Memoirs of Museum Victoria 58(1): 125–136 (2000) REDIAGNOSIS OF THE ENDEMIC SOUTHERN AUSTRALIAN GENUS PARASTACILLAHALE, 1924 (CRUSTACEA: ISOPODA: ARCTURIDAE) WITH DESCRIPTIONS OF TWO NEW SPECIES RACHAELA. KING Crustacea Laboratory, Museum Victoria, GPO Box 666E, Melbourne, Vic. 3001, Australia and Department of Zoology, University of Melbourne, Vic. 3010, Australia ([email protected]) Abstract King, R.A., 2000. Rediagnosis of the endemic southern Australian genus ParastacillaHale, 1924 (Crustacea: Isopoda: Arcturidae) with descriptions of two new species. Memoirs of Museum Victoria 58(1): 125–136. The arcturid genus Parastacilla Hale, 1924 is rediagnosed and a key to its four species presented. All species, P. truculentaHale,1924; P. bakeri Hale, 1924; P. torussp. nov. and P. tingarasp. nov. have limited distribution in southern Australia. Introduction slender with two or three flagellar articles of similar lengths. The fusion of the head and The arcturid isopod genus Parastacilla was pereonite 1, a characteristic of the arcturid erected by Hale (1924) to include two endemic family, is extended anteriorly and incised in South Australian species P. truculenta and species of Parastacilla; this extension is evident P. bakeri. Hale distinguished the new genus on only to a small extent in some species of the basis of the robust antennae, stout uniarticu- Neastacilla. late antenna 2 flagellum, flattened anterior The genus was partially redescribed from the pereopods and unsegmented pleon. types by Hale (1946) but has not been studied Hale believed that Parastacilla resembled since. Two new species have been discovered in Astacilla Cordiner to which he assigned some collections at Museum Victoria, Melbourne, and southern Australian species; these now belong to the description of these species has uncovered Neastacilla Tattersall. The species of Parasta- errors in Hale’s original generic diagnosis. The cilla share many morphological similarities with types of both P. bakeri and P. truculenta have species of Neastacilla from southern Australia: been examined to rediagnose the genus and its elongation of pereonite 4, an extremely genicu- species. The new species described herein and a late body between pereonites 4 and 5 and similar survey of museum collections has extended the sexual morphologies with curved, short appendix known distribution of the genus from South Aus- masculina and simple penial plate. tralia to Victoria, Tasmania and Western Aus- Pereopods 2 to 4 of Parastacilla are uniquely tralia. flattened and sparsely setose. The pereopods of Abbreviations are: NMV, Museum Victoria, Neastacilla species are elongate with closely Melbourne, Australia; SAM, South Australian spaced, long setae. In Parastacilla pereopod 2 Museum, Adelaide, Australia. has a small dactylus and unguis and pereopods 3 and 4 lack a dactylus. Generally, in species of Arcturidae Bate and Westwood, 1868 Neastacilla pereopods 2 to 4 have a dactylus and unguis. In Parastacilla the body is ParastacillaHale, 1924 stout and cylindrical while species of Neastacilla Parastacilla Hale, 1924: 209–212.—Hale, 1946: are elongate and slender. Antenna 2 of 187–188. Parastacilla is stout with a flagellum of two articles; the distal article is very small and Type species. Parastacilla truculentaHale, 1924 bears a claw. Antenna 2 of Neastacilla is (by original designation). 125 126 RACHAEL A. KING Diagnosis.Body cylindrical and strongly genicu- female. Pleon with dorsolateral wings. Uropodal late. Lateral margins of head and pereonite 1 inner ramus with 2 setae of subequal length. Male extended anteriorly and separated by a lateral pleopod 1 exopod laterally notched, with 2 prox- incision. Antenna 2 stout; flagellum of 2 articles, imal setae of unequal length on posterior face. second article very small with claw and spines Male pleopod 2 with appendix masculina short, medially along length. Maxillipedal palp article 4 reaching end of endopod, curved, with ridge on narrower than article 3. Pereopod 1 within margin posterior face, apex simple. of head; with dactylus barely longer than wide, Composition. Parastacilla truculentaHale, 1924; without unguis, with