Gephyrodesmus arcuatus, 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 : 12-13

Gephyrodesmus arcuatus n. sp.

Figs. 6B, 8; map Fig. 12

Holotype: Male. Dyer Creek , near Murrungowar, Vic, 37º38'26"S 148º43'24"E, 140 m, 8 November 2006, R. Mesibov & T. Moule. In MV, K-10633.

Paratypes: In AM: 2 males , Bondi State Forest S of Bombala, NSW, woodlot 1, 37º08'S 149º09'E, 27 September 1980, G. Gowing et al., litter, KS11324 ; 2 males , Errinundra Road , 2.5 km from intersection with Bonang Road at entrance to Errinundra National Park, Vic, 13 June 1999, A. Skates, in log, KS89499 .

In MV: 1 male, Lind National Park , Vic , 2 1/ 2 miles from turnoff, ' Grid 2331(1) Map Ref 207364', no date or collector, 'rather dry open stringybark bloodwood forest bracken undergrowth', K-10630 ; 1 male, Slippery Hill , N of Dargo, Vic, 37º23'05"S 147º12'54"E, 920 m, 25 November 2004, R . Mesibov & T . Moule , K- 10631 ; 1 male, details as for holotype, K-10632.

Other material examined: None available.

Diagnosis: Medial branch of gonopod telopodite large and arcuate, in lateral or medial view with squareedged tab on anterior surface near base and with tip bent anterobasally at ca. 90º; anterior edge of ring 7 aperture meeting anterior edge of prozonite; metatergite sculpture well-defined.

Description: As for the genus. Male approximate measurements: length 18–19 mm, midbody prozonite diameter 1.8–2.0 mm, midbody width across paranota 2.8–3.0 mm. In alcohol, well-coloured specimens fairly uniform light greyish-brown. Antennal sockets separated by ca. 2X a socket diameter. Collum as wide as head, narrower than tergite 2, D-shaped with posterior corners slightly produced. Raised areas on metatergites distinct ( Fig. 6B). Gonopod aperture about one-third width of prozonite, ovate rather than ovoid, longer than wide, anterior portion of aperture extended to meet anterior edge of prozonite, lateral edge raised posteriorly.

Gonopod telopodite ( Fig. 8) with base wide, long setae on posterolateral surface to level of branching at about one-third telopodite height. Solenomere in two sections: basal half massive, mediolaterally flattened and with a slight posterior swelling; distal half much narrower, rounded, slightly tapering, arising at about two-thirds the telopodite length and directed first posteriorly, then abruptly distally, curving slightly posterolaterally. Medial branch large, somewhat flattened mediolaterally, C-shaped from base (concave posteriorly) with a prominent square-edged tab near base on anterolateral surface, then bending at nearly 90º posterobasally above basal section of solenomere and curving laterally to 'enclose' distal section of solenomere, finally bending anteromedially and slightly basally and terminating in a broad, rounded tip, with a pair of small, low, rounded bumps on the anterior surface of the terminal section.

Female not yet recognised.

Distribution: Known from eucalypt forest at five localities from the lowlands to at least 920 m in eastern Victoria and far southeastern New South Wales ( Fig. 12). Co-occurs with G. cineraceus near Murrungowar in East Gippsland. Found in moist leaf litter at the Dyer Creek and Slippery Creek sites. Etymology: Latin arcuatus , curved like a bow, adjective, for the shape of the medial telopodite branch. Remarks: The Slippery Creek male is pale and only 13 mm long but conforms to the gonopod description given above.