Hircella cornigera ( Haswell, 1879b )

Takeuchi, Ichiro & Lowry, James K., 2015, A taxonomic study on the Phtisicidae (Crustacea: Amphipoda) of New South Wales, Australia, Journal of Natural History 50, pp. 603-648 : 617-623

Hircella cornigera ( Haswell, 1879b)

( Figures 7 – 10 )

Caprella cornigera Haswell, 1879b: 4 , 347 – 348, pl. 23, fig. 5. – Haswell, 1882: 313 – 314.

Hircella cornigera . – Haswell, 1885a: 999. – Mayer, 1890: 16 – 17, pl. 5, figs 10 – 11. – Mayer, 1903: 31 – 32. – Stebbing, 1910b: 652. – McCain and Steinberg, 1970: 51 – 52. – Lowry and Stoddart, 2003: 35. – Guerra-Garcia, 2006: 425, fig. 12.

Material examined

1 male, AM P48627, 30°14.5 ʹ S, 153°10.73 ʹ E, rocks and coral zone, Split Solitary Island, New South Wales, 8 m depth, hydroids, 5 February 1996; 1 male, AM P48647, 30°19.05 ʹ S, 153° 09.25 ʹ E, Korffs Islet, Solitary Islands , New South Wales, 16 m depth, hydroids, 6 February 1996; 1 male and 1 mature female, AM P48648, 30°19.05 ʹ S, 153°09.25 ʹ E, Korffs Islet , Solitary Islands , New South Wales, 16 m depth, hydroids, 6 February 1996; 4 males, 3 mature females, 1 premature female, 5 immature females and 2 juveniles, AM P48649, 30°19.05 ʹ S, 153°09.25 ʹ E, Korffs Islet , Solitary Islands , New South Wales, 16 m depth, hydroids, 6 February 1996; 1 mature female, AM P48654, 30°19.05 ʹ S, 153°09.25 ʹ E, Korffs Islet , Solitary Islands , New South Wales, 8 m depth, hydroids, 6 February 1996; 2 males and 2 mature females, AM P48660, 29°55.5 ʹ S, 153°23.23 ʹ E, The Canyons , off North Solitary Island , New South Wales, 6 m depth, hydroids on top of rocks, 8 February 1996; 1 male, AM P48676, 30°18 ʹ S, 153°09 ʹ E, Corambirra Point , Coffs Harbour , New South Wales, 6 m depth, Ecklonia radiata holdfasts, 11 July 1989; 1 male, AM 48742 , 35°08.84 ʹ S, 150°45.71 ʹ E, the base of vertical wall, 1 nautical mile south of Governor Head , out of Jervis Bay , New South Wales, hydroid, 17 m, coll . I . Takeuchi, A . Murray and R . T . Johnson, 28 February 1996; 1 mature female, 1 premature female and 1 juvenile, AM P87329, 30°19.05 ʹ S, 153°09.25 ʹ E, Korffs Islet, Solitary Islands , New South Wales, 8 m depth, hydroids, 6 February 1996 .

Type locality

Clark Island, Port Jackson , New South Wales .

Other records

New South Wales: Spilit Solitary Island, Korffs Islet and The Canyons, off North Solitary Island, Solitary Islands, Corambirra Point, Coffs Harbour, and 1 nautical mile south of Governor Head, out of Jervis Bay (this study).

Description

Based on male, body length 11.56 mm, AM P48647. Head and pereonite 1 combined length 1.97 mm; pereonite 2, 1.18 mm; pereonite 3, 1.56 mm; pereonite 4, 2.18 mm; pereonite 5, 2.44 mm; pereonite 6, 1.77 mm; pereonite 7, 0.46 mm.

Head and pereonites slender. Head smooth, rounded dorsally; eye large, distinctive; head/pereonite 1 dorsal margin slightly convex.

Antenna 1 slender; about 0.5 × body length; peduncle article 2 longest; peduncular article 3 slightly concave along anterior margin; flagellum 0.33 × peduncular length, with seven articles; proximal article result of fusion of 5+ articles. Antenna 2 slender, 0.25 × antenna 1 length; peduncle with several feeble setae; flagellum 0.4 × peduncular length, with three articles.

Upper lip notched, forming rounded quadrilateral projections. Mandible right side incisor with five teeth; lacinia mobilis with four large teeth followed by accessory setal row with 13 setae; palp article 2 with five distolateral setae; article 3 setal formula 0 – 4 – 1; left side incisor with five teeth; lacinia mobilis with five teeth followed by two trapezoid plates; accessory setal row with seven setae; palp article 2 with five distolateral setae; palp article 3 setal formula 0 – 5 – 1. Lower lip finely setose on inner and outer lobes. Maxilla 1 outer plate with six stout apical setal-teeth; palp distal margin with five triangular projections, each with one slender or robust seta, a row of slender lateral setae. Maxilla 2 inner plate triangular with eight apical setae; outer plate elongate with six apical setae. Maxilliped inner plate (basal endite) oval, with two stout serriform setae on inner half of distal margin, with one seta on outer half of distal margin; outer plate (ischial endite) oval, 0.67 × length of inner plate (basal endite), inner margin smooth, with four setae on inner margin; palp article 2 setose on inner margin; palp article 3 with eight distal setae; palp article 4 weakly falcate.

