Memoirs of Museum Victoria 70:17-36 (2013) Published 30-08-2013 1447-2554 (On-line) http://museumvictoria.com.au/about/books-and-journals/journals/memoirs-of-museum-victoria/ Rectarcturidae Poore, 2001 rediagnosed with descriptions of new Australian genera and species (Isopoda: Valvifera) GARY C.B. Poore (http://zoobank.org/urn:lsid:zoobank.org:author:C004D784-E842-42B3-BFD3-317D359F8975) Museum Victoria, GPO Box 666, Melbourne, Victoria 3001, Australia ([email protected]) Zoobank FSID. http://zoobank.Org/urn:lsid:zoobank.org:pub:84546808-FAA2-4838-BFBD-4D3582415F45 Abstract Poore, G.C.B. 2013. Rectarcturidae Poore, 2001 rediagnosed with descriptions of new Australian genera and species (Isopoda: Valvifera). Memoirs of Museum Victoria 70: 17-36. The family Rectarturidae is rediagnosed and three new genera and four new species from Australia added to the single genus of two species known from Argentina. The new genera are differentiated from each other and from Rectarcturus in overall sculptural patterns, the male pleopod 1 exopod, setation, shape and proportion of articles of pereopods 2 and 3, and length and proportion of articles of the antenna. The new genera are Galathearcturus gen. nov., Nowrarcturus gen. nov. and Tasmarcturus gen. nov., and the new species are: Galathearcturus antoniae sp. nov., Nowrarcturus jamesi sp. nov., Tasmarcturus erinae sp. nov. and T. lewisi sp. nov. Arcturus simplicissimus Whitelegge, 1904 is assigned to Tasmarcturus. The South American genus, Rectarcturus, is rediagnosed; its two species, R. kophameli and R. tuberculatus, appear in a key to all species of the family. Keywords Crustacea, Isopoda, Valvifera, Rectarcturidae, Galathearcturus, Nowrarcturus, Rectarcturus, Tasmarcturus, new genera, new species Introduction articulation between pereonites 4 and 5 suggests that not all of these taxa are as ‘straight’ as assumed, and all except In a major revision of the Isopoda Valvifera (Poore, 2001) a Arcturididae can elevate anterior body segments off the clade of eight ‘arcturoid’ families was recognised, in which the substrate, at least slightly, while attaching using pereopods 5-7. body is more or less cylindrical (‘idoteoid’ families are flat), No observations of these taxa alive have been reported. and pereopods 2-4 are usually differentiated from pereopods This paper concentrates on one of these so-called straight 5-7 and bear rows of long, paired setae. In the three largest families, Rectarcturidae. Whereas in the other families pleopod arcturoid families, Arcturidae Dana, 1849, Antarcturidae 1 of the male has the groove on the posterior face of the exopod Poore, 2001 and Austrarcturellidae Poore and Bardsley, 1992, ending on a tapering distolateral apical extension, in Rectarcturus the body is more or less flexed between pereonites 4 and 5, the the groove ends distolaterally on an apex separated from a free anterior half held somewhat or quite erect facilitating filter distal lamina by a notch. The autapomorphy of Rectarcturus in feeding by the long paired setae on pereopods 2-4 (Wagele, 1987). Four of the remaining families have fewer species than Poore’s (2001) analysis is pereopods 2-4 each having a short these three and fall into one clade defined on the basis of having dactylus bearing a longer, setiform unguis. Park and Wagele a ‘straight’ body, without the capability of flexion. This clade (1995) redescribed in detail the two species of Rectarcturus: R. comprises the Rectarcturidae Poore, 2001, Xenarcturidae kophameli (Ohlin, 1901) and R. tuberculatus Schultz, 1981, both Sheppard, 1957, Pseudidotheidae Ohlin, 1901 and Arcturididae from Argentina. Here, an enigmatically described species and Poore, 2001, each with only one genus. In