Natatolana hirtipes ( Milne Edwards, 1840 )

Keable, Stephen J., 2006, Taxonomic Revision of Natatolana (Crustacea: Isopoda: Cirolanidae), Records of the Australian Museum 58 (2), pp. 133-244 : 185-190

Natatolana hirtipes ( Milne Edwards, 1840)

Figs. 25–28

Cirolana hirtipes Milne Edwards, 1840: 236 , pl. 31, figs. 25, 26.– Milne Edwards, 1836–49 [exact publication date unknown, see Sherborn (1922), subsequent to Milne Edwards (1840)]: pl. 67, figs. 6–6i.– Hansen, 1890: 326, pl.1, figs. 2– 2g.– Stebbing, 1910: 421.– Tattersall, 1913: 880.– Vanhöffen, 1914: 501, fig. 38.–? Barnard, 1936: 150.– Kensley, 1975: 39.– 1978: 67, fig. 27 E–F.– Huber, 1992: 58.

Natatolana hirtipes .– Bruce, 1981: 957, 958.–1986: 53, 97, 222.– Brusca et al., 1995: 80.– Kensley, 2001: 230.

Not Cirolana hirtipes .– Heller, 1866: 742.– Stalio, 1877: 1375.– Stossich, 1880: 224 [mis-identification = Natatolana neglecta ( Hansen, 1890) ].

Not Cirolana hirtipes .– Goss, 1855: 133.– White, 1857.– Lo Bianco, 1903: 258 [mis-identification = Natatolana borealis ( Liljeborg, 1851) ].

Not Cirolana hirtipes .– Filhol, 1885: 445, 449, pl. 53 fig. 6.– Nierstrasz, 1931: 158.– Hurley, 1961: 267 [mis-identification = Natatolana rossi (Miers, 1876) ].

Type material. Lectotype: designated here, 3, 24 mm, MNHN Is. 96 . Paralectotype: ♀, 27 mm, MNHN Is. 96. All examined. Type locality: Cape of Good Hope (as Cap de Bonne-Esperance ), South Africa, [34°22'S 18°30'E] .

Material examined. South Africa: 3, 18 mm, ♀, 12 mm and manca, 10 mm, SAM-A14579, False Bay , FAL 587 G–E; 11 33, 6♀♀, ZMUC CRU160 , Table Bay, Swedish South African Expedition, 1935, Zool. Inst. Lund. (Prof. O. Carlgren) ded. 1-7- 1937 ; 3, ZMUC CRU161 , Table Bay [as Tafel Bay], Strandgaard, Studiesaml [teaching collection], ded. 1890, 23-5-1890 .

Diagnosis. Eyes: well developed; elongate, length c. 2× height. Interocular furrow: well developed, extending across the cephalon; smoothly convex. Frontal lamina: lateral margins medially constricted. Antenna: c. 0.4× as long as body, reaching to just beyond the posterior of pereonite 3 (i.e., about ¼ of the way along pereonite 4) or the posterior of pereonite 4. Coxal plates: furrows strongly developed, on all coxae. Pleonite 4: apex slightly rounded. Pleotelson: broad, length 0.82× basal width; anterodorsal depression absent; anterolateral margins convex (in type material), or almost straight and angling posteriorly toward midline; posterolateral margins convex (in type material), or straight, markedly angled to anterolateral margins and meeting at an obtuse angle; apex not produced, lateral margins converging smoothly to a point; with 12–19 RS (18 in lectotype). Pereopod 2: propodus with 1 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 on proximal quarter. Penes: absent. Pleopod 2 appendix masculina: extending subequal with tip of endopod, 0.98× length of endopod; margins very slightly curved laterally; slender; apex not at angle to adjacent margins, bluntly rounded. Uropods: exopod subequal to endopod, 0.98× the length of the endopod.

Additional descriptive characters. Based on the type material, the female paralectotype was used for the whole animal illustration and was checked against the male lectotype that had been slightly squashed, the lectotype was used for all dissected parts. Body: length c. 3× width. Colour translucent cream-white in alcohol. Chromatophores absent. Eyes: with

14 ommatidia in horizontal diameter; with 10 ommatidia in vertical diameter; rectangular; colour tan in alcohol. Frontal lamina: length c. 4× basal width; apex expanded, anterior margin angled. Antennule: peduncular article 1 longer than article 2; article 2 with 1 long narrow pappose seta; article 3 short, subequal to article 1. Flagellum 14-articulate. Antenna: peduncular article 4 with 4 SS at posterodistal angle and 1 penicillate seta at anterodistal angle; article 5 with 1 pappose seta and 1 penicillate seta at posterodistal angle. Flagellum 35-articulate. Mandible: setal row with 17 RS. Maxillule: medial lobe with 3 large and 1 smaller robust pappose setae; lateral lobe with 12 RS on distal surface. Maxilla: lateral lobe with 4 SS (one of which is broken); medial lobe with 11 SS and 9 PS; middle lobe with 16 SS. Maxilliped: endite with 2 coupling hooks, and 7 PS. Pereon: ornamentation consists of 1 strongly developed furrow on the lateral margin of pereonite 1 and 1 short, medial furrow on the lateral margins of pereonites 4–7; pereonites 1 and 5 subequal in length and longest, 2–4 and 6 subequal and longer than 7. 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 subequal with ventral posterolateral margin. Pereopod 7: basis anterior margin sinuate; medial carina with PS and SS present; posterior margin convex, posterior margin PS present. Ischium anterior margin with SS (sparse); posterior margin with 5 RS (submarginal), PS and SS present. Merus posterior margin with 3 RS (submarginal), SS present. Carpus posterior margin with 4 RS, SS absent. Propodus subequal to carpus; posterior margin with 5 RS, SS absent. Pleopod 2 appendix masculina: arising sub- 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 6 RS, PS along entire length. Exopod medial margin convex, with 3 RS, PS on distal three-quarters; apex acute, with 2 RS; lateral margin convex, with 10 RS, PS along entire length (although most have been broken or been rubbed off).

