Natatolana corpulenta ( Hale, 1925 )

Keable, Stephen J., 2006, Taxonomic Revision of Natatolana (Crustacea: Isopoda: Cirolanidae), Records of the Australian Museum 58 (2), pp. 133-244 : 168-169

Natatolana corpulenta ( Hale, 1925)

Fig. 13

Cirolana corpulenta Hale, 1925: 134 , fig. 3 (part).–1929: 248, fig. 239.– Nierstrasz, 1931: 157.– Poore et al., 1975: 33.

Natatolana corpulenta .– Bruce, 1981: 958.– 1986: 79, figs. 51, 53 (part).– Brusca et al., 1995: 80.– Bruce et al., 2002: 150.

Not Cirolana corpulenta .– Hale, 1940: 289 [mis-identification = Natatolana longispina Bruce, 1986 ; Natatolana sinuosa n.sp.].

Type material. Holotype: ♀, SAMA, C275 . Paratypes: 35 specimens, SAMA C276 ; ♀, SAMA C277 . All examined. Type locality: Port Willunga, South Australia, Australia, [35°16'S 138°28'E] .

Material examined. New South Wales: manca, AM P 23040, 500 m east of Merewether Beach, 32°57'S 151°45'E, Shipek [grab] collection transect, 15 m, AM Hunter District Water Board Survey, 30 Nov. 1975 (reported by Bruce [1986]); series from off Grotto Point, Port Jackson , baited trap; 434, AM P47464, 33°49.05'S 151°15.8'E, on sediment, 15 m, S. Keable & J. Lowry, 8–9 May 1988, site 13; 418, AM P38674, 33°49.2'S 151°15.75'E, unknown substrate, probably sediment, 10 m, S. Keable, J. Lowry & D. Townsend, 16–17 Jul. 1988, Site 37; 1, AM P47645, 33°49.2'S 151°15.55'E, baited trap on sediment a few metres from rocky shore, 3 m, S. Keable, J. Lowry & D. Townsend, 16–17 Jul. 1988, site 38 . Tasmania: series from off St Helens Point, c. 41°17.3'S 148°21'E (except as noted), baited trap, J. Lowry, S. Keable & C. McCormick, 13–16 April 1991; 64, AM P47456, sandy bottom, 15 m, TAS-124; 70, AM P47457, sandy bottom, 5 m, TAS-125; 229, AM P47458, sandy bottom, 10 m, TAS-126; 13 mancas, AM P47459, off rocks at northern end, sandy bottom, 15 m, TAS- 139; 1, AM P47462, inside breakwater, Blanche Point, Georges Bay, 41°17.05'S 148°19.9'E, sand bottom, 12 m, TAS-161; 50, AM P47460, in the cove off Beerbarrel Beach, 41°17.2'S 148°21.3'E, sandy bottom, 10 m, TAS-127; 1, AM P47461, off Binalong Beach, Binalong Bay , 41°14.7'S 148°17.6'E, on sand, 8 m, TAS-144; 2, AM P47463, about 25 m off middle of breakwater, Pilot Bay , 42°12.4'S 145°12.4'E, baited trap, unknown substrate, probably sand, 6 m, J. Lowry & S. Keable, 26–27 April 1991, TAS-286 .

Diagnosis. Interocular furrow: absent. Frontal lamina: lateral margins straight, parallel. Antenna: c. 0.27× as long as body, reaching to just beyond the posterior margin of pereonite 2. Coxal plates: furrows strongly developed, on all coxae. Coxa 2 with anteroventral corner produced into an acute tooth. Pleonite 4: posterodorsal margin strongly concave proximal to meeting posteroventral margin at apex; apex forming a broad acute point. Pleotelson: broad, length 0.7× basal width; anterodorsal depression present; anterolateral margins almost straight and angling posteriorly toward the midline, or convex; posterolateral margins concave; apex produced into a large point; with 10–12 RS. Pereopods 1–6: males with conspicuous elongated RS subequal to propodus on the merus of pereopods 1–3 and extending from the carpus to dactylus of pereopods 4–6. Pereopods 2–3: propodus without RS on palm. Pereopod 7: basis narrow, width 0.47× length; distance between anterior margin and medial carina less than between posterior margin and medial carina; posterior margin with setae on distal half or along entire length. Penes: present. Pleopod 2 appendix masculina: extending beyond tip of endopod, 1.14× length of endopod; slender; margins very slightly curved laterally; apex recurved, bent slightly medially, bluntly rounded or acute. Uropods: exopod subequal to endopod, 0.99× the length of the endopod.

