Natatolana chilensis ( Menzies, 1962 )

Keable, Stephen J., 2006, Taxonomic Revision of Natatolana (Crustacea: Isopoda: Cirolanidae), Records of the Australian Museum 58 (2), pp. 133-244 : 167-168

Natatolana chilensis ( Menzies, 1962)

Figs. 11–12

Cirolana chilensis Menzies, 1962: 122 , fig. 39 A–E.– Carvacho, 1977: 40.– Ríos et al., 2003: 6.

Natatolana chilensis .– Bruce, 1981: 958.– 1986: 222.– Brusca et al., 1995: 80.

Type material. Holotype: 3, 19.6 mm, SMNH 3181 ; allotype, ♀, 22.4 mm, SMNH 3181 . Paratypes: 46 specimens, SMNH 3182 . All examined. Type locality: the bay east of the church on Isla Quellín , Seno Reloncaví, Southern Chile, 41°52'30"S 72°53'50"W, 25 m, [Lund University Chile Expedition 1948–49, Station M 39] .

Diagnosis. Interocular furrow: moderately developed, distinct but not extending across the cephalon. Frontal lamina: lateral margins medially constricted. Antenna: c. 0.34× as long as body, reaching to posterior of pereonite 3. Coxal plates: furrows strongly developed, on all coxae. Pleonite 4: apex rounded. Pleotelson: broad, length 0.87× basal width; anterodorsal depression absent; anterolateral margins almost straight and angling posteriorly toward the midline; posterolateral margins convex; apex produced into a small point; with 8–10 RS. Pereopod 2: propodus with 3 RS on palm. Pereopod 3: propodus with 1 RS on palm. Pereopod 7: basis broad, width 0.54× length; distance between anterior margin and medial carina less than between posterior margin and medial carina; posterior margin with setae completely absent along entire length. Penes: absent (area around openings slightly raised but not forming flexible processes). Pleopod 2 appendix masculina: extending subequal with tip of endopod, 0.97× length of endopod; margins very slightly curved laterally; slender; apex not at angle to adjacent margins, bluntly rounded. Uropods: exopod slightly shorter than endopod, 0.82× the length of the endopod.

Additional descriptive characters. Based on paratype, male, 20 mm. Body: length c. 3.41× width. Colour cream in alcohol. Chromatophores present, or absent (there appear to be minute traces of chromatophores); small; red/brown/ grey in alcohol; scattered over body. Eyes: with 8 ommatidia in horizontal diameter; with 7 ommatidia in vertical diameter; ovate; colour red/brown in alcohol. Frontal lamina: length c. 4.8× 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 11-articulate. Antenna: peduncular article 4 with several SS posteromedially, 1 PS and 1 penicillate seta at anterodistal angle; article 5 with 2 PS and 2 pappose setae at posterodistal angle. Flagellum 26-articulate. Mandible: setal row with 18 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 5 SS; medial lobe with 7 SS and 14 PS; middle lobe with 15 SS. Maxilliped: endite with 3 coupling hooks, and 8 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; pereonites 1 and 5–6 subequal in length and longest, 4 and 7 subequal and longer than 2–3 which are subequal. Coxae: pereonite 1, coxae 2–3 with rounded posteroventral corners, coxae 4–7 with produced, broad, acute posteroventral corners. Pleonite 2: dorsal posterolateral margin subequal with ventral posterolateral margin. Pereopod 7: basis anterior margin sinuate; medial carina with PS and SS present (plumose setae sparse, a few proximally and distally, slender setae along entire length); posterior margin convex. Ischium anterior margin with SS (sparse); posterior margin with 7 RS, PS and SS present. Merus posterior margin with 5 RS, SS present. Carpus posterior margin with 4 RS (and 4 submarginally), SS present. Propodus longer than carpus; posterior margin with 12 RS, SS absent. Pleopod 2 appendix masculina: arising sub-basally. Pleopods 1–5: exopod suture feebly developed (complete but very faint) 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 3 RS, PS on distal two-thirds. Exopod medial margin convex, with 2 RS, PS along entire length; apex acute, with 2 RS; lateral margin convex, with 4–6 RS, PS on distal three-quarters.

Variation. Ten paratype specimens were examined for variation in the number of robust setae occurring on the margins of the pleotelson. Of these 20% have 10, 10% have nine and 70% have eight.

Size. Adults to c. 22.4 mm.

Remarks. The dorsal view illustration of Natatolana chilensis by Menzies (1962) is misleading showing far more articles than are present in the antennal flagellum.

This species is similar to a number of others, including Natatolana woodjonesi as noted by Menzies (1962). The incomplete interocular furrow, complete coxal furrows on all coxae, absence of penes, sinuate posterodorsal margin of pleonite 4, convex posterolateral margins of the pleotelson converging smoothly to a point with eight to 10 robust setae, and presence of robust setae on the propodal palm of pereopods 2 and 3, are, however, sufficient characters to distinguish N. chilensis from all other species in the genus.

Distribution. Chile: several localities. In depths of 12– 60 m.

Figures

Fig. 11. Natatolana chilensis, male paratype SMNH 3182. All scales = 0.5 mm.

Fig. 12. Natatolana chilensis, male paratype SMNH 3182. All scales = 0.5 mm.