Pontocrates arcticus Sars 1895
Creators: name: Myers, Alan A.
name: Ashelby, Christopher W.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Oedicerotidae
Pontocrates
Pontocrates arcticus

description: Pontocrates arcticus Sars, 1895
(Fig. 1, 2)
Pontocrates arcticus Sars, 1895, 693.—? Raitt, 1938, 10,11.— Gurjanova, 1951, 525, fig. 343.
Pontocrates norvegicus Schneider, 1883, 17, pl. 2, fig. 15, pl. 3, figs 21–22.— Schneider, 1885a, 13, pl. 1, figs 1–18.— Sars, 1892, 315, pl. 111, fig. 2.
Not Pontocrates norvegicus Boeck, 1871, 171.
Type material. Syntypes (11 animals), Hasvig, West Finmark (UiO F14210)
Material studied. 1 male North Sea, UKCS 16 /29a, 57°57’36.00”N 001°48’57.60”E; 88 m depth; Muddy Sand; leg. Gardline, 16/10/2018. 1 female North Sea, UKCS 16 /29a, 57°57’36.00”N 001°48’57.60”E; 88 m depth; Muddy Sand; leg. Gardline, 16/10/2018. 1 male, 1 female North Sea, UKCS 22 /11, 57°39’46.40”N 001°08’44.00”E; 83.4 m depth; Sand; leg. Fugro, 04/01/2014. 1 male North Sea, UKCS 16 /29a, 57°57’36.00”N 001°48’57.60”E; 88 m depth; Muddy Sand; leg. Gardline, 17/10/2018. 2 females Belfast Lough, 54°43’59.88”N 005°35’60.00”W; 32 m depth; Sand; leg. DAERA, 10/03/2016. 1 female Belfast Lough, 54°43’59.88”N 005°35’60.00”W; 32 m depth; Sand; leg. DAERA, 10/03/2016. 3 females, Belfast Lough, 54°43’59.88”N 005°35’60.00”W; 32 m depth; Sand; leg. DAERA, 10/03/2016. 1 female. Belfast Lough, 54°43’28.20”N 005°34’03.00”W; 34 m depth; Sand and Shell; leg. DAERA, 22/06/2016. 2 females, Belfast Lough, 54°43’59.88”N 005°35’60.00”W; 32 m depth; Sand; leg. DAERA, 05/03/2013. 1 male, 1 female, Belfast Lough, 54°43’59.88”N 005°35’60.00”W; 32 m depth; Sand; leg. DAERA, 10/03/2016. 1 female, Belfast Lough, 54°43’59.88”N 005°35’60.00”W; 32 m depth; Sand; leg. DAERA, 08/03/2018. 2 females, Belfast Lough, 54°43’59.88”N 005°35’60.00”W; 32 m depth; Sand; leg. DAERA, 08/03/2018. 1 female, Belfast Lough, 54°43’59.88”N 005°35’60.00”W; 32 m depth; Sand; leg. DAERA, 08/03/2018. 1 female Tartan Oil Field, 58°21’50.37”N 000°05’21.32”E; 142 m depth; Sandy Mud; leg. APEM, 14/09/2019. 1 female Tartan Oil Field, 58°22’54.30”N 000°04’45.40”E; 141 m depth; Sandy Mud; leg. APEM, 12/09/2019. 1 female Tartan Oil Field, 58°20’54.10”N 000°06’55.71”E; 142 m depth; Slightly sandy mud; leg. APEM, 18/09/2019. 1 female Tartan Oil Field, 58°20’56.47”N 000°06’50.58”E; 142 m depth; Sandy Mud; leg. APEM, 16/09/2019.
Description (male, Belfast Lough 4.5 mm)
Head Head rostrum short, strongly deflected, triangular in frontal view. Antenna 1 less than one third body length, peduncular article 3 much longer than 2; flagellum subequal in length with peduncle, with 7 articles. Antenna 2 very long, subequal in length with body, peduncular article 5 longer than 4, flagellum much longer than peduncle with about 55 articles.