Rectarcturidae, four new species from the southeastern Australian shelf are pereopods 2-4 carry elongate setae as in the larger families; in described; these are significantly different from the South Xenarcturidae, only pereopods 2 and 3 do; in Pseudidotheidae, American species and from each other and warrant three new pereopods 2-4 bear long robust setae; and Arcturididae have genera. Another species, ascribed to this genus, is discussed. similar ambulatory pereopods 2-7 without long setae. The The material examined is lodged in Museum Victoria, eighth family, Holidoteidae Wagele, 1989, with three genera Melbourne (NMV), the Australian Museum, Sydney (AM), (Poore, 2003), also appears to lack pereonal flexion but, at least the Museum of Tropical Queensland, Townsville (MTQ), the in the cladogram published by Poore (2001: fig. 4), is sister National Museum of Natural History, Washington (USNM), family to Austrarcturellidae. This suggests that the straight and the Zoological Museum, University of Copenhagen body-form has been derived twice. Closer examination of the (ZMUC, now the Natural History Museum of Denmark). 18 G.C.B. Poore Photographs (fig. 1) were made using a Leica M205C of the characters he chose is especially diagnostic except for microscope with Leica Application Suite 3.8.0. ‘body much straighter than in most arcturids’. Schultz (1981) included four species. One of these, Microarcturus laevis is Rectarcturidae Poore, 2001 now Austroacturus laevis (Kensley, 1975), a member of Holidoteidae. Park and Wagele (1995) noted that another, Rectarcturidae Poore, 2001: 227. - Poore, 2003: 1843. Arcturus patagonicus Ohlin, 1901, is clearly geniculate Diagnosis. Body strongly vaulted; head and pereonite 1 fused; between pereonites 4 and 5, and has a pair of sharp submedian pereonite 4 of similar length to pereonite 3; all pleonites fused spines on the head. They placed it in Neoarcturus, which they into pleotelson. Body variously tuberculate or spinose but never thought of as similar to Rectarcturus-, Neoarcturus and some with a posterior dorsolateral pair of strong spines on pleotelson; of the species they listed are also in Holidoteidae, but not this pleotelson without dorsolateral ridges ending in mediodorsal one. It and others from their list are now placed in the posterior spine. Dorsal coxal plates 2-7 obsolete, bases of antarcturid genus Fissarcturus Brandt, 1990 (Poore, 2003). pereopods exposed. Mouthparts and pereopod 1 visible in Another, Rectarcturus tatianae Kussakin and Vasina, 1995, lateral view. Eyes well developed. Antenna flagellum of 2 from 6000 m depth in the South Atlantic, is a geniculate articles plus distal claw. Pereopod 1 a gnathopod, pereopods species, so is not in this genus as presently defined. Its setiform 2-4 elongated, differentiated from ambulatory pereopods 5-7. unguis on pereopods 2-4, short antennal flagellum, male Pereopod 1 dactylus evenly curved along anterior margin, pleopod 2 structure, and paired body tuberculation suggest evenly tapering. Pereopods 2-4 with long setae along flexor another species of Fissarcturus, but without the prominent margins of ischium-propodus (up to 9 pairs per article, well¬ posterior pleotelsonic spines. spaced), with short dactylus, unguis longer and setiform. The two species of Rectarcturus are from Argentina. Pereopod 4 similar to pereopod 3. Pereopods of males without Australian species that can be placed in the family are dense fur of fine setae. Oostegites 1-4 functional, supported by sufficiently different from Rectarcturus and diverse to warrant coxal lobes, oostegites 5 present as articulating discs or absent. three new genera. They are diagnosed and four new species Penes fused as a single penial