Tasmaniosoma fragile, 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 : 60-62

Tasmaniosoma fragile sp. n.

urn:lsid:zoobank.org:act:066F3EC2-2202-410C-B7A5-AA99E4C448A6

Fig. 16; map Fig. 25

Holotype. Male, Australia, Tasmania, Apsley River , 41°51'16"S 148°12'05"E ( EP 996655) ± 100 m, 130 m, 20 July 1988, R. Mesibov, QVM 23 :51666.

Paratypes. 1 male, details as for holotype, QVM 23 :46766 ; 1 male, same details but 41°51'16"S 148°11'47"E ( EP 992655) ± 100 m, 19 July 1988, QVM 23 :46765 .

Other material examined. 5 males and 3 females from four other localities (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 and three comparably sized combs of long, stout, rod-like, setae: distally directed on lateral and anterior surfaces, basally directed on posterior surface.

Description. Male/female approximate measurements: length 12/ 14 mm, ring 12 paranota width 1.5/ 1.8 mm. Live colour not known; in alcohol, uniformly pale yellowish brown.

Most non-gonopod details as for T. armatum , but antennomere 3 longest, relative overall widths tergite 6>5>4>(3,2,head)>collum, ring 12 paranota 1.4 × as wide as prozonite, metatergite ca 2.8 × as wide as long, prefemora not as swollen dorsally, leg 6 tarsus 1.3 × as long as femur and femur longer than prefemur. Metatergite almost completely covered with three transverse rows of ca 10 large, low tubercles, each with small seta near posterior edge. Ring 6 sternite with a few fine setae along anterior edge; leg 6 tab short, without setae; leg 7 tab long, thickened, with brush of stout setae. Ring 7 sternite with paired paramedian brushes of fine setae just posterior to gonopod aperture.

Figure |6. Tasmaniosoma fragile sp. n., paratype males. A Posterior view of gonopods in situ (ex QVM 23:46766) B medial view of left gonopod telopodite, setation omitted for clarity (ex QVM 23:46767). Scale bars = 0.2 mm. Th e ‘hole’ at the top of each telopodite is the broken-off tip of the distal extension of the central process.

Gonopod telopodite (Fig. 16) straight, slender, slightly narrowed just above base, divided at ca 2/3 telopodite height into four major processes: (a) short, subcylindrical solenomere arising on medial surface and directed distally; (b) blade-like, acute process arising on anteromedial surface just basal to solenomere origin and directed anterodistally; (c) large central process with posterodistally sloping flat surface, extending medially as round-edged, tab-like structure just posterior to solenomere and extending distally as acute, subcylindrical, posteriorly curving structure; (d) long, blade-like, acute, posterolaterally curving process arising just anterolateral to central process. Three tight clusters of stout, rod-like setae: ca 10 arising on lateral surface just basal to solenomere origin and directed distolaterally, 15–20 arising on posterior surface a little basal to lateral cluster and directed posterobasally, and 5–10 arising on anterolateral surface near apex and directed distally. Sparse fine setae running from posterior surface near base anterodistally along lateral surface to ca 1/2 telopodite height. Prostatic groove running on medial surface directly to solenomere base.

Female with legs 2 missing in the three known specimens.

Distribution. Known from six localities over ca 1000 km 2 in eastern Tasmania up to 630 m elevation, from Mt Allen close to the east coast at Douglas River to ca 10 km east of Campbell Town in the Midlands, and south in the Eastern Tiers to the Swansea area ( Fig. 25 ). Sympatric with T. armatum , co-occurs with T. orientale sp. n.

Etymology. Latin fragilis, “breakable”, adjective. Th e stout, rod-like setae on the gonopod are usually broken. Females are readily distinguished from those of sympatric, similarly sized T. armatum and T. orientale sp. n. by the presence of prominent tubercles on T. fragile tergites.

Figures

Figure 25. A Localities as of 31 January 2010 for Tasmaniosoma barbatulum sp. n. (squares), T. clarksonorum sp. n. (crosses), T. decussatum sp. n. (open circles) and T. fragile sp. n. (triangles). See also Figs 23 and 26. Scale bar = 50 km. B Map of Tasmania showing location of main map (rectangle).