Tasmaniosoma anubis, Mesibov, Robert, 2015

Mesibov, Robert, 2015, Three new species of Tasmaniosoma Verhoeff, 1936 (Diplopoda, Polydesmida, Dalodesmidae) from northeast Tasmania, Australia, ZooKeys 488, pp. 31-46 : 33-36

Taxon classification Animalia Polydesmida Dalodesmidae

Tasmaniosoma anubis sp. n. Figs 1A, D, 2A, D, E, 3

Holotype.

Male, Trevallyn Nature Recreation Area, Tas, -41.4417 147.0800 ± 25 m (Google Earth), 150 m a.s.l., 21 June 2014, R. Mesibov, QVM 23:53863 (ex QVM 23:53817)

Paratypes.

15 males, 28 females, details as for holotype, QVM 23:53817.

Other material.

41 males and 51 females (see Suppl. material 1 for details).

Diagnosis.

Nominate member of the " anubis group" within Tasmaniosoma (see Discussion), distinguished from Tasmaniosoma clarksonorum , Tasmaniosoma compitale , Tasmaniosoma fasciculum , Tasmaniosoma hickmanorum and Tasmaniosoma nicolaus sp. n. by the absence of a distally directed cluster of stout, rod-like setae on the posterior surface of the gonopod telopodite; from Tasmaniosoma barbatulum by the presence of a lateral apical process and by the absence of a setal cluster on the anterior telopodite surface; from Tasmaniosoma fragile by the absence of a setal cluster on the anterior telopodite surface; and from all other " anubis group" members by the presence of an anteromedially directed tab on the anterior telopodite surface.

Description.

Male/female approximate measurements: length 10/10 mm, midbody paranota width 1.2/1.1 mm, maximum vertical diameter 1.1/1.1 mm. Live and freshly preserved adults with reddish brown head and antennae; body (Fig. 1A, D) with pale, yellowish brown ground colour, reddish brown anterolateral margins on paranota, reddish brown paramedian spots or short oblique streaks dorsally; legs darkening to light reddish brown distally. Reddish brown colouring fades in alcohol; long-preserved animals more or less uniformly pale yellowish brown, sometimes with a pair of yellowish paramedian spots on each metatergite.

Male with head sparsely setose; antennal sockets slightly impressed, separated by ca 2 × socket diameter; antennal groove short and shallow. Antenna slender, slightly clavate, when manipulated reaching back to ring 3; antennomere 6 widest, relative antennomere lengths (2,3,6)>(4,5). Collum from above reniform, convex anteriorly, posterior corner rounded. Tergites 2-4 distinctly narrower than more posterior metatergites; overall ring widths 6>(5,head)>(2,4)>(3,collum); rings 6-15 about same width, 16-18 narrowing. In lateral view, margin of ring 2 tergite slightly lower than margins of collum and ring 3 tergite. Ring 2 ventrally on either side without obvious pit. Ring suture and waist distinct on diplosegments (Fig. 1D), no longitudinal striations on waist; prozonites smooth; metatergites with three transverse rows of ca 12 low, rounded tubercles; posterior metatergal margin slightly emarginate medially. Limbus (Fig. 2E) composed of minute, sharply pointed triangular tabs with jagged, pointed margins. Midbody paranota extend metatergite to ca 1.3 × width of prozonite; paranota slightly inflated, marginal groove distinct, anterior corner smoothly convex, posterior corner smoothly convex without projecting posteriorly on any rings, with 1-2 very small tooth-like projections, each bearing small seta; lateral margin very slightly convex, in lateral view slightly oblique (anterior lower) at ca 3/4 ring height. Pore formula 5, 7, 9, 10, 12, 13, 15-18; ozopore small, round, opening dorsolaterally close to margin near posterior corner of paranotum. Spiracles (Fig. 2D) small, round, opening on low, dome-like projections; on diplosegments, projections arise just above and anterior to first leg and about midway between leg bases. Sternites moderately setose with setae longer on anterior rings; sternite wider than long, transverse impression distinct, longitudinal impression indistinct. Anterior legs with prefemur greatly swollen dorsally, femur less so; swellings begin leg 3, decrease gradually to ca leg 15. Midbody legs with tarsus long, slightly curved, ca 1.6 × as long as femur; relative podomere lengths tarsus>femur>prefemur>>(postfemur, tibia). Sphaerotrichomes on tarsus and tibia of anterior legs, shafts tapering to point and inclined strongly towards podomere surface. Sparse brush setae on coxa/trochanter, prefemur, base of femur; brush setae unbranched, tapering to blunt point. Pre-anal ring moderately setose; hypoproct subtrapezoidal; epiproct from above tapering smoothly to rounded tip, extending slightly past anal valves. Spinnerets in square array.

