Natatolana Bruce, 1981

Keable, Stephen J., 2006, Taxonomic Revision of Natatolana (Crustacea: Isopoda: Cirolanidae), Records of the Australian Museum 58 (2), pp. 133-244 : 139-140

Natatolana Bruce, 1981

Natatolana Bruce, 1981: 957 .– 1986: 52.–Brusca & Iverson, 1985: 37.– Botosaneanu et al., 1986: 412.– Wetzer et al., 1987: 2.– Brandt, 1988: 102.–Kensley & Schotte, 1989: 139.– Brusca et al., 1995: 74.–Yu & Li, 2001: 262.

Type species. Cirolana hirtipes Milne Edwards, 1840 , by original designation [not subsequent designation as stated by Brusca et al. (1995)].

Diagnosis. Cephalon: width between 50–60% of pereonite 1; moderately to strongly enclosed laterally by pereonite 1; anterior margin smoothly rounded, or with rostral point, without smooth medial indentation; rostrum not prominent when present. Frontal lamina: forming an angle of c. 45° or less with clypeus; not fused to cephalon; elongate, length c. 3–10× basal width; ventral surface flat, not projecting anteroventrally from posterior. Clypeus: anterior margin abutting frontal lamina, ventral surface not projecting relative to frontal lamina. Antennule: colinear (most species), or geniculate (article 2 at right angles to article 1) ( N. vieta ). Peduncular articles 1–3 not fused; article 3 well developed, longer than articles 1–2 or subequal to article 1. Accessory flagellum absent. Primary flagellum shorter than or subequal to peduncle; without callynophore. Antenna: not sexually dimorphic (most species), or sexually dimorphic; when dimorphic males with longer flagellae than females ( N. vieta ), or with digitate processes on flagellar articles ( N. insignis ). Peduncle of 5 articles; articles 1 and 2 shortest, subequal; article 4 subequal to article 3; article 5 longer than article 4 and all other articles, or subequal to article 4.

Mandible: molar well developed; medial surface smooth, without SS; RS present or absent on margins, numerous when present. Incisor broad, wider than narrowest part of mandible, or narrow, subequal to narrowest part of mandible; serrate; not quadridentate on left mandible. Lacinia mobilis absent. Setal row with numerous RS; intermediate SS absent. Palp 3-articulate; inserted slightly anterior to midlength, opposite molar; article 3 distally narrow. Maxilla: lateral lobe and middle lobe subequal; medial lobe short and broad; lateral lobe with 2–12 SS; middle and medial lobes with numerous setae. Maxilliped: palp medial margin with SS on more than half the length of articles 2–5; lateral margin with SS or PS along most of the length of articles 2–5; article 3 with distal margin width greater than proximal margin of article 4; article 4 with distal margin width greater than proximal margin of article 5. Endite with (most species) or without coupling hooks ( N. endota , N. karkarook , N. prolixa , N. buzwilsoni ).

Pereon: dorsal surfaces without setae; with ( N. amplocula , N. hirtipes ) or without indistinct tubercles (most species); with ( N. vieta ) or without wrinkle like furrows (most species); pereonite 1 longer than pereonite 2. Coxae: not forming sternal plates.

Pleonites: five unfused segments present; all equally visible along dorsal margin (most species), or pleonite 1 partially or completely concealed by pereonite 7 ( N. angula , N. boko , N. curta , N. hirtipes , N. imicola , N. intermedia , N. natalis , N. neglecta , N. obtusata , N. pilula , N. tenuistylis , N. valida , N. wowine , N. brucei , N. helenae , N. aotearoa ). Pleonite 3: epimera with lateral row of setae absent; posteroventral excision absent; enclosing or not enclosing pleonite 4. Pleonite 5: posterolateral margins encompassed by pleonite 4.

Pleotelson: dorsal surface with anterodorsal depression present or absent, otherwise smooth, setae, tubercles, pits and ridges absent; RS present or absent on margins; PS present or absent, when present moderately abundant, restricted to posterolateral margins, or sparse, restricted to apex; marginal teeth-like serrations absent.

