Natatolana sinuosa, Keable, 2006

Keable, Stephen J., 2006, Taxonomic Revision of Natatolana (Crustacea: Isopoda: Cirolanidae), Records of the Australian Museum 58 (2), pp. 133-244 : 224-228

Natatolana sinuosa n.sp.

Figs. 45–47

Cirolana corpulenta .– Hale, 1940: 289 (part) [mis-identification, not Natatolana corpulenta ( Hale, 1925) ].

Natatolana corpulenta .– Bruce 1986: 79, figs. 51–53 (part) [misidentification, not Natatolana corpulenta ( Hale, 1925) ].

Type material. HOLOTYPE: 3, 14.5 mm, AM P47214 . PARATYPE: ♀, 16.5 mm, TM, same collection data as holotype only 100 m off Pilot Beach , 3 m, TAS-285. Type locality: between breakwater and Prater Rock, Pilot Bay, Tasmania, Australia, 42°12'S 145°12'E, [baited trap, probably sand bottom], 10 m, [J. Lowry & S. Keable, 26–27 April 1991, TAS-284] .

Additional material. New South Wales: series from near Newcastle, AM Hunter District Water Board Survey, Shipek [grab] (reported by Bruce [1986]): 1, AM P23034, 1 km east of Belmont Beach, 33°02.36'S 151°41'E, 18 m; 1, AM P 23036, 500 m east of Belmont Beach, 33°02.5'S 151°41'E, 14 m; 2, AM P 23037, 500 m east of Stockton Beach, 32°54'S 151°47.5'E, 6 m; 2, AM P23038, 1 km east of Stockton Beach, 32°54'S 151°47.5'E, 15 m; 1, AM P 23039, 500 m east of Dudley Beach, 32°59'S 151°44'E, 16 m; 37, SAMA C5640, Newcastle, NSW, [32°56'S 151°46'E], from shark liver, T.C. Roughley (reported by Hale [1940]); 156, AM P47221, off Providential Head, 34°44'S 150°39'E, baited trap, 25–30 m, S. Keable & A. Parker 14–15 Jan. 1991, PIO-103. Tasmania: series from off Maurouard Beach, St Helens Point, all c. 41°17.3'S 148°21'E, baited trap, J. Lowry, S. Keable & C. McCormick, 13–14 April 1991; 433, 3♀♀, 31 mancas, AM P47215, sandy bottom, 15 m, TAS-124; 3, AM P47216, sandy bottom, 5 m, TAS-125; 3♀♀, 23 mancas,AM P47217, sandy bottom, 10 m, TAS-126; 64 mancas, AM P47218, sandy bottom, 15 m, TAS- 139; ♀, manca, AM P47219, off Binalong Beach, Binalong Bay, 41°14.7'S 148°17.6'E, baited trap, on sand, 8 m, J. Lowry, S. Keable & C. McCormick, 14–15 April 1991, TAS-144; 21 33, 17♀♀, 15 mancas, AM P47220, about 100 m off Nine Mile Beach near Point Bagot, Freycinet Peninsula, 42°06.2'S 148°13.8'E, baited trap, J. Lowry & S. Keable, 30 April–1 May 1991, TAS-344. South Australia: 3, SAMA C5641, Christies Beach [35°08'S 138°28'E], seaweed on beach, T. Castle, 29 Jan. 1959; 6 paratypes of N. corpulenta, SAMA C 276, Port Willunga [35°16'S 138°28'E].

Diagnosis. Interocular furrow: absent. Frontal lamina: lateral margins straight, narrowing anteriorly. Antenna: c. 0.5× as long as body, reaching to posterior of pereonite 4. Coxal plates: furrows moderately developed, on all coxae but indistinct, particularly on coxa 2. Pereonite 1, coxa 2 posterior margins sinuate, posteroventral corners developed into strong coxal points. Pleonite 4: posterodorsal margin distinctly concave proximal to meeting posteroventral margin at apex; apex forming a broad acute point. Pleotelson: broad, length 0.88× basal width; anterodorsal depression present; anterolateral margins convex; posterolateral margins concave; apex produced into a large 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. Pereopod 7: basis narrow, width 0.42× length; distance between anterior margin and medial carina less than between posterior margin and medial carina; posterior margin with setae along entire length. Penes: present. Pleopod 2 appendix masculina: extending beyond tip of endopod, 1.07× length of endopod; margins very slightly curved laterally; slender; apex not at angle to adjacent margins, bluntly rounded. Uropods: exopod subequal to endopod, 0.93× the length of the endopod.

