Subantarctorchestia bollonsi ( Chilton, 1909 ), 2023

Hughes, Lauren E. & Lowry, James K., 2023, Review of New Zealand Coastal Talitroids with description of three new genera (Crustacea, Amphipoda, Senticaudata), Zootaxa 5268 (1), pp. 1-81 : 47-53

Subantarctorchestia bollonsi ( Chilton, 1909) gen. et. comb. nov.

( Figs. 40–49 , 68 )

Orchestia bollonsi Chilton, 1909: 635 , 636, fig. 6.— Stephensen, 1927: 348.— Stephensen, 1935: 4.— Paviour-Smith, 1956: 552.— Hurley, 1957: 160, figs. 52–68.— Bousfield, 1964: 54, fig. 5.— Shaw & Poore, 2016: 34.

? Transorchestia bollonsi .— Bousfield, 1982: 19.— Bousfield, 1984, 204 (table 6).— Serejo & Lowry, 2008: 200.

Type material. Probable Types: 24 specimens (12 males, 9 females, 3 juveniles including males up to 19 mm), BMNH 1912.5.25.103–112, The Snares, roots of tussocks, November 1907, ‘cotypes’ Prof. Charles Chilton .

Additional material examined. Z male, 13 mm, SEM preparation, AM P.99368, eastern side of Shoal Point, Perseverance Harbour, Campbell Island (52°33′S 169°09′E), boulder beach above high tide, coll. J.K. Lowry and S. Lowry, 4 February 1980 (CA-269); Y female, 12 mm, SEM preparation, AM P.99369, eastern side of Shoal Point, Perseverance Harbour, Campbell Island (52°33′S 169°09′E), boulder beach above high tide , coll. J.K. Lowry and S. Lowry, 4 February 1980 (CA-269); 11 specimens (incl. A male 13.5 mm, B male 20 mm), AM P.100710, east side of Shoal Point, Perseverance Harbour, Campbell Island (52°33′S 169°9′E) 4 February 1980 , coll. J.K. Lowry & S. Lowry, Australian Museum Campbell Island Expedition ( CA 269 ); 13 specimens, AM P.100713, large point at western end, Northeast Harbour, Campbell Island (52°31′S 169°10′E), under old bricks on grass just above shoreline, 7 February 1980 , coll. S. Lowry & D. James ( CA 286 ); 1 specimen, AM P.100714, boulder beach between Complex Point and Sandy Beach, Northwest Bay , Campbell Island (52°33′S 169°3′E), soil under terrestrial plant Cotula sp. , 31 January 1980 , coll. J.K. Lowry & S. Lowry, ( CA 234 ); 19 specimens, AM P.100715, western end of Rocky Bay, Campbell Island (52°34′S 169°1′E), under stones, 12 February 1980 , coll. M.A. Fraser & D. James ( CA 326 ); 100’s specimens (including 12 mm, 12.5 mm, 14 mm, 14.7 mm, 15 mm, 15 mm), AM P.100703, Rima Islet, Western Chain, The Snares , 26 November 1974 , rootlets of Scirpus cernuus , coll. D.S. Horning; 13 specimens (including 15 mm, 17 mm, 20 mm, 21 mm), AM P.100704, Rima Islet, The Snares , 21 November 1976 , coll. J.W. Early; 50 specimens, AM P.100702, Rima Island, Snares Islet , 21 November 1976 , coll. G.D. Fenwick; 1 specimen, AM P.100707, south side of South West Promontory, The Snares , (48°7′S 166°36′E) under rocks, 13 January 1967 , coll. G.A. Knox ( SA 3172 ); 1 specimen, AM P.100708, south side of South West Promontory, The Snares , (48°7′S 166°36′E) under rocks, 13 January 1967 , coll. G.A. Knox ( SA 3172 ); 1 specimen, AM P.100709, south side of South West Promontory, The Snares , (48°7′S 166°36′E) under rocks, 13 January 1967 , coll. G.A. Knox ( SA 3172 ); 300+ specimens, ZMUC unreg, Auckland Island , under tree 25 November 1914 , coll. Dr Th. Mortensen. ( ID Chilton 1 December 1916) .

Type locality. Bounty Islands , The Snares and Ewing Island, Auckland Islands, New Zealand .

Variation. Not significant.

Diagnosis. Pereonites smooth, without transverse ridges. Gnathopod 2 palm without large distal sinus; dactylus lies outside defining distal spine. Gnathopod 2–4 coxa trapezoid and much wider than deep. Pereopod 7 basis with large distally rounded posterodistal lobe reaching into merus. Epimeron 1 with 3 or 4 small robust setae along anterior margin.

Size. Male 21 mm, female 12 mm.

