Orthorhachis weiri, Mesibov, 2008

Mesibov, Robert, 2008, The millipede genera Gephyrodesmus Jeekel, 1983 and Orthorhachis Jeekel, 1985 in southeastern Australia, a new Lissodesmus Chamberlin, 1920 from Victoria, and observations on male leg setae, spinnerets and metatergite sculpture (Diplopoda: Polydesmida: Dalodesmidae), Zootaxa 1790, pp. 1-52 : 44-46

Orthorhachis weiri n. sp.

Figs. 7C, 29; map Fig. 32A

Holotype: Male. Cobark Forest Park, Barrington Tops State Forest, NSW, 31º54'S 151º35'E, 15 November 1981, T. Weir & A. Calder, ANIC berlesate 754, leaf litter, Nothofagus rainforest. In ANIC, 64-000191.

Paratypes: In ANIC: 1 male, 1 female, details as for holotype, 64-000192 .

Other material examined: None available.

Diagnosis: Metatergites with Pattern B sculpture. Brush setae with mid-length branch. Gonopod telopodite with apex bent posterodistally, the medial process widely expanded distally and truncate, the poste- rior corner partly enclosing the base of the solenomere.

Description: As for the genus. Male/female approximate measurements: length 10/ 11 mm, midbody prozonite diameter 0.9/ 1.1 mm, midbody width across paranota 1.5/ 1.8 mm. In alcohol, body colour near-uniform light brown. Antennal sockets separated by 2X a socket diameter. Antennae slender, relative lengths of antennomeres 6>3>2>(4,5). Collum D-shaped, narrower than head and tergite 2. Metatergite sculpture very distinct, Pattern B; prozonite with coarse cellular texture, extending to waist across prozonite/metazonite suture ( Fig. 7C). Paranota with anterior margin sloping posterolaterally to distinct corner, lateral margin more or less parallel to long axis of body ( Fig. 7C). Legs slender, leg 6 tarsus 1.4X as long as femur. Brush setae with mid-length branch as in Fig. 1F.

Gonopod aperture ovoid, slightly wider than long, one-third the width of the ring 7 prozonite, rim raised posterolaterally. Telopodite ( Fig. 29) short, base produced anteriorly, telopodite above base somewhat swollen laterally to about one-third telopodite height and abruptly bending posteriorly at branching point; branching beginning at about two-thirds telopodite height; long setae on posterolateral surface to about one-third telopodite height. Solenomere directed posterodistally, then abruptly bending distally at an 'elbow' and narrowing, then tapering to a point while curving medially. Medial process closely applied to solenomere base, wider than solenomere, directed posterodistally and widening to broad, flat top aligned at about 45º to the telopodite long axis, terminating below the solenomere tip, the posterobasal corner of the top of the medial process curving laterally.

Female slightly larger than male, legs not swollen. Genital aperture with posterior margin slightly raised in wide, flat-edged flange. Cyphopods not examined.

Distribution: Known only from the type locality in the Barrington Tops in northern New South Wales ( Fig. 32A); may co-occur with the much larger O. inflata .

Etymology: For CSIRO entomologist Tom Weir, collector of this species and many other new Australian arthropods.

Remarks: The gonopod telopodite of O. weiri resembles that of O. durabilis ( Fig. 17), and both species have Pattern B metatergite sculpturing ( Fig. 7). The species differ in sculpturing details and in brush setae, which have forked tips in O. durabilis and a mid-length branch in O. weiri ( Fig. 1F).