Tasmaniosoma gerdiorivum, 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 : 62-64

Tasmaniosoma gerdiorivum sp. n.

urn:lsid:zoobank.org:act:6333E909-8104-403A-B6C3-50FB376FB357

Fig. 17; map Fig. 26

Holotype. Male, Australia, Tasmania, Weavers Creek area , 41°25'37"S 147°22'16"E ( EQ 309136) ± 100 m, 540 m, 23 March 1995, R. Mesibov, QVM 23 :51667.

Paratypes. 6 males, 1 female, details as for holotype, QVM 23 :46675 ; 1 male, 1 female, same details but 41°26'00"S 147°21'55"E ( EQ 304129) ± 100 m, 700 m, 4 August 1994, QVM 23 :46667 ; 3 males, 4 females, same locality but 41°24'09"S 147°22'59"E ( EQ 319163) ± 100 m, 970 m, 8 January 1995, R. Mesibov & T. Moule, QVM 23 :46669 ; 2 males, same details but 41°26'58"S 147°22'47"E ( EQ 316111) ± 100 m, 470 m, 22 March 1995, R. Mesibov, QVM 23 :46671 ; 1 male, same details but 41°27'01"S 147°23'04"E ( EQ 320110) ± 100 m, 530 m, QVM 23 :46672 ; 2 males, same details but 41°27'27"S 147°23'13"E ( EQ 322102) ± 100 m, 440 m, QVM 23 :46673 ; 1 male, same details but 41°26'19"S 147°22'04"E ( EQ 306123) ± 100 m, 710 m, 23 March 1995, QVM 23 :46674 .

Other material examined. 66 males and 15 females from 39 other sites (see Appendix).

Diagnosis. Metatergites with three weakly developed, transverse rows of low tubercles, gonopod telopodite apex divided into cluster of four processes including broad, flattened solenomere, the most lateral process directed bent laterally.

Description. Male/female approximate measurements: length 10/ 11 mm, ring 12 paranota width 0.9/1.0 mm. Live colour very pale yellow with sparse, reddish mottling and reticulation on metatergites, mainly along posterior margin, antennae light brown and head pinkish-red dorsally; in alcohol, pale yellowish-brown or completely decoloured.

Male as for T. armatum in most non-gonopod details, but overall widths tergite 6>head>5>4>(3,2)>collum, antennomere 3 longest, leg 6 tarsus 1.5 × as long as femur, femur longer than prefemur, prefemoral swellings not apparent posterior to ring 11. Ring 12 paranota 1.3 × as wide as prozonite; paranotum with distinct shoulder anteriorly, almost quadrate, lateral margin almost straight; metatergite almost completely covered with three transverse rows of 10–12 large, very low tubercles, each with small seta near posterior edge, but tubercles hard to detect with light microscopy. Ring 6 ster-

Figure |7. Tasmaniosoma gerdiorivum sp. n., paratype males ex QVM 23:46675. A Posterior view of gonopods in situ B medial view of left gonopod telopodite. Setation not shown in B dashed line marks course of prostatic groove. Scale bars = 0.1 mm. In A, the bends in the three flattened terminal processes are a preparation artifact; in wet specimens the bent portions seen in (A) are nearly planar.

nite as for T. armatum but with marginal band of fine setae along anterior edge of sternite; at high magnification, band is seen to consist of four evenly spaced, loose clusters.

Gonopod telopodite (Fig. 17) straight, stout, slightly flattened anteroposteriorly; base extended posteriorly and laterally as shelf, concave upwards, with thickened margin; anterior surface with gently convex medial extension at ca 1/2 telopodite height. Telopodite divided at ca 3/4 height into four processes: (a) mediolaterally flattened, tab-like solenomere arising medially, the distal edge subtriangular; (b) anteroposteriorly flattened process arising just lateral to solenomere with acute apex and short, shelf-like posterior extension at base; (c) long, blade-like, bluntly acute, mediolaterally flattened anterolateral process; (d) rod-like, acute process arising just anterolateral to anterolateral process. Sparse tract of fine setae running from basal shelf anterodistally to ca 1/2 telopodite height on lateral surface; a few fine setae on posterolateral surface at ca 1/2 telopodite height. Prostatic groove running on medial surface more or less directly to solenomere base and terminating at apex of triangle on distal solenomere edge.

Female with posterior margin of epigynum produced as rectangular process almost as long as posterior margin.

Distribution. Sometimes locally abundant in wet eucalypt and subalpine forest over ca 1500 km 2 in northeast Tasmania from 80 m to at least 1050 m elevation ( Fig. 26 ). Th e western limit of this distribution coincides approximately with the biogeographical boundary known as the East Tamar Break ( Mesibov 1994, 1997). T. gerdiorivum occurs ca 5 km from the sea in the north of its range; it has not yet been found east of Mt Saddleback or south of the North Esk River. It co-occurs with T. armatum and T. clarksonorum sp. n. in the west of its range, and may be parapatric with T. cacofonix sp. n. and T. decussatum sp. n. in the east.

A male of T. gerdiorivum has been found at Gardners Ridge in north central Tasmania, at least 60 km west of all other known localities. Th is specimen may be from a translocated population, or it may indicate a natural disjunction in the T. gerdiorivum range. A similar northeast-north central disjunction has been found in the distribution of Lissodesmus devexus Mesibov 2006 ( Mesibov 2006) .

Etymology. Latin gerdius, “weaver”, + rivus, “stream”, noun used as adjective, after the type locality, Weavers Creek.

Figures

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).