plate, apically simple. Pleopod 1 described here. The poorly described Arcturus simplicissimus peduncle more elongate than on other pleopods, with marginal Whitelegge, 1904 is allocated to one of the new genera on the setae on rami longer than peduncle; exopod of male thickened basis of the description of a neotype. laterally, with groove on posterior face ending distolaterally on The four genera are separated on the basis of differences in an apex separated from a free distomesial lamina by a notch. overall sculptural patterns, the male pleopod 1 exopod, Pleopod 2 of male with appendix masculina as long as or longer setation, shape and proportion of the antenna and pereopods 2 than endopod, basally less than half width of endopod. and 3. The key uses the most conveniently observed characters; Uropodal exopod tapering, with 2-3 stout distal setae. a key based on the structure of the male pleopod 1 exopod would lead to different dichotomies. Whereas in Rectarcturus Remarks. The family was erected for one genus, Rectarcturus and Tasmarcturus gen. nov. the groove on the posterior face of Schultz, 1981, on the basis of a cladistic analysis of the Valvifera the male pleopod 1 exopod ends obliquely on a truncate (Poore, 2001). The diagnosis given above differs from the distolateral lobe, not extending beyond the distomesial seta- original in some important features. Pereopods 2-4 are bearing lamina, in Nowrarcturus gen. nov. it ends on a conical described as possessing up to nine pairs of well-spaced long apical projection, extending beyond the lamina. The male of setae per article along the flexor margins of the merus- Galathearcturus gen. nov. is unknown, but its only species propodus. These setae are more spaced and fewer than those on differs sculpturally from all others. Arcturidae and Antarcturidae. It is now realised that oostegites 1-4 are supported by coxal lobes, and that a vestigial oostegite Key to genera and species of Rectarcturidae 5 is present as a lobe in three of the four genera. The structure of the male pleopod 1 exopod is better defined as above. 1. Antenna less than twice dorsal length of (head + pereonite Species of the family are recognisable, and distinguished 1); article 4 subspherical, about as long as fused articles (1 from arcturids, antarcturids and austrarcturellids, by their + 2); article 5 at least twice as long as article 4; pereopod straight bodies and reduced setation of pereopods 2-4. The 2 (dactylus body + unguis) 3 times as long as propodus. structure of the male pleopod 1 exopod separates rectarcturids .2 from other ‘straight’ families—the groove ends in a distolateral - Antenna at least 2.5 times dorsal length of (head + lobe separated from a distomesial lamina by a deep notch (see pereonite 1); article 4 cylindrical, at least twice as long as Poore, 2001: fig. 3 for examples from other families). fused articles (1 + 2); article 5 shorter than or at most 1.5 Monotypic Xenarcturidae is also straight but has a flat body times as long as article 4; pereopod 2 (dactylus body + and ambulatory pereopod 4. The only species of Arcturididae unguis) shorter or at most 2.5 times as long as propodus ... is straight and cylindrical, and all pereopods except the first .5 are essentially ambulatory. Pseudidoteidae have almost raptorial pereopods 2-4 (Poore and Bardsley, 2004), and 2. Head with paired, submedian tubercles, pereonites with Holidoteidae have a uniquely structured male pleopod 1 smooth, transverse ridges, anterior pleonites barely exopod and uropodal rami (Poore, 2003). Schultz (1981) elevated; antenna article 3 cuboid, as long as deep, without diagnosed his new genus as a member of Arcturidae, but none ventrolateral flange (fig. 