Natatolana paranarica, Keable, 2006

Keable, Stephen J., 2006, Taxonomic Revision of Natatolana (Crustacea: Isopoda: Cirolanidae), Records of the Australian Museum 58 (2), pp. 133-244 : 210-211

Natatolana paranarica n.sp.

Figs. 36–37

Type material. HOLOTYPE: 3, 31 mm, NMNZ . PARATYPES: 333, 5♀♀, manca, NMNZ Cr 4992; 3 , ♀, QM W18897. Type locality: Palliser Bay , off Carls Beach, North Island, New Zealand, [c. 41°S 175°E], 5.5m, [14 Jan. 1986] .

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. 0.48× as long as body, reaching to posterior of pereonite 4. Coxal plates: furrows variously developed, incomplete on coxae 2–3, absent on coxae 4–7. Pleonite 4: posterodorsal margin strongly concave proximal to meeting posteroventral margin at apex; apex forming a narrow acute point. Pleotelson: broad, length 0.9× basal width; anterodorsal depression absent; anterolateral margins convex; posterolateral margins convex; apex not produced, lateral margins converging smoothly to a point; with 10–14 RS. Pereopod 2: propodus with 0–2 RS on palm. Pereopod 3: propodus without 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: just shorter than endopod, 0.92× length of endopod; margins very slightly curved laterally; slender; apex not at angle to adjacent margins, bluntly rounded. Uropods: exopod longer than endopod, 1.08× the length of the endopod.

Additional descriptive characters. Based on holotype. Body: length c. 2.8× width. Colour cream/yellow in alcohol. Chromatophores absent. Eyes: with 14 ommatidia in horizontal diameter; with 11 ommatidia in vertical diameter; round; lacking pigment in alcohol. Frontal lamina: length c. 3.9× basal width; apex expanded, anterior margin angled. Antennule: peduncular article 1 longer than article 2; article 2 with 1 large pappose seta and 3 penicillate setae; article 3 short, subequal to article 1. Flagellum 16-articulate. Antenna: peduncular article 4 with 6 SS medially on posterolateral margin, 2 SS near posterodistal angle and 4 SS at anterodistal angle; article 5 with 2 pappose setae at posterodistal angle, 4 SS and 1 penicillate seta at anterodistal angle. Flagellum 28-articulate. Mandible: setal row with 21 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 4 SS; medial lobe with 15 SS and 8 PS; middle lobe with 18 SS. Maxilliped: endite with 2 coupling hooks, 1 PS and 2 SS. Pereon: ornamentation consists of 1 strongly developed furrow on lateral margin of pereonite 1, 1 short curved furrow on lateral margin of pereonites 2–3, 1 short medial furrow on lateral margins of pereonites 4–7; pereonite 1 longest, 2–6 subequal, 7 shortest. Coxae: pereonite 1 and coxa 2 with rounded posteroventral corners, coxa 3 with square posteroventral corner, 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 slightly convex; 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 (9 submarginally), SS present. Carpus posterior margin without RS, SS present. Propodus longer than carpus; posterior margin with 5 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 convex, with 4 RS, PS on distal three-quarters. Exopod medial margin convex, with 4 RS, PS along entire length; apex acute, with 2 RS; lateral margin convex, with 8 RS, PS along entire length.

Variation. Several of the paratypes have one or two robust setae on the palm of pereopod 2 but this is not a consistent feature. The holotype has 11 robust setae on the pleotelson. Robust setal counts from margins of paratypes (n=10): pleotelson: damaged (20%); 5:6 (20%); 6:6 (30%); 6:7 (30%). Endopod, medial: 6 (70%), 5 (30%); lateral: 2 (10%), 3 (30%), 4 (60%). Exopod medial: 3 (20%), 4 (60%), 5 (20%); lateral: 7 (10%), 8 (30%), 9 (40%), 10 (20%).

Size. Adults to 31 mm.

Etymology. Refers to the similarity this species has to Natatolana narica .

Remarks. Natatolana paranarica is almost identical to N. narica but differs in that the posterolateral margins of the pleotelson meet at an acute angle, rather than being broadly rounded; the uropod endopod medial margin is smoothly convex, not sinuate; the ventral margin of the posterior coxae is straight not sinuate; there are slender setae at the uropod endopod and exopod apices that are shorter than the length of these rami, rather than being as long as them. Natatolana paranarica and N. narica are the only species of Natatolana in which the uropod exopod is distinctly longer than the endopod. The uropod exopod is as long as the endopod in N. endota but that species differs in many characters, including having only four robust setae on the pleotelson and antennae that are longer than the body.

Distribution. New Zealand: known only from the type locality. At a depth of 5.5 m.

Figures

Fig. 36. Natatolana paranarica, n.sp., holotype. Scales = 0.5 mm.

Fig. 37. Natatolana paranarica, n.sp., holotype. Scales = 0.5 mm.