Austrasphaera springthorpei, Bruce, 2003

Bruce, N. L., 2003, New genera and species of sphaeromatid isopod crustaceans from Australian marine coastal waters, Memoirs of Museum Victoria 60 (2), pp. 309-369 : 315-319

Austrasphaera springthorpei sp. nov.

Figures 5–7

Material examined. Holotype. Female (ovigerous 3.2 mm), WA, Red Bluff, Kalbarri, 27°42´S, 114°0.9´E, 10 Jan 1984, mixed corallines, R. T. Springthorpe ( AM P51057 ).

Paratypes. 10 males (2.2–2.5 mm), 17 females (with visible ova 2.5–3.5 dissected, 3.5, non-ovigerous 2.4–3.3 mm), c. 64 unmeasured male, female, and mancas, same data as holotype ( AM P41124 ) . Male (2.4 mm), female (ovigerous 3.0 mm), same data as holotype except mixed algae and sediment ( AM P41128 ) . 2 males (2.4, 2.5 mm), female (2.5 mm), Point Peron , 48 km S of Perth, 32°16´S, 115°41´E, 27 Jan 1972, 4 m, Posidonia and algae, W.F. and J.M. Ponder ( AM P51060 ) . 2 females (ovigerous 2.7, 2.9 mm), Mississippi Bay , 48 km E of Esperance, 34°0.0´S, 122°170´E,?1972, 2 m, mixed algae, W.F. and J.M. Ponder ( AM P51058 ) .

Non-type material. Vic. Henty Reef , Apollo Bay , Mounts Bay, 38°47.0´S, 143°40.5´E, 18 m, red algae on boulder ( AM P51059 ). SA. W of “The Hotspot” reef, Flinders I., 33°40.8´S, 134°22.5´E, 21 m, large red algae ( NMV J39699 ) ; 17 m, assorted algae ( NMV J39726 ) ; 21 m, large red algae ( NMV J39718 ) . North of Tiparra Light , Tiparra reef, 34°4´S, 137°23´E, 10 m, red algae ( NMV J26209 ) . WA. Dongara ( NMV J39725 ) .

Description of female. Body about 3.8 times as long as greatest width, ovate, widest at pereonites 5 and 6; dorsal surfaces smooth, without setae or microtrichs. Cephalon anterior margin without transverse ridge, ventral rostral process weakly developed. Head and pereonites 1 subequal in length in dorsal view, pereonite 1 about 1.2 times as long as pereonite 2; pereonites 2–7 of approximately equal length, 5 and 6 slightly longer than 7 and 4; coxae with sutures, ventrally directed, inferior margins with setulose fringe. Pleon mesial portion indistinctly raised, posterior margin indicated short lateral suture. Pleotelson posterior margin depressed, terminally with minute indentation, forming open exit-channel with uropods; ventral margin with shallow exit channel not extending to posterior of pleotelson.

Antennule peduncle article 2 1.6 times as long as wide, about 0.9 times as long as article 2; article 2 flattened, with large anterodistal lobe; anterior margins of both articles 1 and 2 with gel-like layer and fine tubular setae; article 3 about one-third as long as article 2, inserted at midpoint of posterior margin; flagellum 3-articled, extending to pereonite 1, about 1.7 times as long article 3. Antenna peduncle articles 1–3 short, combined lengths about equal to that of article 5; articles 4 and 5 subequal in length; flagellum about 0.7 as long as peduncle, extending to anterior margin of pereonite 2, with 7 articles.

Epistome and mouthparts conforming to the generic characters and generally similar to that of A. berentsae . Maxilliped palp articles 2–5 mesial margins with 7, 7, 6 and 8 setae respectively.

Pereopods similar to A. berentsae .

Pleopod 1 exopod and endopod with 18 and 10 PMS respectively; endopod 0.9 times as long as exopod, slender, 3.3 times as long as greatest width, proximal lateral margin distinctly concave. Pleopod 2 exopod and endopod with 18 and 9 PMS respectively; endopod 1.4 times as long as exopod. Pleopod 3 exopod and endopod with 10 and 8 PMS respectively. Pleopod 4 and 5 with both rami with prominent ridges, both with incomplete transverse suture; pleopod 5 exopod with 3 scale patches. Uropod rami flattened, margins provided with gel-like layer and fine setae; exopod 0.6 times as long as fused endopod ovate, twice as long as greatest width, distal margin broadly rounded; endopod broadly rounded, mesial margin oblique to lateral margin, dorsally with 2 clusters of sensory setae.

Male. Penial processes about 1.3 times as long as basal width, tapering to rounded apex. Pleopod 2 endopod 1.3 times as long as exopod; appendix masculina weakly sinuate, mesial margin curving laterally slightly, surface with scattered microtrichs, about 8.6 times as long as wide, 1.4 times as long and 0.6 times as wide as endopod, apex narrowly rounded.

Size. Males 2.2–2.6 mm, ovigerous females 2.5–3.5 mm, non-ovigerous females 2.4–3.3 mm.

Etymology. For Roger T. Springthorpe (Australian Museum), whose field-collecting has over the years contributed many new discoveries.

Distribution. Western Vic., SA and WA to Kalbarri; 2–18 m, from coralline and red algae and Posidonia .

Remarks. See Remarks for A. berentsae for the differences that separate the two species of Austrasphaera . As the appendages of these two species are so similar an abbreviated description is given for this species.

Figures

Figure 5. Austrasphaera springthorpei sp. nov.A, B, holotype, remainder female paratype (AM P41124).A, dorsal view; B, lateral view; C, antennule; D, antenna; E, maxilliped; F, left mandible.

Figure 6. Austrasphaera springthorpei sp. nov. Female paratype (AM P41124). A–C, pereopods 1, 2, and 7.

Figure 7. Austrasphaera springthorpei sp. nov. A–E, G, female paratype, F, H–J male paratype (AM P41124), A–E, pleopods 1–5; F, penial processes; G, uropod; H, pleopod 2, male; I, pereopod 2, male; J, pereopod 1 male.