2).Galathearcturus antoniae Rectarcturidae Poore, 2001 rediagnosed with descriptions of new Australian genera and species (Isopoda: Valvifera) 19 - Head, pereonites and anterior pereonites with paired Distribution. Southern Qld, Australia. blade-like submedian and sublateral tubercles/carinae, all Remarks. The sole species of Galathearcturus shares a short secondarily tuberculate; antenna article 3 cuboid, as long antenna and long pereopod 2 dactylus with the three species of as or little longer than deep, with ventrolateral teeth (fig. Tasmarcturus, but differs in dorsal sculpture; this species is the lb-d).Tasmarcturus.3 least sculptured of all rectarcturid genera. Unfortunately, the 3. Head ornamentation of strong acute tubercles separated in male is unknown. lateral view; submedian processes on pereonite 3 erect, digitiform, spinulose, especially in female, with prominent Galathearcturus antoniae sp. nov. secondary process posteriorly (fig. Id). Zoobank LSID. /Tt/p://cooZ?awk.or^/urn:lsid:zoobank.org:act: .Tasmarcturus simplicissimus C2E736F0-6E2D-4680-A446-C2DD94E8FA2D - Head ornamentation of flat tubercles almost contiguous in Figures 2, 3 lateral view; submedian processes on pereonite 3 longitudinally flattened.4 Material examined. Holotype. Australia, Qld, off Maroochydore (26°33'S, 153°31'E), 86 m, 5 Nov 1951 (<Galathea stn 539), ZMUC 4. Head ornamentation rounded anteriorly in lateral view (ovigerous female, 6.3 mm). (fig. lc).Tasmarcturus lewisi Description. Ovigerous female. Pereonites 2-4 swollen, taller - Head ornamentation prominently square anteriorly in and broader than more anterior and posterior segments, smooth lateral view (fig. lb).Tasmarcturus erinae between major sculptures, 2.6 times as long as greatest width. Pleotelson 0.3 times total body length. 5. Head with paired submedian tubercles, pereonites with Head with pair of submedian tubercles on anterior margin, smooth transverse ridges (pereonite 3 with second ridge pair of submedian, erect, obliquely transverse blades, followed anterior to major one), anterior pleonites barely elevated by pair of submedian, sharp, erect ridges converging (fig. la).Nowrarcturus jamesi posteriorly and divided along their lengths by a shallow, dorsal - Head, pereonites and anterior pleonites with paired blade¬ notch; maxillipedal segment indistinguishable from cephalon; like submedian and sublateral tubercles or carinae, ventrolateral margin smooth, with deep fissure between head smooth or barely secondarily ornamented. and pereonite 1. Pereonite 1 without sculpture; pereonite 2 .Rectarcturus.6 with obsolete submedian and sublateral bosses; pereonites 3 and 4 with obsolete submedian bosses and prominent sublateral 6. Sculpture dominated by rows of submedian, sublateral, conical tubercles; pereonites 5-7 with sublateral rounded lateral and supracoxal longitudinal blades. tubercles. Submedian and sublateral tubercles on pereonites 1 .Rectarcturus kophameli and 2 simple; submedian processes on pereonite 3 obsolete. - Sculpture dominated by rows of submedian, sublateral, Pereonites 1-7 + maxillipedal segment with supracoxal, lateral and supracoxal longitudinal complex tubercles. rounded-triangular, slightly excavate plates on 2-4, weaker on .Rectarcturus tuberculatus 5-7. Pereonites without supplementary ridges. Pleonites 1-2 with pair of obsolete submedian ridges; pleonite 3 barely Galathearcturus gen. nov. distinguished from pleonite 2; posterior pleotelson with broad sublateral domes, with rounded lateral wings; pleotelson Zoobank LSID. http://zoobank.org/urnrlsid: zoobank.org: act: tapering evenly to sharply rounded apex, tapered section 0.5 E79071AD-6121-4517-A9AB-A325E25456BA times as long as wide. Type species. Galathearcturus antoniae sp. nov., by monotypy Antennule flagellum with 1 pair plus 1 aesthetascs, article and original designation. 