Tasmarcturus simplicissimus ( Whitelegge, 1904 )

Poore, Gary C. B., 2013, Rectarcturidae Poore, 2001 rediagnosed with descriptions of new Australian genera and species (Isopoda: Valvifera), Memoirs of Museum Victoria 70, pp. 17-36 : 33

Tasmarcturus simplicissimus ( Whitelegge, 1904)

Zoobank LSID. http://zoobank.org/ urn:lsid:zoobank.org:act:

DE7CA413-50A1-4F4F-9E95-2264DA513FF7

Figures 1d , 11 , 12

Arcturus simplicissimus Whitelegge, 1904: 406–408 , fig. 114a–c.

– Springthorpe and Lowry, 1994: 132. – Poore et al., 2002: 256.

Types. Australia, NSW, off ‘ Wata Mooli’ (now Wattamolla, 34°08'S, 151°07'E), 99–106 m (3 syntypes now lost).

Material examined. Neotype of Arcturus simplicissimus Whitelegge, 1904 . Australia, NSW, E of Long Reef (33° 43'S, 151°46'E), 19 Dec 1985, 174 m (stn K85-21-08), AM P.90298 (male, 4.8 mm).

Figured material. Tas., eastern Bass Strait, 100 km NE of North Point, Flinders I, (38°52.36'S, 148°25.12'E), 140 m, 15 Nov 1981, (stn BSS 170), NMV J23735 (male, 6.1 mm); NMV J23741 (ovigerous female, 4.9 mm); NMV J23736 (ovigerous female, 8.8 mm); NMV J8758 (28 individuals, all stages, 3.0– 7.3 mm).

Other material. Tas., Vic., NSW, c. 180 specimens from eastern Tas., eastern Bass Strait , eastern NSW; 35–42°S, 60–1096 m depth (see Museum Victoria database http://collections.museumvictoria. com.au/ for details). (All collected by WHOI epibenthic sled or SM grab by G.C.B. Poore et al., Museum Victoria.)

NSW, NE of Wollongong (34°20'S, 151°18'E), 13 Dec 1978, 161 m (stn K78-27-11), AM P.32669 (manca, 3.8 mm) .

Qld. NE of Lady Elliot I. (24°02.7'S, 152°49.4'E), 150 m, 4 Jul 1984 ( Kimbla stn 3), AM P.35630 (26 specimens), MTQ W34193 (15 specimens) .

Description. Ovigerous female. Pereonites 2–4 swollen, taller and broader than more anterior and posterior segments, visibly pustulose between ridges and major sculpture, 2.9 times as long as greatest width. Pleotelson 0.3 times total body length.

Head ornamentation of strong tubercles in lateral view, comprising 3 pairs of submedian dorsal tubercles, first conical, second longer and thinner, third broadly conical, plus pair of small sublateral cones, all secondarily tuberculate; maxillipedal segment with microtuberculate transverse ridge with submedian and sublateral tubercles; ventrolateral margin tuberculate, with anterior short spine. Pereonites 1–4 each with pair of submedian and pair of sublateral blunt tubercles on transverse ridge; pereonites 5–7 with 5 pairs of blunt spinulose tubercles on transverse ridge. Submedian and sublateral tubercles on pereonites 1 and 2 simple; submedian processes on pereonite 3 erect, digitiform, spinulose, with prominent secondary process posteriorly. Pereonites 1–7 + maxillipedal segment with supracoxal semicircular plates on 2–4, weaker on 5–7. Pereonites 3 and 4 with pair of short, conical submedian tubercles anterior to major ridge and smaller pair posterior to ridge on 3 only, all secondarily spinulose. Pleonites 1 and 2 elevated, with pairs of submedian and sublateral tubercles; pleonite 3 with pair of submedian tubercles, with rounded marginal lobes; posterior pleotelson with pair of submedian and 1 medial tubercle, with triangular lateral wings; pleotelson tapering evenly to sharply rounded apex, tapered section 0.7 times as long as wide.

Antennule flagellum article 1 with 3 pairs plus 1 aesthetascs, article 2 with 2 aesthetascs. Antenna, fused articles (1 + 2) short, stout, with ventrolateral flange; article 5 2.7 times as long as article 4; flagellum of 3 articles, 0.7 times length of peduncle article 5.

Pereopod 1 propodus 2.3 times as long as wide. Pereopod 2 tuberculate, especially basis and flexor margin of carpus; dactylus unguis 1.2 times length of dactylus body. Pereopod 4 dactylus body 1.3 times as long as propodus, unguis setiform, 0.3 times length of dactylus body. Pereopods 5–7 with 2 to several tubercles on extensor margin of basis and ischium, 1 each on carpus and propodus. Pereopod 7 dactylus body 0.6 times as long as propodus, unguis stout, 0.5 times length of dactylus body.

Oostegites 1–4 supported by oval coxal plates; oostegites 5 a pair of adjacent oval discs.

Uropodal exopod 0.9 times length of endopod.

Male. Of even dimensions throughout length. Male pleopod 1 exopod little more than 3 times basal width; posterior face without erect lobes along groove; lateral margin bearing row of 13 pectinate setae; distomesial seta-bearing lamina well separated from apex by deep triangular notch and well exceeding it in length.

Distribution. Southeastern Australia, 24– 42°S, 60–1096 m depth.

Remarks. Whitelegge (1904) described the species in detail but provided figures of only the antenna, maxilliped and pereopod 2. His remark that the body is not flexed between pereonites 4 and 5 is consistent with a species of Rectarcturidae . Key features noted by him suggest that this new abundant material can be referred to his species: the surface is covered with tubercles and ridges, is granulose and the granules are ‘subspiniform’, the head has four pairs of conical spines, the pereonites have a transverse ridge with submedian and lateral tubercles that tend to form a longitudinal ridge, and the pleotelson has tubercles on each side of the mesial line. Whitelegge’s illustrations are consistent with the new material, notably the apparently setiform unguis of pereopod 2. His three syntypes are now lost ( Springthorpe and Lowry, 1994). His description cannot be reconciled with that of any of the other non-flexed arcturid-like taxa, and a neotype is herein selected from a locality close by. The neotype is a small male, not as heavily sculptured as larger specimens. Whitelegge’s species was included in incertae sedis by Poore et al. (2002).

This widespread species occurs over a considerable depth range. The pairs of conical tubercles on the head and the dominant one on pereonite 3 of the male are distinctive.

Figures

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.

Figure 11. Tasmarcturus simplicissimus (Whitelegge, 1904). Female, NMV J23736: habitus; P3–P5, oostegites and coxal plates of pereonites 3–5. Male, NMV J23735: a1, antennule; a2, antenna; ur, uropodal rami.

Figure 12. Tasmarcturus simplicissimus (Whitelegge, 1904). Male, NMV J23735: p1, p2, p4, p7, pereopod 1 with details of distal articles, pereopods 2, 4 and 7; pl1, pleopod 1 with detail of exopod; pl2, pleopod 2.