Orchestia forchuensis, Myers & Lowry, 2020

Myers, Alan A. & Lowry, James K., 2020, A revision of the genus Orchestia Leach, 1814 with the reinstatement of O. inaequalipes (K. H. Barnard, 1951), the designation of a neotype for Orchestia gammarellus (Pallas 1776) and the description of three new species (Crustacea: Amphipoda: Talitridae Talitrinae), Zootaxa 4808 (2), pp. 201-250 : 218-221

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https://doi.org/ 10.11646/zootaxa.4808.2.1

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scientific name

Orchestia forchuensis

sp. nov.

Orchestia forchuensis View in CoL sp. nov.

( Figs 12–14 View FIGURE 12 View FIGURE 13 View FIGURE 14 )

Orchestia gammarella View in CoL .― Bousfield, 1958: 885, figs 1e, 10a.― Bousfield, 1973: 159, pl. 45.1.

Orchestia gammarellus View in CoL .― Ingólfsson, 1996: 39, fig. 10.― Henzler & Ingólfsson, 2007: 1.

Not Orchestia gammarellus ( Pallas, 1776) View in CoL : 191, pl. 14, fig. 25.

Types. Holotype, male, 12.0 mm ( CNMC 1984-462 View Materials ), Cape Fourchou , Yarmouth County, Nova Scotia, 5 July,1956, E.L. Bousfield.

Paratypes. 4 males, 8 females ( CNMC 1984-462 View Materials ), same data as holotype .

Other material studied. 3 females, 25 juveniles ( CNMC 1984-472 View Materials ), 3 miles west of Le Cou Harbour , southwestern Newfoundland (47 o 38’N 58 o 41’W), 8 June 1966 GoogleMaps , D.E. McAllister; 2 males, 5 females ( CNMC 1984-465 View Materials ) Gilbert Point , Digby County, Nova Scotia, E.L. Bousfield, 9 July 1958 ; 3 males, 5 females, 2 juveniles, ( CNMC 1984-460 View Materials ), above Murphy’s river , Salmonier Estuary, Newfoundland, 15 August, 1954, E.L. Bousfield ; 7 males, 11 females, Nauthólsvík , between Kópavogur (pubby seal bay) and Reykjavík, Iceland (64.117714 oN 21.900876 oW), September 2019 , Davíð Gíslason ; 9 males, 10 females, salt-marsh, under stones in the saltmarsh grass Puccinella maritima beds Galgahavn , Iceland (64.0549 oN 21.5728 oW), 23 September 2019 , Jorundur Svavarsson .

Type locality. Cape Fourchu, Nova Scotia.

Etymology. Named after the type locality.

Description of adult male (15 mm).

Head. Eyes of moderate size. Antenna 1 short, just reaching beyond peduncular article 4 of antenna 2; accessory flagellum absent; primary flagellum with 5 articles. Antenna 2 peduncular article 5, 1.3 × length of peduncular article 4; flagellum longer than combined length of peduncular articles 4 and 5, with 19-20 articles, final article cone shaped, with terminal cluster of imbricated setae. Labrum without epistome. Mandible left lacinia mobilis with 4 cusps. Maxilliped palp article 2 with distomedial lobe.

Pereon. Gnathopod 1 subchelate, coxa smaller than that of coxa 2; posterior margin of carpus and propodus each with lobe covered in palmate setae; propodus length to carpus length 1:1.6; propodus strongly triangular; dactylus shorter than palm. Gnathopod 2 subchelate; basis 2.3 × as long as broad; merus posterior margin with 3-5 short setae; propodus weakly triangular, distal width 1.7 × proximal width. Pereopods 3–7 bicuspidactylate, cusps sometimes becoming lost in large males. Pereopods 3–4 dactylus unguis relatively slender, acute, becoming short and blunt on pereopod 7 in large males Peropod 4 dactylus thickened proximally with a notch midway along posterior margin. Pereopod 5 basis subovoid. Pereopod 7 basis posterior margin distinctly serrate; merus elongate, weakly triangular, becoming 2 × as wide distally as proximally in large males; carpus elongate pyriform, 1.5 – 2 × as long as broad; carpus subequal to merus in small males, becoming 1.5 × longer in large males; propodus 1.2 × length of carpus.

