Description

“Antennuloniscus subellipticus, new species

 

Diagnosis: Antennuloniscus with anterior border of cephalon with obtusely rounded rostrumlike frontal margin. Peraeon with subparallel lateral margins. Pleotelson evenly rounded, laterally serrated, postero­lateral angles project less than uropods; medial pos­terior margin extends beyond uropods, as a convex lobe. Peraeopod one with seta on inner medial margin of dactylus; peraeopod seven apparently without such a seta. Male with 6, female with 4, and intersex with 5 flagellar articles on first antenna. All seven peraeonal somites separated dorsally. Dorsum of cephalon and of pleotelson with a very marked abrupt change in curvature along lateral margins.

 

Measurements: Holotype male 2.0 mm long; allo­type female 2.1 mm; three paratype females each 2.1 mm; and one intersex 1.4 mm long.

 

Type-locality: Off Cape Horn, Eltanin Sta. 126; start, Lat. 57°12'S, Long. 62°45'W; finish, Lat. 57° 14'S, Long. 62°50'W; July 29, 1962; 3733-3806 m. Holotype male and allotype female (AHF 625) ; 3 paratype females and 1 paratype intersex (paratypes also deposited in the Allan Hancock Foundation).

 

Photographs taken near the type locality show a uniform sandy bottom with ripple marks.

 

Distribution: In addition to the type-locality, other nearby station collections contained A. subellipticus specimens, viz. Eltanin Stations 120, 1 male 2.0 mm long (deposited in the AHF) ; 155, 2 males 2.2 and 2.0 mm and 1 female 2.4 mm long (USNM 113325) ; and 394, 2 females 2.6 and 2.0 mm long (USNM 113326) . All four stations, including the type-locality, are off the tip of South America.

 

Affinities: The new species differs from A. armatus in the shape of the rostrum and the shape of the pos­terior part of the pleotelson. The new species also differs from A. armatus in the shape of the posterior part of the pleotelson (which is similar in other re­spects also) and in the shape of the anterior margin of the cephalon. The regularly rounded convex lateral borders of the whole body set the species apart from other Antennuloniscus species.”

 

(Menzies, Robert, & et al, 1968: 147)