Natatolana zebra, Keable, 2006

Keable, Stephen J., 2006, Taxonomic Revision of Natatolana (Crustacea: Isopoda: Cirolanidae), Records of the Australian Museum 58 (2), pp. 133-244 : 237-241

Natatolana zebra n.sp.

Figs. 51–53

Type material. HOLOTYPE: 3, 11 mm, AM P47225 . PARATYPES: 562 specimens, AM P47226 ; ♀, AM P47227 ; subadult 3, AM P47228 ; 3, ♀, TM, BMNH, USNM, ZMUC. Type locality: about 25 m off middle of breakwater, Pilot Bay , Tasmania, Australia, 42°12.4'S 145°12.4'E, [baited trap, unknown substrate, probably sand], 6 m, [J. Lowry & S. Keable, 26–27 April 1991, TAS-286] .

Additional material. Tasmania: 2, AM P47229, about 250 m offshore, and just to the east of Hannants Bight on a line toward large bluff of Ocean Beach north side of Cape Sorell, 42°11.5'S 145°11.4'E, baited trap, sand, 25 m, J. Lowry & S. Keable, 26– 27 April 1991, TAS-282; 16, AM P47230, between breakwater and Prater Rock, Pilot Bay , 42°12'S 145°12'E, baited trap, probably sand bottom, 10 m, J. Lowry & S. Keable, 26–27 April 1991, TAS-284; 59, AM P47231, same data as holotype, except 100 m off Pilot Beach, 3 m, TAS-285 .

Diagnosis. Interocular furrow: absent. Frontal lamina: lateral margins medially constricted. Antenna: c. 0.4× as long as body, reaching to posterior of pereonite 4. Coxal plates: furrows strongly developed, on all coxae. Pleonite 4: apex slightly rounded. Pleotelson: broad, length 0.95× basal width; anterodorsal depression present; anterolateral margins convex; posterolateral margins convex; apex produced into a small point; with 10 RS. Pereopods 1–6: males with conspicuous elongated RS subequal to propodus on the merus of pereopods 1–3 and extending from the carpus to dactylus of pereopods 4–6. Pereopods 2–3: propodus without RS on palm. Pereopods 5–7: propodus long, on pereopod 5 greatly elongate, 2× that of pereopod 7. Pereopod 7: basis narrow, width 0.35× length; distance between anterior margin and medial carina less than between posterior margin and medial carina; posterior margin with sparse setae on distal half. Penes: present. Pleopod 2 appendix masculina: extending beyond tip of endopod, 1.17× length of endopod; margins sinuate; slender; apex not at angle to adjacent margins, bluntly rounded. Uropods: exopod subequal to endopod, 0.91× the length of the endopod.

Additional descriptive characters. Based on holotype. Body: length c. 2.6× width. Colour translucent white to yellow in alcohol. Chromatophores present; large; greyblack in alcohol; arranged in bands. Eyes: with 7 ommatidia in horizontal diameter; with 7 ommatidia in vertical diameter; round; colour tan in alcohol. Frontal lamina: length c. 3.75× basal width; apex expanded, anterior margin angled. Antennule: peduncular article 1 longer than article 2; article 2 with 1 large pappose seta; article 3 short, subequal to article 1. Flagellum 10-articulate. Antenna: peduncular article 4 with 5 SS on posterolateral margin and 1 SS at anterodistal angle; article 5 with 2 pappose setae and 3 SS at posterodistal angle, c. 5 SS and 1 penicillate seta at anterodistal angle. Flagellum 21-articulate. Mandible: setal row with 16 RS. Maxillule: medial lobe with 3 large robust pappose setae and 2 small SS; lateral lobe with 12 RS on distal surface. Maxilla: lateral lobe with 4 SS; medial lobe with 5 SS and 10 PS; middle lobe with 12 long and 3 short SS. Maxilliped: endite with 1 coupling hook, and 5 PS. Pereon: ornamentation consists of 1 strongly developed furrow on lateral margin of pereonite 1; pereonites 1, 4–6 subequal and longest, 2–3 and 7 subequal. Coxae: pereonite 1, coxae 2–3 with rounded posteroventral corners, coxae 4–7 with increasingly produced, broad, acute posteroventral corners. Pleonite 2: dorsal posterolateral margin subequal with ventral posterolateral margin. Pereopod 7: basis anterior margin straight; medial carina with PS along entire length; posterior margin convex, SS present. Ischium anterior margin with SS; posterior margin with groups of RS present, PS present. Merus anterior margin with 1 SS; posterior margin with 2 RS, SS present. Carpus posterior margin with 2 RS, SS absent. Propodus subequal to carpus; posterior margin with 2 RS, SS absent. Penes: forming well separated flattened lobes. Pleopod 2 appendix masculina: arising basally. Pleopods 1–5: exopod suture strongly developed on pleopods 1–5; endopod PS on most of margins on pleopods 1–4, absent on pleopod 5. Uropods: endopod triangular; medial margin convex, with 3 RS, PS along entire length; apex with 2 RS; lateral margin slightly convex, with 2 RS and 1 penicillate seta, PS along entire length. Exopod medial margin convex, with 3 RS, PS along entire length; apex acute, with 2 RS; lateral margin convex, with 6 RS, PS along entire length.

