Pygolabis Wilson, 2003

Keable, Stephen J. & Wilson, George D. F., 2006, New species of Pygolabis Wilson, 2003 (Isopoda, Tainisopidae, Crustacea) from Western Australia, Zootaxa 1116, pp. 1-27 : 3-4

Pygolabis Wilson, 2003

Pygolabis Wilson, 2003: 7 .

Type species. Pygolabis humphreysi Wilson, 2003 ; by original designation.

Remarks. The species described below conform to the original diagnosis and description of the genus ( Wilson, 2003), so we do not revise the family or the generic diagnoses. Wilson (2003) indicated that the group is clearly a member of the higher isopods, informally referred to as “Flabellifera sensu lato,” the classification of which was substantially reorganised by Brandt & Poore (2003). Although Brandt & Poore (2003) introduced a subordinal name for the Tainisopidae , their analysis had no well–defined basal structure for the higher isopods, and did not establish a sister group relationship between the Tainisopidae and any other clade. The overall classification introduced by Brandt & Poore (2003) disagrees with other recent phylogenetic studies and classifications (e.g., Tabacaru & Danielopol 1999; Martin & Davis 2001; Dreyer & Wägele 2002). Recent genetic analyses (C. Francis, personal communication), although only using similarity procedure, found a species of Pygolabis and an idoteid isopod to have similar sequences. The relationships of the higher isopods apparently require further research, so the subordinal status of the Tainisopidae within the isopods should be left open until a better corroborated analysis of the higher isopods is available.

The sexually dimorphic pleopod 1 endopod is an additional character of generic importance. In males of Pygolabis , this limb is twisted, usually around the elongated penes that extend through it, and has several long denticulate setae on the distal margin (PLP 1 in Figs. 7 , 9 , 11 , 13 ). In females, pleopod 1 is flattened with a few short plumose setae on the distal margin.

The Tainisopidae show two distinctly different morphologies for the pleotelson and the position of the anus ( Wilson & Ponder 1992: fig. 3A; Wilson 2003: fig. 6F). Because the section of the pleotelson anterior to the insertion of the uropods is elongate in Pygolabis , the anus is separated from the pleopodal region by a small ridge and faces posteroventrally. In Tainisopus species, where the anterior part of the pleotelson is short relative to the posterior part, the anus is covered by the pleopods, faces ventrally and is not marked by an anterior ridge.

Figures

FIGURE 7. P. eberhardi sp. nov. Pleopods in dorsal view. Male 1 (AM P 70408); male 2 (WAM C 34942); female (WAM C 34944). Scale bar 1 mm.

FIGURE 9. P. weeliwolli sp. nov. Holotype male (WAM C 34948); paratype male 2 (AM P 70413). Scale bar: pereopods, 1 mm; pleopods 0.5 mm.

FIGURE 11. P. paraburdoo sp. nov. Paratype male 2 (AM P 70416); holotype male (WAM C 34951). Scale bar 0.5 mm.

FIGURE 13. P. gascoyne sp. nov. Holotype male (WAM C 34953). Scale bar 0.5 mm.