setae on the medial and P. bakeriHale, 1924;P. torussp. nov.; P. tingara oblique distal margin. Pereopods 2 to 4 flattened sp. nov. and compact, with paired sparse and widely spaced setae; setae on ischium and carpus shorter Remarks. The flagellum of the second antenna than the article. Pereopod 2 with very small consists of two articles, not one as described by dactylus present on mesial surface, with unguis Hale (1924). Hale believed that all four anterior (sometimes with secondary unguis). Pereopods 3 pereopods consisted of six articles, ending in a and 4 dactylus absent. Pereopods 5 to 7 progres- rounded setose propodus. Examination has sively shorter; dactylus with primary and slightly shown that in all species the second pereopod has smaller secondary unguis (sometimes fused); a small dactylus and unguis. Some specimens pereopod 5 basis twice length of pereopod 6 have a secondary unguis on the dactylus of basis. Pereonite 4 up to 9 times as long as pere- pereopod 2. onite 3; males with pereonite 4 as long as in Key to species of Parastacilla 1. Pereonites without large dorsal elevations...................................P. truculenta — Pereonites with dorsal elevations.................................................................. 2 2. Head without dorsal elevation; antenna 2 articles 4 and 5 with tuberculate elevations.......................................................................................... P. bakeri — Head with dorsal elevation; antenna 2 articles mostly smooth, may have some tuberculation.........................................................................................3 3. Female pereonite 4 expanded laterally; large anteriorly directed dorsal ele- vations on pereonites 3 and 4; male without elevation on pereonite 3, eleva- tion on pereonite 4 with 2 apices..........................................................P. torus — Female pereonite 4 not expanded laterally; elevations on pereonites 3 and 4 of equal size to elevation on head.....................................................P. tingara Parastacilla truculentaHale combined lengths of pereonites 5 to 7; with small dorsolateral wings. Parastacilla truculenta Hale, 1924: 210–211, fig. Eyes lateral. Antenna 1 extending to end of 1.—Hale, 1946: 187–188, fig. 15 A. peduncle article 2 of antenna 2; uniarticulate flag- Material examined.Holotype. South Australia. Beach- ellum with lateral and distal aesthetascs. Antenna port, 5–7 m, dredge, H.M. Hale, SAM C237 (1 female, 2 stout, more than half length of body; flagellum 18.5 mm). of 2 articles and claw, with a medial row of comb- Other material. South Australia. Flinders Island, like spines full length. “The Hotspot” reef, 5 n. miles W of Flinders Island (33°40.80´S, 134°22.50´E), 21 m, large red algae, Pereopod 1 dactylus barely longer than SCUBA, G.C.B. Poore on FV Limnos, 20 Apr 1985 (stn wide, without unguis, bearing 2 medial and 3 SA-69), NMV J16696 (manca 2, 6.0 mm). oblique setae. Pereopod 2 with dactylus and unguis. Pereopods 3 and 4 without dactylus. Diagnosis. Female: Head with dorsal elevation. Pereopods 5 to 7 dactlyus with unguis and Fusion of head and pereonite 1 indicated by a dor- secondary unguis. solateral groove with the lateral margin extended Uropodal exopod oblique, not reaching mid- anteriorly and incised laterally. Pereonites 2 to 7 point of endopod, with 2 distal setae of equal smooth. Pereonite 4 more than 9 times as long length. as pereonite 3. Pereonites 5 to 7 progressively shorter. Pleon length greater than the Distribution.South Australia; subtidal. THE ARCTURID GENUS PARASTACILLA 127 Remarks. This redescription was based on the Hale re-illustrated the flagellum of antenna 2 and holotype (SAM C237). This specimen is an pereopod 1 of what he recorded was the same immature female in which the oostegites are not specimen, apparently not mounted. The specimen fully formed. Male specimens have not been (SAM C238) redescribed here was unmounted found. A specimen from Museum Victoria (NMV and undissected before being partially dissected J16696) is a manca 2 stage: a juvenile with a for this redescription. It is possible that Hale’s developed pereopod 7 and undeveloped sexual (1946) illustrations were done without any dis- appendages. secting and mounting. I assume that this is the holotype as a second specimen was never men- tioned. The holotype designated by Hale was a Parastacilla bakeri Hale male and is the only specimen available. Figure 1 The appendix masculina was examined in situ Parastacilla bakeri Hale, 1924: 211–212, fig. 2.