2 without aesthetascs. Antenna, fused articles (1 + 2) short, stout, with ventrolateral flange; article 5 2.4 times length of Diagnosis. Head with paired submedian tubercles, pereonites article 4; flagellum of 3 articles, 0.7 times length of peduncle with smooth transverse ridges, anterior pleonites barely article 5. elevated. Antenna 1.5 times dorsal length of (head + pereonite Pereopod 1 propodus twice as long as wide. Pereopod 2 1); article 3 cuboid, as long as deep, without ventrolateral tuberculate only along flexor margins; dactylus unguis as long flange; article 4 subspherical, about as long as fused articles (1 as dactylus body. Pereopod 4 with triangular lobe on extensor + 2); article 5 cylindrical, 2.4 times as long as article 4, 5 times margin of basis; dactylus body 1.5 times as long as propodus, as long as wide. Pereopod 2 propodus palm convex, denticulate; dactylus unguis setiform, 0.3 times length of dactylus body. (dactylus body + unguis) 3 times as long as propodus; unguis Pereopods 5-7 with 2 small tubercles on extensor margins of setiform, as long as dactylus body. Pereopod 3 similar to ischium-carpus. Pereopod 7 dactylus body 0.75 times as long pereopod 2, unguis shorter. Male pleopod 1 exopod unknown. as propodus, unguis stout, 0.3 times length of dactylus body. Oostegites 5 a pair of adjacent oval discs. Oostegites 1-4 supported by oval coxal plates; oostegites 5 Etymology. From Galathea, the ship and expedition that a pair of adjacent oval discs. collected the type species, and Arcturus, generic stem. Uropodal exopod 0.8 times length of endopod. Composition. Type species only. Etymology. For my granddaughter, Antonia Salter. 20 G.C.B. Poore Figure 1. Dorsal and lateral views of four species of Rectarcturidae, males on top, females below, (a) Nowrarcturus jamesi sp. nov. (with ventral view of oostegites 3-5), male, NMV J19187; female, NMV J23734. (b) Tasmarcturus erinae sp. nov., male, NMV J16686; female, NMV J62082. (c) Tasmarcturus lewisi sp. nov., male and female, NMV J23743. (d) Tasmarcturus simplicissimus (Whitelegge, 1904), male and female, NMV J8758. Scale bars = 1 mm. Rectarcturidae Poore, 2001 rediagnosed with descriptions of new Australian genera and species (Isopoda: Valvifera) 21 Figure 2. Galathearcturus antoniae sp. nov. Female holotype, ZMUC: habitus; al, a2, antennule, antenna; ur, uropodal rami; P3-P5, oostegites and coxal plates of pereonites 3-5. Distribution. Southern Qld, Australia, 26°S, 86 m depth. article 5 cylindrical, 1.5 times as long as article 4, 5 times as long as wide. Pereopod 2 propodus palm convex, denticulate; Remarks. For similarities see notes for the genus. The only (dactylus body + unguis) 2.5 times as long as propodus; unguis specimen is an ovigerous female; the male is unknown. setiform, little longer than dactylus body. Pereopod 3 similar to pereopod 2, unguis shorter. Male pleopod 1 exopod groove Nowrarcturus gen. nov. ending obliquely on conical apical projection, extending Zoobank LSID. http://zoobank.org/urn:\sid:zooba.nk.org:SLCt: beyond distomesial seta-bearing lamina. Male pleopod 1 6D11DFB5-917A-4D1C-8F2A-AAC9969DD029 endopod about three-quarters exopod length. Oostegites 5 a Type species. Nowrarcturus jamesi sp. nov., by monotypy and pair of adjacent oval discs. original designation. Etymology. From Nowra, a town in NSW near to the type Diagnosis. Head with paired submedian tubercles, pereonites locality of the type species, and Arcturus, generic stem. with smooth transverse ridges (third with second ridge anterior to major one), anterior pleonites barely elevated. Antenna 2.5 