Pereon. Pereonite 2 with small antero-lateral projection, with mid-lateral projection. Pereonite 3 with small antero-lateral projection, with paired mid-dorsal projections, with triangular dorsodistal projection. Pereonite 4 with paired small mid-dorsal projections, with small dorsodistal projection. Pereonite 5 longest, with paired mid-dorsal to dorsodistal projections, with small dorsodistal projection.

Gnathopod 1 propodus triangular, with a row of submarginal setae on distal part (near anterior margin); palm begins about 1/3 along posterior margin, smooth, with two robust setae (one large and one small) near corner of palm; dactylus curved. Gnathopod 2 situated in middle of pereonite 2; gill length about 3 × width, about 1/ 2 × pereonite length; coxa vestigial; basis 1.5 × length of pereonite 2, with small projection near proximal margin; carpus 0.13 × propodus length; propodus elongate (subrectangular), large, length 3 × width, anterodistal margin convex; palm proximal projection with three robust (one large and two small) setae, palm margin almost straight, smooth, with narrow well developed distal shelf.

Gill 3 length about 1/4 × corresponding pereonite, straight. Gill 4 length about 1/8 × corresponding pereonite, straight. Pereopod 5 tiny, conical. Pereopod 6 basis shorter than propodus; carpus with four setae on anterior margin; propodus with four robust setae on posterior margin, with 12 robust setae along palm; dactylus curved, not setose. Pereopod 7 similar to pereopod 6; merus subequal in length to basis.

Pleon. Uropod 1 uniarticulate, uniramous; peduncle fused to abdomen; ramus length about 6 – 8 × width. Uropod 2 similar to uropod 1.

Female (sexually dimorphic characters). Based on female, body length 7.07 mm, AM P 48654. Length of head and pereonite 1 combined 0.69 mm, and pereonites 2–7, 0.82 mm, 0.78 mm, 1.46 mm, 1.62 mm, 1.39 mm and 0.31 mm, respectively. Head/ pereonite 1 dorsal margin straight. Antenna 1 0.33 × body length; flagellum 0.5 × peduncular length, with five articles. Antenna 2, flagellum with two articles. Basis of gnathopod 2 0.8 × pereonite 2 length; propodus oblong, with convex palm. Pereonite 3 with anterolateral projections and paired mid-dorsal projections. Gill 3 length about 1/ 3 × corresponding pereonite. Gill 4 length about 1/5 × corresponding pereonite. Pereopod 5 lacking.

Remarks

Mayer (1882) established the genus Hircella based on the single species, Caprella cornigera Haswell, 1879b , which was collected from Clark Island, situated in the middle of Port Jackson. The type specimens are lost ( Springthorpe and Lowry 1994). The field survey during 1995/96 as well as the survey of the deposited specimens at the Australian Museum failed to find H. cornigera from Port Jackson. However, H. cornigera was found from Spilit Solitary Island, Korffs Islet, and North Solitary Island, the Solitary Islands, Corambirra Point, Coffs Harbour, and south of Governor Head, out of Jervis Bay, New South Wales. In addition to the coast of New South Wales, H. cornigera was recorded from North Stradbroke Island, which is situated near the southern border of Queensland ( Guerra-García 2006). These indicate that H. cornigera is still distributed widely along the east coast from Jervis Bay, the New South Wales to North Stradbroke Island, Queensland facing the Pacific Ocean, while the species seems to have disappeared from Port Jackson and the inner parts of Jervis Bay. Hence, in the present study, a mature male and a mature female collected from the Solitary Islands have been described in detail.

Close observation of the present specimens shows that article numbers in the flagellum of antenna 2 increase from two to three during growth ( Figure 10 ). Of the 11 males measured, all males larger than 7.4 mm in body length posses a 3-articulate flagellum. Of females, most have two articles in the flagellum, but the third largest mature female has three articles in the flagellum.

In addition to H. cornigera , two additional species of Hircella have been recorded recently; H. inermis Guerra-García and Takeuchi, 2004 from Tasmania and Western Australia ( Guerra-García and Takeuchi 2004; Guerra-García 2004a) and H. berentsae Guerra-García, 2006 from North Stradbroke Island, Queensland ( Guerra-García 2006). The present species, H. cornigera , is clearly distinguished from H. inermis and H. berentsae by the projections on pereonites 2 to 5. Hircella cornigera possesses midlateral projection on pereonite 2, mid-dorsal projections on pereonites 3 to 5 and dorsodistal projection on pereonites 3 and 5. Both H. inermis and H. berentsae lack projections on the corresponding pereonites.

Figures

Figure 7. Hircella cornigera (Haswell, 1879b) from Korffs Islet, Solitary Islands, New South Wales. Male, 11.56 mm, AM P48647; female, 7.07 mm, AM P48654. Bar indicates 1.0 mm.

Figure 8. Hircella cornigera (Haswell, 1879b) from Korffs Islet, Solitary Islands, New South Wales. Male, 11.56 mm, AM P48647, A1, A2, G1, G2, P5, P6, P7, ABD (LT); female, 7.07 mm, AM P48654, G2. Bars in G1, P5 and ABD (LT) indicate 0.10 mm, those in G2 (M), G2 (F), P6 and P7 indicate 0.50 mm.

Figure 9. Hircella cornigera (Haswell, 1879b) from Korffs Islet, Solitary Islands, New South Wales. Male, 11.56 mm, AM P48647. Bars indicate 0.05 mm.

Figure 10. Hircella cornigera (Haswell, 1879b) from Solitary Islands, Coffs Harbour, and out of Jervis Bay, New South Wales. Number of articles in the flagellum of antenna 2 against the body length.