Natatolana natalensis ( Barnard, 1940 )

Keable, Stephen J., 2006, Taxonomic Revision of Natatolana (Crustacea: Isopoda: Cirolanidae), Records of the Australian Museum 58 (2), pp. 133-244 : 203-207

Natatolana natalensis ( Barnard, 1940)

Figs. 33–35

Cirolana natalensis Barnard, 1940: 393 .– Roman, 1970: 167.– Kensley, 1978: 69, fig. 28D.

Natatolana natalensis .– Bruce 1981: 958.– 1986: 222.– Brusca et al., 1995: 82.– Kensley, 2001: 230.

Type material. Lectotype: designated here, 3, 12 mm, SAM- A8183 (examined) . Paralectotypes: ♀, 16 mm (examined) and 2 others (not examined) SAM A-8183 ; 3 specimens, BMNH 1937.11 .10.68 (examined). Type locality: Illovo , Natal, South Africa, [30°06'S 30°51'E] .

Diagnosis. Interocular furrow: absent. Frontal lamina: lateral margins straight, narrowing anteriorly. Antenna: c. 0.3× as long as body, reaching to posterior of pereonite 3. Coxal plates: furrows moderately developed on all coxae, difficult to see on coxae 2–4 and becoming increasingly weak on coxae 5–7. Pleonite 4: apex forming a broad acute point. Pleotelson: narrow, length 1× basal width; anterodorsal depression present; anterolateral margins convex; posterolateral margins convex; apex not produced, lateral margins converging smoothly to a point; with 12 RS. Pereopod 2: propodus with 4 RS on palm. Pereopod 3: propodus with 4 RS on palm. 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 third. Penes: absent. Pleopod 2 appendix masculina: extending beyond tip of endopod, 1.2× length of endopod; margins sinuate; slender; apex recurved, bent slightly medially, bluntly rounded. Uropods: exopod slightly shorter than endopod, 0.85× the length of the endopod.

Additional descriptive characters. Based on lectotype. Body: length c. 2.5× width. Colour cream to white in alcohol. Chromatophores present, or absent (these are not obvious and appear to have faded after preservation). Eyes: with 9 ommatidia in horizontal diameter; with 9 ommatidia in vertical diameter; round; colour red in alcohol. Frontal lamina: length c. 3.4× basal width; apex expanded, anterior margin angled. Antennule: peduncular article 1 longer than article 2; article 2 with 1 large pappose seta and several smaller penicillate and SS; article 3 short, subequal to article 1. Flagellum 14-articulate. Antenna: peduncular article 4 with a group of 8 long SS and 1 penicillate seta on posterolateral margin; article 5 with 2 conspicuous pappose setae on posterolateral margin. Flagellum 23-articulate. Mandible: setal row with 14 RS. Maxillule: medial lobe with 3 large and 1 smaller robust pappose setae and 1 SS; lateral lobe with 13 RS on distal surface. Maxilla: lateral lobe with 6 SS; medial lobe with 3 SS and 15 PS; middle lobe with 14 long SS on outer row and 3 short SS on inner row. Maxilliped: endite with 1 coupling hook, 6 PS and 1 SS. Pereon: ornamentation consists of 1 strongly developed furrow on lateral margins of all pereonites, oblique on pereonites 1–3, short straight and medial on pereonites 4– 7; pereonites 1, 4–6 subequal and longest, 2–3 and 7 subequal. Coxae: pereonite 1, coxae 2–4 with rounded posteroventral corners, coxae 5–7 with sinuate posterior margins formed into moderately large coxal points. Pleonite 2: dorsal posterolateral margin subequal with ventral posterolateral margin. Pereopod 7: basis anterior margin convex; medial carina with PS along entire length; posterior margin convex, SS present. Ischium anterior margin with SS; posterior margin with 3 RS (submarginal). Merus anterior margin with SS; posterior margin with 7 RS, SS present. Carpus posterior margin with 3 RS, SS present. Propodus subequal to carpus; posterior margin with 3 RS, SS present. Pleopod 2 appendix masculina: arising subbasally. Pleopods 1–5: exopod suture feebly developed on pleopods 3–5; endopod PS on most of margins of pleopods 1–4, only 1 seta on pleopod 5. Uropods: endopod lanceolate; medial margin convex, with 3 RS, PS along entire length; apex with 2 RS; lateral margin angled close to midpoint, each half approximately straight, with 1 RS, PS along entire length. Exopod medial margin convex, with 2 RS, PS along entire length; apex acute, with 2 RS; lateral margin straight, with 5 RS, PS along entire length.

Size. Adults to 13 mm ( Barnard, 1940; Kensley, 1978), but a female paralectotype in SAM A-8183 (newly measured) is 16 mm.

Remarks. It is unclear how many specimens were in the original type series of Natatolana natalensis but there were several and “no adult males or ovigerous females” ( Barnard 1940). Seven specimens were initially registered as types at the SAM but only four of these remain (L. Hoenson, SAM, in litteris), three apparently being transferred to the BMNH. The collection data on the label of the SAM type material (Illovo Beach, Natal. 1934. Det. Barnard) matches that given in the original description but contrary to the description the sample contains a well-developed male. Barnard did not illustrate the type material and the original description consists largely of a comparison to N. hirtipes , apparently based on the description of that species by Hansen (1890). Because N. natalensis is difficult to identify from the original description, and from female specimens, the male is designated here as a lectotype to avoid future taxonomic confusion regarding identification of this species. The remaining type specimens become paralectotypes. The lectotype is consistent with Barnard’s description and important characters, such as the 12 robust setae on the pleotelson, lack of an interocular furrow, rounded posterolateral margins of coxa 4 and shape of the pereopod 7 basis, match perfectly.

The distinct dorsal depression on the pleotelson, the presence of robust setae on the propodal palm of pereopods 2 and 3, the broad basis of pereopod 7 and the absence of penes in adult males, distinguish N. natalensis from all other species.

Distribution and ecology. South Africa: Natal. Madagascar. Shallow, infratidal-subtidal ( Kensley, 1978; Bruce, 1986). Scavenger, “An enemy of fishes, and anglers’ bête noire” ( Barnard, 1940).

Figures

Fig. 33. Natatolana natalensis. Whole animal = paralectotype female, all other parts = lectotype male. Scales = 0.5 mm, except MX2 = 0.2 mm.

Fig. 34. Natatolana natalensis, lectotype male. Scales = 0.5 mm.

Fig. 35. Natatolana natalensis, lectotype male. Scales = 0.5 mm.