Composition. Type species only. times dorsal length of (head + pereonite 1); article 3 cylindrical, Distribution. Southern NSW, Australia. twice as long as deep, without ventrolateral flange; article 4 cylindrical, more than twice as long as fused articles (1 + 2); Remarks. The sole species of Nowrarcturus is distinguished by 22 G.C.B. Poore Figure 3. Galathearcturus antoniae sp. nov. Female holotype, ZMUC: pi, p2, p4, p7, pereopods 1, 2, 4 and 7, with details of distal articles. Rectarcturidae Poore, 2001 rediagnosed with descriptions of new Australian genera and species (Isopoda: Valvifera) 23 smooth transverse ridges on pereonites 1-4 and the elongate Male pleopod 1 exopod 4 times as long as basal width; articles of the antennal peduncle. The relationship between the posterior face with 2 longitudinal erect lobes parallel to two lobes of the major transverse ridge on pereonite 3 and the groove; lateral margin bearing row of 8 long simple setae pair of smaller lobes opposing it anteriorly, especially evident proximally, 11 short simple setae distally; distomesial seta- in females, is unique. This genus is the only rectarcturid in bearing lamina well separated from much longer apex by which the groove on the exopod of the male pleopod 1 ends triangular notch. obliquely on a conical apical projection, extending beyond the Uropodal exopod 0.7 times length of endopod. distomesial seta-bearing lamina. Ovigerous female. Pereonites 2-4 swollen, taller and broader than more anterior and posterior segments. Submedian processes Nowrarcturus jamesi sp. nov. on pereonite 3 flat transversely, anteriorly curved, overhanging, meeting as a deep notch, and opposing a pair of more anterior Zoobank LSID. http://zoobank.org/urn:lsid:zoobank.org:act: erect submedian tubercles. Oostegites 1-4 supported by oval 1C749725-DF07-48BB-8B5A-7364487E1812 coxal plates; oostegites 5 a pair of adjacent oval discs. Figures la, 4-6 Distribution. Southern NSW, Australia, 34-42°S, 990-1118 m Material examined. Holotype. Australia, NSW, 54 km ESE of Nowra depth. (34°52.7'S, 151°15.04'E), 990-996 m, 22 Oct 1988 (stn SLOPE 53), NMV J23444 (male, 6.3 mm). Etymology. For my grandson, James Salter. Paratypes. Collected with holotype. NMV J23734 (ovigerous Remarks. Females of the new species are immediately female, 6.5 mm); NMV J19188 (1 male, 2 females, 1 manca); J19747 (ovigerous female, 6.5 mm). recognisable by the dorsal sculpture, particularly the NSW, off Nowra (34°52.3'S, 151°15.0'E), 1096-1118 m, 15 Jul characteristic submedian ridges and lobes on pereonite 3. This 1986 (stn SLOPE 7), NMV J19187 (male, 6.0 mm; female, 4.8 mm). structure is less well developed in males. (All collected by WHOI epibenthic sled by G.C.B. Poore et al.. Museum Victoria.) E of Broken Bay (33°36’S, 152°09’E), 1097 m, 4 Rectarcturus Schultz, 1981 Dec 1979 (stn K79-20-07), AM P.32672 (male, 6.0 mm). Rectarcturus Schultz, 1981: 67-68. - Park and Wagele, 1995: Description. Male. Of even dimensions throughout length, 69-71. sparsely and microscopically pustulose between transverse ridges, 3.2 times as long as greatest width. Pleotelson 0.25 Type species. Arcturus kophameli Ohlin, 1901, by original designation. times total body length. Diagnosis. Head, pereonites and anterior pereonites with Head with 3 pairs of submedian dorsal blunt tubercles: first paired blade-like submedian and sublateral tubercles or conical, second broader, third ridge-like, all simple; maxillipedal carinae, smooth or barely secondarily ornamented. Antenna segment with simple transverse ridge; ventrolateral margin 2.5-3 times dorsal length of (head + pereonite 1); article 3 smooth, with anterior triangular projection. Pereonites 1-7 each cuboid, as long as deep, without