Austrasphaera berentsae, 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 : 311-315

Austrasphaera berentsae sp. nov.

Figures 1–4

Material examined. Holotype. Female (ovigerous 3.6 mm), Vic., Bay of Islands, 38°35.0´S, 142°49.5´E, 28 Apr 1988, 2.5 m, red algae, R. T. Springthorpe and P.B. Berents ( AM P51061 ).

Paratypes. Vic. 10 males (2.4–2.5 dissected, 2.6 mandibles dissected, 2.8 mm), female (ovigerous. 3.5 mm, dissected), same data as holotype ( AM P41342 ). 8 females (ovigerous 3.5–3.8 SEM, 3.9 SEM, 3.9 mm), 1 km E of Harmers Haven , 38°34´S, 145°40´E, 6 Mar 1982, 6 m, 300 m offshore, rocky, R . S. Wilson and C. Larsen ( NMV J26391 ). Female (3.7 mm), same data as previous ( NMV J26394 ). Male (2.8 mm), same data as previous, but 11 m ( NMV J26229 ). Male (2.9 mm), female (3.4 mm), 50 m E of Petrel Rock, Venus Bay, 38°39´S, 145°42´E, 5 Mar 1982, 8 m, rocky, M. MacDonald, M. Gomon and G. Barker ( NMV J26393 ). Male (2.8 mm), female (3.5 mm), 75 m SW of Eagles Nest, Venus Bay, 38°40´S, 145°40´E, 5 Mar 1982, 8 m, rocky, R . S. Wilson and G. Barker ( NMV J26390 ). Male (2.5 mm), 50 m offshore, east side of S point, Twin Reefs, 38°41´S, 145°39´E, 11 m, C. Larsen, G. Barber and R . S. Wilson ( NMV J26395 ) .

Non-type material. Vic. Laurence Rocks , Portland, 38°34.0´S, 141°40.5´E, 23 m, Herdmania momus with encrusting sponge and red algae ( AM P41379 ) . Whalers Point Lighthouse , Portland, 38°20.5´S, 141°37.5´E, 10 m, brown algae from boulder bottom ( AM P41399 ) . SA. “The Hotspot” reef, Flinders I., 33°40.8´S, 134°22.5´E, 21 m, large red algae ( NMV J39716 ) ; 33°40.5´S, 134°22.05´E, 12 m, assort- ed algae ( NMV J39724 ) ; 33°40.5´S, 134°22.0´E, 17 m, algae, large forms ( NMV J39696 ) . NE end of West I., 35°37.0´S, 138°36.0´E, 12 m, red algae ( NMV J39697 ) . Western River Cove , Kangaroo I., 35°43´S, 137°35´E, 6 m, coralline algae ( AM P51064 ) . WA. Mississippi Bay, E of Esperance , 34°0.0´S, 122°170´E,? 2 m, algae ( AM P41125 ) . Point Peron , S of Perth, 32°16´S, 115°41´E, 4 m, Posidonia and algae ( AM P51063 ) . Green I., Rottnest I., 32°01´S, 115°30´E, mixed algal turf ( AM P41113 ) . Dongara–Port Denison Beach , 29°16.0´S, 114°55.0´E, 5 m, red algae, mainly Laurencia ( NMV J26152 ) ; 3 m, drift red algae on sand ( NMV J26168 ) . Seven Mile Beach, Dongara , 29°12.0´S, 114°53.0´E, 1 m, epiphytes on Amphibolus ( NMV J39700 ) ; D. Edgar ( NMV J39698 ) . Red Bluff, Kalbarri , 27°42´S, 114°0.9´E, 10 Jan 1984, mixed corallines ( AM P51062 ) .

Description of female. Body about 3.5 times as long as greatest width, ovate, widest at pereonites 3 and 4; dorsal surfaces smooth, without scattered setae. Cephalon anterior margin without transverse ridge, ventral rostral process weakly developed. Head and pereonites 1 subequal in length in dorsal view, pereonite 1 about twice as long as pereonite 2, with 1 or 2 low indistinct sublateral bosses; pereonites 2–7 of approximately equal length; pereonite 7 with low indistinct median boss; coxae with sutures, ventrally directed. Pleon with weak median boss, posterior margin indicated by short lateral sutures. Pleotelson posterior margin smoothly rounded; ventral margin with shallow exit channel not extending to posterior of pleotelson.

Antennule peduncle article 2 2.6 times as long as wide, about 1.3 times as long as article 2; article 2 flattened, inferior margin convex; inferior margins of both articles 1 and 2 with mass of flattened scales and fine tubular setae; article 3 about one-quarter as long as article 2, inserted midpoint of posterior margin; flagellum 3-articled, extending to pereonite 1, about 1.7 times as long as article 3. Antenna peduncle articles 1–3 short, combined lengths about equal to that of article 5; article 4 about 0.8 as long as article 5, both articles 4 and 5 with inferior margins convex; flagellum about equal in length to peduncle, extending to anterior margin of pereonite 2, with 8 articles.

