Gnathophausia ingens (Dohrn, 1870)

Meland, Kenneth & Aas, Pål Øyvind, 2013, A taxonomical review of the Gnathophausia (Crustacea, Lophogastrida), with new records from the northern mid-Atlantic ridge, Zootaxa 3664 (2), pp. 199-225 : 203-204

Gnathophausia ingens (Dohrn, 1870)

( Fig. 2 )

Lophogaster ingens Dohrn, 1870: 610 –617.

Gnathophausia inflate Willemoes-Suhm, 1873 : in MS (nomen nudum).

Gnathophausia ingens— G.O. Sars 1885: 30–33.—Ortman 1906: 28-29. —W.M. Tattersall 1939:224–225.—Fage 1941: 15– 24.—O.S. Tattersall, 1955: 31–35.—Kathman et al. 1986: 160–161. —Casanova 1996a: 129.—Casanova et al. 1998: 60.—Price et al. 2009: 923–928

Gnathophausia calcarata G.O. Sars, 1885: 35 –38.

Gnathophausia bengalensis Wood-Mason & Alcock, 1891b: 269 .

Gnathophausia doryphora Illig, 1906: 227 –228.

Neognathophausia ingens— Petryashov 1992: 47.

Material examined. In formaldehyde (transferred to ethanol). Stn 28-356-1110, 1 specimen (ZMBN 86613); Stn 28-357-1115, 2 specimens (ZMBN 81294); Stn 36-365-1144, 1 specimen (ZMBN 86559); Stn 44-369-1151, 2 specimens (ZMBN 81295).

In ethanol. Stn 14-340-1052, 1 specimen (ZMBN 86533).

Diagnosis. Body broad. Carapace rigid; rostrum denticulate and as long as carapace in young specimens, short triangular and less denticulate in mature individuals; posterodorsal spine reduced in mature individuals; dorsal keel interrupted in its central region, extending anteriorly onto the rostrum and posteriorly onto the posterodorsal end, raised keel proximal to rostrum reduced with age; upper lateral keels continuous; lower lateral keels continuous, posterior extensions of carapace produced into posterolateral spines, spines are reduced in fully grown individuals; supra-orbital and branchiostegal spines pronounced in young individuals, reduced with age. Antennal scale small, spines on outer margin develop from two to eight with growth. Ventrolateral margins of the abdominal somites produced into two spines. Telson large, linguiform, exceeds uropods, apex extends outwards forming lappets. Largest known species of Lophogastrida , obtains lengths up to 210 mm.

Distribution. In the Mar-Eco collection seven Gnathophausia ingens specimens were identified. Specimens were distributed among stations north of the Azores Islands and also in the vicinity of the Charlie-Gibbs Fracture Zone at 175–1770 m depths.

During the voyage of H.M.S. Challenger only one specimen of G. i n g e n s was captured in the Arafura Sea between New Guinea and Australia at a depth of 1463 m. In addition, two specimens described as G. c a l c a r a t a were caught, one with the aforementioned specimen of G. ingens in the Arafura Sea, and the other in the vicinity of the Talaur Islands, south of Mindanao ( Philippines) at a depth of 915 m (G.O. Sars 1885).

G. ingens has also been recorded from the eastern Pacific, 3991 m off Santa Catalina Islands , at 113 m off central California, and also from the Gulf of Mexico (Ortmann 1906). During the Discovery expedition G. i n g e n s was recorded at many localities, most from the coast of South Africa, and one specimen east of La Plata in the south-west Atlantic. Depth ranges varied from 2580– 2480 m (west of Cape Town), 175– 125 m (Gulf of Guinea), but most between 600 and 1500 m (O.S. Tattersall 1955).

With the discovery of the mid-Atlantic populations in this study, G. ingens must be considered as a true cosmopolitan species, distributed throughout the world’s oceans at depth ranges from 125 to 3991 m.

Remarks. G. ingens was first described by Dohrn (1870) based on a specimen sent to him from the Zoological Museum of Hamburg, which he recognized as a true Schizopod and described it as Lophogaster ingens . Willemoes-Suhm (1873) disagreed on the generic placement within Lophogaster , which he remarked in his manuscript notes under the name Gnathophausia inflate . However, as noted by G.O. Sars (1885), being first described by Dohrn (1870) the species name ingens has priority over inflate

Years after its erection, Ortman (1906) demonstrated that several Gnathophausia specimens, which had been described as new species ( G. calcarata G.O. Sars, 1885 ; G. bengalensis Wood-Mason and Alcock ; 1891; and G. dorypthora Illig 1906 ), were actually representatives of various developmental stages of G. ingens .

Petryashov (1992) proposed that G. gigas and G. ingens be removed from the genus Gnathophausia to form the new genus Neognathophausia . This proposal was later rejected by Casanova at al. (1998) (see “Remarks” for G. gigas ).

Figures

FIGURE 2. Gnathophausia ingens (Dohrn, 1870). A, adult female (lateral view); B, adult female (dorsal view); C, antennal scale and proximal part of flagellum; D, posterior abdominal somites with basal part of uropods (ventral view); E, telson and uropods (from G. O. Sars 1885, Pl. II: figs. 1,2,4,6,7).