— from the holotype but not illustrated. Hale, 1946: 187–188, fig. 15 B. Material examined.Holotype, South Australia. Marino Parastacilla tingarasp. nov. Reef, W.H. Baker, SAM C238 (1 male, 9.5 mm). Figures 2–4 Diagnosis. Male: Head with small dorsal eleva- tion. Fusion of head and pereonite 1 indicated by Material examined. Holotype. Tasmania, Waterhouse dorsolateral groove with lateral margin slightly Point (40º49.25´S, 47º40.04´E), 5 m, seagrass: Amphi- bolus antarctica, G. Edgar, 24 Apr 1992, NMV J39333 extended anteriorly and incised laterally. Pere- (1 female, 13.5 mm). onite 2 smooth. Pereonite 3 with dorsal elevation. Paratype. South Australia, Edithburgh (35º05´S, Pereonite 4 about 9 times as long as pereonite 3 137º45´E), 3 m, red algae: Caulocystis cephalomithos, with midlength dorsal elevation of similar height hand collection, R.A. King, 14 Mar 1999, NMV J39334 to elevation on pereonite 3. Pereonites 5 to 7 pro- (1 juvenile, 8.0 mm). gressively shorter, smooth. Pleon longer than Diagnosis.Head with dorsal elevation. Pereonite combined lengths of pereonites 5 to 7, with small 3 with dorsal elevation, smaller than elevation on lateral expansions, small dorsal elevation at two- head. Pereonite 4 with elevation, smaller than thirds length and 2 dorsolateral wings. elevation on pereonite 3. Antenna 2 with some Eyes lateral. Antenna 1 extending to end of the granulation on peduncular articles 3 and 4. peduncle article 2 of antenna 2; uniarticulate flag- ellum with aesthetascs attached laterally and dis- Description. Female: Anterolateral margins of tally. Antenna 2 stout, more than half as long as head with small tubercles, rostral point very body, tuberculate elevations with setae on dorsal small. Head with large dorsal blunt elevation, surface of peduncle articles 3–5; flagellum of 2 with setae extending out of elevation. Fusion of articles and claw, with a medial row of spines head and pereonite 1 indicated by dorsolateral along full length. groove with lateral margin extended slightly ante- Pereopod 1 dactylus barely longer than wide, riorly and incised laterally. Pereonite 2 smooth without unguis, bearing 2 medial setae and 3 with small tuberculate anterolateral extensions, oblique setae on the distal margin. Pereopods 2 to with some dorsal setae. Pereonite 3 with large 4 tuberculate. Pereopod 2 with dactylus on medial dorsal elevation of a similar size to elevation on surface, with unguis. Pereopods 3 and 4 without head, with dorsal setae; anterolateral extensions dactylus. Pereopods 5 to 7 with an unguis and a small and tuberculate. Pereonite 4 about 7 times secondary unguis. Pereopods 5 and 6 dactylus as long as pereonite 3; with row of dorsolateral denticulate; pereopod 7 dactylus smooth. tubercles along anterior margin and small ante- Uropodal exopod not reaching midpoint of rolateral expansions; not markedly wider than endopod, with 2 distal setae of equal length. previous pereonites; with smaller dorsal elevation Male pleopod 2 appendix masculina with ridge at midlength, with dorsal setae. Pereonites 5 to 7 on posterior face, apex simple, curved and short lateral margins not expanded but slightly tuber- (see Remarks). culate, progressively shorter posteriorly, dorsal surfaces with numerous setae. Pleon longer than Distribution.South Australia; subtidal. combined lengths of pereonites 5 to 7, with small Remarks. Hale’s original description stated that lateral expansions, a small dorsal elevation at the type of Parastacilla bakeri(SAM C238) was quarter length and 2 dorsolateral wings. ‘mounted in Balsam’ and so it was only possible Eyes lateral. Antenna 1 extending almost to end to figure the whole animal and antenna 1. In 1946 of peduncle article 2 of antenna 2; uniarticulate 128 RACHAEL A. KING Figure 1. Parastacilla