Additional descriptive characters. Based on holotype. Body: length c. 2.26× width. Colour yellow in alcohol. Chromatophores present; large; black in alcohol; arranged in bands. Eyes: with 7 ommatidia in horizontal diameter; with 7 ommatidia in vertical diameter; round; colour redbrown in alcohol. Frontal lamina: length c. 5× basal width;

apex expanded, anterior margin angled. Antennule: peduncular article 1 longer than article 2; article 2 with 1 large pappose and several small penicillate setae; article 3 long, larger than article 1 or 2 but shorter than their combined lengths. Flagellum 12-articulate. Antenna: peduncular article 4 with 6 SS and 1 penicillate seta medially and 3 SS at posterodistal angle, 5 SS and 1 penicillate seta at anterodistal angle; article 5 with 1 large pappose seta at posterodistal angle and 8 SS at anterodistal angle. Flagellum 23-articulate. Mandible: setal row with 15 RS. Maxillule: medial lobe with 3 large and 1 smaller robust pappose setae and 2 small SS; lateral lobe with 13 RS on distal surface. Maxilla: lateral lobe with 5 SS; medial lobe with 4 SS and 15 PS; middle lobe with 12 long SS on outer row and 7 shorter SS on inner row. Maxilliped: endite with 2 coupling hooks, and 9 PS. Pereon: ornamentation consists of 1 weakly developed furrow on lateral margin of pereonite 1; pereonites 1, 4–6 subequal and longest, 2–3 and 7 subequal. Coxae: coxal points strongly developed on posteroventral corners, on all coxae. Pleonite 2: dorsal posterolateral margin subequal with ventral posterolateral margin. Pereopod 7: basis anterior margin convex; medial carina with PS and SS present (plumose proximally, mostly slender distally but with a few plumose setae also); posterior margin convex, SS present. Ischium anterior margin with SS; posterior margin with groups of RS present, PS present. Merus anterior margin with SS; posterior margin with 2 RS, SS present. Carpus posterior margin with 6 RS, 1 SS. Propodus subequal to carpus; posterior margin with 6 RS, SS absent. Penes: forming well separated flattened lobes. Pleopod 2 appendix masculina: arising basally. Pleopods 1–5: exopod suture strongly developed on pleopods 3–5; endopod PS on most of margins on pleopods 1–4, absent on pleopod 5. Uropods: endopod triangular; medial margin slightly convex and obtusely angled proximal to peduncle, with 4 RS, PS along entire length; apex with 2 RS; lateral margin slightly convex, with 4 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. Small males (to 10.5 mm) are apparently immature and do not have conspicuously elongated robust setae on pereopods 1–6, they also have the appendix masculina shorter than the pleopod endopod. There is also a mixture of specimens both with and without obvious chromatophores in the additional material examined.

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. Adults to 16.5 mm.

Etymology. From the Latin “sinuosus” (full of windings) in reference to the sinuate posterior margins of the coxae.

Remarks. Natatolana sinuosa is most similar to N.corpulenta , N. debrae n.sp. and N. femina n.sp. Natatolana sinuosa can be distinguished from these species because it has strongly developed coxal points on the posterolateral margins of pereonite 1 and coxae 2–7. It also lacks an acute tooth at the anteroventral corner of coxa 2 that is found in N. corpulenta . Natatolana longispina is also very similar but is distinguished from N. sinuosa by having less strongly developed coxal points and the pleotelson with convex posterolateral margins.

Distribution and ecology. Australia: New South Wales, east and west coast of Tasmania, and South Australia. Intertidal to 30 m depth.

Figures

Fig. 45. Natatolana sinuosa n.sp., holotype. Scales = 0.5 mm.

Fig. 46. Natatolana sinuosa n.sp., holotype, except; P5 = male (immature) AM P47215; female = paratype female TM. Scales = 0.5 mm.

Fig. 47. Natatolana sinuosa n.sp., holotype. Scales = 0.5 mm.