Natatolana lilliput, Keable, 2006

Keable, Stephen J., 2006, Taxonomic Revision of Natatolana (Crustacea: Isopoda: Cirolanidae), Records of the Australian Museum 58 (2), pp. 133-244 : 196-199

Natatolana lilliput n.sp.

Figs. 31–32

Type material. HOLOTYPE: 3, 12 mm, AM P47237 . PARATYPE: 3, TM. Type locality: about 0.5 km east of shore, Garretts Bight , Tasmania, Australia, 43°22.2'S 147°3.6'E, [baited trap], 25 m, [J.K. Lowry & S.J. Keable, 20–21 April 1991, TAS-228] .

Additional material. Tasmania: 32, AM P47238, about 50 m off south side of Huon Point, 43°17.6'S 147°5.9'E, baited trap, probably sandy bottom, 13 m, J.K. Lowry & S.J. Keable, 18–19 April 1991, TAS-188; 7, AM P47239, in the middle of the cove on the south side of Huon Point, 43°17.8'S 147°5.2'E, baited trap, probably muddy substrate, 18 m, J.K. Lowry & S.J. Keable, 18–19 April 1991, TAS- 191; 1, AM P47240, in small cove just north of Esperance Point , 43°19.5'S 147°4.1'E, baited trap, probably rocky substrate, 3 m, J.K. Lowry & S.J. Keable, 18–19 April 1991, TAS-196 .

Diagnosis. Interocular furrow: well developed, extending across the cephalon; smoothly convex. Frontal lamina: lateral margins medially constricted. Antenna: c. 0.17× as long as body, reaching to approximately one third of the way along pereonite 2. Coxal plates: furrows strongly developed, on all coxae. Pleonite 4: apex rounded. Pleotelson: broad, length 0.89× basal width; anterodorsal depression absent; anterolateral margins convex; posterolateral margins convex; apex produced into a small point; with 4–6 RS. Pereopods 2–3: propodus without RS on palm. Pereopods 5–7: propodus short and robust on each pereopod. Pereopod 7: basis broad, width 0.71× length; distance between anterior margin and medial carina greater than between posterior margin and medial carina; posterior margin with setae on proximal two-thirds. Penes: absent. Pleopod 2 appendix masculina: just shorter than endopod, 0.94× length of endopod; margins bent slightly medially; slender; apex not at angle to adjacent margins, bluntly rounded. Uropods: exopod short, 0.76× the length of the endopod.

Additional descriptive characters. Based on holotype. Body: length c. 4× width. Colour cream/tan in alcohol. Chromatophores absent. Eyes: with 8 ommatidia in horizontal diameter; with 7 ommatidia in vertical diameter; round with upper margin flat; colour tan in alcohol. Frontal lamina: length c. 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 10-articulate. Antenna: peduncular article 4 with 2 SS medially on posterolateral margin, 1 SS at posterodistal angle, 4 SS and 1 penicillate seta at anterodistal angle; article 5 with 2 conspicuous pappose setae and 1 SS at posterodistal angle, 5 SS and 1 penicillate seta at anterodistal angle. Flagellum 17-articulate. Mandible: setal row with 13 RS. Maxillule: medial lobe with 3 large and 1 smaller robust pappose setae (left side) or with 3 large robust pappose setae (right side); lateral lobe with 13 RS on distal surface. Maxilla: lateral lobe with 5 SS; medial lobe with 6 SS and 10 PS; middle lobe with 10 SS. Maxilliped: endite with 1 coupling hook, and 6 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 4–6 subequal and longer than 1 and 7 which are subequal and longer than 2–3. Coxae: pereonite 1, coxae 2–4 with rounded posteroventral corners, coxae 5–7 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 (1 submarginally), PS present. Merus posterior margin with 6 RS, SS present. Carpus posterior margin with 2 RS (and 1 submarginally), 1 SS. Propodus subequal to carpus; posterior margin with 3 RS, SS absent. Pleopod 2 appendix masculina: arising sub-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 lanceolate; 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 on distal two-thirds. Exopod medial margin convex, with 2 RS, PS on distal three-quarters; apex acute, with 2 RS; lateral margin straight, with 3 RS, PS along entire length.

Variation. The holotype has four robust setae on the pleotelson. Of 42 additional specimens examined five (12%) have a damaged pleotelson, two (5%) have six robust setae on the pleotelson, eight (19%) have five robust setae on the pleotelson and 27 (64%) have four. Some of the specimens from Huon Point ( AM P47239) have orange pigment on the posterolateral margins of pleonite 4 and on the uropod peduncle .

Size. Adults to 14 mm.

Etymology. Derived from Lilliput, a place in the novel Gulliver’s Travels by Jonathan Swift where everything is reduced in size, in reference to the short nature of the antennae.

Remarks. Natatolana lilliput can be most readily separated from similar species by the following characters: the short antennae that reach just beyond the posterior margin of pereonite 1 and have relatively few flagellar articles; the complete interocular furrow; the rounded apices and posterior margins of the uropod endopod and pleotelson. Natatolana kahiba is most similar but has an incomplete interocular furrow. Natatolana rusteni n.sp. is also similar but differs in having a narrow and more acute pleotelson, usually with six robust setae on the posterolateral margins, an incomplete interocular furrow and slightly shorter antennae with fewer articles in the flagella.

Distribution and ecology. Australia: known only from the east coast of Tasmania. At depths of 3– 25 m. Scavenger.

Figures

Fig. 31. Natatolana lilliput n.sp., holotype. Scales = 0.5 mm, except MX2 = 0.2 mm.

Fig. 32. Natatolana lilliput n.sp., holotype. Scales = 0.5 mm.