bakeri male holotype (SAM C238): a, lateral view; distal end of antenna 2; pereopods 1 to 7. Scales: a = 1.0 mm; b (P1–P7) = 0.5 mm. THE ARCTURID GENUS PARASTACILLA 129 Figure 2.Parastacilla tingarafemale holotype (NMV J39333): a, dorsal view; b, lateral view; c, ventral view with oostegites detailed; antennae 1 and 2. Scales: a, b = 1.0 mm; c = 1.0 mm; A1 = 0.5 mm; A2 = 1.0 mm. 130 RACHAEL A. KING Figure 3. Parastacilla tingarafemale (NMV J39333): mouthparts; distal end of uropod. Scales a (MP, MX1, MX2, lMD, rMD) = 0.5 mm; b (U) = 0.5 mm. flagellum with distal aesthetascs. Antenna 2 stout, Uropodal exopod oblique, not reaching mid- more than half length of body, margins with some point of endopod, with 2 setae of subequal length. tuberculation; flagellum of 2 articles and claw, Oostegites present on pereopods 1 to 4; with medial row of comb-like spines along full oostegite 4 without suture. length. Distribution. South Australia to Tasmania; Maxilla 1 inner lobe with 3 terminal setae; subtidal. outer lobe with 10 distal robust setae. Maxilla 2 inner lobe with 16 plumose setae; middle lobe Etymology.“Tingara”is an Australian aboriginal with 4 setae; outer lobe with 3 setae. Maxillipedal word meaning the sea. endite with 19 mesial setae; 1 coupling hook pre- sent; palp article 2 with mesial setal rows; article Remarks. This species most closely resembles 3 with mesial and lateral setal rows; article 4 nar- Parastacilla bakeri. Males are generally only rower than article 3 and with mesial and lateral slightly smaller than females in this genus but the setal rows; article 5 with distal setae. male specimen of P. bakeriis much smaller than Pereopod 1 included within margin of head; the female of P. tingara(9.5 mm vs 13.5 mm) and propodus as long as carpus; dactylus barely yet both are fully mature. Ornamentation of the longer than wide, without unguis, with 3 medial head, usually highly species specific, differs setae and 3 setae on the distal oblique margin. between P. bakeri and P. tingara. Antenna 2 of Pereopod 2 with dactylus, unguis and secondary P. bakeri is more slender than antenna 2 of unguis. Pereopods 3 and 4 without dactylus. Pere- P. tingara The morphology of antenna 2 is usu- opods 5 to 7 with unguis and secondary unguis ally extremely similar between sexes of the same two-thirds length of primary unguis; dactylus species. The scales on the antenna 2 flagellum in barely denticulate with raised setose area close to P. bakeri and P. tingara are different. P. bakeri dactylus/propodus suture; pereopod 5 basis length has simple scales and P. tingara has comb-like twice pereopod 6 basis. scales as does P. torus. Denticulation of the THE ARCTURID GENUS PARASTACILLA 131 Figure 4. Parastacilla tingarafemale (NMV J39333): pereopods 1 to 7. Scale = 0.5 mm. 132 RACHAEL A. KING dactylus of pereopods 5 to 7 also differs between projecting around pereonite 3; markedly wider P. bakeri and P. tingara. Examination of other than previous pereonites; with large dorsal ele- species of Parastacilla leads me to believe that vation; small posterior lateral projections also there may be differences in the denticulation of present. Pereonites 5 to 7 relatively smooth with the dactylus of pereopods 5 to 7 between the row of tubercles along each posterior dorsal sexes but this variation is not as pronounced as margin; progressively shorter posteriorly. Pleon the differences between P. bakeri and P. tingara. longer than combined lengths of pereonites 5 to 7; Although the male of P. tingaraand female of with small anterior lateral expansions, a small Parastacilla bakeri are unknown, I believe the dorsal elevation and with dorsolateral wings. differences between specimens is more than can Eyes lateral. Antenna 1 extending midway be expected from sexual dimorphism. along peduncle article 2 of antenna 2; small tuber- cles on dorsal surface of peduncle article 1; flag- Parastacilla torussp. nov. ellum uniarticulate with aesthetascs along distal Figures 5–8 and lateral edge. Antenna 2 stout, more than half as long as body; flagellum of 2 articles and claw, Material examined. Holotype. Victoria, Venus Bay with medial row of comb-like spines