Natatolana aotearoa, Keable, 2006

Keable, Stephen J., 2006, Taxonomic Revision of Natatolana (Crustacea: Isopoda: Cirolanidae), Records of the Australian Museum 58 (2), pp. 133-244 : 152-155

Natatolana aotearoa n.sp.

Figs. 5–6

Type material. HOLOTYPE: 3, 19 mm, NIWA 18748 . PARATYPES: all from New Zealand: ♀, ZMUC CRU108 , Milford Sound , 44°34'S 167°48'E, mud with sand and clay, 136 m, Galathea Station 619, 19 Jan. 1952 ; ♀, 533, NMNZ 9203 , Akaroa Harbour entrance, c. 44°S 173°E, black mud, 13–15 m, RV Acheron , 20 Feb. 1979 , BS 782; 3♀♀, NMNZ 9204 , northwest of Manawatu River , 40°22.5'S 174°59.5'E, 86 m, RV Acheron , 2 Mar. 1976 , BS 495. Series from off the west coast of the South Island, dredge-anchor box, P.K. Probert: manca, NIWA 18750 , 42°48.5'S 169°53.5'E, silt-clay, 520 m, 20 Feb. 1982 ; 2 mancas, NIWA 18751 , 41°25.5'S 171°10.3'E, silt-clay, 172 m, 25 Feb. 1982 ; manca, NIWA 18752 , 42°24.5'S 170°57.5'E, sand-silt-clay, 133 m, 28 Feb. 1982 ; ♀, manca, NIWA 18753 , 42°23.4'S 170°53.6'E, sand-silt-clay, 167 m, 4 Mar. 1982 ; 3, 2 mancas, NIWA 18754 , 42°57.7'S 170°12.4'E, silt-clay, 109 m, 18 Feb. 1982 ; 3, NIWA 18756 , 41°33.4'S 171°25'E, sand-siltclay, 140 m, 25 Feb. 1982 ; ♀, NIWA 18755 , 42°25.7'S 171°01.8'E, sandsilt-clay, 87 m, 28 Feb. 1982 . Type locality: off west coast of South Island , New Zealand, 41°25.5'S 171°10.3'E, silt-clay, 172 m [dredgeanchor box, P.K. Probert, 25 Feb. 1982] .

Diagnosis. Eyes: vestigial. Interocular furrow: well developed, forming a ridge that extends across the cephalon; smoothly convex. Frontal lamina: lateral margins straight, narrowing anteriorly. Antenna: c. 0.4× as long as body, reaching to half way along pereonite 4. Coxal plates: furrows variously developed, strongly developed on coxae 2–3, absent on coxae 4–6, moderately developed on coxa 7. Pleonite 4: posterodorsal margin strongly concave proximal to meeting posteroventral margin at apex; apex forming a narrow acute point. Pleotelson: broad, length 0.86× basal width; anterodorsal depression absent; anterolateral margins convex; posterolateral margins convex; apex not produced, lateral margins converging smoothly to a point; with 6 RS. Pereopod 2: propodus with 2 RS on palm. Pereopod 3: ischium anterodistal angle produced, but not as produced as on pereopods 1 and 2, similar to pereopod 4. Propodus with 1 RS on palm. Pereopod 7: basis of medium breadth, width 0.5× length; distance between anterior margin and medial carina less than between posterior margin and medial carina; posterior margin with setae on proximal third. Penes: absent. Pleopod 2 appendix masculina: extending subequal with tip of endopod, 1.01× length of endopod; margins very slightly curved laterally; slender; apex not at angle to adjacent margins, bluntly rounded. Uropods: exopod slightly shorter than endopod, 0.8× the length of the endopod.

Additional descriptive characters. Based on holotype. Body: length c. 2.6× width. Colour cream in alcohol. Chromatophores absent. Eyes: with 7 ommatidia in horizontal diameter; with 7 ommatidia in vertical diameter; round; colour white in alcohol. Frontal lamina: length c. 4.5× basal width; apex expanded, anterior margin rounded. Antennule: peduncular article 1 longer than article 2; article 2 with 1 large pappose seta; article 3 long, larger than article 1 or 2 but shorter than their combined lengths. Flagellum 13-articulate. Antenna: peduncular article 4 with 4 SS on posterolateral margin, 8 SS and 1 penicillate seta at anterodistal angle; article 5 with 2 pappose setae at posterodistal angle, 6 SS at anterodistal angle. Flagellum 27- articulate. Mandible: setal row with 19 RS. Maxillule: medial lobe with 3 large and 1 smaller robust pappose setae; lateral lobe with 13 RS on distal surface. Maxilla: lateral lobe with 6 SS; medial lobe with 5 SS and 17 PS; middle lobe with 20 SS. Maxilliped: endite with 2 coupling hooks, and 9 PS. Pereon: ornamentation consists of 1 strongly developed furrow on lateral margin of pereonite 1 and 1 short, medial furrow on lateral margins of pereonites 4–7; pereonite 1 longest, 4–6 subequal and longer than 2–3 and 7 which are subequal. Coxae: pereonite 1, coxa 2 with rounded posteroventral corners, coxa 3 with a square posteroventral corner, coxae 4–7 with increasingly produced, acute posteroventral corners. Pleonites: 1–5 visible but 1 almost completely concealed along dorsal margin by pereonite 7. Pleonite 2: dorsal posterolateral margin clearly projecting posterior to ventral posterolateral margin. Pereopod 7: basis anterior margin sinuate; medial carina with PS along entire length; posterior margin convex, PS present. Ischium anterior margin with SS; posterior margin without RS, PS present. Merus anterior margin with SS; posterior margin without RS (2 submarginally), SS present. Carpus posterior margin without RS (3 submarginally), SS present. Propodus longer than carpus; posterior margin with 6 RS, SS present. Pleopod 2 appendix masculina: arising sub-basally. Pleopods 1–5: exopod suture strongly developed on pleopods 3–5; endopod PS on most of margins of pleopods 1–4, only a few setae on pleopod 5. Uropods: endopod lanceolate; medial margin convex, with 5 RS, PS along entire length; apex with 2 RS; lateral margin slightly sinuate, with 4 RS, PS on distal three-quarters. Exopod medial margin convex, with 4 RS, PS on distal three-quarters; apex acute, with 2 RS; lateral margin convex, with 6 RS, PS along entire length.

Size. Adults to c. 20 mm.

Etymology. From the Māori for New Zealand, meaning land of the long white cloud or long bright land, in reference to the species distribution.

Remarks. Natatolana aotearoa is most similar to N. thurar . In both of these species the eyes have indistinct ommatidia that lack pigment, the interocular furrow is developed into a ridge and the posterodorsal margin of pleonite 4 is concave with the apex developed into a narrow acute point. Natatolana aotearoa , however, differs in having the ischium of pereopods 1–2 more produced, with distinctly concave anterodistal margins, and in having the ischium of pereopod 3 less produced. The apex of the frontal lamina is also less acute and the lateral margins not parallel as in N. thurar .

Distribution. New Zealand; known only from the west coast. At depths of 13– 520 m.

Figures

Fig. 5. Natatolana aotearoa, n.sp., holotype. Scales = 0.5 mm.

Fig. 6. Natatolana aotearoa, n.sp., holotype. Scales = 0.5 mm.