ventrolateral flange; article 4 with pair of submedian and pair of sublateral blunt tubercles on cylindrical, more than twice as long as fused articles (1 + 2); transverse ridge. Submedian and sublateral tubercles on article 5 cylindrical, 0.7 times length of article 4, 5 times as pereonites 1 and 2 secondarily pustulose; submedian processes long as wide. Pereopod 2 propodus palm straight, smooth; on pereonite 3 flat transversely, anteriorly curved, meeting as (dactylus body + unguis) as long as or little shorter than shallow notch. Pereonites 1-7 + maxillipedal segment with propodus; unguis setiform, little shorter than dactylus body. supracoxal tubercles, weaker on 5-7. Pereonites 3 and 4 with Pereopod 3 similar to pereopod 2, unguis shorter. Male pleopod sharp, bilobed, middorsal, transverse, posteriorly sloped ridge 1 exopod groove ending obliquely on truncate distolateral lobe, anterior to main ridge (less well defined on 4). Pleonites 1 and 2 not extending beyond distomesial seta-bearing lamina. Male with obsolete lateral bosses; pleonite 3 domed middorsally, with pleopod 1 endopod about as long as exopod length. Oostegites rounded marginal lobes; posterior pleotelson evenly domed, 5 absent. with rounded lateral wings; pleotelson tapering evenly to sharply rounded apex, tapered section 0.7 times as long as wide. Composition. Rectarcturus kophameli (Ohlin, 1901), R. Antennule flagellum article 1 with 3 pairs plus 1 tuberculatus Schultz, 1981. aesthetascs, article 2 with 2 aesthetascs. Antenna, fused Distribution. Argentina. articles (1 + 2) short, stout, with ventrolateral flange; article 5 1.5 times length of article 4; flagellum of 3 articles, almost as Remarks. Rectarcturus comprises two Argentinian species long as peduncle article 5. differentiated from those in the three Australian genera. The Pereopod 1 propodus 2.5 times as long as wide. Pereopod genus is most similar to Tasmarcturus but lacks the strong 2 tuberculate, especially basis and flexor margin of carpus; secondary ornamentation of the principal pereonal tubercles, dactylus unguis 1.2 times length of dactylus body. Pereopod 4 has a much longer article 4 on the antenna, has a straight palm dactylus body 1.4 times as long as propodus, unguis setiform, on pereopod 1 (all other genera are denticulate), the dactylus 0.5 times length of dactylus body. Pereopods 5-7 with several and unguis of pereopod 2 are little if at all longer than the small tubercles on extensor margin of basis-carpus. Pereopod propodus (much longer in all other genera), its unguis is shorter 7 dactylus body 0.6 times as long as propodus, unguis stout, than the dactylus body (as long as or longer in others), and 0.5 times length of dactylus body. oostegites 5 are absent. 24 G.C.B. Poore Figure 4. Nowrarcturus jamesi sp. nov. Female paratype, NMV J23734: habitus; P3-P5, oostegites and coxal plates of pereonites 3-5. Male holotype, NMV J23444: al, antennule; a2, antenna. Rectarcturus kophameli (Ohlin, 1901) Description. Male. Pereonites 2-4 swollen, taller and broader than more anterior and posterior segments, sparsely and Arcturus kophameli Ohlin, 1901: 272-273, fig. 5. microscopically pustulose between transverse ridges, 3 times Antarcturus kophameli. - Stebbing, 1908: 53. Microarcturus kophameli. - Nordenstam, 1933: 128. as long as greatest width. Pleotelson 0.3 times total body Rectarcturus kophameli. - Schultz, 1981: 68, fig. 3A-G. - Park length. Head with 2 pairs of broad, blunt submedian tubercles, and Wagele, 1995: 71-75, figs 9-12. - Poore, 2003: 1843. followed by single medial tubercle. Antennule flagellum article 1 with 3 pairs plus 1 Types. Northern Argentina, 38°S, 56°W, 52 fm [95 m] depth, aesthetascs, article 2 with 2 