full length. (38º39.57´S, 145º42.00´E), 9 m, SCUBA, 6 Mar 1982, Maxilla 1 inner lobe with 3 terminal setae; NMV J16691 (1 female, 9.5 mm ). Paratypes. Victoria. Twin Reefs, 11 m, 4 Mar 1982, outer lobe with 11 distal robust setae. Maxilla 2 NMV J16693 (1 male, 6.0 mm). Venus Bay, 8 m, 5 Mar inner lobe with 18 plumose setae; middle lobe 1982, NMV J16695 (2 juvenile males). Cape Paterson with 4 setae; outer lobe with 3 setae. Maxillipedal (38º40.22´S, 145º36.53´E), 6 m, 5 Mar 1982 NMV endite with 19 mesial setae; 2 coupling hooks J16692 (1 juvenile). Harmers Haven, 6 m, 6 Mar 1982, present; palp article 2 with mesial setal rows; NMV J16690 (2 juveniles). Nepean Bay (38º18.26´S, article 3 with mesial setal rows; article 4 narrower 144º39.57´E), 8 Apr 1998, NMV J39297 (1 female, 8.5 than article 3, with mesial and lateral setal rows; mm; 1 immature female, 7.0 mm). article 5 with distal setae. South Australia. Flinders Island (39º 52.17´S 148º Pereopod 1 included within margin of head; 01.02´E), SCUBA, 18 m, 19 Apr 1985, NMV J16688 (1 male, 7.0mm). “Hotspot Reef”, 5 n. miles W of Flinders propodus as long as carpus; dactylus barely Island (33°40.80´S, 134°22.50´E), 21 m, 20 Apr 1985, longer than wide, without unguis, with 3 medial NMV J16689 (1 female, 8.0 mm). setae and 4 setae on distal oblique margin. Pereo- Tasmania. Pegleg Cove, Deal Island (43º56.31´S, pod 2 with small dactylus with unguis and some- 147º18.59´E), 8 m, 13 Apr 1983, NMV J16687 (1 male, times secondary unguis (see Remarks). Pereopods 6.5 mm). 3 and 4 dactylus absent. Pereopod 5 to 7 with Western Australia. North Lumps, 2 km Off Mullaloo unguis and secondary unguis, dactylus denticu- (31º47.12´S, 115º43.54´E), 8 m, 2 May 1986, NMV late; pereopod 5 basis length twice pereopod 6 J39296 (1 female, 8.0 mm). basis. Diagnosis.Head with dorsal elevation. Pereonite Uropod exopod oblique, not reaching midpoint 3 in female with an anteriorly directed dorsal ele- of endopod, with 2 setae of subequal length. vation. Pereonite 4 in female with large anteriorly Oostegites present on pereopods 1 to 4; directed elevation covering the entire dorsal oostegite 4 with suture. surface, with anterolateral expansions. Males Male: Anterolateral lobes of head rounded, rostral without the elevation on pereonite 3 or the ante- point undetected. Fusion of head and pereonite 1 rolateral expansions; with a dorsal elevation on indicated by dorsolateral groove with lateral pereonite 4 with 2 apices. margin extended anteriorly and incised laterally. Description. Female. Anterolateral margins of Head with large blunt elevation. Pereonites 2 and head rounded, rostral point very small. Head with 3 smooth, lateral margins not expanded. Pereonite large blunt elevation. Fusion of head and pere- 4 around 8 times length of pereonite 3, with large onite 1 indicated by dorsolateral groove with lat- forward facing dorsal elevation with 2 apices; as eral margin extended anteriorly and incised later- wide as previous pereonites; lateral margins not ally. Pereonite 2 smooth, lateral margins visible in expanded. Pereonites 5 to 7 relatively smooth, dorsal view with small tubercles. Pereonite 3 with lateral margins not expanded. Pleon length large anteriorly directed dorsal elevation, half greater than combined lengths of pereonites 5 to height of elevation on head, lateral margins 7, with small anterior lateral expansions, large visible in dorsal view with small tubercles. Pere- dorsolateral wings present. onite 4 about 8 times as long as pereonite 3; Eyes small, subtriangular and positioned later- anterolateral expansions rounded and tuberculate, ally. Antenna 1 and antenna 2 as for female. THE ARCTURID GENUS PARASTACILLA 133 Figure 5. Parastacilla torus, female holotype (NMV J16691): a, lateral view; b, dorsal view; e, ventral view with oostegites detailed. Male: c, dorsal view; d, lateral view. Scale = 1.0 mm 134 RACHAEL A. KING Figure 6. Parastacilla torus, female holotype (NMV J16691): left maxilliped, left maxillae 1 and 2, left and right mandibles, antennae 1 and 2, distal end of uropod. Scales: a (MP, MX1, MX2, lMD, rMD, U) = 0.5 mm; b (A1) = 0.5 mm; c (A2a) = 1.0 mm; d (A2b) = 0.5 mm.