Natatolana virilis ( Barnard, 1940 )

Keable, Stephen J., 2006, Taxonomic Revision of Natatolana (Crustacea: Isopoda: Cirolanidae), Records of the Australian Museum 58 (2), pp. 133-244 : 231-235

Natatolana virilis ( Barnard, 1940)

Figs. 48–50

Cirolana virilis Barnard, 1940: 393 fig. 7d.– Kensley, 1975: 39 (part, specimen from SST.101.D).–1978: 72, fig. 29I.–1984: 215.

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

Not Cirolana virilis .– Kensley, 1975: 39 (part, specimen from SST.54.N) [mis-identification = Natatolana n.sp.].

Type material. Holotype: 3, 13.5 mm, SAM-A150997 (examined). Type locality: Algoa Bay , South Africa, 33°59'S 25°43'E, 60 m.

Material examined. South Africa: ♀, 10.5 mm, SAM A- 19334, 31°59.3'S 29°22.5'E, dredge, RV Meiring Naude, 150– 200 m, 25 Jun. 1979, Sta No:SM 250 .

Diagnosis. Eyes: well developed; elongate, length c. 2× height. Interocular furrow: moderately developed, distinct

but not extending across the cephalon (but very faint partial furrow medially). Frontal lamina: lateral margins medially constricted. Antenna: c. 0.4× as long as body, reaching to between the posterior of pereonite 3 and three-quarters of the way along pereonite 4. Coxal plates: furrows moderately developed, on all coxae. Pleonite 4: apex forming a broad acute point. Pleotelson: broad, length 0.89× basal width; anterodorsal depression absent; anterolateral margins convex; posterolateral margins convex; apex not produced, lateral margins converging smoothly to a point; with 14–16 RS. Pereopod 2: propodus with 1–2 RS on palm. Pereopod 3: propodus with 1–2 RS on palm. Pereopods 5–7: propodus long, but on pereopod 5 less than 2× the length of that of pereopod 7 (apparently, but uncertain because the distal articles of pereopod 7 are missing in the material examined). Pereopod 7: basis narrow, width 0.37× length; distance between anterior margin and medial carina less than between posterior margin and medial carina; posterior margin with setae completely absent along entire length. Penes: absent. Pleopod 2 appendix masculina: extending subequal with tip of endopod, 1.03× length of endopod; margins very strongly curved laterally; broad; apex not at angle to adjacent margins, truncate. Uropods: exopod subequal to endopod, 0.93× the length of the endopod.

Additional descriptive characters. Based on holotype. Body: length c. 3× width. Colour cream to white in alcohol. Chromatophores absent. Eyes: with c. 16 ommatidia in horizontal diameter; with c. 9 ommatidia in vertical

diameter; narrower anteriorly; colour burgundy red 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 large pappose seta; article 3 long, larger than article 1 or 2 but shorter than their combined lengths. Flagellum 12-articulate. Antenna: peduncular article 4 with 1 penicillate seta medially on posterolateral margin, 2 SS at posterodistal angle, 2 penicillate setae and 1 SS at anterodistal angle; article 5 with 2 large pappose setae at posterodistal angle. Flagellum 29-articulate. Mandible: setal row with 17 RS. Maxillule: medial lobe with 3 large and 1 smaller robust pappose setae; lateral lobe with 13 RS on distal surface. Maxilla: lateral lobe with 4 SS; medial lobe with 6 SS and 8 PS; middle lobe with 12 SS. Maxilliped: endite with 2 coupling hooks, and 6 PS. Pereon: ornamentation consists of 1 weakly developed furrow on lateral margins of pereonites 1 and 4–7; pereonites 1 and 6 subequal in length and longest, 2–5 subequal and longer than 7. Coxae: pleonite 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 straight; medial carina with SS; posterior margin convex. Ischium damaged and other distal articles missing. Pleopod 2 appendix masculina: arising sub-basally. Pleopod 5: exopod suture strongly developed; only a few endopod PS present. Uropods: endopod lanceolate; medial margin convex, with 5 RS, PS along entire length; apex with 2 RS; lateral margin slightly convex, with 5 RS and 1 penicillate seta, PS along entire length. Exopod medial margin convex, with 4 RS, PS along entire length; apex acute, with 2 RS; lateral margin straight, with 10 RS, PS along entire length.

Size. Adults to 13.5 mm ( Barnard, 1940; Kensley, 1978).

Remarks. Barnard (1940) stated that he only had a single male specimen of Natatolana virilis (i.e., the holotype).The material described here is registered as the holotype but this status is questionable because of differences to the original description and because of the presence of body parts from more than one individual as noted below. In this material a previous dissection has separated pleonites 2–5, the pleotelson and uropods from the rest of the body, pleopods 1–5 have also been removed from the left side and pleopods 1–3 (and part of pleopod 4) from the right side. Pereopods 1 and 7 from the left side and pereopod 6 from the right side have also been previously removed. Both the dissected pereopod 7 and that still attached to the body are incomplete.There is also an additional pereopod 6 or 7 from a larger specimen and a single pleopod 2 that has the appendix masculina straight and slender, not very stout and strongly curved as described and illustrated by Barnard (1940). These additional parts have not been used in the redescription of the species.

The body in the type material matches the brief description of Barnard (1940) reasonably well, although he described the interocular furrow as confined to the hind margins of the eyes and not continuous across the median area. A faint discontinuous furrow can, however, be traced between the eyes. Barnard also indicated that the pleotelson has 16 robust setae but in this material there are only 14 and no sockets to indicate there may have been more.

Among the parts that appear to have been dissected from the apparent holotype, there is a pair of second pleopods with appendix masculina that match the original description and illustration perfectly. This distinguishes N. virilis from all other species of Natatolana . Unfortunately, because these pleopods cannot be conclusively linked with the material with which they are registered, some doubt must remain as to the validity of the parts described here as type material. No further male specimens identified as N. virilis are available in SAM collections to help resolve this question. A female specimen examined (SAM A-19334), however, matches the assumed type material in diagnostic features other than the sexual characters. This indicates that the parts identified as type material are unlikely to have been mixed together from more than one species or individual.

A female specimen from off Still Bay ( Kensley, 1975; SAM A-14593) was also examined. This specimen is similar to the material identified here as Natatolana virilis but has sinuate, rather than straight, posterior margins on coxae 3– 6 with their posteroventral margins formed into notched coxal points rather than being rounded or broadly acute. The antennae of this specimen reach to the posterior of pereonite 5 rather than to the anterior of pereonite 4 as described by Barnard (1940) and also found in the other material examined in this study. This specimen is from a new species but the material is inadequate to describe.

Distribution. South Africa: Port Elizabeth to Natal. At depths of 60–200 m ( Barnard, 1940; Kensley, 1975, 1978; Bruce, 1986; this study).

Figures

Fig. 48. Natatolana virilis holotype male. Scales = 0.5 mm.

Fig. 49. Natatolana virilis holotype male. Scales = 0.5 mm.

Fig. 50. Natatolana virilis holotype male. Scales = 0.5 mm.