Gonopore on distomedial bulge of leg 2 coxa, protected by tall, thin cowl. Short brushes of setae on sternite between legpairs 4 and 5. Legs 6 and 7 bases (Fig. 2A) well- and equally separated; no sternal tab by leg 6; tall, rounded sternal tab by leg 7 with medial brush of thick, rod-like, pointed setae; leg 7 coxa with short, rounded distomedial bulge.

Gonopod aperture ovoid, ca 1/2 as wide as ring 7 prozonite, posterolateral margin raised. Gonocoxa short, subcylindrical, slightly tapering distally. Telopodites (Fig. 3) almost straight, parallel; extending nearly to leg 6 bases when retracted. Telopodite straight, subcylindrical, divided at about 3/4 telopodite height into three major processes: (a) short, slightly helicoid, pointed solenomere posteromedially, directed distally; (b) large, wide, anteroposteriorly flattened central process with apex twisted and flattened mediolaterally with rounded apical margin and narrow bursa-like fold at apex base, and with medial margin of central process curving posteriorly as rounded tab; (c) long, rod-like, tapering, apically rounded lateral process directed distally and slightly laterally. Telopodite projecting posteriorly at base as thin shelf, concave distally. Anterior surface of telopodite at about 2/3 telopodite height with tapering, anteromedially directed tab, longer than wide. Sparse, fine, mainly short setae on lateral and posterolateral surfaces to about 1/2 telopodite height, and on basal shelf. Two closely packed clusters of stout, rod-like, pointed setae: one (ca 12 setae) on posterior telopodite surface, arising just over 1/2 telopodite height and directed basally, the other (ca 10 setae) arising posterolaterally at level of solenomere base and directed distally and slightly posteriorly. Prostatic groove running more or less straight to base of solenomere on medial surface.

Female with legs more slender and prefemora and femora not swollen. Epigynum ca 1/3 width of ring 2, posterior margin produced medially as small, rounded triangle with irregular margin. Cyphopods not examined. (See also Remarks, below.)

Distribution.

Eucalypt forest and woodland within a range envelope of <12 km in the city of Launceston, Tasmania, with a core habitat area of <6 km2 (Figs 4A, 5A). Locally abundant in the core habitat area and readily found in bark litter at the bases of Eucalyptus viminalis trees (Fig. 4B). Co-occurs with Tasmaniosoma armatum and the introduced julid millipedes Ommatoiulus moreleti (Lucas, 1860) and Cylindroiulus spp.

Name.

Greek “Anubis”, a jackal-headed god of ancient Egypt; noun in apposition. The tip of the gonopod telopodite in posterolateral view resembles popular representations of the head of Anubis (Fig. 5B). The “snout” of the jackal corresponds to the medial tab of the central process, and the “ears” to the the lateral process and the apical portion of the central process. This name was suggested by collector Lisa Clarkson.

Remarks.

The core habitat area for Tasmaniosoma anubis sp. n. includes the 440 ha Trevallyn Nature Recreation Area (TNRA; Fig. 4A), which is managed as urban parkland. Large populations of Tasmaniosoma anubis sp. n. can be found in grassy woodland adjacent to bitumenised roads in the TNRA.

Tasmaniosoma anubis sp. n. has not been found more than ca 1.5 km from the South Esk River near its confluence with the Tamar River at Cataract Gorge in the city of Launceston (Fig. 4A). The land snail Pasmaditta jungermanniae (Petterd, 1879), the pseudoscorpion Neopseudogarypus scutellatus Morris, 1948 and the spider Migas plomleyi Raven & Churchill, 1989 are also believed to be restricted to the Cataract Gorge area, or to the Gorge area and small outlying localities ( Fearn 2003). However, one possible male specimen of Tasmaniosoma anubis sp. n., examined years ago and unfortunately now lost, and two possible female specimens (QVM 23:52256) have been collected in small, degraded remnants of native vegetation close to the South Esk River in the town of Evandale, ca 15 km southeast of Launceston. I suspect that Tasmaniosoma anubis sp. n. was more widespread along the lower South Esk River in pre-European times, i.e. before the early 19th century. Millipede populations would have declined as sheep grazing degraded the local eucalypt woodlands, and would have disappeared over most of the Launceston area as woodlands were cleared for residential development.

Unlike the similar-sized, co-occurring dalodesmid Atrophotergum pastorale Mesibov, 2004 and unlike most Tasmaniosoma species, Tasmaniosoma anubis sp. n. do not usually run away rapidly when disturbed, but remain “crouched” and stationary on the bark, leaf or wood pieces among which the animals are sheltering.

As with Tasmaniosoma compitale Mesibov, 2010 and Tasmaniosoma hickmanorum Mesibov, 2010 ( Mesibov 2010), most Tasmaniosoma anubis sp. n. females are missing their second pair of legs and have plugs of sclerotised scar tissue where these legs have broken off.