Victoriombrus, Mesibov, 2004

Mesibov, Robert, 2004, A new genus of millipedes (Diplopoda: Polydesmida: Dalodesmidae) from wet forests in southern Victoria, with brief remarks on the Victorian Polydesmida, Memoirs of Museum Victoria 61 (1), pp. 41-45 : 41-43

Victoriombrus gen. nov.

Type species. Victoriombrus acanthus sp. nov., by present designation.

Diagnosis. Dalodesmids c. 15 mm long with head + 20 segments, rounded and somewhat swollen paranota and pore formula 5, 7, 9–19. Telopodite of gonopod short, wide, divided by a transverse constriction into a setose, posteromesally excavated basal portion and a bare distal portion bearing a small mesal branch comprising a long, tapering solenomere accompanied by a distally flattened and roughened process, a much larger lateral branch, and between the two a narrow, more or less rod-like process arising posteromesally.

Description. Head with moderately deep impression lateral to antennal base; bases separated by about twice a socket diameter; vertigial sulcus faintly indicated; head moderately setose with moderately long setae on clypeus and frons, a few long setae on the vertex. Antenna ( Fig. 1 ) short, slender; antennomere 2 the longest, 6 the widest. Collum about as wide as head and second somite; sparsely setose with moderately long setae; posterior margin straight, anterior margin gently convex, corners rounded. Somite 2 with lateral margin of paranotum well below collum corner, somite 3 margin at about the level of the collum corner. Somites with well-defined waist ( Fig. 1 ); a few setae on somite 2, remaining somites bare and apparently smooth (very small seta-like processes scattered over dorsal surface of metazonite, only visible under high magnification); paranota on most somites just above midlateral ( Fig. 1 ), somewhat swollen, laterally with a very narrow, upwardly concave groove bordered by a slightly thickened margin; from above, anterior margin of paranotum gently curved, lateral margin very slightly convex, posterior margin slightly concave on anterior somites, more so on posterior somites, where the posterior corner projects slightly and bluntly; limbus a comb of fine, straight teeth. Ozopores small, opening dorsolaterally just above and near the posterior end of the paranotal groove on somites 5, 7 and 9–19. Sternites slightly longer than wide, cross impressions well-defined. Anterior legs ( Fig. 1 ) with swollen podomeres, prefemur strongly arched dorsally; posterior legs less swollen; tarsus about as long as next longest podomere, the femur. Sphaerotrichomes on tibia and tarsus only, from leg 3 rearwards, diminishing in number on the more posterior legs and absent from the last leg. Dense ‘brushes’ of setae ventrally on prefemur, femur and postfemur of most legs from 3 rearwards. Leg 2 coxa somewhat extended mesally, the genital opening a simple pit on this extension. Legpairs 4 and 5 not separated at bases, legpairs 6 and 7 well-separated; flexed gonopod telopodites reaching to legpair 6. Spiracles simple in structure with slightly raised rims; on diplosegments the anterior spiracle just above and anterior to the anterior leg, the posterior spiracle just anterior to the midway point between the leg bases. Preanal ring moderately setose; epiproct tapering to blunt, rounded and depressed tip extending well past anal valves; hypoproct paraboloid in outline.

Gonopod aperture ovoid ( Figs 2 , 4 ), wider than long, about one-half width of somite 7 prozonite, with posterior margin in the form of a flattened ‘V’and posterolateral portions of rim projecting ventrally. Gonocoxa in overall form a truncated cone, tapering distally, with moderately long setae on posteromesal surface; gonocoxae fairly firmly joined along midline but not quite fused into a syncoxite. Cannula prominent. Gonopod telopodites ( Figs 2 , 4 ), short, wide, closely appressed but not joined; partly fused with gonocoxa on anterior side of base; basal portion clearly separated from branched distal portion by a transverse constriction; basal portion excavated posteromesally, sparsely setose, mainly posterolaterally; distal portion bare, divided into a small mesal branch with a long, tapering solenomere joined basally to a distally flattened and roughened process, a much larger lateral branch, and a narrow, more or less rod-like posterior process arising posteromesally.

Females somewhat larger than males, with the same colouring; legs smaller than corresponding male legs and not swollen; posterior rim of epigynum projecting slightly, more so in centre; cyphopods not examined.

Distribution. Southern Victoria.

Etymology. Victoria + Greek ombros (“rainshower”), masculine.

Remarks. It is not clear how Victoriombrus is related to other Australian dalodesmid genera. The new genus shares with Tasmanian Bromodesmus ( Mesibov, 2004) a long, tapering, acutely pointed solenomere and telopodite elements fringed with teeth, but the gonocoxae in Victoriombrus are more nearly fused into a syncoxite than in the Tasmanian genus, the telopodites are much shorter and wider, and the pore formula is 5, 7, 9–19 instead of 5, 7, 9, 10, 12, 13, 15–19.

Figures

Figure 1. Victoriombrus spp. details. A, V. acanthus sp. nov., male paratype from NMV K-8849; B, V. seminudus sp. nov., male paratype from NMV K-8856. 1, Antenna; 2, posterior leg on somite 6; 3, posterior leg on somite 12; 4, dorsal outline view of somite 12; 5, posterior outline view of somite 12. Scale bar = 1.0 mm; setation and antennal cones not shown.

Figure 2. Victoriombrus acanthus sp. nov., male, paratype. Posterior view of gonopods in situ (specimen from NMV K-8849). Scale bar = 0.5 mm.

Figure 4. Victoriombrus seminudus sp. nov., male, paratype. Posterior view of gonopods in situ (specimen from NMV K-8853). Scale bar = 0.5 mm.