Variation. The female specimen described by Bruce (1986) from Point Leo, Victoria has only 10 robust setae on the pleotelson, not 12 as in the holotype. The male, 7.2 mm, from Stockton Beach, New South Wales, illustrated by Bruce (1986) has an acute apex on the appendix masculina whereas in a male, 15 mm, examined here from Tasmania (AM P47458) the apex was bluntly rounded. The material from New South Wales examined by Bruce (1986) has been re-examined (see remarks), most of it is not Natatolana corpulenta . Unfortunately it cannot be determined if the male illustrated by Bruce (1986) is among these specimens.

Sexual dimorphism. Females lack the conspicuously elongated robust setae present on the merus of pereopods 1–3 and on the carpus of pereopods 4–6 of adult males.

Size. Adults to c. 12 mm.

Remarks. Natatolana corpulenta can be most easily separated from similar species by the presence of an acute produced tooth on the anteroventral corner of coxa 2. This tooth was illustrated and described in the holotype female of N. corpulenta but not emphasized ( Hale, 1925) and was omitted in the redescription of the species by Bruce (1986). Natatolana nitida is the only other species of Natatolana , examined in this study, which has a similar tooth, although it is indicated in the illustrations of N. pallidocula and N. anophthalma .

Natatolana corpulenta has been confused with a number of other species. Hale (1940) stated that prior to his record, of a female specimen of N. corpulenta from Tasmania, only one other specimen (the type female) had been recorded. This is erroneous as Hale (1925) mentioned a single specimen from the body cavity of a Port Jackson shark collected at Brighton. Hale (1925) also stated that a small series of mostly immature specimens was obtained at Port Willunga. These additional specimens are registered in the collections of the South Australian Museum (C277 and C276 respectively) as paratypes of N. corpulenta . The specimen from the Port Jackson shark is a female of N. debrae n.sp. Of the 35 specimens from Port Willunga (SAMA C276), 29 are N. corpulenta and six are N. sinuosa n.sp. The female specimen recorded by Hale (1940) from Elliott Cove (as Eliott Cove), West Coast, Tasmania is held at the Australian Museum (E6757). This specimen is N. longispina not N. corpulenta . Hale (1940) also mentioned specimens sent to him from New South Wales by T.C. Roughley. These specimens are N. sinuosa not N. corpulenta . Three species are present in the material recorded by Bruce (1986) from the Australian Museum Hunter District Water Board Survey series, collected near Newcastle, NSW (P23034–40, P23042, P23047). The specimens from off Stockton Beach are N. sinuosa , those from off Belmont Beach are a mixture of N. longispina and N. sinuosa , and the specimen off Dudley Beach is N. sinuosa . Only the manca specimen from off Merewether Beach is N. corpulenta .

Apart from the tooth on coxa 2, Natatolana corpulenta can be separated from most other species of Natatolana by the shape and setation of the pleotelson which is similar to that illustrated by Bruce (1986). The concave posterolateral margins, with c. 12 robust setae and strongly produced acute apex are distinctive.

Natatolana pallidocula , known only from the holotype (not examined), appears to be extremely similar to N. corpulenta . Many important characters, such as the presence or absence of penes in males, have not been recorded for N. pallidocula . The description given by Kussakin & Vasina (1982a) indicates that N. pallidocula differs from N. corpulenta in having rectangular eyes with 14 ommatidia in the horizontal row (not oval with five ommatidia in the horizontal row), lacking conspicuously elongated robust setae on pereopods 1–6 in males and in having the appendix masculina of the male pleopod 2 slightly shorter than the endopod. The male characters, however, are only fully developed in mature specimens and the holotype of N. pallidocula could be immature.

Distribution and ecology. Australia: central New South Wales, Victoria, Tasmania, and South Australia. At depths of 3– 15 m. Scavenger.

Figures

Fig. 13. Natatolana corpulenta, female, 19 mm, AM P47458.