Haploops similis Stephensen 1925

Kaim-Malka, R. A., Bellan-Santini, D. & Dauvin, J. C., 2021, Complement to the knowledge of the Haploops species (Crustacea, Gammaridea Ampeliscidae), with the description of two new species from North Atlantic Ocean [Contribution to the knowledge of the Haploops genus. 10.], Zootaxa 5048 (2), pp. 151-175 : 166-168

Haploops similis Stephensen 1925

Type species collected by the R. V “ Ingolf”, one specimen, (sex?) length: 4.5 mm, Station 36: 61°50’N – 56°21’W, depth 2702 m, bottom: sediment type unknown .

BIOICE material examined. Station 2314: nine specimens, 11September 1992, depth 156 m, 63° 42.16’N – 23°03.50’W ; bottom:muddy sand.Station 2328: four specimens, 3 May 1993, depth 429m, 63°20.00’N – 10°57.00’W; bottom: sand. Station 2616: four specimens, 11 July 1994, depth 535 m, 67°11.38’N – 16°50.40’W; bottom: sandy silt. Station 2873: one specimen, 22 August 1996, depth 555 m, 64°37.41’N – 27°14.28’W; bottom: gravely sand. Station 2946: two specimens, 28 August 1996, depth 229 m, 65°47.90’N – 25°38.70’W; bottom: sandy silt. Station 3026: five specimens, 8 July 1997, depth 564 m, 63°53.96’N – 12°44.18’W; sediment type unknown. Station 3099: two specimens, 21August 1999, depth 229 m, 67°11.02’N – 21°45.68’W; bottom: gravely sandy silt. Station 3282: four specimens, 16 September 2001, depth 1808 m, 62°48.00’N – 16°14.80’W; bottom: sandy silt. Station 3531: two specimens, 9 September 2002, depth 1712 m, 62°43.26’N – 14°34.70’W; bottom: sandy silt. Station 3544: 16 specimens, 11September 2002, depth 1632 m, 61°33.005’N – 13°40.14’W; bottom: gravely sand. Station 3598: one specimen, 10 September 2003, depth 768 m, 62°17.37’N – 26°37.58’W; bottom: silty sand.

All specimens of these stations are females.

Diagnosis. Blind species; body without long dorsal setae on the pereon, pleon and urosome; A1 = 8–9/10 A2, A2 = 2/3 body; coxa 4 heart-shaped, Pereopod 7: basis narrow, anterior distal lobe of the carpus developed.

Description. Head: Square shaped, without corneal lenses, anterior margin oblique and straight. Antenna 1 length is 8–9/10 of Antenna 2 length; Antenna 2 length is 2/3 body length.

Pereon: without long dorsal setae. Gnathopod 1: coxa 1 roughly oval, distal margin rounded and fringed with long setae; basis long, slightly curved, approximately rectangular with many long setae, as long as ischium + merus + carpus, the merus, carpus and propodus bearing long setae; propodus oval. Gnathopod 2: coxa 2 approximately rectangular, distal margin straight with few setae; basis long, slightly curved, with many long setae, as long as ischium + merus + carpus; the merus, carpus and propodus bearing long setae; propodus oval. Pereopod 3: coxa 3 approximately rectangular, distal margin straight with few setae; basis, merus and carpus with long setae on the posterior margin; dactylus slender, curved and longer than propodus. Pereopod 4: coxa 4 heart-shaped, basis, merus and carpus with long setae on the posterior margin, and tuft of long setae on distal anterior margin of merus and propodus; dactylus slender, curved and shorter than propodus. Pereopod 5: coxa 5 rectangular, basis roughly rectangular with few setae on the anterior margin; carpus rectangular, anterior margin with few setae, posterior margin with rows of little spines, postero-distal lobe with short spines and a long one; propodus rectangular, longer than carpus, with few short setae on anterior margin, and long distal setae; dactylus short and curved.

Pereopod 6: basis rounded with few short setae on the anterior margin; carpus rectangular, posterior margin with rows of little spines, postero-distal lobe ornamented with short spines and a very long one; propodus a little longer than carpus, with few short setae on anterior margin, and long distal setae; dactylus short and curved. Pereopod 7: basis narrow, anterior and posterior margin slightly concave, lobe not deflected, rounded with few long setae, not reaching the ischium-merus joint; ischium quadrangular; merus rectangular with an antero-inferior lobe, anterior and posterior margin ornamented with few little spines and long postero-distal setae; carpus oval, with spines on the anterior and posterior margin, anterior distal lobe developed; propodus and dactylus short and narrow.

Pleon: without long dorsal setae. Epimeral plate 1: anterior margin oblique and straight, ventral margin and posterior margin straight, corners rounded. Epimeral plate 2: inferior and posterior margins slightly convex, postero-inferior corner rounded. Epimeral plate 3: anterior margin straight, posterior margin oblique and straight, inferior one slightly convex, anterior corner rounded, posterior corner slightly acute.

Urosome: carina small. Uropod 1: the rami are long and slender, of unequal length (2/3). Uropod 2: rami short, of equal size, and armed with a row of spines on each ramus. Uropod 3: peduncle short and strong; rami of unequal length, ornamented with numerous setae.

Telson: triangular, apically rounded, cleft on 2/3 of the length; two setae at the apex of each lobe.

Distribution: North Atlantic Ocean; wide bathymetric range species: this species was collected at 2702m depth ( Stephensen,1925), between 100–2900 m ( Mills,1971), between 156–1808 m, on sand, sandy silt, silty sand, muddy sand, gravely sand, gravely sandy silt (BIOICE samples), one specimen at 1024 m on bathyal mud in the south of the Bay of Biscay ( Dauvin & Bellan-Santini,1996).

Taxonomic remarks. H. similis belongs to the sub-group of blind species with a narrow Pereopod 7 basis and without dorsal tuft setae, which includes six other species: H. abyssorum , H. vallifera , H. lodo , H. dauvini , H. bjarnii , and H. faroensis . It differs from these species by having:

— Antennae: Antenna 1= 8–9/10 Antenna 2, Antenna 2 = 2/3 body length; the antennae are longer than the body length for H. bjarnii ; they are half body length for H. vallifera , H. dauvini , and H. faroensis ; for H. lodo , A1= ped A2, A2 shorter than body (in Barnard, 1961).

— Coxa 4 heart-shaped (also the case for H. bjarnii and H. vallifera ); but square shaped for H. abyssorum , H. lodo , H. dauvini and H. faroensis .

— Epimeral plates 3 with posterior margin oblique and straight (also for H. faroensis ); slightly convex for H. bjarnii and H. dauvini ; rounded for H. vallifera and H. lodo (not indicated by Chevreux 1908 for H. abyssorum ).

— Uropod 1: the rami are long and slender, of unequal length (2/3); the rami are subequal for H. bjarnii , H. vallifera ; H. lodo and H. dauvini ; they have the same size for H. abyssorum and H. faroensis .