Orthorhachis oresbia, 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 : 36-37

Orthorhachis oresbia n. sp.

Fig. 23; map Fig. 31

Holotype: Male. The Big Culvert, 2.5 km ENE of Mt Observation, Vic , 37º33'36"S 145º52'15"E, 26 October – 28 December 1995, G. Milledge, pitfall traps, Nothofagus cunninghamii forest. In MV, K-10689.

Paratype: In WAM: 1 male , Cumberland Falls , Vic, 37º34'S 145º53'E, 27 May 1991, M.S. Harvey & M.E. Blosfelds, T 76139 .

Other material examined: None available.

Diagnosis: Gonopod telopodite curving anteriorly above pronounced mid-length constriction; medial process small, forked, the two tips enclosing the solenomere base.

Description: As for the genus. Male approximate measurements: length 17 mm, midbody prozonite diameter 1.5 mm, midbody width across paranota 2.3 mm. Body slightly discoloured, light brown (paratype). Antennal sockets separated by 2X a socket diameter. Antennae slender, relative lengths of antennomeres (2,3)>6>(4,5). Collum D-shaped, as wide as head and narrower than tergite 2. Metatergite sculpture very distinct, Pattern A. Paranota with anterior margin distinctly roughened, almost serrate, sloping to join lateral margin in gentle curve, lateral margin more or less straight and slightly flared outwards posteriorly, marginal notches very distinct. Legs slender, leg 6 tarsus 1.5X as long as femur. Brush setae with forked tips.

Gonopod aperture ovoid, slightly wider than long, about one-third the width of the ring 7 prozonite, rim raised posterolaterally. Telopodite ( Fig. 23) short, base strongly produced basally on medial side; long setae on posterolateral surface to one-third telopodite height; branching beginning above three-quarters telopodite height. Above broad base, telopodite more or less cylindrical to one-half telopodite height, then abruptly tapering and nearly C-shaped in lateral view (concave posteriorly). Solenomere cylindrical, very short, directed posterodistally, curving slightly medially, the tip mediolaterally flattened. Medial process closely applied to solenomere base, forked at base, with bluntly rounded posterior branch paralleling and adjoining solenomere and terminating at about one-half solenomere height, and with short, bluntly pointed anterior branch directed laterally, curving slightly basally and lying anterior to solenomere base. Prostatic groove running laterodistally for short distance on anterior surface of telopodite, then distally to abrupt taper in telopodite, then laterodistally and slightly anteriorly to solenomere, and terminating at solenomere tip.

Female not yet recognised.

Distribution: Known only from two sites in eastern Victoria less than 5 km apart ( Fig. 31). Possibly sympatric with O. durabilis .

Etymology: Greek oresbios, mountain-living, adjective, referring to the mountains where this species occurs.