Variation. Immature males lack the conspicuously elongate robust setae on pereopods 1–6.

Sexual dimorphism. Females lack the conspicuously elongated robust setae present on the merus of pereopods 1–3 and on the carpus of pereopods 4–6 of adult males.

Size. Up to c. 13.5 mm.

Etymology. Named after the equine quadruped, the zebra, in reference to the striped pattern of chromatophores.

Remarks. The most distinctive character that separates Natatolana zebra from other species of Natatolana is the elongate propodus of pereopod 5 (longer than that of pereopod 6 and twice as long as that of pereopod 7). The distinct dorsal depression on the pleotelson, presence of penes, lack of robust setae on the propodal palm of pereopod 2, relatively narrow basis of pereopod 7 and conspicuously long robust setae on pereopods 1–6 of males also help to distinguish this species from all others in the genus.

Distribution and ecology. Australia: known only from southwest Tasmania in the vicinity of the type locality. At depths of 3– 25 m. Scavenger.

ACKNOWLEDGMENTS. This study would not have been possible without the support, help and understanding of my wife Debra. It was undertaken in partial fulfilment of a PhD degree, Macquarie University, while in receipt of a Macquarie University Postgraduate Scholarship. Financial assistance was also provided by a grant from the Joyce W.Vickery Research Fund of the Linnean Society of New South Wales. I am grateful for the support of the recent Directors and Trustees of The Australian Museum in allowing me to use the facilities of the museum.

I would particularly like to thank my supervisors Dr James Lowry and Dr Noel Tait for their assistance, advice and encouragement during the course of this study, and for their constructive criticism of the manuscript. Additionally, Dr George (Buz) Wilson was extremely patient and supportive of my many and varied requests for advice during the course of the study, publication of which would not have occurred without his continual encouragement and generous allowance of research time. I am also indebted to Ms Helen Stoddart for guidance in taxonomic procedures and Dr Penny Berents for allowing me time to edit the manuscript for publication.

Dr Niel Bruce provided much needed encouragement, commented on early species descriptions and through the Zoological Museum, University of Copenhagen, provided funding that made it possible for me to examine material held at the Phuket Marine Biological Centre, Thailand. He also provided references, specimens and notes (including information regarding the species of Natatolana , described in this study, from New Zealand), and added details regarding the distributions and synonymies of the north Atlantic species of Natatolana . I thank him for his contribution and continued interest. Two anonymous referees also provided a wealth of advice for improvement of the manuscript. For assistance in composing and inking many of the final figures I thank Mr Roger Springthorpe.

The following individuals assisted in making specimens from various institutions available to me: Ms M. Lowe (BMNH); Dr C. Carpine (IOM); L. Cederholm (Lund University, Sweden); Dr D. Defaye (MNHN); Mr R. Webber (NMNZ); Ms K. Coombes (NTM); Mr P. Anderson (NIWA); Mr P. Davie and Mr J. Short (QM); Ms L. Hoenson (SAM); Ms K. Gowlett Holmes (SAMA); Ms K. Sindemark (SMNH); Dr N. Nunomura (TSM); Ms M. Schotte (USNM); Ms J. Griffith (WAM); Dr N. Bruce (ZMUC).

Figures

Fig. 51. Natatolana zebra n.sp., holotype. Scales = 0.5 mm.

Fig. 52. Natatolana zebra n.sp., holotype, male, 11 mm except; P5. = paratype male (immature) AM P47228; female = paratype female AM P47277. Scales = 0.5 mm.

Fig. 53. Natatolana zebra n.sp., holotype, except; PL2 = paratype male (immature) AM P47228. Scales = 0.5 mm.