Gasterogramma extremum, Mesibov, 2003

Mesibov, Robert, 2003, The millipede genus Gasterogramma (Diplopoda: Polydesmida: Dalodesmidae) in Tasmania, Australia, with descriptions of seven new species, Memoirs of Museum Victoria 60 (2), pp. 207-219 : 211

Gasterogramma extremum sp. nov.

Figures 2 , 12 (map)

Material examined. Holotype. Male. Australia, Tasmania. Deadmans Bay , DM 592802 [43º31´47´´ 146º29´42´´], <40 m, 26 Jan 1994, R. Mesibov, wet eucalypt forest and rainforest, QVM 23 :14018.

Paratypes. Male (dissected), near Hastings Caves, approx. DM870960 [43º23´18´´ 146º50´22´´], 5 Dec 1952, V.V. Hickman, QVM 23 : 8059; male (dissected for SEM), Lake Sydney , DN 686070 [43º17´20´´ 146º36´46´´], 690 m, 2 Feb 1994, R, Mesibov, rainforest, QVM 23 :14019.

Diagnosis. Gonopod without tibiotarsus; femoral process unbranched; prefemoral process curved laterally, then posteriorly, with short, tooth-like projections near tip; solenomerite arising near base of prefemoral process.

Description. Males c. 15–17 mm long and c. 1.6–1.8 mm wide at midbody. Body in both sexes ivory-coloured with faint pink-purple mottling. Gonopod telopodites massive at base (fig. 2), lightly joined mesally for most of their length, with a few short, coarse basal setae, setate area extending just outside aperture. Aperture more or less ovoid, long axis transverse, posterior margin not noticeably raised. Telopodite axis more or less straight. Telopodite base ending abruptly at about one-half length of telopodite, with a relatively slender, anterioposteriorly flattened prefemoral process arising from anteromesal corner of top of base. Prefemoral process tapering gradually to a fine point, bending first laterally, then posteriorly, and bearing set of 10–20 short, simple or bifid teeth on posterolateral surface just proximal to tip. Tibiotarsus not evident. Femoral process massive, tapering gradually to a fine point, arising from posteromesal corner of top of telopodite base and curving laterally, then anteriorly, then distally and slightly laterally. Solenomerite a short, helical, somewhat flattened process arising at base of prefemoral process on its posterior face. Prostatic groove running first posteriorly and distally across mesal face of telopodite base to its posterior surface, then curving laterally, distally and mesally around base of femoral process, then extending distally to enter solenomerite base on its mesal side.

Distribution. Rainforest and wet eucalypt forest at 3 locations in far southern Tasmania (fig. 12) from near sea level to 690 m, with maximum linear range of c. 30 km. Likely to be more widespread in this little-sampled part of Tasmania.

Etymology. From Latin extremus, farthest, adjective. This species extends to the southern-most part of mainland Tasmania.

Figures

Figure 2. (left) G. extremum sp. nov., Lake Sydney, southern Tasmania, QVM 23:14019; SEM of gonopods in situ. Scale-bar = 0.5 mm. (right) G. extremum sp. nov., Hastings Caves, southern Tasmania, QVM 23:8059; outline sketch of right gonopod, lateral view, showing course of prostatic groove (dashed line).

Figure 12. Localities for males of G. austrinum sp. nov. (n south), G. extremum sp. nov. (+, far south), G. imber sp. nov. (s, west and southwest), G. rusticum sp. nov. (nn, north-central), G. tarkinense sp. nov. (*, north-west) and G. wynyardense sp. nov. (•, north-west), and for all specimens of G. plomleyi sp. nov. (half-filled squares, north-east).