Pereopods 1–7: dactylus with secondary unguis present or absent; secondary unguis not large or strongly sclerotized when present. Pereopods 1–3: ischium anterodistal angle produced subequally or noticeably reduced on pereopod 3. Merus anterodistal angle produced subequally. Dactylus shorter than propodus. Pereopod 1: merus anterodistal angle produced to posterodistal extent of carpus or beyond. Pereopod 7: basis noticeably broader in distal half compared to proximal half; anterior margin with long PS along entire length; medial carina with PS and SS along most of length of article; posterodistal angle with long PS present. Ischium anterior margin with PS and SS present or absent, PS sparse when present and only occurring distally; posterior margin with PS and SS present. Merus anterior margin SS present or absent, PS absent; posterior margin with PS and SS present or absent, PS sparse when present.

Penes: present or absent (vasa deferentia opening flush to surface of sternite 7); when present short and flattened, or long and tubular.

Pleopods: peduncle respiratory branchiae absent; accessory lobe reduced, without complex folding. Endopods 1–4 with PS on most of margins, 5 with only a few or no PS on margins; 1–4 without elongate laterally curving lobe arising from proximomedial angle. Exopods 1–4 without slender accessory lamella at posterior proximolateral angle. Pleopod 1: not operculate; peduncle length shorter than breadth; exopod and endopod broad, or only endopod narrow; exopod margin rounded, broad at apex; endopod width greater than 0.5× width of exopod. Pleopod 2 appendix masculina: arising basally or sub-basally; shorter or longer than endopod; broad, width equal to or greater than half pleopod peduncle length, or slender.

Uropods: inserted ventrolaterally on pleotelson; extending subequal to or beyond pleotelson, or not extending beyond pleotelson. Peduncle moderately or strongly produced along medial margin of endopod. Endopod and exopod margins with RS present or absent; PS on most of margin length; apices entire, not bifid or sub-bifid, with at least 2 RS. Endopod lateral margin with or without prominent lateral excision; without distinct pit.

Remarks. Kensley & Schotte (1989) placed Natatolana in the subfamily Conilerinae , based on the classification outlined by Botosaneanu et al. (1986). The subfamily divisions of the Cirolanidae , however, appear to be weakly defined and require revision through a phylogenetic analysis of the entire family, as suggested by Brusca et al. (1995) and Bruce (1995b). Natatolana is difficult to incorporate in phylogenetic analyses because of its diversity (Riseman & Brusca, 2002) and because no unique apomorphies have been proposed that define it ( Wetzer et al., 1987). The approach of using an exemplar for the genus presents difficulties because of polymorphism across the species. For example, Brandt & Poore (2003) use N. woodjonesi as a representative species in analysing suborder and superfamily relationships and characters. They score the pleopod 5 endopod as lacking setae whereas they are present in small numbers in several other species of Natatolana ( Brandt, 1988, fig. 50; Brusca et al., 1995; Keable, 1996b; this study, e.g., Fig. 28 ). It is an objective of this study to address some of these issues by clarifying character distribution within the genus and species identification.

Examination of specimens and descriptions of all species of Natatolana indicates that a putative synapomorphy that can unambiguously define the genus as a monophyletic group is the setation pattern on pereopod 7. This pattern entails the presence of long plumose setae on the length of the anterior margin and at the posterodistal angle of the basis, and the lack of plumose setae on the length of the anterior margin of the ischium. The plumose setae at the posterodistal angle of the basis are as long or longer than the ischium. This setation pattern is unique among the known taxa of the Cirolanidae (although it may occur in Sintorolana , a genus known only from a juvenile specimen in which pereopod 7 is missing). A similar setation pattern occurs in Dolicholana elongata but in this species plumose setae are present along the entire length of the anterior margin of the ischium and on the posterior margin of the merus. Of the species placed in Natatolana , plumose setae on the posterior margin of the ischium of pereopod 7 have only been observed in N. angula , N. karkarook , N. narica and N. tenuistylis . In these taxa these setae are sparse and do not extend all the way along this margin. In D. elongata plumose setae, however, are abundant and occur all the way along the margin. Only N. boko and N. tenuistylis are known to have plumose setae on the posterior margin of the merus of pereopod 7. Species of Dolicholana also differ from those

Figures

Fig. 28. Natatolana hirtipes, lectotype male. Scales = 0.5 mm.