Neastacilla deducta Hale, 1925

King, R. A., 2003, Neastacilla Tattersall, 1921 redefined, with eight new species from Australia (Crustacea: Isopoda: Arcturidae), Memoirs of Museum Victoria 60 (2), pp. 371-416 : 380-383

Neastacilla deducta Hale

Figures 4–6

Neastacilla deducta Hale, 1925: 33 , fig. 16.— Hale, 1929: 313, fig. 315.— Monod, 1970: 1139.— Poore et al., 2002: 259.

Astacilla deducta . — Hale, 1946: 174–175, fig. 7.

Astacilla vicaria Hale, 1946: 175–176 , fig. 8.— Monod, 1970: 1139.

Material examined. Holotype. Australia: SA, Port Adelaide (Gulf St Vincent) (1 male) SAM C 273 . Paratypes. Australia: SA, Port Adelaide (Gulf St Vincent) SAM C 274 .

Syntypes of Astacilla vicaria Hale, 1946 . NSW, off Yarra Bay , Botany Bay, AM P8967 (8 specimens) .

Other material. Australia: NSW. Jervis Bay , 35º08.0'S, 150º43.0'E, 2 m, 23 Apr 1985 , NMV J11199 (2 females, 4 males, 1 immature female). Port Kembla , 34º29.0'S, 150º55.0'E, Mar 1978 , NMV J16516 (1 female) . Vic. Oberon Bay , 39º04.2'S, 146º19.4'E, 21 m, 05 Feb 1982 , NMV J11200 (11 females, 7 males, 5 immature males, 2 manca 2). Tas. 43º17.0'S, 147º15.'E, 3 m, 20 Mar 1988 , NMV J48664 (1 female) ; 39º32.8'S, 144º16.0'E, 18 m, 1 Nov 1980, NMV J8840 . SA. Venus Bay , 33º13.2'S, 134º40.1'E, 2 m, 23 Apr 1985 , NMV J40673 (1 female, 11.5 mm) , NMV J 40674 (1 male, 11.3 mm) , NMV J16569 (12 individuals) ; Venus Bay , 33º13.8'S, 134º40.1'E, 3 m, 21 Apr 1985 , NMV J16570 (2 females, 1 male, 2 immature females, 1 immature male, 3 juveniles, 2 manca-2). NE side of Topgallant I., 33º43.0'S, 134º36.6'E, 20 m, 21 Apr 1985 , NMV J16568 (3 females) .

Description of female. Head without dorsal elevation, anterolateral lobes angular, small rostral point present; lateral margin of head and pereonite 1 incised. Pereonite 1 with an anterolateral expansion. Pereonites 2 and 3 similar width, without dorsal elevations, without lateral extensions. Pereonite 4 about 10 times as long as pereonite 3, with some small anterior dorsal elevations, anterior anterolateral margins extended, not greatly wider then previous pereonites. Pereonites 5–7 progressively shorter posteriorly, without dorsal elevations. Pleon length greater than combined lengths of pereonites 5–7, without dorsal elevations, with small anterior lateral wings, apex blunt.

Eyes small and subtriangular. Antenna 1 reaching to the end of second peduncular article of antenna 2; aesthetascs present laterally and distally on flagellum. Antenna 2 slender, more than half as long as body; flagellum of 2 articles, ending with claw, with row of scales along full length.

Maxilla 1 mesial lobe with 3 terminal setae; lateral lobe with 9 distal robust setae. Maxilla 2 mesial lobe with 26 plumose setae, middle lobe with 3 setae, lateral lobe with 3 setae. Maxillipedal endite with 11 mesial setae; 1 coupling hook; palp article 2 with mesial setal rows, article 3 with mesial and lateral setal rows, article 4 with mesial setae, article 5 with distal setae.

Pereopod 1 propodus as long as carpus; dactylus slightly longer than wide, without unguis. Pereopods 2–3 dactylus present. Pereopod 4 dactylus absent. Pereopods 5–7 dactylus not denticulate, with unguis and secondary unguis; secondary unguis two-thirds length of primary unguis. Uropodal exopod with 2 setae of subequal length. Oostegite 4 with suture at midlength.

8.0– 10.5 mm.

Male. Head and pereonites 1–3 as for female. Pereonite 4 about 10 times as long as pereonite 3; without dorsal elevations, constricted for the first quarter length. Pereonites 5–7 progressively shorter posteriorly, without dorsal elevations. Pleon length greater than combined lengths of pereonites 5–7, without dorsal elevations, with small lateral wings, apex blunt.

Antenna 1 extending past the end of the second peduncular article of antenna 2; aesthetascs present laterally and distally on flagellum. Antenna 2 slender, more than half as long as body; flagellum of 3 articles and claw; with a row of scales along full length.

Mouthparts, pereopods and uropods as for female.

Pleopod 1 exopod with lateral notch and 2 plumose lateral setae of unequal length. Pleopod 2 appendix masculina with ridge on posterior face, curved, extending quarter length past the endopod, apex simple. Penial plate widened proximally, tapering distally, apex notched.

7–10 mm.

Distribution. Australia: New South Wales, Victoria, Tasmania, South Australia; subtidal to 21 m depth.

Remarks. Neastacilla deducta was described from South Australia from a single male by Hale (1925). He later described a female and ‘subadult’ male of Astacilla vicaria from eight syntypes from New South Wales ( Hale, 1946). The distinction between the two species has never been clear. Hale (1946) argued that the structure of the second antenna, including the number of flagellar articles; eye size and expansion of pereonite 1 were differences. Examination of type material of N. vicaria and A. deducta and of other material at Museum Victoria has shown that the two are synonymous, a view shared by Poore et al. (2002). The type males of A. vicaria males were all immature, some up to 1 or 2 moults from maturity as shown by the underdeveloped appendix masculina. Juveniles and females always possess two antenna 2 flagellar articles; only mature males have a flagellum of 3 articles. This condition is also seen in N. coonabooloo sp. nov.

Figure 5. Neastacilla deducta Hale, 1924 , female ( NMV J40673): A1, A2, P1, P3, P4. Male ( NMV J40674): A1, A2. Scales: a (A1, A1) = 0.5 mm; b (A2, A2) = 1.0 mm; c (P1, P3) = 0.5 mm.

Neastacilla deducta looks most similar to N. monoseta and N. kanowna sp. nov. It is distinguished from N. monoseta by the blunt pleotelson without lateral expansions and from N. kanowna by the presence of a shallow dorsolateral groove between the head and pereonite 1, which is incised laterally.

Figures

Figure 4. Neastacilla deducta Hale, 1924, female (NMV J40673): A, lateral view; B, dorsal view; E, ventral view with oostegites. Male (NMV J40674): C, ventral view; D, dorsal view. Scale = 1.0 mm.

Figure 6. Neastacilla deducta Hale, 1924, male (NMV J40674): PL1, PL2, Pe. Female (NMV J40673): P5, U. Scales a (P5) = 0.5 mm; b (PL1, PL2, Pe, U) = 0.5 mm.