Pleon. Epimeron 3 posterior margin weakly crenulate. Uropod 1 peduncle longer than rami, without distolateral robust seta; rami subequal. Uropod 2 peduncle subequal in length with rami, rami subequal; exopod with 2 marginal robust setae; endopod with 3 marginal robust setae and 2 robust setae on inner face. Uropod 3 peduncle only a little longer than broad; ramus 2.3 × as long as broad 0.6 × length of peduncle, outer margin with 6 robust setae. Telson with about 9 apical robust setae on each side.

Female (sexually dimorphic characters). Gnathopod 2 mitten-shaped; basis 2 × as long as broad, broadest proximally, anterodistal margin substraight; carpus 1.4 × length of propodus. Pereopod 7 stout, basis posterior margin weakly serrate, merus and carpus unexpanded.

Habitat. Limestone, gravel and pebble beaches; marshes among the saltmarsh grass Puccinella maritima .

Remarks. Orchestia forchuensis sp. nov. is close to O. gammarellus ( Pallas, 1776) but can be distinguished by the shape of the adult male pereopod 7 that has the merus almost parallel-sided, only about twice as broad distally as proximally in O. forchuensis sp. nov. (strongly triangular, almost three times as broad distally as proximally in O. gammarellus ) and the carpus much longer than broad (almost as broad as long in O. gammarellus ). The basis of pereopod 5 has a weakly developed posterodistal lobe in O. fouchouensis sp. nov. (well-developed in O. gammarellus ) and the basis of the female pereopod 7 of Orchestia forchuensis sp. nov. is subovoid (approaches subquadranglar in O. gammarellus ). That the North American populations of ‘ Orchestia gammarellus’ were probably a previously unrecognised species, was first pointed out by Perez-Schultheiss (2014, p. 30).

Distribution. Canada Newfoundland: Campell’s Creek Cove, Port-au-Port peninsula; Little Bay, near Springfield; Exploits estuary; Philip’s Head; Placentia; Salmonier estuary; Trepassey, head of Mutton Bay; Fox Cove ( Bousfield 1955); above Murphy’s river, Salmonier Estuary (present study); Gooseberry Cove (47°03.3’N 54°05.7’W), Kingwell Arm (47°33.5’N 54°06.O’W),Dirty Rocks (47°23.7’N 54°16.1’W),Margery Cove (47°24.5’N 54°09.0’W) ( Fenwick & Steele 1983), Cou Harbour, south-western Newfoundland (47 o 38’N 58 o 41’W) (present study).

Nova Scotia. Machias Seal Rock; St. Andrews; Argyle ( Bousfield 1955). Gilbert Point, Digby County, Nova Scotia (present study).

New Brunswick. Bay of Fundy ( Bousfield 1960); Tidal Cove; Machais Seal Islands ( Bousfield 1958).

USA (New England); coast of Maine to Casco Bay ( Bousfield 1973).

Iceland. Extreme southwest, from the Vestmannaeyjar Islands to Reykjavíc and the northwest peninsula area associated with warm springs; Hvassahraun (64°01’11’’N 22°09’19’’W) Reykjanestjörn (63°47’52’’N 22°43’912’’W), Hveravik, Steingrimsfjördur (65°41’47’’N 21°33’55’’W); Bjarnarstadir, Isafjördur (65°49’16’’N 22°2’919’’W) and Reykjanes, Reykjafjördur (65°55’25’’N 22°25’53’’W); Kaldrananes (65°46’N 21°24’W) and Skarð (65°29’N 20°59’W) ( Ingólfsson 1973, 1977, Morritt & Ingólfsson 2000, Ingólfsson et al. 2007, Henzler & Ingólfsson 2007).














Orchestia forchuensis

Myers, Alan A. & Lowry, James K. 2020

Orchestia gammarellus

Henzler, C. M. & Ingolfsson, A. 2007: 1
Ingolfsson, A. 1996: 39

Orchestia gammarella

Bousfield, E. L. 1973: 159
Bousfield, E. L. 1958: 885
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