Remarks. Subantarctorchestia bollonsi co-occurs with S. aucklandiae , separating these species across locations, The Snares, the Auckland Islands and Campbell Island, with populations of various body sizes is challenging. In S. aucklandiae the male gnathopod 2 propodus has a large distal sinus which differs from S. bollonsi where the palm is entire. In S. bollonsi the male pereopod 7 basis is narrow and the merus has an anterior distal lobe which develops as a hook, seen in male specimens greater than 15 mm, while in S. aucklandiae of a similar size the pereopod 7 basis is broad and the merus is without a hook structure. However, in extremely large specimens of S. aucklandiae (25–40 mm) pereopod 7 is more similar to S. bollonsi , where the basis becomes acute and the merus is hooked (see figs. 36 and 44).

The swollen antenna 2 and more expanded articles of pereopod 7 in S. bollonsi indicate that these specimens are sexually dimorphic mature males and are not a juvenile form of the larger S. aucklandiae species. Indeed, in the largest specimens of S. aucklandiae the gravid females have developing eggs as large as S. bollonsi .

Habitat. Supralittoral, under guano ( Chilton 1909), in the roots of tussocks (Paviour-Smith 1959), under leaf mould ( Hurley 1957).

Distribution. New Zealand. The Snares: Rima Islet, Sinkhole, Southwest Promontory ( Chilton 1909; current study). Bounty Islands ( Chilton, 1909). Auckland Islands: Ewing Island ( Chilton 1909); Auckland Islands: Ewing Island, Ocean Island ( Chilton 1909; current study). Campbell Island; Northeast Harbour, Northwest Bay, Rocky Bay, (current study).

Figures

FIGURE 40. Subantarctorchestia bollonsi (Chilton, 1909) habitus male, 20 mm, AM P.100710, east side of Shoal Point, Perseverance Harbour, Campbell Island, New Zealand. Scales, 0.2 mm.

FIGURE 41. Subantarctorchestia bollonsi (Chilton, 1909) male, 20 mm, AM P.100710, east side of Shoal Point, Perseverance Harbour, Campbell Island, New Zealand. Scales, 0.2 mm.

FIGURE 42. Subantarctorchestia bollonsi (Chilton, 1909) SEM, male 13 mm, AM P.99368, eastern side of Shoal Point, Perseverance Harbour, Campbell Island, New Zealand. Scales, A1, 200 µm; A2, 500 µm.

FIGURE 43. Subantarctorchestia bollonsi (Chilton, 1909) SEM, male 13 mm, AM P.99368, eastern side of Shoal Point, Perseverance Harbour, Campbell Island, New Zealand. Scales, 100 µm, except Mxp 200 µm.

FIGURE 44. Subantarctorchestia bollonsi (Chilton, 1909) SEM, male 13 mm, AM P.99368, eastern side of Shoal Point, Perseverance Harbour, Campbell Island, New Zealand. Scales, 500 µm.

FIGURE 45. Subantarctorchestia bollonsi (Chilton, 1909) SEM, male 13 mm, AM P.99368, eastern side of Shoal Point, Perseverance Harbour, Campbell Island, New Zealand. Scales, 1 mm, except P4, 500 µm.

FIGURE 46. Subantarctorchestia bollonsi (Chilton, 1909) SEM, male 13 mm, AM P.99368, eastern side of Shoal Point, Perseverance Harbour, Campbell Island, New Zealand. Scales, Ur, U1, 500 µm; U2 200µm; U3, T, 100 µm

FIGURE 47. Subantarctorchestia bollonsi (Chilton, 1909) SEM, female 12 mm, AM P.99369, eastern side of Shoal Point, Perseverance Harbour, Campbell Island, New Zealand. Scales, 100 µm, except A2, 500 µm.

FIGURE 48. Subantarctorchestia bollonsi (Chilton, 1909) SEM, female 12 mm, AM P.99369, eastern side of Shoal Point, Perseverance Harbour, Campbell Island, New Zealand. Scales, 500 µm.

FIGURE 49. Subantarctorchestia bollonsi (Chilton, 1909) SEM, female 12 mm, AM P.99369, eastern side of Shoal Point, Perseverance Harbour, Campbell Island, New Zealand. Scales, 500 µm.

FIGURE 68. Fieldguide to New Zealand Coastal Talitrids Subantarctorchestia aucklandiae (Spence Bate, 1862) gen. et comb. nov., Subantarctorchestia bollonsi (Chilton, 1909) gen. et comb. nov., Bellorchestia spadix (Hurley, 1956), Tatahipeke cookii gen. et. comb. nov., T. tumida (Stebbing, 1887) gen. et comb nov. (Part 2 of 3).