aesthetascs. Antenna, fused holotype, female, 11 mm, lost. articles (1 + 2) short, stout, with ventrolateral flange; article 5 Material examined. Argentina, Beagle Channel (55°S, 68°W, 63 m, Nov 0.5 times length of article 4; flagellum of 3 articles, 0.7 times 1994, A. Brandt (Victor Hansen stn 1213), NMV J47040 (two specimens). length of peduncle article 5. Rectarcturidae Poore, 2001 rediagnosed with descriptions of new Australian genera and species (Isopoda: Valvifera) 25 Figure 5. Nowrarcturus jamesi sp. nov. Male holotype, NMV J23444: pi, p2, p4, p7, pereopod 1 with details of distal articles, pereopods 2,4 and 7; ur, uropodal rami. 26 G.C.B. Poore Pereopod 1 propodus 1.9 times as long as wide. Pereopod over the whole body. Park and Wagele (1995) redescribed new 2 with tubercle on extensor margin of basis only; dactylus material, taken at shallower depths in the Straits of Magellan, unguis 0.9 times length of dactylus body. Pereopod 4 dactylus Argentina than the type locality. Their observations were body 0.9 times as long as propodus, unguis setiform, 0.4 confirmed by additional material from the same region times length of dactylus body. Pereopods 5-7 without (representatives of a larger collection at the Zoological tubercles on extensor margin. Pereopod 7 dactylus body 0.7 Museum, Hamburg). W. Wagele (pers. comm.) observed the times as long as propodus, unguis stout, 0.4 times length of absence of oostegites 5 on the female described by Park and dactylus body. Wagele (1995) and now at Zoologisches Forschungsmuseum Male pleopod 1 exopod more than 4 times as long as basal Alexander Koenig, Bonn, Germany. width; posterior face without erect lobes along groove; distomesial seta-bearing lamina well separated from apex by Rectarcturus tuberculatus Schultz, 1981 deep triangular notch and equalling it in length. Uropodal exopod 0.5 times length of endopod. Rectarcturus tuberculatus Schultz, 1981: 68-70, fig. 4. - Park and Ovigerous female. See detailed description by Park and Wagele 1995: 75-83, figs 13-18. Wagele (1995). Oostegites 5 absent. Material examined. N of South Shetland Is., 57°09'S, 58°58'W - Distribution. Northern Argentina, 38°S, 95 m (type locality); 58°00'S, 58°50'W, 3477-3590 m (Eltanin stn 6-363), USNM 181263 Straits of Magellan, Argentina, 52°S, 10-12 m depth. (ovigerous female, 9.5 mm). Remarks. Ohlin (1901) based his new species on an ovigerous Description. Antennule flagellum article 1 with 3 pairs plus 1 female from off northern Argentina at 95 m depth. Schultz aesthetascs, article 2 with 2 aesthetascs. Antenna, articles 1-2 (1981) selected this as the type species of his new genus and short, stout, with ventrolateral flange; article 5 0.7 times length redescribed it on the basis of new material, ovigerous females of article 4; flagellum of 3 articles, 0.7 times length of peduncle from off Isla de los Estados, southern Argentina, at 84-208 m article 5. depth. The holotype appears lost; it could not be found in the Pereopod 1 propodus twice as long as wide. Pereopod 2 major museums in Stockholm, Hamburg or Berlin. Other with tubercle on extensor margin of basis only; dactylus authors transferred the species to other genera, Antarcturus and the nomen nudum, Microarcturus. The species is unguis 0.9 times length of dactylus body. Pereopod 4 dactylus characterised by sharp submedian, sublateral and lateral body 0.9 times as long as propodus, unguis setiform, 0.4 longitudinal ridges on each pereonite, and sublateral ridges on times length of dactylus body. Pereopods 5-7 with 2 stout pleonites 1 and 2. The lateral mid-length pleotelson marginal tubercles on extensor margin of basis, 1 each on carpus- wings are weak. Ohlin commented on the ‘very small hairs’ propodus.