Variation. The male lectotype has pleonite 1 clearly visible between pereonite 7 and pleonite 2, in the female paralectotype pleonite 1 is just visible. The male, female and manca specimens from False Bay (SAM A-14579) all have pleonite 1 just visible. On these non-type specimens the antennae reach the posterior of pereonite 4 (not just beyond the posterior of pereonite 3 as in the types) and smaller specimens have fewer articles in the antennal flagellum. Seventeen specimens from Table Bay (ZMUC CRU160) were also examined for variations in the numbers of robust setae occurring on the pleotelson and uropods. These robust setae are quite long in Natatolana hirtipes and appear to be readily dislodged from the animals, resulting in considerable variation between specimens as the setae regenerate. Also, robust setal counts on the pleotelson and uropods often varied from one side of a specimen to the other. These counts showed no correlation with the size of the animal, small specimens occasionally having more setae than large specimens. The male lectotype has 18 robust setae on the pleotelson. Variations in the number of robust setae present, were as follows: on the pleotelson, ranged from 12–19 (average 14, 40%); on the uropod endopod medial margin, ranged from 4–6 (average 5, 59%); on the uropod endopod apex 2 were present (or sockets indicated their presence) in all specimens; on the uropod endopod lateral margin, ranged from 5–8 (average 7, 35%); on the uropod exopod medial margin ranged from 1–4 (average 3, 53%); on the uropod exopod apex 2 were present (or sockets indicated their presence) in all specimens; on the uropod exopod lateral margin, ranged from 8–14 (average 10, 29%). The specimens examined from Table Bay (ZMUC CRU160, ZMUC CRU161) all have 5 pleonites clearly visible. Males in ZMUC CRU160 all have two indistinct tubercles dorsally on the surface of pereonite 2, however, these are not discernible in the type material. Some specimens in ZMUC CRU160 also have the pleotelson margins straighter and more angular than in the type material. Hansen (1890) described the specimen ZMUC (CRU161) (20 mm in length) from Table Bay, this specimen has 18 robust setae on the pleotelson and an antennal flagellum with 35 articles but is otherwise indistinguishable from the lectotype of N. hirtipes .

Sexual dimorphism. Large males (greater than 24 mm) may have two closely spaced, indistinct tubercles, medially on the dorsal surface of pereonite 2.

Size. Hansen (1890) and Kensley (1978) record lengths of 20 mm. Milne Edwards (1840) states a length of 1 pouce, i.e., 25 mm. The paralectotype female (newly measured) is c. 27 mm. A manca of 10 mm and a female of 12 mm were also examined here.

Remarks. Because Natatolana hirtipes is the type species of the genus and, as it shows some variation and may be difficult to separate from other species the male syntype is illustrated, redescribed and designated as a lectotype. The purpose of this is to avoid future taxonomic confusion in applying the generic name and identifying the species. The female syntype becomes a paralectotype.

The type specimens of Natatolana hirtipes match the few features discernible in the brief original description and two illustrations of Milne Edwards (1840). Figure 26 of Milne Edwards is misleading, however, showing the antennal peduncle as longer than the flagellum. This is not the case, the flagellum was probably foreshortened in the original illustration.

Natatolana hirtipes is extremely similar to N. rossi in most features, as noted by Chilton (1909). Consistent differences between N. hirtipes and N. rossi include a smoothly convex interocular furrow (medially produced in N. rossi ), a angled anterior margin to the eye (convex in N. rossi ), a convex ventral margin to the cephalon (concave in N. rossi ) and a slightly more sinuate anterior margin of the basis of pereopod 7 in N. hirtipes .

Natatolana hirtipes is also similar to N. matong . The development of the coxal furrows does not reliably separate the two species as suggested by Bruce (1986).The shape of pleonite 4 is, however, consistently different, N. hirtipes having a more sinuate posterodorsal margin. The interocular furrow is smoothly convex and the basis of pereopod 7 basis is also broader in N. hirtipes .

Distribution and ecology. South Africa: Luderitz to East London. Intertidal to 200 m depth ( Kensley 1978; Bruce 1986). Hansen (1890, 1905) assigned earlier records from the Adriatic Sea to Natatolana neglecta and from the Mediterranean Sea to N. borealis . The records of N. hirtipes by Filhol (1885), also listed by Nierstrasz (1931) and Hurley (1961), from Cook Strait, New Zealand, were considered to be a mis-identification of N. rossi by Barnard (1936) who additionally noted that the two species are very similar. Barnard (1936) also recorded a female specimen, 13.5 mm, from the Strait of Hormuz (as Strait of Ormuz), Persian Gulf, and an immature specimen, 8.5 mm, from west of Mangalore, southwest India. He also doubtfully recorded a male specimen of 6 mm from off Southern Myanmar ( Burma). These records have not been included in the distribution reported by Kensley (1978) or Bruce (1986) and the material was not examined in this study.

Vanhöffen (1914) reported specimens from Simonstown that were apparently scavenging, along with ostracods, on fish caught in nets.

Figures

Fig. 25. Natatolana hirtipes. Whole animal = paralectotype female, all other parts = lectotype male. Scales = 0.5 mm.

Fig. 26. Natatolana hirtipes lectotype male. Scales = 0.5 mm.

Fig. 27. Natatolana hirtipes, lectotype male. Scales = 0.5 mm.

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