Epistome smooth, narrow, laterally encompassing labrum, anteriorly truncate. Left mandible incisor without distinct cusps, lacinia mobilis without cusps, spine row of 3 serrate curved spines; right mandible with 3 indistinct cusps, spine row of 1 broad-based multidigitate spine and 3 serrate blunt spines; molar process irregular, largely smooth, without serrate margins or ridged surfaces; palp article 1 longest, without setae; article 2 with 4 biserrate setae, article 3 with 6 biserrate setae, terminal seta being largest. Maxillule mesial lobe with 2 long, weakly pectinate setae and 1 shorter simple seta; lateral lobe with 10 terminal and peripheral RS on gnathal surface, eleventh seta set between these; lateral most RS are weakly serrate on distal part of seta. Maxilla lateral lobe and middle lobe each with 3 and 4 curved RS respectively, mesial lobe with 6 RS, variously serrate, mesial-most seta only being acute, remainder terminally rounded. Maxilliped endite extending about half way along palp article 4, distal margin with 1 conical RS, 3 rounded RS, 2 cactus RS and 2 slender CP RS; palp articles 2–5 with about 10, 15, 14 and 11 setae respectively.

Pereopod articles generally with abundant widely-spaced microtrichs. Pereopod 1 basis about 1.7 times as long as greatest width, approximately half as long as propodus; inferodistal angle with 1 simple setae; ischium as long as basis, twice as long as greatest width; merus about 0.4 as long as ischium, 0.8 times as long as greatest width, carpus (inferior margin) 0.6 as long as merus, 0.5 as long as wide; propodus twice as long as ischium, 3 times as long as greatest width; dactylus about half as long as propodus, unguis strongly recurved, inferior margin with prominent serrate cuticular scales, secondary unguis recurved with 2 basal cusps. Pereopods 2 and 3 similar to pereopod 1; pereopod 2 with 1, 1 and 4 setae on inferior margins of merus, carpus and propodus respectively; pereopod 3 with 2, 2 and 3 setae on inferior margins of merus, carpus and propodus respectively. Pereopods 5 and 6 similar, shorter than pereopods 1 and 2. Pereopod 6 propodus inferior margin without setae. Pereopod 7 short, slightly longer than pereopod 6, articles robust and laterally flattened, merus slightly shorter than wide, appearing rounded in lateral view, inferior margin with setulose fringe and CP setae; propodus 2.8 times as long as proximal width, tapering distally, inferior margin with fringe of CP setae, superior margin with numerous scale-setae; dactylus 0.7 times as long as propodus.

Pleopod 1 exopod and endopod with 13 and 8 PMS respectively; endopod 0.8 times as long as exopod, slender, 4 times as long as greatest width, proximal lateral margin weakly concave. Pleopod 2 exopod and endopod with 16 and 10 PMS respectively, those of the proximal two-thirds of the exopod lateral margin only feebly plumose; endopod 1.8 times as long as exopod. Pleopod 3 exopod and endopod with c. 17 and 8 PMS respectively. Pleopod 4 both rami with prominent ridges, exopod lateral 0margin with 4 fine setae. Pleopod 5 both rami with prominent ridges; exopod with 3 scale patches and transverse suture. Uropod rami flattened, margins provided with continuous flattened scales and fine setae; exopod 0.4 times as long as fused endopod, 1.8 times as long as greatest width, distal margin broadly rounded; endopod broadly rounded, dorsal with 3 clusters of sensory setae.

Male. Anterior margin of head produced slightly dorsally (in contrast to female in which is produced anteriorly). Males lack indistinct nodules on pereonite 1, pleon and pleotelson. Pereopod 1 propodus proximomesial surface with 2 strongly pectinate robust submarginal setae. Penial processes separate, adjacent, about 2.5 times as long as basal width, tapering to rounded apex. Pleopod 2 endopod 1.7 times as long as exopod; appendix masculina lateral margins diverging slightly, surface with abundant microtrichs, about 5.3 times as long as wide, and 1.2 times as long as endopod, apex obliquely truncate; widest at approximately three-quarters of its length.

Size. Males 2.1–2.8 mm, ovigerous females 3.5–3.8 mm, non-ovigerous females 3.2–3.6 mm.

Etymology. For Dr Penny B. Berents (Australian Museum), amphipod taxonomist and collector of much valuable peracarid material.

Distribution. Vic., SA, WA, north to Kalbarri; 2.5–23 m, with red and brown algae, including the red alga Laurencia and the seagrass Posidonia .

Remarks. Austrasphaera berentsae is readily distinguished by the head being strongly produced anteriorly, an ovate body shape, the uropods being posterolateral in position and not meeting posteriorly and by the short uropod exopod. The uropods of the sympatric A. springthorpei fold across the posterior margin of the pleotelson, and the penial processes are relatively shorter and the appendix masculina less massive than that of A. berentsae .

Figures

Figure 1. Austrasphaera berentsae sp. nov.A, B, D, female holotype, G–I, female paratype, (AM P41342), remainder as indicated.A, lateral view; B, dorsal view; C, frons and anterior of head in ventral view; D, pleon and pleotelson, ventral view; E, head and anterior pereonites, female 3.5 mm Flinders I. (NMV J39716); F, head and anterior pereonites, male 2.8 mm paratype (AM P41342); G, antennule; H, antennule, detail of marginal setae; I, antenna.

Figure 2. Austrasphaera berentsae sp. nov. All figs female paratype (AM P41342). A, maxilliped; B, maxillule, mesial and lateral lobes; C, apex, maxillule lateral lobe; D, maxilla mesial lobe apex; E, maxilla; F, robust setae from maxilla middle lobe; G, right mandible; H, distal left mandible; I, mandible molar; J, pereopod 1; K, pereopod 1, dactylus unguis and secondary unguis.

Figure 3. Austrasphaera berentsae sp. nov. A–D, pereopods 2, 3, 6 and 7; E–I, pleopods 1–5.

Figure 4. Austrasphaera berentsae sp. nov. A, uropod, female paratype (AM P41342). B–D, male NMV J26391). B, male pereopod 1; C, penial process and pleonal sternite; D, pleopod 2.