercles; leg 7 sternal tab with dense brush of stout, rod-like setae; gonopod telopodite with central, flattened process notched into three parts, a single comb of long, stout, rod-like, setae on posterior surface, and anteromedial process lying obliquely against central process.

Description. Male/female approximate measurements: length 16/ 16 mm, ring 12 paranota width 1.7/ 1.7 mm. Freshly preserved specimens finely mottled or reticulated reddish-brown (Fig. 1E); head reddish above, antennae dark brown, legs pale, reddish distally; prozonite with paired paramedian yellowish patches contrasting with adjoining dark brown patches; metatergites sometimes with paired paramedian, yellowish patches near anterior edge; rings laterally (Fig. 1I) finely mottled reddishbrown with small, pale patch under paranotal margin. In alcohol, pale reddish or decoloured.

Male as for T. armatum in most non-gonopod details, but overall widths 6>5>(4,head)>(3,2,collum), antennomere 3 longest, ring 12 paranota 1.4 × as wide as prozonite, leg 6 tarsus 1.4 × as long as femur. Anterior margin of metatergite smoothly curving into lateral edge of paranota (shoulder less distinct than in T. armatum ); metatergite almost completely covered with three transverse rows of 10–12 large, low tubercles, each with small seta near posterior edge. Ring 6 sternite ( Fig. 5D ) with no

Figure |9. Tasmaniosoma hickmanorum sp. n. A Posterolateral view of gonopods in situ, voucher male ex QVM 23:46055 B anterior view of tip of left gonopod telopodite, paratype male ex QVM 23:46065 C anterior view of left gonopod telopodite, paratype male ex QVM 23:46057. Setation not shown in C dashed line marks course of prostatic groove. Scale bars: A, C = 0.2 mm, B = 0.1 mm.

leg 6 tab; leg 7 tab long, thickened, with brush of stout setae; anterior margin without setae but with medial notch, about 1/3 width of margin.

Gonopod telopodite (Fig. 19) straight, in cross-section with posterior, anterolateral and anteromedial longitudinal ridges, divided at ca 3/4 telopodite height into tight cluster of four processes: (a) small, slender, acute, medial solenomere, directed distally but curving laterally; (b) large, anteroposteriorly flattened laminate process divided by notches into three acute portions, their lengths decreasing from anteromedial to posterolateral; (c) large, blade-like, acute lateral process curving laterally; (d) blade-like, acute process arising near medial edge of anterior surface, directed distolaterally and closely pressed to anterior surface of laminate process. Sparse group of fine setae near base posterolaterally; ca 20 fine setae laterally from ca 2/3 to ca 3/4 telopodite height; two dense, adjoining clusters of stout, rod-like setae on posterior surface ridge at ca 2/3 telopodite height, the basal cluster of 10–15 setae directed mainly posterobasally, the distal cluster of ca 30 setae directed distally with a few outlying setae in line extending towards base of lateral process. Prostatic groove running along medial surface more or less directly to solenomere base.

Female with sternites as wide as long, legs 2 usually missing (Mesibov, in preparation).

Distribution. Often locally abundant in wet eucalypt forest (with or without a cool temperate rainforest understorey), riparian tea-tree forest and coastal dune scrub over the whole of western Tasmania (ca 28 000 km 2), from the northern part of King Island (northwest of the main island of Tasmania) to Melaleuca in the far south, with an elevation range from sea level to at least 940 m ( Fig. 23 ). Part of the eastern range boundary is congruent with the Mersey Break, a major biogeographical divide in north central Tasmania ( Mesibov 1999; species coded as Tasmaniosoma sp. 2). T. hickmanorum is sympatric with T. fasciculum sp. n., broadly parapatric with T. armatum along the Mersey Break, and at some localities tightly parapatric with T. compitale sp. n. (Mesibov, in preparation), with an overlap zone less than 500 m wide.

T. hickmanorum is remarkably abundant in Eucalyptus globulus and E. nitens plantations established on sites converted from native forest. I have not yet found it in plantations established on former pasture.

Etymology. In honour of V. V. Hickman (1894–1984) and his son J. L. Hickman (1926–2007), Tasmanian invertebrate zoologists and collectors of this millipede species and many others.

Remarks. This species varies a little in size and colouration over its large range, and in some populations females are smaller than males. Gonopod structure, however, is nearly constant.

Long-preserved, decoloured females of T. hickmanorum sp. n. and T. compitale cannot be separated. Live and freshly preserved females can be distinguished by colour: T. hickmanorum reddish-brown with only a small yellowish patch under paranotal margin (Fig. 1I), T. compitale yellowish-brown with a large, prominent yellowish patch just under the paranotal margin (Fig. 1G).

Figures

Figure 5. Male ring 6, ventral view (anterior to top) showing variation in structure. A Tasmaniosoma armatum Verhoeff, 1936; no leg 6 tab; short, thin leg 7 tab with brush of fine setae; paired and raised brushes of fine setae medially on anterior margin of sternite B T. barbatulum sp. n.; short leg 6 tab with a few fine setae; long, thickened leg 7 tab with brush of stout setae; a few scattered setae on anterior margin C T. fasciculum sp. n.; short leg 6 tab with a few fine setae; long, thickened leg 7 tab with brush of stout setae; no setae on anterior margin D T. hickmanorum sp. n.; no leg 6 tab; long, thickened leg 7 tab with brush of stout setae; anterior margin with wide median notch. Scale bars = 0.2 mm.

Figure 23. A Localities as of 31 January 2010 for Tasmaniosoma hickmanorum sp. n. (squares), T. compitale sp. n. (stars) and T. armatum Verhoeff, 1936 (crosses). Scale bar = 100 km. B Preliminary mapping of eastern parapatric boundary between T. compitale sp. n. (stars) and T. hickmanorum sp. n. (squares). Bounding rectangle as in map (A); scale bar = 20 km.