Orthorhachis serrata, 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 : 40-41

Orthorhachis serrata n. sp.

Fig. 26; map Fig. 32A

Holotype: Male. Creek Road, Beaury State Forest, NSW, 28º24'S 152º27'E, 4 February–9 April 1993, M. Gray & G. Cassis, pitfall trap. In AM, KS 103053.

Paratypes: In AM: 2 males, 1 female , details as for holotype, KS93759 ; 1 male, 1 female , same details but Tucker Box Road , Beaury State Forest, NSW, 28º28'S 152º24'E, KS93751 .

Other material examined: In AM: 1 male , Tweed Range , NSW, 28º28'S 153º08'E, 1000–1200 m, 17 February 1989, A.P. Smith, H.B. Hines, D. Pugh & P. Webber, Mt Warning Caldera Survey, cool temperate rainforest, pitfall trap T2.14 , KS50114 ; 1 male , details as for holotype but Stockyard Fire Trail , Chaelundi State Forest, NSW, 29º57'S 152º31'E, KS93753 ; 1 male , same details but Mt Tindal Road , Ramornie State Forest, NSW, 29º42'S 152º35'E, 20 CM, KS94871 ; 1 male , same details but Opposum Creek upstream of Foamy Creek Road, Marengo State Forest, NSW, 30º06'S 152º25'E, KS94880 ; 1 male , same details but ca. 600 m down small track off Dorrigo-Bellingen highway, <1 km W of Summervilles Road, NSW, 30º25'S 152º45'E, 31 CG, KS94883 ; 1 male , same details but 100 m SW of junction of Hallgraths Trail and Sherwood Road, Conglomerate State Forest, NSW, 30º06'S 153º03'E, 22AR, KS94887 ; 1 male , same details but headwaters of Valorem Creek , track off Mt Tindal Road, Ramornie State Forest, NSW, 29º42'S 152º35'E, 20 CG, KS94890 .

Diagnosis: Gonopod telopodite with toothed crest on anterior surface from one-half telopodite height to branching point, and with medial process broadly rounded distally, not extending posterolaterally.

Description: As for the genus. Male/female approximate measurements: midbody prozonite diameter 1.2/ 1.5 mm, midbody width across paranota 2.0/ 2.4 mm. In alcohol, well-coloured specimens near-uniform chestnut brown. Antennal sockets separated by 2X a socket diameter. Antennae slender, relative lengths of antennomeres 3>(2,6)>(4,5). Collum D-shaped with posterior margin slightly emarginate on either side, as wide as head and narrower than tergite 2. Metatergite sculpture indistinct, Pattern A. Paranota with anterior margin slightly convex, hardly roughened; lateral margin very slightly convex. Legs slender, leg 6 tarsus 1.4X as long as femur. Brush setae with forked tips.

Gonopod aperture ovoid, slightly wider than long, one-third the width of the ring 7 prozonite, rim raised posterolaterally. Telopodite ( Fig. 26) short, more or less cylindrical, constricting above broad base and tapering gradually, distally curving slightly posteriorly; long setae on posterolateral surface to between one-third and one-half telopodite height; branching beginning above three-quarters telopodite height. Solenomere cylindrical, directed posterodistally, slightly tapering. Medial process closely applied to solenomere base, broadly rounded, flattened mediolaterally, terminating at about one-half solenomere height, with a small, bluntly rounded tooth on posterior edge. Telopodite with a similar tooth on posterior surface of telopodite at or just below branching point. On anterior surface of telopodite, a row of ca. 10 teeth with anterobasally curving tips, diminishing in size from telopodite branching point to ca. one-half telopodite height. Prostatic groove running laterodistally for short distance on anterior surface of telopodite, then distally to solenomere, running just lateral to row of teeth on anterior surface of telopodite, and terminating at solenomere tip.

Female larger than male, legs slender and not swollen. Genital aperture with posterior margin slightly raised in very slightly convex flange, bent slightly anteriorly at corners. Cyphopods not examined.

Distribution: Known from ca. 20000 km 2 in far northeastern New South Wales, from just south of the Queensland border to just south of Dorrigo ( Fig. 32A). Overlaps in range with O. yabbra ; possibly parapatric with O. jubata , O. kerewong and O. weiri .

Etymology: Latin serratus, saw-toothed, adjective, for the line of teeth on the anterior surface of the gonopod telopodite.

Remarks: Male and female lengths could not be estimated, as all specimens examined are from pitfall traps and much 'loosened' by partial maceration.

The Tweed Range male is assigned to this species only tentatively. It is considerably larger than other O. serrata and the posterior corners of the paranota are more extended. The gonopod telopodite in this specimen agrees in details with that of the types but is more strongly curved posteriorly.