Tasmaniosoma fasciculum, 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 : 58-60

Tasmaniosoma fasciculum sp. n.

urn:lsid:zoobank.org:act:C6C55E40-6555-4146-9BB6-7401CFDD9858

Figs 1D, 1H, 5C, 15; map Fig. 26

Holotype. Male, Australia, Tasmania, Little Claytons Rivulet , 41°12'24"S 146°12'07"E ( DQ 330378) ± 25 m, 100 m, 27 December 2009, R. Mesibov & T. Moule, QVM 23 :51664.

Paratypes. 1 male, same locality as holotype but 41°12'28"S 146°12'12"E ( DQ 331377) ± 100 m, 100 m, 30 November 1997, R. Mesibov & T. Moule, QVM 23 :46644 ; 2 males, 1 stadium VI male, 2 stadium VI females, same details as holotype, QVM 23 :51665 .

Other material examined. 20 males and 3 females from 17 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, anvil-shaped process and two comparably sized combs of long, stout, rod-like setae on posterior surface, both directed distally.

Description. Male/female approximate measurements: length 12 / 11 mm, ring 12 paranota width 1.2/ 1.2 mm. Live and freshly preserved specimens with reddishbrown head and antennae and complex pattern of strongly contrasting yellow and brown patches on most rings (Figs 1D, 1H): prozonites have paired paramedian yellow patches with brown patches medially and laterally, metazonites have paired paramedian yellow patches anteriorly and posteriorly, strongly contrasting with dark brown patches marginally on paranota and more diffuse paramedian brown bands along posterior margin and just anterior to transverse furrow. Live specimens similarly coloured but yellow not so intense; in alcohol, long-preserved specimens completely decoloured.

Figure |5. Tasmaniosoma fasciculum sp. n., paratype males. A Right posterolateral view of gonopods in situ (ex QVM 23:46638) B lateral and slightly anterior and C medial views of left gonopod telopodite (ex QVM 23:46635). Scale bars = 0.2 mm.

As for T. armatum in most non-gonopod details, but relative widths tergite 6>5>(4,head)>(3,2)>collum, leg 6 tarsus 1.5 × as long as femur. Metatergite almost completely covered with three transverse rows of 10–12 large, low tubercles, each with a small seta near posterior edge. Ring 2 pit not apparent except as slight concavity near anterior margin of ring. No setae on anterior margin of ring 6 ( Fig. 5C ); leg 6 tab short, with a few fine setae; leg 7 tab long, thickened, with brush of stout setae.

Gonopod telopodite (Fig. 15) arching anteriorly, strongly narrowed at ca 1/4 telopodite height, tip divided into four processes: (a) small, subcylindrical, distally tapered solenomere arising on medial surface and directed distally, curving medially near tip; (b) thick, tab-like bulge arising posterolaterally and bearing a tight cluster of 6–8 long, stout, rod-like setae directed anterodistally and slightly laterally; (c) anvilshaped process arising on anteromedial surface, flattened anteroposteriorly, rounded medial end and pointed lateral end of “anvil” both curving posteriorly; (d) long, blade-like, acute process arising on anterolateral surface and directed distally. Second tight cluster of ca 15 stout, rod-like setae arising on posterior surface just basal to division of telopodite into processes, setae reaching almost as far distally as solenomere; sparse fine setae on posterior surface near base and along lateral surface to level of telopodite division into processes. Prostatic groove running on medial surface directly to solenomere base.

Female with sternites as wide as long.

Distribution. Known from eucalypt forest over ca 2000 km 2 in north central Tasmania to 550 m elevation ( Fig. 26 ). Not yet found west of the Dial Range, south of Maggs Mountain or east of the Birralee Road. Co-occurs with T. hickmanorum sp. n.

Etymology. Latin fasciculus, diminutive of fascis, “sheaf”, adjective, for the tight sheaf of stout, rod-like setae on the tip of the gonopod.

Remarks. I have not been able to recognise species-diagnostic features in long-preserved, decoloured females of T. fasciculum . As a result, I cannot confidently assign to T. fasciculum a number of possible female specimens from localities within the known range (in the QVM collection) because no there are no associated males. The description of the female (above) is based on three specimens found close to sites in the Gog Range and Dial Range where I have also collected males.

I may also have overlooked T. fasciculum outside its known range in north central Tasmania. In the field, an adult of this uncommon species can easily be mistaken for a stadium V or VI juvenile of the co-occurring T. hickmanorum sp. n.

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 26. A Localities as of 31 January 2010 for Tasmaniosoma cacofonix sp. n. (crosses), T. fasciculum sp. n. (squares), T. gerdiorivum sp. n. (triangles) and T. orientale sp. n. (open circles). See also Fig. 23. Scale bar = 50 km. B Map of Tasmania showing location of main map (rectangle).