Natatolana buzwilsoni, Keable, 2006

Keable, Stephen J., 2006, Taxonomic Revision of Natatolana (Crustacea: Isopoda: Cirolanidae), Records of the Australian Museum 58 (2), pp. 133-244 : 161-164

Natatolana buzwilsoni n.sp.

Figs. 9–10

Type material. HOLOTYPE: 3, 14 mm, AM P47241. PARA- TYPES: All North-West Shelf, WA, collected CSIRO; ♀, AM P47242, 19°29.9'S 118°52.0'E, 37 m, 24 Oct. 1983, 05-D1-S; 3, AM P47243, 19°04.4'S 118°47.5'E, 82–83 m, 16 Feb. 1983, 01- B6-S; 3, AM P47244, 19°29.9'S 118°52'E, 38 m, 25 Oct. 1993, 05-D9-S. Type locality: North-West Shelf, WA, Australia, 19°56.9'S 117°53.7'E, 42–43 m, [22 May 1983, 02-B2-S].

Diagnosis. Interocular furrow: weakly developed, indistinct and not extending across the cephalon. Frontal lamina: lateral margins straight, parallel. Antenna: c. 0.3× as long as body, reaching to posterior of pereonite 3. Coxal plates: furrows moderately developed, on all coxae. Pleonite 2: ventral posterolateral margin not produced. Pleonite 4: apex rounded. Pleotelson: broad, length 0.71× basal width; anterodorsal depression absent; anterolateral margins convex; posterolateral margins broadly rounded; apex not produced, lateral margins converging smoothly to a point; with 5 RS. Pereopod 2: propodus with 3 RS on palm. Pereopod 3: propodus with 2 RS on palm. Pereopods 5–7: propodus short and robust on each pereopod. Pereopod 7: basis broad, width 0.53× length; distance between anterior margin and medial carina less than between posterior margin and medial carina; posterior margin with setae on proximal half. 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, acute. Uropods: exopod short, 0.78× the length of the endopod.

Additional descriptive characters. Based on holotype. Body: length c. 3.2× width. Colour cream-white in alcohol. Chromatophores absent. Eyes: with 10 ommatidia in horizontal diameter; with 10 ommatidia in vertical diameter; round; without pigment in alcohol. Frontal lamina: length c. 3.2× basal width; apex expanded, anterior margin angled. Antennule: short, just reaching pereonite 1. Peduncular article 1 longer than article 2; article 2 with 1 large pappose seta; article 3 short, subequal to article 1. Flagellum 13- articulate. Antenna: peduncular article 4 with short penicillate and SS at distal margin; article 5 subequal in length to article 4, with 2 pappose setae on posterolateral margin, short penicillate and SS along distal margin. Flagellum 35-articulate. Mandible: incisor narrow, with posterior tooth not strongly developed; setal row with 8 RS. Maxillule: medial lobe with 3 large RS; lateral lobe with 11 RS on distal surface. Maxilla: lateral lobe broad, with 3 SS; medial lobe with 7 SS and 2 PS; middle lobe reduced, with 6 SS. Maxilliped: palp medial margin RS present. Endite with coupling hooks absent, 4 SS present. Pereon: ornamentation consists of 1 strongly developed furrow on lateral margin of pereonite 1; pereonites 1, 4–6 subequal and longest, 2–3 and 7 subequal. Coxae: pereonite 1, coxae 2–3 with rounded posteroventral corners, coxae 4–7 with increasingly produced, broad, acute posteroventral corners. Pleonite 2: dorsal posterolateral margin clearly projecting posterior to ventral posterolateral margin. Pereopod 7: basis anterior margin slightly convex; medial carina with SS; posterior margin convex, PS present. Ischium width subequal to length; anterior margin with SS; posterior margin without RS, SS present. Merus posterior margin with 3 RS (and 2 submarginal RS), SS present. Carpus posterior margin with 5 RS, 1 SS. Propodus subequal to carpus; posterior margin with 4 RS, SS. 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 subcircular; medial margin rounded, with 5 RS, PS along entire length; apex with 2 RS; lateral margin slightly convex, curving in slightly before apex, with 1 RS, PS on distal half. Exopod ovate; medial margin convex, with 2 RS, PS on distal two-thirds; apex rounded, with 2 RS; lateral margin convex, with 5 RS, PS along entire length.

Variation. The holotype has five robust setae on the pleotelson as does one of the male paratypes. The other male paratype has six robust setae and the female paratype has four robust setae here.

Size. Adults to c. 14 mm.

Etymology. Named after Dr George (Buz) Wilson, in recognition of the help he has given me with this study.

Remarks. The mouthparts of Natatolana buzwilsoni are unusual; the narrow incisor of the mandible and lack of coupling hooks on the maxilliped endite occur in N. endota , N. prolixa and N. karkarook . Natatolana helenae also has a narrow mandible incisor. A reduction of the lateral lobe and middle lobe of the maxilla is also found in N. karkarook . The lack of setules on the robust setae of the maxillule medial lobe is a unique character state within the genus. The robust setae on the medial margin of the maxilliped palp are also unlike those found in other species.

Natatolana buzwilsoni is superficially similar to N. pilula but differs in numerous characters, most noticeably in having a broadly rounded pleotelson with robust setae, rather than a truncate pleotelson lacking robust setae. The apex of the appendix masculina is also distinct in the two species, being tapered to an acute point in N. buzwilsoni , whereas in N. pilula it forms a minute digitiform process.

Distribution. Australia: known only from the North-West Shelf of Western Australia. At depths of 37– 83 m.

Figures

Fig. 9. Natatolana buzwilsoni n.sp., holotype. Scales = 0.5 mm.

Fig. 10. Natatolana buzwilsoni n.sp., holotype. Scales = 0.5 mm, except MX2 = 0.2 mm.