Pereon. Gnathopod 1 coxa distally convex; basis stout, 4 x as long as broad, anterior margin substraight; merus blunt ending or with small posterodistal spine, but without distal extension; carpus reduced, with long, slender, distal process, extending to the tip of the dactylus; propodus slender subovoid, twice as long as broad, palm fimbriate, strongly oblique, with about 15 club-shaped robust setae each with a distal filament; dactylus elongate, slender, opposable to carpal process. Gnathopod 2 coxa subrectangular; basis very elongate, slender, parallel-sided; carpus small but with elongate spur that extends beyond tip of the propodus; propodus very elongate, slender, chelate, palm with club-shaped robust setae each with a distal filament; Pereopod 3 coxa elongate and sender, subrectangular; basis slender, 3.5 x as long as broad, posterior margin convex, anterior margin proximally concave, distally straight; merus anterior margin strongly convex; carpus and propodus elongate, subequal in length; propodus subrectangular, distally truncate; dactylus small almost hidden by long setae, anterodistal margin of merus and posterior margins of merus carpus and propodus and distal margin of propodus clothed in very long setae. Pereopod 5 basis anterior margin strongly convex, merus anterodistal margin strongly convex and with exceedingly long setae; carpus short, posterior margin irregular, with long setae; propodus longer than carpus, slender, anterior margin with long setae; dactylus elongate slender more than one third length of propodus. Pereopod 6 similar to pereopod 5 but more elongate; basis posterior margin with very long setae, anterior margin substraight; propodus subequal in length with carpus. Pereopod 7 very long, more than half body length, basis pyriform; merus, carpus, propodus and dactylus very long and slender.
Pleon. Epimera 1–3 rounded. Uropods 1–3 slender, peduncles extending about the same length. Uropod 1 peduncle much longer than subequal rami. Uropod 2 peduncle a little longer than subequal rami Uropod 3 rami subequal with each other and with peduncle. Telson distally rounded, not incised.
Female (sexually dimorphic characters). Antenna 2 only a little longer than antenna 1; flagellum with 10 articles.
Habitat and distribution. Sars (1892) recorded this species from 11–18 m depth. The material examined in this study expands this depth range to 8-323 m. The specimens were recovered from sandy substrates, with varying degrees of mud, shell or fine gravel. Pontocrates arcticus is found off all British Coasts, extending to the edge of the continental shelf off the South-West of Britain and to the limits of UK territorial waters. Beyond UK waters the species is recorded only from Norwegian waters.
Remarks. Pontocrates arcticus differs from all other Pontocrates species in its gnathopod 1–2 palms, which are fimbriated and bear club-shaped robust setae. It differs from P. moorei sp. nov., in its gnathopod 1, in that species the merus has a distal extension (absent in P. arcticus), and the propodus is less than 2 x as long as broad and more rectangular (2 x as long as broad in P. arcticus), in its gnathopod 2 in which the coxa is distally straight (convex in P. arcticus), in its pereopods 3 and 4 which are very short (elongate in P. arcticus) and in its pereopod 6 where the propodus is less than half length of the carpus (subequal in length in P. arcticus). It differs from P. arenarius (Spence Bate, 1858), in the subrectangular coxa 1 (subtriangular in P. arenarius), the elongate, subovoid propodus of gnathopod 1 (broad, subtriangular in P. arenarius) and the subrectangular coxa 2 (posterior margin sinuous in P. arenarius). It differs from P. norvegicus in the un-narrowed distal portion of coxa 1 (distally narrowed in P. norvegicus) and in the elongate carpus and propodus of pereopod 3 (short carpus and propodus of pereopod 3 in P. norvegicus).
description: Published as part of Myers, Alan A. & Ashelby, Christopher W., 2022, A revision of the genus Pontocrates Boeck, 1871 (Amphipoda, Oedicerotidae) with the description of P. moorei sp. nov. and the re-establishment of P. norvegicus (Boeck, 1860), pp. 582-598 in Zootaxa 5115 (4) on pages 583-586, DOI: 10.11646/zootaxa.5115.4.8, http://zenodo.org/record/6361696