Apseudes grossimanus Norman, 1886

Esquete, P. & Cunha, M. R., 2017, The Apseudomorpha (Crustacea: Tanaidacea) of the Gulf of Cadiz and Horseshoe Continental Rise (NE Atlantic): A taxonomic review with new records, species, and ecological data, Zootaxa 4276 (1), pp. 61-95 : 63-64

Apseudes grossimanus Norman, 1886

Apseudes grossimanus Norman & Stebbing 1886: 93 –95, pl. 19. Lang 1955: 74, figs. 12–15; 1968: 28–33. Holdich & Jones 1983a: 34 –35, fig. 9; Błażewicz-Paszkowycz et al. 2011: 9 –10, fig. 5.

Material examined. Gulf of Cadiz—Mud volcanoes. Gemini MV: St. 64PE253_06, 418 m, 2 specimens ( DBUA 0001987.01 ) . Lazarillo de Tormes MV: St. 64PE237_ 20, 516 m, 1 ♀ (DBUA0001988.01; St. 64PE237_ 21, 498 m, 1 neuter; St. 64PE253_38A, 494 m, 1 neuter; St. 64PE253_38B, 497 m, 1 neuter; St. 64PE253_38F, 497 m, 1 ovigerous ♀ (DBUA0001987.02–04). Meknès MV: St. MSM01-03_ 319, 695 m, 1♀, 10 neuters (DBUA0001989.01). Yuma MV: St. TTR14_AT 524, 960 m, 2 neuters (DBUA0001990.01). Ginsburg MV: St. TTR16_AT 607, 983 m, 1 neuter (DBUA0001999.01).

Gulf of Cadiz—Carbonate and coral mounds. Pen Duick Escarpment: St. 64PE237_07, 570 m, 1 ♂ ( DBUA 0001988.03 ) ; St. 64PE253_ 52, 622 m, 1 ♂; St. 64PE253_ 56, 622 m, 1 neuter (DBUA0001987.05). Mound B: St. 64PE268_11A, 489 m, 1 specimen; St. 64PE268_ 29, 508 m, 1 specimen (DBUA0001992.01–02).

Gulf of Cadiz—off mound and reference samples. El Arraiche area: St. 64PE268_09, 428 m, 1 neuter ( DBUA 0001992.03 ) . Carbonate Province : St. 64PE268_04, 597 m, 1 neuter; ( DBUA 0001992.04 ) .

Other records in the GoC. See Błażewicz-Paszkowycz et al. (2011).

Remarks. Apseudes grossimanus was described from the west coast of Ireland ( Norman & Stebbing 1886); decades later, K. Lang (1955, 1968) provided illustrations and further description of specimens from various locations of western Africa. Because of the limited dispersal capacity of tanaidaceans, records from South Africa and the Mediterranean Sea were suggested to be “regarded with some suspicion” ( Błażewicz-Paszkowycz et al. 2011), while Bochert (2012) confirmed its presence in shallow waters of the coast of Angola. The specimens examined here are morphologically in accordance with the illustrations and descriptions provided by Norman (in Norman & Stebbing 1886) and those provided by Lang (1968) from Angola and Namibia. Under these circumstances, there is no reason to consider the African material and that from the European margin (including that from the GoC) as belonging to different species.

Ecology and distribution. Apseudes grossimanus has been recorded along the Eastern Atlantic continental margin, from Ireland to South Africa and in the Mediterranean Sea, from 163 to 1345 m depth (see Bochert 2012; Holdich & Jones 1983a, b; Sieg 1983). This species was found previously in chemosynthetic habitats in the hydrothermal system of the Mid-Atlantic Ridge ( Larsen et al, 2006).

The distribution of Apseudes grossimanus in the GoC is restricted to the El Arraiche field and the southern area of the Carbonate Province, at depths between 319 and 983 m. It was found at the crater of Gemini, Ginsburg, Yuma and Meknès MVs, and in Lazarillo de Tormes MV. In the latter, it reached 5 cm depth in the sediment. It was generally found in low densities, with a maximum of 44 individuals.m -2, in silt/clay sediments with biogenic carbonate debris and in mud breccia with clasts.

All these data indicate that the species tolerates a wide range of depths and latitudes, as well as substrate conditions (i.e., presence of mud breccia or carbonate debris). On the other hand, all the records in the literature and in the GoC correspond to sediments with high proportions of fine fractions, i.e., mud and silt/clay.